BY EDWARD G. LE JEINE*In this, the second in my series on estimating concretework, well examine foundation walls bearing on footingsand directly on compacted earth. Well also discuss under-pinning an existing foundation wall and how to estimate theform area and concrete for piers below grade and for build-ing slabs on fill.Readers should refer back to the Outline for Concrete Esti-mating which appeared on page 210 of the June, 1967, Is-sue of CONCRETE CONSTRUCTIONFoundat i on wal l sOn foundation walls I take off the quantities for forms(in 4-foot heights), 2 by 4 keys, slab seat bearing and con-crete. After the word forms I place the words in 4-footheights in brackets. I separate my forms every 4 feet byheight for pricing and I use one price for material and la-bor for walls up to 4 feet high. From 4 feet to 8 feet, I usehigher prices. From 8 feet to 12 feet, 12 feet to 16 feet andover I use increasingly higher unit prices per square footof wall forms. I do this because more bracing is requiredfor higher walls and the additional cost is in both laborand material. A lot of contractors dont believe in break-inguptheirfoundationwalltakeoffsintodiffere n theights but actually it makes a tremendous differe n c e.For example, if a 4-foot-high wall form is on a footing, IESTIMATING CONCRETE WORK - IIEstimating Foundation WallsFoundat i on Wal l s on Foot i ngsLineal FeetSquare FeetSlab SeatCubic FeetEstimatedDescriptionNumber Dimensions FormsBearingConcreteQuantityUnit3A. Foundation Walls on Footings W x H x L 2HxL L WxHxLLine A - 1-0 x3-6 x 78 546-273Line B-1-2 1/2x7-10x 40 627- 380Bsmt: (at Brick Ledge)1-0 x9-6 x1562964-1482Bsmt: (for Brick Ledge)0-4 x3-0 x156468-( - 156 )=Form 1 sideBsmt: Seat Bearing 0-4 x0-6 x156 -156( - 26 )Bsmt: Door Box-Out 1-0 x7-0 x 418- ( - 28 )Bsmt: WindowBox-Outs6x 0-8 x3-0 x 4 60-( - 48 )-34680X156X1877X = Concrete = 70 Cubic Yards 274x6 Slab Seat Bearing = 156 Lineal Feet 0 to 4 H. Forms =1070 Square Feet 4 to 8 H. Forms = 650 Square Feet 8 to 12 H. Forms =2960 Square Feet 468 Square Feet x 1/2/Square Feet + 10% = Dove-Tail Slots for Brick Ledge = 260 Lineal Feet The above walls represent typical conditions. Line A is a typical wall below frost line. Line B shows that a wall is measuredto the fraction of an inch for width and to the closest inch for height. The basement walls show that where a brick ledgeexists, the wall must be figured the full height of 9 feet 6 inches. Then add in additional forms for the brick ledge area andsubtract the concrete.Slab seat bearing is figured in lineal feet and then you must subtract for the concrete. Door and window box-outs have theadditional forms added and again you must subtract for the concrete openings. The deductions for the concrete are inparenthesis to call attention to the subtraction. The slab seat bearing is listed in lineal feet for ease in pricing and is notadded into stripping and cleaningof forms. All walls are listed in the same takeoff and separated into 4-foot variations inheight in the last column for ease in pricing when they are extended to the recap sheet.Dove-tail slots for nailing to forms (for brick anchorage) are also easily picked up at this time. If the foundation walls havepilasters on them, add in the additional formwork and concrete for the pilasters and mark that section of wall (for example) 0-foot to 4-foot-high forms with pilasters.The cost will be figured higher for this section of wall both for material andlabor.figure a carpenter will erect about 300 square feet a dayIf the wall form runs between 4 feet and 8 feet high, acarpenter can erect about 250 square feet a day; from 8feet to 12 feet, a carpenter can erect about 160 squarefeet a day. This will give you some idea of the differenceb e t ween a 4-foot-high and 12-foot-high wall, as far ase rectionlaboraloneisconcerned.Ofcourse,theamount of bracing material required increases with theheight of the wall. These figures are for erection laboro n l y. They do not include re m oving the form s. I figureform stripping separately because I always figure labor-er time only for stripping. This isnt always possible, be-cause theoretically the carpenters are supposed to dothe stripping if the formwork is going to be reused on thejob. But most of the time laborers do it.For erection of form s, however, I figure a ratio of onecarpenter to one-half of a laborers time. My cost per dayfor a carpenter always includes one-half a days time fora labore r. If a carpenter is to set up 300 square feet offorms per day then on that job he needs one-half of a dayof labore rs time to help him. The time might be spenthandling forms and lumber, unloading tru c k s, or otherways of helping the carpenter. The figuring of pro d u c-tion per carpenter per day, the cost of a carpenter and la-borer ratio and how to apply them will be discussed ful-ly later. At present, I will confine the discussion to gettingthequantitytakeoffproperlyaccomplished.Now,should you take off wall columns separately or shouldyou take them off as part of the wall? It depends on howbig the column is and how much extra work it causes. Ifits a lot of work, take it off separately and call it a columnto put it into the correct price bracket. If it is only about4 inches wider than the wall by about 1 foot long, call ita pilaster and include the forms and concrete with thewall. If a wall has pilasters every 20 feet apart they are nota large enough cost item to take off separately. Figure thewall forms straight through the pilasters and then takeoff the pilasters separately and let the formwork doubleu p. This simplifies the takeoff, and the extra forms willpay the differential of your pilaster cost. When I pri c ewall forms with pilasters I also deduct 10 percent fro mGrade Beam Wal l s2 feetMinimum WidthHandExcvationArea Square FeetCubic FeetEstimatedDescriptionNumber Dimensions Square FeetFo rm s ConcreteQuantityUnit3B. Grade Beam Walls: W x H x L(W+1)xL 2HxLWxHxLLine A-1 x3 x 50100 300 150Line B - 0-8 x6 x150 3001800600Line C-1-4 1/2x7-l1x 831971314 901Line D - 1-6 x8-6 x154 385 2618 1964-2 -2980X 6030X3615X= Concrete 134 Cubic Yards 27Hand Excavation Area =980 Square Feet 0 to 4 H. Forms =300 Square Feet 4 to 8 H. Forms = 3110 Square Feet8 to 12 H. Forms = 2620 Square Feet All walls that bear directly on earth belong under this group. They are separated from foundation walls on footings be-cause of the need for hand excavation and also because a 2 by 6 leveling plate is usually needed on the ground beforethe forms are set. The cost of this leveling plate is most easily put in the wall forming unit prices. Line A shows a typicalgrade beam on caissons; line B shows a wall less than 12 inches. Line C is shown to illustrate that the width is carried tothe closest fraction of an inch, the height to the closest inch and the length to the closest foot. Line D shows a wall over8 feet high.the erection time used in figuring a straight wall withoutpilasters.Grade beamsfoundation walls without a concre t efooting under themmust be treated separa t e l y. I takethem off separately, because I include the cost of a mudsill in the square feet of wall area. I do this by figuring 10percent more in the material cost and 10 percent less inthe square feet erected per day. For simplicity in pricing,take off a seat bearing on a wall for slabs by total linealfeet. These usually run about 4 inches by 6 inches. If theyare not too high, brick ledges in walls should also be tak-en off for pricing by the lineal foot. If brick ledges run 2feet or more in height, it will most likely be necessary toplace one form inside another. In other word s, yo ul lh a ve to double-form the wall. The best way to accountfor this in takeoff is to double the form area. Be sure todeduct the concrete volume for this area. Once again, wea re trying to be most accurate on the concrete vo l u m ebecause concrete makes up a high percent of the totalcost of the estimate. I take off a retaining wall with a bat-tered face as follows: I start first with the straight side ofthe retaining wall. This falls in the regular price for wallforming work. Then take off the battered face separate-l y. This is a distinct problem. You can erect the stra i g h twall and brace the other end off of it, but still that bat-tered face is a special problem as far as getting the laborCubic FeetHand Square FeetSquare FeetCubic FeetEstimatedDescriptionNumber Dimensions ExcavationFormsConcreteQuantityUnitD3C. Underpinning:W x H x L WxHxL HxL WxHxLHand Excavation }4 x 4 x24 192 From 45 Line2Wall1-6 x 4 x 24144 96 144Footing 2-0 x 1-6 x 24 - 36 72Footing Excavation - 3-0 x 1-6 x 24108-2 444130216X27 = Concrete 8 Cubic YardsForms = 130 Square Feet44427 = Hand Excavation = 17 Cubic Yards2 x 4 Keys =24 Lineal FeetTo underpin an existing foundation wall the work is usually done in alternate 4-foot-long sections as shown on elevation A-A.All sections marked 1 are completed before the sections marked 2 are started. If the architect shows every third sectionto be done at one time for additional safety, it merely makes three separate operations of underpinning.The hand excavation must be figured from an estimated machine excavation line usually at a 45 degree angle from the bot-tom of the existing wall. This is slow work because the section of the wall is only 4 feet long and it is important not to dis-turb the ground beyond the inside of the existing wall. Forms are figured for one side of the wall and footing. The concretefooting is usually regular concrete and the wall is specified to be a dry-pack concrete. Sometimes the wall is regular con-crete stopped about 4 inches below the existing wall and allowed to set up and take its initial shrinkage.The top 4 inches under the existing wall is then packed with a dry-pack grout which has little or no shrinkage upon drying.The quantities are calculated as if the underpinning would all be done at one time.All of these quantities must be clearly marked for underpinningon the recap sheet so that the pricing estimator can makean allowance for the slow work in his labor units because only 4 foot lengths of wall and footing can be done at each place.UInderpi nni nginto your cost. When figuring your labor to erect the bat-tered face, reduce the production output per day on it byabout20percentfromwhatyouwouldfigureonastraight wall of the same height. In wall forming takeoffw o rk, it is ve ry important for the takeoff estimator toh a venotationsastothetypeofworkthatmustbep riced. This is needed whether he prices it himself, orm o re import a n t l y, if the work will be priced by anotherestimator.The form area for walls is twice the height times thelength. The concrete volume in cubic feet is the heighttimes the length times the thickness, all in feet, of course.No deduction for reinforcing steel should ever be madefrom the concrete volume. In listing walls on the takeoffsheet the length should be given to the closest foot, theheight to the closest inch and the thickness to the fra c-tion of an inch. A wall that is 1 1/2 inches thick should bef i g u red as a decimal of 1.04 feet thick. These are neces-s a ry to get the correct concrete quantities. These samerules apply, in general, for all concrete takeoff work.Pi ers bel ow grade Estimating form area and concrete for piers belowgrade is relatively simple. Piers below grade are piers thatwill have earth backfill around them. These piers can beformed with rough lumber and this is why they are kepts e p a rately fromcolumns.The form w o rkistwicethewidth plus twice the length times the height, or onceagain,thecontactarea.Theconcretevolumeisthewidth times the length times the height.Bui l di ng sl abs on fi l lUnder this category I include sand fill, edge forms, ex-pansion joints, finish area and concrete. The sand fill isthe area of the slab times the thickness of the sand bed.However, you must add 25 percent to the actual volumeyo uve figured for sand fill, or crushed stone. This is forcompaction and loss in handling and is very important.Edge forms are listed by the height in total lineal feet. Expansion joints are listed by the thickness and heightin total lineal feet. The finish area is the total area of theslab. The concrete is the area of the slab times the thick-ness in a decimal of a foot, i.e., 5 inches is .42 feet. Whenf i g u ringconcreteforaslabonfilladd3percentforw a s t e. You should also be sure to consider vapor barri-e r s, screed material and curing and protection items.Pi ers Bel ow GradeSquare Foot Cubic FootEstimatedDescriptionNumberDimensionsFormsConcreteQuantityUnit4. PiersBelowGrade:W x L x H (2W+2L).H WxLxHF1 6 x 1 x 1 x2-6 6015F2 3 x 1 x 1 x3-0 36 9F3 2 x 1 -0 x1 -4x5-9 5416F4 2x 0-10x1-6x5-95416-413200X56X= Concrete 3 Cubic Yards 27(13) Forms 200Square Feet At Slab: 1/2x5 Expansion Joint 56 Lineal Feet The form material for piers below grade is us ually1-inch dimension lumber and not expensive but thelabor of forming piers is high because of the smallarea of forms per pier. Therefore, they must be tak-en off as a separate item. The labor of casting piersishigh becaus e of the s mall amount of concre t eper pier. Marking the number of piers to be formed(13) is important. It tellsthe pricing es timator theaverage s quare feet of formsper pier (15 s quarefeet). If the pricing es timator allowsone hour car-penter time per pier then he can figure (8 hourstimes15 s quare feet) or 120 s quare feet of piere rection per day. In fact the number of piers to bee rected s etsthe allowance for forming labor insquare feet per day. The 1/2-inch by 5-inch expan-sion joint around the piers at the slab is most easi-lytaken off under this item.Figure a vapor barrier under the slab by taking the totala rea plus 10 percent for lap and waste. Screed materi a landcuringandprotectionitemsarepricedbythes q u a re feet of slabs. Me m b rane curing is the exact slabarea, but if paper or polyethylene materials are used add10 percent for lap and waste. Most of these items are in-cluded under the last part of recapping, miscellaneousi t e m s. They can generally be picked out from the take-off sheet without referring to the drawings. However, anyitems that you can pick off the drawings as you go alongshould bedone.This isone more timesaver on yo u rtakeoff time. * The author, a civil engineering graduate from the Uni-versity of Notre Dame, has been estimating concre t ework for the past 17 years. For eight of these years, Mr.Le J eune was president of his own estimating serv i c e .The author presently is associated with the W.E. ONeilConstruction Company, Chicago, Illinois.Bui l di ng Sl abs on Fi l lSquare Feet Cubic Feet EstimatedDescriptionNumberDimensions AreaConcreteQuantityUnit5. Bldg. Slabs on Fill:W x L x DWxLWxLxDE. Wing 40 x 63 x 0-525201059Center44 x 36 x 0-51584 666W. Wing 40x63 x 0-5 2 5201059Boiler Room 21 x 21 x 0-8441296Entries2 x 6 x 8-6 x 0-61025137170X 3131X27 = Concrete116 Cubic Yards Hand Grade Earth Under Fill =7170 Square Feet 7170 Square Feet x 6 = 3585 Cubic Feet = 133 Cubic Yards + 25% Compaction = 6 Sand Fill =166 Cubic Yards (10% Added for Lap) = .006 Polyethylene Vapor Barrier = 7900 Square Feet Finish Slabs = 717 Square Feet 6 H. Edge Forms =42 Lineal Fee 1/2 x 5 H. Expansion Joints =672 Lineal Feet 1/2 X 8 H. Expansion Joints = 8Lineal Feet Building slabs at different elevations such as basementfloors and slabs at ground floor level should be kept sep-arate because of the different labor cost per cubic yardfor placing these slabs.If all slabs are of the same thickness, only the quantityfor the areas should be extended, and the concretequantity may be obtained by multiplying the total area bythe slab thickness. An estimator should always lookahead for any time-saving step that he can use.The hand grading of earth under fill is only needed whenthe ground is excavated to provide for the slab. If theslab is to be placed on fill material furnished under the excavation specifications, then the work required of the concretecontractor would be the final hand grading of the fill material under the slab. Whenever a fill is specified such as a 6-inchsand bed under the slab, this should be figured in cubic yards to which should be added 25 percent to cover compactionand loss in delivery. The polyethylene vapor barrier should have 10 percent added to the area required, to take care of lapsand waste. The necessary edge forming is easily taken off from the drawings at this time and listed to the closest linealfoot. Expansion joints are obtained by referring to both drawings and specs, and should be listed to the closest lineal foot.PUBLICATION #C670249Copyright 1967, The Aberdeen GroupAll rights reserved