Section 3.3 Estimating

7/31/2019 Section 3.3 Estimating

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3.2 ESTIMATING

Calculating Block, Concrete & RebarThe following pages contain information on estimating block, concrete and rebar. An

example plan with calculations can be found at the end of this section.

Block Estimation -- calculate types and sizes needed:

8 inch concrete core (xed web)qStandards

q90 corners

q45 corners

qTop/Taper

qEnds

qSpacers

6 inch concrete core (xed web)qStandards

q90 corners

q45 corners

qTop/Taper

qEnds

qSpacers

4, 6, 8, 10, 12 inch core (2-4-2 and Gblox panels)qPanels

qWebs

q90 cornersq45 corners

Additional block may be needed if your plans call forqGables

qPilasters

qButtress walls

qInterior walls

qStep footers

qNumerous T-walls


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Estimating 6 and 8 inch Core Fixed-Web BlockLn Objective/Outcome Operation

Line

ReferenceCalculations

1* Perimeter ADD all sides

1a* Find Wall Height SEE PLANS

2 Buildings wall sq ft MULTIPLY Perimeter by Height Ln 1 x 1a

3 Gross Blocks DIVIDE Bldg wall sq ft by 4.0 Ln 2 4.0

4 Square Footage of OpeningsCheck plans and/or Window /

door schedule

5

Total Square Footage of all

Openings

ADD windows & doors sq ft to

obtain total sq ft Line 4

6 Openings - Block reductionDIVIDE Total Openings

sq ft by 4.0Ln 5 4.0

7 Net BlocksSUBTRACT Openings from

Gross BlocksLn 3 - Ln 6

8 Number of 90 Corners See plans

8a Height of 90 Corners in ft See plans



10Total Number of 90 Corner

Blocks

MULTIPLY 90 Blocks per

Corner by Number of CornersLn 8 x Ln 8a

10aTotal Number of 45

Corner Blocks



11Number of

Standard Blocks

SUBTRACT Corner Blocks

From Net blocks

Ln 7- (Lns

10+10a)

12Total Number of

Top Blocks

DIVIDE Perimeter by 4.0 Minus

Number of Corners

(Ln 1 4.0) -

(Lns 8 + 9)

13Total Number of

Standard Blocks

SUBTRACT Top Blocks From

Standard BlocksLn 11 - Ln 12

14Account for 3-4% waste

For 90 Corner Blocks

MULTIPLY Total 90 Corner

Blocks by 1.04 **Ln 10 x 1.04** Total 90 Corners:

14a Account for 3-4% wasteFor 45 Corner Blocks

MULTIPLY Total 45Corner Blocks by 1.04* *

Ln 10a x 1.04** Total 45 Corners:


For Top Blocks

MULTIPLY Total

Top Blocks by 1.04Ln 12 x 1.04 Total Taper/Tops:


For Standard Blocks

MULTIPLY Total

Standard Blocks by 1.04Ln 13 x 1.04 Total Standards:

* In the case where your walls have different heights, you will need to do a separate estimating sheet

for each section of a different height and add all estimates to calculate your total block needed.

** Round total number of corners up to an even number (corners are packaged and shipped in pairs.

You should receive your corners in bundles packed lefts and rights. If not, please contact your

local Greenblock representative.

NOTE: All block will be rounded up to pallet counts/sizes. Check with shipping for counts.

3.2 ESTIMATING


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Estimating short cut:

Calculate total wall sq footage (L x W x H minus square footage of windows and1.

doors)

Divide by 4 for total block count2.

Count 90 degree corners on layout3.

Multiply number of corners times height (equals total 90 degree corners needed)4.Repeat step 3 and 4 for 45 degree corners (equals total 45 degree corners5.

needed)

Subtract corners from total block count6.

Divide total linear footage of layout by 4 to get subtotal top/taper blocks needed7.

Subtract number of corners in linear layout from top/taper blocks needed8.

Calculate total standards by subtracting from total block needed (ln 2), the 90s (ln9.

4), 45s (ln5), and the top/taper blocks (ln 8)

Add 3-4 % to the standards for waste10.

Estimating Panels

A. Use the estimating sheet found at the end of this section to calculate the required

quantities of each type of block required to complete your job.

B. Multiply the total from line 16 (Total Standards) by 2 to determine required panels.

C. Multiply the total from line 16 (Total Standards) by 8 to determine required webs.

- Webs are available in 4, 6, 8, 10 or 12 inch core sizes.

D. Estimating corner block for the panel systems.

-The4inchpanelsystemutilizescornersspecictothatsize.

-The6and8inchpanelsystemutilizecornersfromthexed6and8inch

systems.

- Persons using the 10 & 12 inch panel system will need to miter the corners.

E. Estimating taper/top block for the panel systems.

- Not available in the 4, 10 or 12

-The6and8inchpanelsystemsutilizetapers/topsfromthexed6and

8 inch systems.

Reminder: All block will be rounded up to pallet counts/sizes. Check with shipping

for counts.

3.2 ESTIMATING


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Concrete EstimationUse this basic chart for concrete calculations. Please be sure to follow the steps.Use the following for Line 6: (4 core - 81, 6 core - 54, 8 core - 40, 10 core -32, 12 core 27)

Ln Objective/Outcome Operation Ln Ref Calculations

1 Perimeter ADD all sides

2 Gross Wall sq ftMULTIPLY Perimeter by

Wall Height

3 Openings sq ft

ADD each window and

door sq ft to obtain total

sq ft

4 Net Wall sq ftSUBTRACT Openings sq

ft from Gross Wall sq ftLn 2 - Ln 3

5Corner Adjustment

(Final Wall Net Sq ft)

Add corner blocks*

and Subtract 1 sq ft per

corner block from Net

sq. ft.

Ln 4 - ?

6Yards of Concrete

Needed

DIVIDE Final Wall Net sq

ft by ?? sq ftLn 5 ??

An easy way to determine how many corner blocks you have is to count howmany corners there are and multiply that amount by the wall height. If you

have variations in wall heights do each wall height as a separate section.

Rule of thumb concrete estimating method:4 core - 1 yard of concrete per 81 Wall sq. ft.

(multiply L X H of wall and divide by 81)6 core - 1 yard of concrete per 54 Wall sq. ft.8 core - 1 yard of concrete per 40 Wall sq. ft.10 core - 1 yard of concrete per 32 Wall sq. ft.12 core - 1 yard of concrete per 27 Wall sq. ft.

3.2 ESTIMATING


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Alternate Rule of thumb:4 core - 1 yard of concrete for every 20 forms installed6 core - 1 yard of concrete for every 13 forms installed8 core - 1 yard of concrete for every 10 forms installed10 core - 1 yard of concrete for every 8 forms installed12 core - 1 yard of concrete for every 6 forms installed

Calculate amounts of concrete needed by using the Final Wall Net Square Footage(Line 6).

We recommend you double check your gures for concrete amount needed orhave your supplier do so

NOTE: Check with your local supplier for aggregate and any slump/trucking requirements.

Greenblock recommends:

Minimum 2500 PSI4.5 - 6.5 slump deliveredPea gravel ( aggregate) for: 4 and 6 cores

NOTE: Larger rebar size and/or volume may require smaller aggregatefor proper concrete placement and consolidation

3.2 ESTIMATING


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Rebar Estimation

Rebar reinforcement within concrete walls reduces cracking and buckling underdifferent building loads (i.e. backll, wind, etc) and helps manage crackingcaused by temperature swings. Properly installed reinforcement around doorsand windows is imperative for the buildings structural soundness.

Footing/slab dowels are often spaced every 24 inches, with a minimum of2 horizontal rows in the footing or thickened slab. You will need to estimatethe necessary rebar for required steel placement determined by codes orengineering.*

Horizontal wall rebar should be inserted as required during placement of theblock in each course. Make certain you lay it with the correct overlap lengths,normally 40 times the bar diameter. As each course with horizontal rebar is laid,if possible offset it to the previous course. Continue alternating the rebar thisway for the entire structure.*

Lintel steel needs to be positioned above doors and windows to support theload over these openings. Lintel rebar depends on many factors and should becalculated by an engineer or taken from PCAS Prescription Method; or to localcodes.*

Vertical rebar should be installed only after all courses and horizontal rebarhave been laid. Dont forget to put vertical rebar under the windows andwithin 6 inches of both sides of each opening. Check codes for vertical rebarspecications for below and above grade building. (In the rare case local codes

require the vertical rebar be tied to the footing/slab dowels - use 4 ft. to 5 ft.lengths, dropping the block over the rebar.)*

If another story is to be constructed, be sure to install connecting vertical rebar.Check local codes or engineering specs for height requirements *

All rebar placement should be calculated to local codes, ACI 318, PCAsPrescriptive Methods for ICF Residential Construction or engineersspecications.

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Example PlanDisclaimer:Theseestimationsaregivensolelyasanexampleofhowtogure

amountsofblock,concreteandrebarforyourproject.Actualspecicationsshould

be provided by approved engineering tables, local codes, or the site engineer.

Example Layout(for demonstration purposes only)Figure 1

From our example plan we can calculate the following:

_____Perimeter 148 linear feet

_____Exterior walls 9 feet high

_____Two 30 doors (21 square feet each; 42 square feet total)

_____Eight 4x 3 windows (12 square feet each; 96 square feet total)

_____Eight 90 corners

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Rebar EstimationAssume: Number 4 rebar, 20 foot sticks Vertical overlap between oors is 24 inches Horizontal overlap is 20 inches (HINT: 4 webs) Vertical spacing for dowels and rebar is 20 inches

Calculate Horizontal rebarCalculate rebar needed per row in 1 course (be sure to include requiredoverlaps) multiply that times rows or horizontal rebar needed.

_____ Perimeter 148 linear feet or 1776 linear inches_____ Using 20 ft. sticks and 20 inches overlap = each stick will span 184 or

220 inches_____ 1776 (perimeter linear inches) by 220 inches (each bars span) = 8.07

rebar required per row_____ 9 courses_____ +1 extra rebar bottom course

_____ +1 extra rebar top course_____ =11 rows needed at 8.07 rebar per row_____ = 89 - 20 foot rebar sticks needed or 1780 linear feet_____ Doors add one extra bar over each door_____ To extend 24 inches either way for overlap_____ Therefore each extra rebar will be 84 inches (36 + 24 + 24)_____ 2 30 doors = 2 x 84 inches = 168 inches 12 = 14 linear feet_____ Windows one extra bar over each window_____ (8 48 inches x 36 inches) 8 x 48 inches = 384 inches_____ add 24 inch overlap each side x8 windows = (48 inches x 8) = 384 inches_____ 384 inches + 384 inches = 768 inches 12 = 64 ft.

_____ Footer calculate footer rebar requirements_____ Vertical_____ Calculate height of walls times spacing._____ If this story is top story, rebar should be cut 3 below top of block.

_____ If this is a connecting story rebar needs to be cut for connection to next level.

ADD: Footers as requiredHorizontal 1789Windows 64Doors 14Vertical 900

2767Waste 3% 83

Rebar needed for example 2850 Linear Feet

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Concrete Estimation

Greenblock 6 inch Fixed Web:_____Approximately one yard of Concrete for every 54 square feet of wall

_____Calculate amount of concrete needed by using the Net Wall Square Footage

TIP:Itisrecommendedthatyoudoublecheckyourguresforconcreteamount

needed or have your supplier do so.

LnObjective/

OutcomeOperation

Ln

RefCalculations

1 Perimeter ADD all sides 20+10+14+20+14+10+20+40=148

2 Gross Wall sq ftMULTIPLY Perimeter by Wall

Height148X9 = 1332

3 Openings sq ftADD each window and door

sq ft to obtain total sq ft96+42 = 138

4 Net Wall sq ftSUBTRACT Openings sq ft

from Gross Wall sq ft

Ln 2 -

Ln 31332-138 = 1194

5

Corner Adjustment

(Final WallNet Sq ft)

Add corner blocks* and

Subtract 1 sq ft per cornerblock from Net sq. ft.

Ln 4 /

54 1194 / 54 = 22.11

22.11 Yards of Concrete Needed

NOTE: Check with local supplier for aggregate and slump /trucking

requirements.

3.2 ESTIMATING


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Blank Estimation WorksheetsEstimating 6 inch and 8 inch Core Block (Call to estimate panel systems)

Ln Objective/Outcome Operation Line Reference Calculations

1* Perimeter ADD all sides

1a* Find Wall Height SEE PLANS

2 Buildings wall sq ftMULTIPLY Perimeter by

Height Ln 1 x 1a

3 Gross Blocks DIVIDE Bldg wall sq ft by 4.0 Ln 2 4.0

4 Square Footage of OpeningsCheck plans and/or Window /

door schedule

5 Total Square Footage of all OpeningsADD windows & doors sq ft

to obtain total sq ftLine 4

6Openings -

Block reduction

DIVIDE Total Openings

sq ft by 4.0Ln 5 4.0

7 Net BlocksSUBTRACT Openings from

Gross BlocksLn 3 - Ln 6





10 Total Number of 90 Corner BlocksMULTIPLY 90 Blocks per


10aTotal Number of 45

Corner Blocks



11Number of

Standard Blocks

SUBTRACT Corner Blocks

From Net blocksLn 7- (Lns 10+10a)

12Total Number of

Top Blocks

DIVIDE Perimeter by 4.0

Minus Number of Corners

(Ln 1 4.0) -

(Lns 8 + 9)

13Total Number of

Standard Blocks

SUBTRACT Top Blocks

From Standard BlocksLn 11 - Ln 12

14 Account for 3-4% wasteFor 90 Corner Blocks MULTIPLY Total 90 CornerBlocks by 1.04 ** Ln 10 x 1.04* Total 90Corners:

14aAccount for 3-4% waste

For 45 Corner Blocks

MULTIPLY Total 45

Corner Blocks by 1.04* *Ln 10a x 1.04*

Total 45

Corners:


For Top Blocks

MULTIPLY Total

Top Blocks by 1.04Ln 12 x 1.04

Total Taper/

Tops:


For Standard Blocks

MULTIPLY Total

Standard Blocks by 1.04Ln 13 x 1.04

Total

Standards:

* In the case where your walls have different heights, you will need to do a separate estimating sheet

for each section of a different height and add all estimates to calculate your total block needed.

** Round total number of corners up to an even number (corners are packaged and shipped in pairs.

You should receive your corners in bundles packed lefts and rights. If not, please contact yourlocal Greenblock representative.

NOTE: All block will be rounded up to pallet counts/sizes. Check with shipping for counts.

3.2 ESTIMATING


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Concrete Estimation for 6 core block*




Wall Height

3 Openings sq ft

ADD each window and


sq ft

4 Net Wall sq ftSUBTRACT Openings sq

ft from Gross Wall sq ft

Ln 2 -

Ln 3

5 Yards of Concrete NeededDIVIDE Net Wall sq. ft. by

54 sq. ft.

Ln 4 /

54

Concrete Estimation for 8 core block*




Wall Height

3 Openings sq ft

ADD each window and


sq ft

4 Net Wall sq ft

SUBTRACT Openings sq

ft from Gross Wall sq ft

Ln 2 -

Ln 3

5 Yards of Concrete NeededDIVIDE Net Wall sq. ft. by

40 sq. ft.

Ln 4 /

40

Substitute sq. ft. on line 5 above with the following to obtain:

81* for the 4 inch core system

27* for the 12 inch system

For 8 Core blockHorizontal below and above grade requirements for 8 concrete core blocks can be found bychecking with national or local codes (ACI 318), engineering or PCAs Prescriptive Method forInsulating Concrete Forms in Residential Construction.

Add 1% to 2% waste.

For All Other Core blocks -Check your engineering and/or local codes.Add 1% to 2% waste.

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Crew and Labor Estimating

Building with Greenblock requires:Less manpower than most other types of constructionLess labor than most of our ICF competitors

A good working size crew for a residential home mightinclude:

One qualied carpenterTwo to three laborers

Larger jobs will be nished quicker with larger crews. Ithelps if someone has minimal experience with concrete, butit is not mandatory.

Fixed web systems:In general, a good building rate for a 3-4 man crew is approximately 15 formseach per hour._____15 forms of 6 inch = 60 square feet (15 x 4.0)_____15 forms of 8 inch = 60 square feet (15 x 4.0)

Panel Systems:In general, a good building rate for a 3-4 man crew is approximately 12 formseach per hour._____12 forms of 4 inch = 48 square feet (12 x 4.0)

_____12 forms of 6 inch = 48 square feet (12 x 4.0)_____12 forms of 8 inch = 48 square feet (12 x 4.0)_____12 forms of 10 inch = 48 square feet (12 x 4.0)_____10 forms of 12 inch = 40 square feet (10 x 4.0)

Calculations include cutting and bending rebar, installing alignment systems,building and installing window and door bucks. Therefore a 3000 gross wallsquare foot structure may possibly require:_____62 hours labor for 6 inch panel system_____50 hours labor for 8 inch xed web system

Additional oors, gables, T-walls, and 45 corners may reduce overallproductivity and slightly increase construction times.

TIP: Contact your local Greenblock representative for help during yourrst estimate, build and pour.

Tip!

3.2 ESTIMATING

Documents

Section 3.3 Estimating