Estimating I Notes

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i

Summary

These notes are a rough guide for the beginning of Estimating, students should
refer to their book for in depth discussion
.


ii

CMGT 343 Estimating Table of Contents

Summary

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i

Table of Contents

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iii

Chapt 1

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5

Why Estimate?

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5

Owners perspective

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5

Contractor’s perspective

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5

Who are estimators?

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5

Estimating Process

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6

Types of Estimates

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7

/ Project Comparison/ Parametric (Conceptual)

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7

Square Foot or SF (Preliminary)

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7

Assembly
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..............................
7

Unit Price/ Item/ Q
uantity survey (Detailed)

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.......
7

The Estimator (1
-
4)

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7

Contract Documents 1
-
7

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8

Plans and Specs

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8

Addenda

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8

Cha
pt 2

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8

Agreement Provisions

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8

Bonds

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8

Insurance

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8

Chapt 3

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8

CSI MASTERFORMAT

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8

General Conditions (3
-
7)

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9

Supplemental Conditions (3
-
8)

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9

Technical Trade sections (3
-
9)
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...
9

Alternates (3
-
10)

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9

Addenda (3
-
11)

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9

Errors in Specs (3
-
12)

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9

Chapt 6

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9

Overhead, Contingencies or Mark ups
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9

Overhead (6
-
1,2,3)

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.............
10

Contingency (6
-
5)

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10

Profit

10

Escalation

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10

Chapt 7

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10

Labor

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10

Union Labor

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11


iii

Non union l
abor (open shop)

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11

State/ Local Public Works

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................................
.
11

Davis Bacon wage
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11

Other Resources

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.............................
11

Equipment

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11

Renta
l Rates

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.......................
11

Contractor owned

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12

Materials

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..
12

Time

12

Money

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13

Subcontracts

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13

Estimating

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13

Parametric Estimating Total Cost Method (TCM)

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13

Procedure for Preliminary/ Parametric Example (Total Cost Method)

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13

Preliminary/ Parametric Example

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13

Square Foot Estimate

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14

Procedure for SF Estimate

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14

SF Example

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15

Unit Price/ item estimate

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16

Unit Pri
ce Data Book Data

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16

Line Item Bid Procedure

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16

Line Item Example

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17

Excavation
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19

Soil Type

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19

Swell & Co
mpaction

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19

Equipment

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19

New Site Grades and Rough Grading

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20

Top Soil Removal

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20

General Excavation

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20

Ba
ckfilling
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21

Asphalt Paving

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21

Concrete

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21

Estimating Procedure

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21

Reinforcing

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22

Vapor Barrier

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22

Expansion Joint fillers
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22

Concrete finishing

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22

Concrete Curing

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23

Forms

23

Wood

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23

Floor Framing

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23

Wall Framing

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24

Ceiling Assembly

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25

Roof Assembly
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25

Thermal and Moisture Protection

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26

Insulation
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26


iv

Roofing

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26

Doors and Windows

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26

Windows

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26

Doors

26

Finishes

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27

Drywall

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27

Flooring

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27

Electrical

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27

Mechanical

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27




5

Chapt 1

Course goal: expose students to the process of estimating and develop
skills need to produce
quantity estimates. This course will not make you a skilled estimator, only OJT in the
construction field can to that. This course will provide a solid background in the tools,
processes, and techniques to apply in the field.

Why E
stimate?

Owners perspective

Need a way to develop budgets and cost proposals. Owners estimates are often done before
design is completed, design may only be about 5% complete, really only conceptual.

Contractor’s perspective

Contractors will “Bid” a proje
ct. Need to understand what it will cost and best method to build a
project. Contractor estimate will be the most accurate. Normally done after design is finalized.

Who are estimators?

Typically people who do the grunt work to win the jobs. Extremely k
nowledgeable about
construction cost and methods. Their knowledge combined with PM’s field and contract smarts
will win
profitable

jobs.

Sample organizations:



6


What are the wages of these individuals?

Occupation

Guess

Industry

Owner


0
-

?

President


$100K +

PM


$60

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Estimating Process

Review overhead

10 factors to consider when deciding to bid:

1.

Type of project

2.

Size of project

3.

Location

4.

Who th
e A/E or Architect is & quality of plans & specs

5.

Who the owner is

6.

Specialized work

7.

Anticipated problems

Owner
Estimator
Worker
Subs
Very Small
Construction Co
Owner/ President/
Board
Very Large
Construction Co
Construction
Executive
PM
PM
PM
Jobs/ Sups/
Engrs
Jobs/ Sups/
Engrs
Jobs/ Sups/
Engrs
STAFF
Subcontract Admin
Estimator
Engineer
Purchasing
Office Manager
Scheduler
Safety
Quality Control

7

8.

Safety considerations

9.

Need for work

10.

Bonding capacity

Types of Estimates

/ Project Comparison/ Parametric (Conceptual)

The roughest estimate. Normally o
nly done to determine a “ball park” price. Cost of new
construction based on past projects. Need to be careful with this approach, must use recent and
similar projects. Used by owners to determine if project is go no go.


Square Foot or SF (Preliminary
)

A little better than preliminary but still typically only used as a guide. Again mostly used by
owners to gain approval of project/ or decide if project is viable. Design is incomplete, maybe
only 20
-
40%. Use published data on SF cost to estimate prop
osed cost of project. Data is
published in means BCCD book.


Assembly

Intermediate estimate. Assembles typical work into groups ie excavating, forming, and pouring
concrete spread footers, find a price by LF. Need to know how project will be built, des
ign may
be 40
-
70% complete. Normally used by engineering and architectural firms when developing
cost of a project. Used by Contractors for repetitive things they do in combination with unit
price estimate. Will not be done in this class, but next term
we will learn how to build
assemblies.


Unit Price/ Item/ Quantity survey (Detailed)

Final and most accurate estimate. Based on completed design and how construction will actually
be performed. This combined with assemblies is how contractors bid project
s. The item
estimate take the most amount of time, it is expensive for contractor to do, yet very important.
This class will focus on this type of estimate. Quantity Survey are typical of Highway jobs.


The Estimator (1
-
4)

Must have…

1.

Read & quantify plan
s

2.

Knowledge of math

3.

Patience

4.

Able to visualize project

5.

Construction experience

6.

Knowledge of labor productivity and operations

7.

Computer guru, excel, data base, specialized commercial software

8.

Work under pressure


8

Contract Documents 1
-
7

Plans and Specs

Projec
ts designed and let for bid or negotiation. Specifications, particularly the “general
conditions” form the rule of how project will be administered. These add cost to a project but a
subject for an entire other class. Need to understand the plans are no
t by themselves, specs also
form the contract and need to be gone over before a project is bid.

Addenda

Modifications to the contract documents
before

bids are received.


Bids must be made based on the contract documents not just the plans


Chapt 2

Agreeme
nt Provisions

Scope of the work

Time to completion

Progress Payments

Retainage

Schedule of values

Bonds

Bid bond
, ensures contractor will enter into contract if bid is accepted.

Performance bond
, guarantees to the owner that the project will be completed i
f contractor
defaults

Payment bond
, guarantees workers and suppliers will get paid


Bonding
rates

based on

experience, total cost of work, past record,
1
-
3%

Insurance

L&I

required by law,
rates based on

incidence rate & type of work, 1
-
30%

General Liabil
ity

use of motor vehicles, third party, in this class use 3%

Chapt 3


CSI MASTERFORMAT

Most widely used method of organizing and coding construction work. You need to memorize
the CSI MASTERFORMAT. All construction documents, estimates, costs, budgets,
bids etc are
organized after the CSI MASTERFORMAT.

Divisions:

1.

General Conditions, the rules of the contract, payments, submittals, etc

2.

Site Work, excavation, backfilling, pavement, landscaping


9

3.

Concrete, footings, slabs, beams, walls, reinforcing

4.

Masonry, C
MU, brick, rock

5.

Metals, fasteners, structural steel, metal studs, stairs

6.

Wood and Plastics, framing, floors, wood decking, fiberglass, countertops

7.


Thermal & Moisture Protection, insulation, roofs, sealant

8.

Doors & Windows, all shapes and sizes, curtain wal
ls

9.

Finishes, Gypsum board, terrazzo, wood floors, carpet, painting, wall papr

10.

Specialties, wall hangings, partitions, bathroom accessories

11.

Equipment, food service, retail, medical

12.

Furnishings, casework, furniture

13.

Special Construction, clean rooms, pre
-
eng
ineered buildings, underground tanks

14.

Conveying Systems, elevators, moving walks, bridge cranes

15.

Mechanical, plumbing, fire systems, HVAC

16.

Electrical, wiring, receptacles, lighting


General Conditions (3
-
7)

Generally how owners does biz, right and responsibi
lities of all parties

Supplemental Conditions (3
-
8)

Specific to this job

Technical Trade sections (3
-
9)

Follow CSI, details that accompany plans, ie paint requirements, steel type, performance
requirements ie work in

20 to 110 degrees F

Alternates (3
-
10)

Typically deductive or additive items because the owner has a tight budget and not sure he can
afford them.

Also gets up front competitive if he adds them later on

Addenda (3
-
11)

Errors in Specs (3
-
12)

How are plans and specs made?

Will have errors or hole
s

RFI = Request For Information = Clarification

Becomes Change Order = Modification when RFI answer involves more time or $

Chapt 6

Overhead, Contingencies or Mark ups

Things added to the final cost of items and subcontractors to include cost that are not

included in
an item by item estimate.



10

Overhead (6
-
1,2,3)

For small contractor may be a small normally 10% to large contractor that calculate a different
OH # for each project.

OH cost normally separated in field and home

Home Office OH

salaries, office
rent, electricity, etc, generally
stated as a percentage

Field or job OH

cost: trailer, super, materials handling, Bonds, telephone, etc,
generally listed
by line item + a percentage.


In this class we will not detail this out in our bids or estimates. Bu
t you need to understand
normally an estimator will make a list of line items of these things and account for them in an
estimate. We will use a straight 10%.

Contingency (6
-
5)

May put this into a bid if rushed to finish estimate or the work is particular
ly difficult ie
rehabilitation work. May add to you bid if you are second low on a number of bids. This value
may be about 1
-
10%.

Profit

How much $ does the company want to make on this project after all cost? Depends on the
market, in tight markets this

number is 3
-
5%, in good times it may go as high as 15%.

Escalation

May put this into the bid if not expected to do the work for awhile, or you are escalating the cost
of due to a particular owner or Architect. Ie brother’s car shop in Bellingham, GC who
doesn’t
really want to but builds custom home (mansion) for client.


Chapt 7

Labor

Very general rule of thumb, labor is about ½ the cost of construction.

Labor rates are published in cost books or required by state, federal or union rules. Labor is very
m
uch a function of supply and demand. In Seattle a skilled carpenters can do very well, in
Klictitat co carpenters make only $10/ hour.


Labor in terms of cost to a contractor is not just $ paid to workers. Contractors must pay what is
called labor burden
. Burden is fringe benefits, mandatory taxes, (FICA, L&I), unemployment
insurance etc.


When using labor rates must make sure you know what is included in the $/hr figure.


Labor productivity is a function of: labor availability, working conditions, clima
tic conditions,
job site set up


11

Union Labor

Mandated rates for contractor that are union shops. Must make sure are estimating with
currently negotiated contract.

Non union labor (open shop)

Contractor will maintain database of labor cost per region, city
they do work in. If haven’t done
work in this city for awhile, may use cost guides to adjust labor cost. Ie Means location codes.

State/ Local Public Works

Mandate a labor rate to be paid in areas of the state. Go over hand out in class. But estimate
n
eeds to reflect cost of obtaining good skilled labor. IE VK Powell in Kickitat county with
carpenters State wage says $10/hr, but his skilled carpenters from Yakima won’t work for that
wage. If you want an efficient job, need to pay more than the “state
” required wage sometimes.

Davis Bacon wage

Federally mandated wage rate, normally based on what unions are paying in metropolitan areas.
As above need to use care in applying to rural settings.


Other Resources

Construction involves combining or managing

5 resources

1.

Labor

2.

Equipment

3.

Materials

4.

Time

5.

Money

Subcontractors may constitute a major portion of 1
-
3

Equipment

Basically two types; contractor owned and rental. Your Means book provides rental rates in the
General Requirements section. When we estimate

work in this class we will use items that
include the cost of the equipment in the crew listings. But if you need to estimate equipment
cost for a specific project, type or phase of work Means is a good place to start.

Rental Rates

Rental rates include
: vendors cost of ownership, OH, & profit.

We will use the means book in this class.

For rental rates go to Division 1, section 016 in Means

Means list “operating cost” less operator ie fuel, etc and “rental cost” If you need an hourly rate
for both operat
ing and rental cost you must calculate it.

Note Means lists “Crew Equipment Cost” which is based on a weekly rental rate.


(Operating cost +rental rate)/ per hour = Crew equipment cost/8


What’s the hourly rate that includes both rental and operation cost
for a “whacky packer” page
19.


12


$31.55/day /8 hr/ day = approx $4/hr


What’s the hourly rate that includes both rental and operation cost for a “Backhoe, ¾ Cy
capacity” page 19.

$218/day/ 8 hr/ day = $27.25


Need to be real careful what cost you quoate f
rom Means or any book, be sure you understand
what they are including.


How do contractor estimate rental costs
?

Get copies of rental rates from vendors they normally use, or in the location of the job site,
this
can change drastically
. Also need to be aw
are of delivery cost. For a small piece of equipment
the contractor may just throw it in the truck, for heavy equipment there may be a $500 charge for
both pick up and delivery.

Contractor owned

Cost continues whether or not the equipment is being used or

not. (reason a lot of contractor
don’t own a lot of equipment)


General rule of thumb is that Contractor ownership cost is about 70% of rental cost.

So for “Whacky packer” above contractor ownership cost is about

(0.&) x ($31.55/day) = approx $22/day


Con
tractors use various methods to establish ownership cost to include in their bids. But this rule
of thumb is what State/ federal and Architect use to establish “fair and reasonable” price during
change orders or force account work.


What is Force Account w
ork? Typical of highway work, when in a changed condition the
contract will specify what rate equipment will be paid at.


Materials

In this class we will use the Means BCCD book for material prices. Real contractor’s use quotes
from local vendors. This
is done over the phone or through price list. Typicall a formal process
is developed so estimators are on mailers form vendors and prices are adjusted accordingly. This
is going to electronic data…but not quite there yet.


Also Sweets Catalog is a collec
tion of Manufactures Catalogs. Contractors use this to find
material that will meet specs & call vendors to get current prices. Sweets has several books and
generally laid out following the CSI MASTERFORMAT.


Need to include the cost of taxes

Time

Topic
of another course, scheduling. Estimates on big jobs are done in conjunction with the
schedule to determine the # of crews, shifts, and method of construction.


13


For this class you need to know time has a value associated with it. As a general rule the
contractor that can complete a project on time or ahead of schedule will make $.

Money

Major resource to contractors. They typically have to fund a certain portion of the work until
they are paid. Generally a contractors is paid for his work by periodic
payments. Example of the
ships building when $1M invoice got delayed.


In this class we will assume $ is available to finance the start and finish of all projects.

Subcontracts

How most of the work gets done nowadays. Some consider the subcontractors as
resources that
need to be managed. In this class we may get prices from subs to perform a portion of the work.

Estimating

Parametric Estimating Total Cost Method (TCM)

Method to estimate cost of similar construction. Used a rough guide for preliminary, f
easibility
or check on detailed estimate. Most contractors will contain data bases that contain this type of
information.

Uses a TCM to adjust cost based on complexity or project

TCM= SF
0.9

buildings

TCM= SF
0.6

complex projects, hospitals, plants

Where SF

= Size Factor = Proposed size/comparison size

Procedure for Preliminary/ Parametric Example (Total Cost Method)

1.

Find similar projects to the one you are estimating, establish $/SF cost

2.

Set up an organized table to work from

3.

Find
S
ize
F
actor, SF= Proposed
Size/ Comparison size

4.

Find Total Cost Multiplier, TCM= SF
0.9

buildings, TCM= SF
0.6

complex projects

5.

Find Adjusted Unit Cost by multiplying TCM x comparison unit cost.

6.

Find Projected Total Cost by multiplying Adjusted Unit Cost by project SF.

7.

Round to an ap
propriate value. Never use cents in final answer. For preliminary estimates
round to nearest $100 or $1000.

8.

Ask your self does this value make sense?








Preliminary/ Parametric Example

Given: 4000 SqF small office building, and want preliminary cost


14

K
nown: 5500 SqF office building @ $675K, 2000 SqF office building @ $215K



Example # 1

Example # 2

Total Area SF

5500

2000

Total Cost

$475K

$215K

Unit Cost $/SF

$675K/5500= $122.73/SF

$215K/2000= $107.50/SF

Size factor

4000/5500= 0.73

4000/2000= 2

Cos
t Multiplier

0.73
0.9
= 0.75

2.0
0.9
= 1.87

Adjusted Unit Cost

$122.73 x 0.75= $92.1/SF

$107.5 x 1.87= $200.6/SF

Projected Total Cost

$92.1 x 4000= $368K

$200.6 x 4000= $802K


Cost Multiplier

TCM= SF
0.9

for buildings


Rounded to nearest $1000, notice range
$368K to $802K. Need to be very careful with these
types of estimates, should use higher value when giving to client or management. Why? If
project gets approved at higher cost and actually cost less can add things. If a project gets
approved at lower c
ost and actually comes in higher, project may get killed, or will cause plenty
of “illwill”.


Square Foot Estimate

Similar to preliminary and only a little more accurate. This method uses published data, e.g.
Means Square Foot Cost

and your book BCCD has
a section in the back with SF cost. This is
used much more often in industry by A/E firms to get an early estimate of a projects cost. Must
be very careful when using this method because it’s not very accurate. Joe Robbie stadium in
Miami, owners or A &

E firms tried to use this as a bench mark SF cost guide. What they didn’t
know was the owner ran low on money at the end, and lot of “extras” were cut from the project
like paving the parking lots, finishes were left “rough”, etc. When A/E firms used th
is as a SF
guide the value was mistakenly low.


SF cost are also useful as a rough guide for estimators bidding projects. If bid has a SF cost that
is out of line something may be wrong.

Procedure for SF Estimate

1.

Determine the type, SF, # stories, and per
imeter of proposed building.

2.

Determine the general type of construction, i.e. steel frame, exterior cladding, and generally
if proposed building is economy, average or luxury.

3.

Look up SF cost from Means and multiply proposed building SF times look up value
.

4.

Preferable to use SF cost book but in this class we will use Division 17 in your book for SF
cost, remember these are average prices.

5.

Use ¼, median, ¾, e.g. ¼ means 25% had lower cost the this value, ¾ means 75% had lower
cost than this value. Use “judg
ement” to choose correct percentage.

6.

Find your SF cost then multiply by the city code.

7.

Then multiply it by the size code. Get credit for size factor.



15

SF Example

Want to build a 128,000 SF Fred Myer in Ellensburg, What is an estimated cost based on SF?
C
ity of Ellensburg has many histrotical requirements & site work with moving a stream.

Only information we have is a department store @ 128,000 SF


Got to table in BCCD page 473 find total cost of ¾ based on stringent requirements of city of
Ellensburg of $
63.80/ SF. What if Bi
-
Mart was coming to current location?


Cost = 128,000 x $63.80/ SF = $8,166,400


City code, or Location factor, page 650 use Yakima

$7,942,400 x 102.2 = $8,346,100 rounded to nearest $100


Size factor page 574 (explain why you wouldn
’t use retail store)

Proposed / typical size from chart

128,000/90,000 = 1.42 SHOW OH


Enter area conversion scale on chart on pg 574

Find cost multiplier of .97


$8,346,100 x 0.97 = $8,096,000 rounded to nearest $1000


A/E may use this value as a prel
iminary figure. Bidder may use this to check unit price bid, e.g.
what if bid estimate came in around $5M?

SF Example






Fred Myer






SF

BCCD
$/SF pg
473

Cost




128,000

63.8

8166400










Location Factor



cost



BCCD pg 650
Yakima

1.022

816
6400

8346061









Size Factor
128000/90000

1.42


Final Cost rounded to
$1000

Cost multiplyer
from page 574

0.97

8346061

8096000




16

Unit Price/ item estimate

Construction Estimate deals with 5 or 6 resources, need to account for:

1.

Labor, trades and
OH types

2.

Equipment, bulldozers, cranes, rentals

3.

Materials, bricks and mortar

4.

Time, how long something takes and scheduling

5.

Money, how much the contractor has to finance, mark ups

6.

Subcontractors

In this class we will use Means for costing data to develop un
it price estimates. Very few
contractors use Means, except for a check or starting point. They use their own “means”
developed over the years of contracting. So what we use is similar but not the same as each
contractor will have developed.


Unit Price
Data Book Data

How we will do our estimates, by using the Means BCCD book.

Labor, Equipment, & Materials are combined to form the estimate. OH is included in these line
items or added at the end. In this class we will develop estimates with “
bare cost
” th
en add our
own mark ups.

Estimate is set up with a hierarchy:



Phase (one of the 16 divisions)



Task, work that requires resources of material, time, equipment, material to complete e.g.
build concrete retaining wall (excavate, form, pour concrete, finish) o
r lay pipe (excavate,
place bedding stone, place pipe, backfill)



Line item, the smallest individual unit of work listed in BCCD. E.g. excavate, form, pour
concrete, finish are all line items.


Line Item Bid Procedure

This is a process I want you to follow,

most companies do something similar, mostly what is
different is amounts of mark ups and where or when they are applied in the estimate. Try to keep
it simple.

1.

Determine unit quantities from plans and specs. Try and do the same procedure every time,
ie
go left to right or clockwise on drawings. Estimate as the job gets built, ie excavation,
footers, floors, etc

2.

Apply means BCCD to find bare cost for Materials, labor and equipment.

3.

Apply mark ups to bare cost:



Materials 8%



Labor Mark up 25
-
50 %, based on

crew Type and inside back cover of BCCD. Only apply
Column B & C. For example 022
-
286
-
0010 uses crew B
-
10B, mostly equipment operator
(med), from inside back cover Column B=
11.4
% then mark up = 11.4+16.5 or about 28%



Equipment mark up 10%

4.

Combine Materi
als + Labor + Equipment to obtain subtotal

5.

Add mark ups:


17



B & O Tax use 0.5% this is mandated by state and is based on volume and type of work
contractor is classified as



Insurance, use 1.5% percent we’ll use this as liability and builders risk, rates based

on
industry and developed track record



Bond use 2%, normally these are prorated by value ie 0
-
$1M is 2% , $1
-
10M is 1.5%



Overhead is 1
-
10% depends on how much you account for in general conditions



Profit 2
-
10%, based on size, complexity, need, etc

Line It
em Example

Example from page 180
Framing, Sills Treated Lumber

Show a line item for framing using 2” x 4” treated lumber, 06110
-
560
-
4600

See “UNIT” in means is in MBF or 1000 Board Feet, also known as mfbm or 1000 feet of board
measure:

BF=(WxTxL)/12, W =
with, T=Thickness, L=Length

How many MBF in 800 studs?, where stud is 2”x4” by 8’

MBF = ((2”x4”x 8’)/12)x800studs/1000BF/MBF = 4.27MBF

Typically dealing with wood you include a waste factor, depends on project, amount and type of
framing, ie small project
not a lot of cuts 2
-
3%, large custom built houses framing project 5
-
10%.


If your project required 850BF of treated 2”x4” lumber for sills the material would cost:

BCCD ref 06110
-
560
-
4600 page 180

($
985
/1000BF) 850 = $837.25 remember this is bare must add
mark ups, O & P


Labor to frame is similar, Wood framing Studs, 8’ wall, manual nailing say 2MBF

2” x 4”, your labor cost would be: pg 181 BCCD ref 0611
-
560
-
6020


($
850
/MBF) x (2MBF) = $1700 remember this is bare must add mark ups, O & P


Backyard Basketba
ll Court, just form, WWF & Crete

Form with 2”x6”x10’ boards

SOG 20’ x 20’, 400ft
2
, 80LF, (400SF)x(51/2”x1’/12”)/27CY/CF=6.79CY

Plus 10% waste, use 71/2 CY crete


18


SOG 20' x 20' basket ball court









Form, WWF, crete










Perimeter is
80LF

80










SF is
400SF

400










CY of crete
is 7.5CY

7.5






















Item

pg

BCCD ref

MTL

Lab
or

Equi
p

unit
me
asu
re

unit

$mtl

$lab

$equip

total

Form

96

03110
-
445
-
3000

0.32

1.42

0

80

LF

26

114

0


WWF

107

03220
-
200
-
0200

10.55

16.2
5

0

4

C
SF

42

65

0


Crete

110

03310
-
240
-
4700

74

26.5

0.41

7.5

CY

555

199

3










623

377

3








8%
mtl

0.08

50









C
-
14e
use
11.5+16.5
28%

0.36


135.85








Equip
10%

0.1



0










673

513

3

1189










B&O

0.005

6










Insura
nce

0.01
5

17










Bond

0.02

23










OH

0.05

59










Profit

0.1

118











total

1415











Bid

1415



19

Excavation

The first work typically done on a construction project. Need to determine amount of soil to be
excavated , cut or filled, ba
ck filled, compacted etc.

You will learn to calculate excavation quanitites from topographic maps, excavation
requirements for footings, slabs, and parking lots. Also we’ll learn how to calculate asphalt
paving requirements.


Soil Type

1
st

thing an estima
tor will consider. Type of soil impacts cost of excavation, fill or disposal. For
example, most specs say to remove excess material from the site. If this material is clean topsoil,
the topsoil may be sold or at least delivered for free, but if material

is unsuitable for topsoil
contractor may have to pay to have this material deposited somewhere.


Example, building Child Care Center, had a change order to increase the size of the parking lot.
This requires excavating more soil than in original contract
. But also had a ball field project that
needed fill material. I had the Child Care Center contractor deliver the soil to the ball field and
got a credit from the ball field builder.

Swell & Compaction

Soil expands when it is dug up, called swell, or % g
ained above original volume. When soil is
delivered to the site and compacted this is called shrinkage, % of volume loss.


Percentage of Swell and Shrinkage

Material

Swell Percentage

Shrinkage Percentage

Sand and Loam

10
-
18%

95
-
100%

Loam

15
-
25%

90
-
100%

Dense clay

20
-
30%

90
-
100%

Solid Rock

40
-
60%

85%


Example

Gravel sub
-
base for concrete slab. 100’ x 100’ x 6”, How many CY do you order from the pit?
Assume shrinkage of 95%

Required CY=(100’ x 100’ x 6”/12’)/12ft
3
/CY = 185.2 CY

CY with allowance for

shrinkage = 185.2CY/0.95 = 195CY


Equipment

Should know generally what equipment is used for what jobs. Selection is of prime importance,
based on economics, ie backhoe or large excavator, backhoe is cheaper but less efficient, large
excavator very produ
ctive but very expensive.

Shovel, all excavations require some hand work, but always kept to a minimum.

Front End Loaded, wheel or track, used in pits, large excavations, can load trucks directly.

Bulldozer, shallow excavations, clear and grub, roads, leve
ling.


20

Backhoe, mainstay of smaller construction because is so versatile, basements, trenches, pier
footings etc.

Scrapper, mostly just for roads or very large sites, can cut, transport and fill soil.

Grader, just for leveling.

Excavator, digs large holes,
attachments for breaking and moving rock.

Small “landscaping” ie bobcats use in tight locations, residential.

New Site Grades and Rough Grading

From site plans can get topographic information to calculate the amount of cut or fill required at
a site. Cutt
ing is removing soil, fill is bring soil to the site to raise it to the requires level.

GO OVER EXAMPLE FROM SITE WORK HANDOUT

CLASS ASSIGNMENT SIMILAR TO EXAMPLE.


Top Soil Removal

Specs normally require top soil be spread over any areas that were disturb
ed. Top soil depth
varies from almost nothing to many feet. Specs will say to what depth to save topsoil. If there
isn’t enough soil, may be required to buy topsoil. Typically this topsoil is striped off and saved
on site.

General Excavation

Handout co
pies of pages 107
-
117

Normally need to dig for footings, basements, parking lots etc. For footings need to account for
space for the workers to form up footers. Normally this distance is 1
-
2’. Deep excavations need
to be sloped to prevent cave in, this
slope is determined from the “angle of repose”. If not sloped
must use sheet piling, in trenches must use cave in protection devices.









Material

Angle of Repose

Wet

Moist

Dry

Gravel

15
-
25

20
-
30

24
-
40

Clay

15
-
25

25
-
40

40
-
60

Sand

20
-
35

35
-
50

25
-
40


Depth of cut = Top of the grade


bottom of fill under slab or footing. If top soil has been
removed then deduct this from depth of cut.


To determine amount of excavation, need to find:

1.

Building footprint

2.

Distance footing projects from wall

3.

Working
space required between footing and soil (normally 2’)

Angle of Repose

Excavation

Soil


21

4.

Elevation of existing land

5.

Type of soil, found from boring samples.

6.

Whether excavation is sloped or sheet piled.

7.

Required depth of excavation, found by subtracting bottom of excavation elevation from si
te
elevation.


Show average length of cut as shown on page 109


Go thru example on page 110.

Backfilling

Need to replace soil back against the footing. Best method is to calculate area of back fill
required and multiply be LF of footer to find CY. Will
also need to spread topsoil to get to finish
grade. Specs normally require at the very least reseeding and normally will require landscaping (
almost always subcontracted out.


Asphalt Paving

Typically has four layers

Compacted subgrade (compacted the exi
sting material)

Subbase course (normally 6” of gravel or crushed rock)

Binding Course (asphalt normally about 2”)

Wearing course (asphalt normally about 1”)


Asphalt paving is almost always subcontracted due to specialized equipment required.

Will want to

plan you project normally put the binding course down early, to get the site out of
the mud, then wearing course is done last to look good.

Concrete

Handout copies of pages 126
-
129

One of the most versatile construction materials. Easy to work with, very

strong, and made into
almost any shape. Mostly use for foundations, slabs, beams and columns, but can be used as an
architectural feature, ie Psychology building.


Concrete is made form Cement, water and aggregates(sand and rocks) Too much water makes
weak concrete. Can be specified to various strength levels, typically get 3000psi concrete from
the batch plant (this is called ready mix). But with certain admixes can get concrete over 10ksi.
Always sold by the CY, includes delivery, may be additional

fees for short loads ie less than
4CY, or on Saturdays. Concrete take time to cure, normally about 3 days, wait at least a couple
of days before putting materials on it.


Estimating Procedure

1.

Review the specs for: Type, strength, color of concrete require
d.

2.

List each concrete item required on the project.


22

3.

Determine the quantities from the drawings, footings can be found on the profile views of
wall sections.


Go thru example on page 126 & 127, show how to build spread sheet like one on page 132.


Explain:
Footings, simple spread footing. Formed piers, foundation walls, grade beams, SOG,
roof slabs.

Reinforcing

Handout pages 138
-
142

Reinforcing bars, or rebar or deformed bars, what gives concrete it’s tensile strength. Rebar is
sized by #’s, #’s represent t
he # of 1/8
th

of an inch it’s diametr is eg #3 rebar ahs a bar diameter
of 3/8”. Rebar is estimated by the LF but bought by $/100 pounds or $cwt. Specs may require
special costing, ie zinc/ galvanized or painted, this thyoe of rebar is much more expensiv
e and
must be special ordered. Need to allow for splicing & waste, see splicing lengths on page 140.
Normally rebar is mostly fabricated in the shop and sent to the site, less waste and easier to work
on in the shop. Also rebar needs to be specially pla
ced in the concrete, to ensure it provide the
proper tensile strength and coverage. Use “chairs” or blocks to raise rebar.


WWF or Welded Wire Fabric, used mostly in slabs but also as “temperature” steel in columns
and beams. This mesh is specified as 6x
6 10/10 which means the wire spacing is 6” x 6” and it
uses #10 gage wire. WWF is sold by the roll, (roll = 750 SF), unless very small quantity is
required. Therefore when estimated need to determine how many rols to buy.


Show example pages 141
-
142, go
thru continuous footing long and short bars, Vertical & Hz
wall bars, and dowels (error, should read 2’ dowels)


Do example of wire mesh reinforcing, page 146, find # of rolls.

Vapor Barrier

Polyethylene is laid down under concrete to prevent moisture from

coming up through the slab.
This is division 7 stuff but normally estimated with the concrete work.

Expansion Joint fillers

Made from ashpaltic materials, or sponge rubber, as required by the specs. Almost always
between a slab and a vertical surface.
Estimates by the LF and come in sizes ranging from ¼” to
8 “.


Concrete finishing

Depends on the finish required, but all exposed concrete will require some finish if even to just
knock off the rough spots.

Specs will define:

Troweling, SOG, walks, stairs
can be mechanical or by hand

Float, SOG, walks, stairs

Broom, mostly for walks & stairs


23

Sandblasting, exposes the aggregates, decorative walls, looks like pebbles on exterior

Rubbed, with burlap & grout, creates a rough finish that looks like rough plaster

used on
decorative walls


Concrete Curing

Concrete gets it’s strength from the chemical reaction of water and cement, curing may be
specified as 3
-
14 days depending on type and location.

May need additional moisture to keep from cracking.

Must be kept fro
m freezing, by heating or insulation blankets. Some contracts may limit
concrete placement to certain temperature requirements.

If special heating or moisture requirements are needed the estimator must account for them.

Forms

Most concrete is poured in fo
rms, sometimes can save $ by pouring “neat” eg use footers without
forms, to save on forming material and time, but this method normally take more CY of
concrete.

Forms are estimated by SFCA, Square Feet of Contact Area. Calculate by LF x depth of form.

F
orms are made from :

Wood, most versatile, needs to account for bracing, ties, wales etc, can get many uses out of
wood forms if properly taken care of ( spray with oil and carefully taken off).

Metal, mostly steel, normally lined with something. Normally

used in larger construction
projects, ie pans like roof in Hogue tech. Also used in residential construction I seen metal one
for basements that leave a wall that looks like brick.

Wood

Actual dimensions are less than advertised due to milling process. E.
g. 2”x4” (called nominal
size) measure 1
-
1/2” x 3
-
1/2”.

Lumber typically sold by mfbm (1000 Feet of Board Measure)or 1000board feet & estimating
productivity tables use mfbm or cfbm (100fbm). Board feet is calculated using nominal board
size.

Floor Framin
g

Handout pages 207
-
238

Show overhead of picture on page 207

Girder normally built up from smaller lumber eg 2

2x12’s, or from manufactured beams made
from laminated wood, I beams, composite wood. Estimated by simple measurement.


Sill, normally specs ca
ll for treated lumber, estimated by finding the perimeter of building.


Joist, normally 2x8, 10, or 12 spread 16”OC. Estimating steps are:

1.

From foundation & wall section find the size of floor joist.

2.

Find # of joist = # of spaces + 1. Eg 50’ long sill 16”

OC 50’/16”/12”/1’=38spaces(round
up) + 1= 39 Joist.

3.

Multiply be # of bays

4.

Add one extra joist for each partition that runs parallel to joist.


24

5.

Find board feet = # joist x joist size


Go thru example on page 210 & 211


Trimmers & Headers, special framing u
sed for fireplaces, access doors, any holes thru floor.
Trimmers run with the direction of the joist, headers run perpendicular to the joist.

Estimated by:

1.

Sketch floor joist with out openings

2.

Sketch opening on joist

3.

Use available cuttings from hole & det
ermine boards required. Double trimmers will be the
length of a joist & required for hoes >4’.


Joist header, show picture on page 211 & 216, estimated by LF of headers along perimeter.


Bridging, metal or wood cross racing. Metal is fastest to install,
required every 8’. Wood is
same size of joist, normally one bridging per bay.


Decking/ Subflooring, normally plywood, press board or waferboard.

Sheet of plywood = SF coverage/ SF sheet +waste

Show figure page 218, mention nailing schedule (won’t have
2’ lengths when joist are 16”OC).

Wall Framing

Exterior Walls

Most common residential is single bottom with double top plate combined with 8’ studs to
produce 8’ ceiling (gyp board comes in 8’), see figure on page 220.

Estimates Plates in mfbm= find perime
ter LF x # of plates


Studs, typically 2x4, spaced 16” OC, may see 2x6 walls spaced 24” OC (why? Extra insulation)



Estimating Exterior Studs:

1.

Studs = LF perimeter/ spacing + 1 for last space

2.

Add studs for each corner 2 per corner, see figure page 222

3.

Add

studs for framing wall openings, each window or opening will require at least 2 studs.

4.

Studs also required for gable ends of buildings,






studs =
(gable length/ spacing +1) x Average gable height. Average gable height is 2/3 height of
roof.


Heade
rs, used to support the weight of the building above openings. Made from large lumber
4x10 or built up form 2x 10’s.

Header length is opening with + 2(1.5), rest on 2x4’s

Estimate headers by listing openings and adding up length, convert to mbfm


Wall she
athing, what goes on the exterior of buildings, normally two layers.

1.

Urethane insulation, or TYVEX type material

2.

Covering, wood (planks, T
-
111), AL, brick etc


25

Estimated by finding total SF required/ SF sheet (or material) If account for openings add waste
or don’t account for openings. Also include sheathing for gable ends (area of 2 triangles) Need
to check specs for sloped soffit (9’) or boxed soffit (8’), see figures on page 228 & 229.


Interior stud walls are estimated just like exterior but need to re
ad the specs, may only be 24”
OC, extra thick to hide chases.

Ceiling Assembly

Made from joist or trusses, depends on cost & if space will be sued as an attic space.

Ceiling joist estimated same as floor:

1.

Size and spacing determined

2.

# of joist = length/ sp
acing + 1

3.

Multiply # of joist by joist length, account for bridging and openings.

Roof Assembly

Rafters the hypotnuse of the triangle, need to account for the overhang. Normally spread 16” or
24” OC, made from 2x8,10,12’s.







Rafter length = (12
2
+3
2
)
1/2

+1.5 = 10.87’ or 10’10”
-
3/8”

Estimate rafters, Quantity of rafters should equal joist quantity, then multiply by length.


Collar ties boards to keep the rafters from separating, typically required every 3 rafters, 1/3 of the
way down from the ridge,
size is normally 2”x4”.

Length is determined from similar triangles.









3/24=1/x, x = 24/3 = 6’

Estimate collar ties = (rafters/3 +1) x length


Ridge board see figure page 236, normally 2x10 or 12, one size larger than the rafter, estimate is
just
LF of ridge


Lookouts, needed to frame soffit (note soffit not specified on “cheap” homes) see figure on page
236

Estimate, # of lookouts = LF of each side wall/spacing +1), then multiply by, length of lookout.

24’
=
3’
=
1.5’
=
24’
=
3’
=
2’


26


Roof sheathing material, mostly exterior ply
wood plywood

Estimate Total SF/ SF sheet, note, must use rafter length.


Exterior Trim and Facias, many types, estimated by finding LF required.

Thermal and Moisture Protection

Handout pages 253
-
256

Insulation

Put in ceiling, walls and under floors to prov
ide thermal protection. Rated in R value, higher the
R the more insulation value of material. Home typically use rolls made to fit between the joist ie
joist 16” OC will have 15” wide insulation, called “batt insulation”. Above ceiling may be
blown, fib
erglass.

Estimating, find SF of area to be covered/ SF roll of insulation, be sure to use “effective
coverage of roll. I.e.:

Rolls = 1000SF/16”x56’(effective size of 15“ batt) = 14 rolls

Do not account for openings or allow 5% waste.

Roofing

Roofs are esti
mated by the “square” = 100ft
2
.

Asphalt Shingles are the most common for homes. Common sizes are strip shingles, 12 or 15”
wide by 36 “ long. The exposed portion of a shingle is only about 4
-
5”. They are made in many
colors, textures and thickness, with

a “30 year shingle” better than most. Shingles are nailed to
the plywood sheathing with large head galvanized nails. They have an underlayment of felt or
“tar paper” normally 2 layers overlapped.

Estimating, need to double singles at eaves, hips and rid
ges are taken off as LF & considered 1ft
wide.

Shingles, Squares = area of roof (in 100SF)+ eaves(in 100 SF)

Ridge = LF of ridge/ inches of exposure per shingle = # shingles

Felt = Find roll coverage, (Width
-
lap)x (SF of roll) then SF of roof/ roll covera
ge. Round up # of
rolls to a whole #.

Doors and Windows

For residential almost always wood framed and are stock ordered.

Windows

Estimated by developing a window schedule (table) or schedule is provided in specs.

If subcontractor need to make sure all hard
ware is accounted for and who installs the windows.
Estimate # of windows and calculate installation time.

Doors

Generally indoor (hollow) and exterior (solid). Residential door are almost always “pre hung” &
specs need to be reviewed carefully because p
rice varies considerably depending on veneer
finish. Home typically have sliding glass doors or “French doors”. As with windows, door
typically have a schedule that the type and #.


27


Finishes

All types drywall (sheet rock), plaster and lath, etc

Drywal
l

Or Gypsum board or sheet rock. Normally 4’ wide, by 8’,9’,10 or 12’ long. Thickness is
normally ½” or 5/8”. Comes in various types, “green board” for use in bathrooms, fire rated and
normal. Gyp board must be hung on studs or furred out from concret
e/ block walls. It needs to
be finished, e.g. taped, mud applied (joint compound), smoothed, and painted or wall paper
applied. Must account for fasteners, screws or nails and trim to hide edges.

Estimated by:

1.

Determine # of sheets required, LF/4’ +5% wa
ste



Flooring

Home use mostly tile, wood, vinyl/ linoleum and carpeting.

Resilient, or vinyl/ linoleum.

Typically have underlayment of “luan” or particle board, need this to provide smooth surface.
An adhesive is used to hold tile/ linoleum to floor. Es
timated by the SF with consideration for
waste.

Carpeting.

Comes in many sizes, colors and degrees of “quality”, e.g. thickness, pile fibers and weight.
Carpet has an underlayment or cushion, sort of egg crate material made from rubber/ recycled
materia
ls, this material also comes in varying grades of quality. Carpeting is estimated by the
SF.

Tile

Used on floors and walls. E.g. home entry way tile set in grout or color mortar. Also used to see
this a lot in bathrooms, on floors and walls. Premounted

on sheets is quickest to install. Tile is
estimated by the SF.

Painting

Normally estimated in area of actual SF. Interior and exterior. Specs will list coatings, color,
and method i.e. spray or roller. Sequenced to be done after drywall before trim is

applied.

Electrical

Almost always subcontracted out. Not always let to the lowest bidder. Can get SF cost based on
type of construction to check subs bids. Electrical estimating requires each outlet and fixture be
taken off and listed, also include qua
ntities of wire in estimate.

Mechanical

Almost always subcontracted out. . Not always let to the lowest bidder.

Plumbing is done similar to electrical, estimate all fixtures, lines, vents, etc.

HVAC for residential construction is normally a heat pump, g
as / oil furnace that blow hot air or
heats water pipes.