This document is a detailed breakdown of how to estimate the many different materials used in the Exterior Finishes Phase of construction projects
The square footage of flat roof area, the lineal footage of roof edge, and the lineal footage of roof ridge line will be brought forward from the basic takeoffs in order to determine quantity. Below is more information that you will need to know to successfully estimate roof materials.
The starter course is placed along each horizontal roof edge as the starter course for the shingles. House Plan 10-1 shows a view of the roof plan from the building drawings. Each horizontal roof edge is calculated around the perimeter of the roof starting in the top left-hand corner and moving towards the right. Odd size dimensions can be rounded up or down to the nearest quarter foot.
58′ + 21′+ 10′ 8″+ 6′+ 6′+ 15′= 116′8″
Ice and water shield will be installed both along the edges of the roof and in the valleys as valley flashing. This length of 116.67 feet from the header section will also be used for ice and water shield. In addition, the valley will have an ice and water shield.
The roof plan shows two valleys at the front of the roof where there is a front porch. The length of the valley can be determined by using the following Roof Valley Multiplier factor in the header section. To use this, multiply the run of the roof by the factor to determine the valley length. Roof plan shows the width of the front porch as 12′1½″. The length of the run will be half of the porch roof width or 12′1½″ / 2 = 6′¾″. Entering the roof slope of 6″ per foot will display a value of 1.5 as the value in the Roof Valley Multiplier cell. Multiplying the run length by the multiplier will result in the following:
6′¾″ × 1.5 = 9′1-1/8″
The width of the valley flashing is usually added to the calculated valley length to account for the angle cuts and overlap on the valley flashing. The ice and water shield is three feet wide, therefore, the length of ice and water shield used for flashing in each valley will be
9′ 1-1/8″ + 3′ = 12′ 1-1/8″
There are two valleys on the roof, so this quantity will be multiplied by two, which would result in the following quantity rounded up to the nearest quarter foot:
2 × 12′ 1-1/8″ = 24′ 2 ¼″
The total for the ice and water shield would be
116.67′ + 24.25′ = 140.92′
This quantity will be entered in the header section.
The roof slopes at a ratio of six inches of vertical rise for every 12 inches of horizontal length.
Identify the correct roof felt material for your project. The roof plan identifies the roof felt as 30# felt for this project.
Rolls of traditional roofing 30 lb. felt is usually identified as containing two squares even though the roll actually contains 212 square feet, but it will only cover 200 square feet with the standard overlap. Rolls of 15 pound felt contain 425 square feet and will cover 400 square feet of roof area.
Synthetic roof felt is usually sold in rolls identified by the width and length, such as 4 feet wide by 250 feet long. Standard lapping width might be 3-6 inches. Synthetic felt with 1,000 square feet will only cover 937.5 square feet of roof area with a 3-inch lap distance, and 875 square feet with a 6-inch lap distance. In addition, the felt may or may not be placed on top of the ice and water shield, or the ice and water shield may be used as the first low of felt as shown in Figures 10-2 and 10-19.
The correct shingle material for your project will need to be determined.
Identify the correct starter course material for your project.
A slightly modified version of the SFQuantity custom function will be used to calculate the quantity of ridge cap needed. The LF Ridgeline input in the header section will be used to determine the quantity of ridge cap shingles needed. The correct Ridge Cap material information is placed in the Materials, Size, Units, and Unit Cost cells using the materials userform. The basic SFQuantity custom function will be entered into the quantity cell as follows:
SFQuantity (E22, F11, B22, F22)
A slight modification of the function will be added to change the lineal foot input from the LF Ridgeline input in the header section. The modification is done by multiplying the LF of Ridgeline by the width of the ridgeline. The width of the ridge shingles is commonly one foot, so the length of the ridgeline will be multiplied by one foot. The modified formula is shown as follows:
SFQuantity (E22, F11* 1, B22, F22)
The modified formula entered into the spreadsheet is shown in Excel Figure 10-7.
Excel Figure 10-7 Modified ridge cap function entered into the spreadsheet.
Several types of roofing nails will be needed to install the roofing. The most common are cap nails for the roofing felt and roofing nails for the shingles. Cap nails are used to anchor the roofing felt to the sheathing. The cap nails are commonly spaced at six to eight inch intervals along both edges and the center of the felt. Based upon an eight inch spacing each cap nails are calculated to cover 0.67 square footage of felt per nail. Based upon a six inch spacing each nail will cover 0.5 square footage of felt per nail. The Materials, Size, Units, and Unit Cost for the correct nail will be entered into the spreadsheet using the Materials userform. The formula will be written to take into account a nail spacing of eight inches along each edge and in a single row across the middle and will use a 0.67 factor.
The written formula will be:
SF Sloped Roof Area * (1+ WasteFactor) / 0.67/ Size
Entered into the spreadsheet the formula would be:
= F15 * (1+B23) / 0.67 / F23
Excel Figure 10-8: Cap nails function entered into the spreadsheet.
Roofing nails will be calculated in a similar manner, using nails for a pneumatic roofing nailer. The nails are manufactured in individual coils and package in a box of 7,200 nails. Shingles are attached with either four or six nails per shingle. The quantity of nails can be calculated from the number of shingles purchased. Asphalt shingles are purchased in bundles of 27 shingles for standard size shingles and 21 for metric shingles.
The formula will be written as follows:
Bundles of Shingles * Shingles per Bundle * Nails Per Shingles * Waste Factor / Size
Entered into the spreadsheet the formula would be:
= I20 * 21 * 6 * (1 + B24) / F24
Excel Figure 10-9 shows the formula entered into the spreadsheet. The 10 percent waste factor will be included to account for the nails used to attach the starter strip and hip and ridge shingles. In this case, the quantity will not be rounded up as the leftover nails can be used on future jobs.
Excel Figure 10-9: Roofing nail function entered into the spreadsheet.
The LFQuantity custom function will be used to calculate the quantity of ice and water shield that will be needed based upon the quantity entered into the header section. Entered into the spreadsheet the formula would be:
LFQuantity (E26, F13, B26, F26)
Excel Figure 10-10 shows the completed formula entered into the spreadsheet.
Excel Figure 10-10: Ice and water shield formula entered into the spreadsheet.
The correct drip edge material information is placed in the Materials, Size, Units, and Unit Cost cells using the materials userform. The basic LFQuantity custom function will be entered into the Quantity cell to calculate the amount of drip edge based upon the LF Roof Edge from the header section. The formula would be
LFQuantity (E27, F10, B27, F27)
Excel Figure 10-11 shows the completed formula entered into the spreadsheet.
Excel Figure 10-11: Drip edge formula entered into the spreadsheet.
A continuous ridge vent material will be used along the top ridge of the roof. The LFQuantity custom function will be used to calculate the quantity needed, based upon the information placed in the header section. If individual turtle style vent is used, then the quantity needed would be a count and list item. The correct ridge vent material information is placed in the Materials, Size, Units, and Unit Cost cells using the materials userform. The formula would be:
LFQuantity (E28, F11, B28, F28)
Excel Figure 10-12 shows the completed formula entered into the spreadsheet.
Excel Figure 10-12: Roof vent formula entered into the spreadsheet.
The valley flashing was calculated with the ice and water shield. No additional material will be needed, and the cells are left blank.
There is no chimney on the project, and no chimney flashing will be needed. The cells are left blank.
The step flashing quantity will be manually inputted. The total will be calculated by using the sloped roof length divided by the lap length of each flashing. Excel Figure 10-13 shows the Roof Slope Length Multiplier value, which is displayed in the header section of the roofing subsection. The multiplier is determined by the Roof Slope (In per ft.) variable. Changing the variable will change the multiplier. The six-twelve slope of the roof shows a slope length multiplier of 1.12.
Excel Figure 10-13: Roof slope multiplier.
The slope length of the roof is calculated by multiplying the run of the roof by the slope multiplier. Figure 10-38 shows the span of the garage roof as 24 feet. The run of the garage roof would be calculated as half of the length of the span or 12 feet.
Figure 10-38: Roof slope length.
The sloped length would be as follows:
12 ft. x 1.12 = 13.44 ft.
Figure 10-39 shows the lap length for the step flashing based upon the 5 5/8 inches exposure length of a metric sized shingles. The step flashing will have the same exposure amount.
Figure 10-39: Step Flashing lap length.
Calculating the number of step flashing pieces is done by dividing the slope roof length of 13.44 feet by the exposure length of 5 5/8 inches. The 5 5/8 inches will also need to be converted to feet by dividing by 12. The equations for doing this is as follows:
This number would be rounded up to 27 pieces and entered into the spreadsheet (Excel Figure 10-14).
Excel Figure 10-14: Step flashing quantity.
The number and size of plumbing vents flashing needed for residential construction depends heavily upon the location and size of the fixtures and is subject to some fine-tuning by the plumber. The building code does require at least one outside vent, and each plumbing trap is required to be vented; however, there are a number of ways to accomplish the task. Each plumbing fixture could have its own individual outside vent, but this can be costly and can increase the chance of roof leaks as the number of roof penetrations increase. Figure 10-31 shows a single plumbing vent and Figure 10-33 shows four separate roof vents. Typically, vents for fixtures located close to each other, such as in a bathroom, are combined together so that there is a single roof penetration for the vent. Fixtures farther away may require their own roof vent. For example, in the sample plan the bathroom and kitchen are close together and could likely share a single vent, whereas, the laundry room is some distance away and may need its own roof vent. Based upon that assumption, two plumbing vent flashings will be estimated: flashing for a three-inch vent pipe and one for a two-inch vent pipe. These will be manually entered into the spreadsheet.
This document provides a detailed overview of the process for estimating materials in the Vinyl Siding Section of the ExtFin tab of the Estimating workbook.
Often, residential house plans do not have extensive information about the specific details for installing vinyl siding, siding trim, and flashing. The construction estimator will need to understand the specifics about each project. Some information can be obtained from the plans, but other details may be left up to the siding installer or to some established company standard. For this activity, the following methods for installing vinyl siding will apply:
The house wrap is calculated by determining the length of the exterior walls covered by the house wrap including the area of the gable ends. The lengths of the exterior walls and the garage walls can be taken from the Basic Takeoffs. The house wrap covers the wall and the floor joist space down to the top of the foundation. For standard 8-foot-high exterior walls with a 12-inch-thick floor framing system this would typically be around 9 feet. House wrap is typically sold in standard rolls 9 feet wide, so 9 feet will be used to calculate the height of the area covered by the house wrap. Figure 10-155 shows the exterior walls portion of the basic takeoffs with the exterior wall and garage wall lengths highlighted.
Figure 10-155 Exterior walls section of the basic takeoffs.
Totaled together, the wall lengths would be
114 ft. + 62 ft. = 176 ft.
The area of the exterior walls is multiplied by the 9-foot house wrap material size for a total square footage of exterior wall area of
176 ft. x 9 ft. = 1584 ft.2
The square foot area of the gable ends is also added to the area. Figure 10-156 shows the garage gable end view. The width of the building is dimensioned at 32 feet. The roof run would be half of the building width calculated as
32 ft. ÷ 2 = 16 ft.
The roof has a 6:12 slope and the roof rise would be calculated as
6/12 × 16 ft. = 8 ft.
The square footage of the gable end area is calculated as the area of a triangle.
Figure 10-156 Right elevation view showing gable ends.
There are two gable ends shown in this view, however, they are nested within each other and can be estimated as one large gable end as the piece cut from the large gable will fit the smaller gable. The gable end on the other side of the project is also the same size. The total square foot area of house wrap would be calculated as
Wall Area: 1,584 ft.2 + Right End Gable: + 128 ft.2 + Left End Gable: 128 ft.2 = 1,840 ft.2
The area of doors, windows, and other openings are not subtracted from the total as the house wrap is installed over the openings and the house wrap cut out as waste. The total of 1840 square feet is placed in the header section of the estimating template.
The square footage of siding is calculated by totaling the individual areas of siding. A small wall siding area calculator is provided with the estimating template (Figure 10-157).
Figure 10-157 Wall siding area calculator.
The right elevation view shown in Figure 10-156 can be used to calculate the square footage of siding on that side of the project by calculating the individual areas.
Total Right Side House Area: 202.13 ft.2 + 91.88 ft.2 = 294 ft.2
The area of the garage door is calculated as follows:
16 ft. 4 in. × 7 ft. 2 in. = 117.06 ft.2
This is greater than 25 square feet, so the garage door area is subtracted from the wall area total, and this amount is entered into the wall siding area calculator with a 10 percent waste factor.
294 ft.2 – 117.06 ft.2 = 176.94 ft.2
The right gable end area was previously calculated as follows:
The quantity is also entered into the wall siding area calculator with a 30 percent waste factor.
Figure 10-158 shows the front house elevation. The siding for the front elevation is calculated with the following:
263.13 ft.2 + 175.42 ft.2 = 438.55 ft.2
The window and door sizes can be obtained from the window and door schedules or from the basic takeoffs in the estimating template. Excel Figure 10-21 shows a portion of the basic takeoffs with the applicable cells highlighted.
Excel Figure 10-21 Basic takeoffs with front windows and doors highlighted.
The windows and doors are subtracted from the total.
2 Windows Type Mark E: 5 ft. 0 in. × 5 ft. 0 in. = 50 ft.2
2 Windows Type Mark F: 7ft. 6 in. × 5 ft. 0 in. = 75 ft.2
1 Door, Door Number 1: 6 ft. 8 in. × 5 ft. 6 in. = 36.852
50 ft.2 + 75 ft.2 + 36.85 ft.2 = 161.85 ft.2
Wall Area – Opening Area: 438.55 ft.2 – 161.85 ft.2 = 276.70 ft.2
This number is entered into the wall area calculator with a 10 percent waste factor. The width dimension of 9 feet, 6 inches, and the known roof slope is used to calculate the gable end area of the front porch, and that quantity is entered into the spreadsheet with a 30 percent waste factor.
Figure 10-159 shows the left elevation view.
Figure 10-159 Left elevation view.
The building width and wall height is used to calculate the wall area.
Left Wall Area: 32 ft. 0 in. × 9 ft. 2-1/4″ in. = 294.67 ft.2
This quantity is entered into the wall siding area calculator with a 10 percent waste factor. The left gable end area is calculated the same as the right gable end area.
Figure 10-160 shows the rear elevation of the house. The area of the rear wall siding is calculated from the dimensions.
Rear Wall Area: 56 ft. 0 in. × 8 ft. 9-1/8 in. = 491.17 ft.2
The double window unit with the Type Mark B is the only window or door opening on this elevation that is over 25 square feet. The area of this window will be subtracted from the wall area total, and all other windows and doors will be ignored.
Wall Area – Opening Area: 491.17 ft.2 – 30 ft.2 = 461.17 ft.2
This quantity will be entered into the wall siding area calculator with a 10 percent waste factor. Excel Figure 10-22 shows all of the wall area totals entered into the wall siding area calculator.
Excel Figure 10-22 Wall siding area complete.
Starter strip will be used anywhere the siding course starts with a full width siding piece. The length can be estimated from the elevation views. The right elevation view, Figure 10-156 shows one 10-foot wall and the short walls on each side of the garage door. The length of the starter strips on both sides of the garage doors can be determined by subtracting the width of the garage door from the width of the wall.
Starter Strip on Garage Wall: 22 ft. – 16 ft. 4 in. = 5 ft. 8 in.
This is added to the 10-foot length on the right house wall for a total of
Total Right Elevation Starter Strip: 10 ft. + 5 ft. 8 in. = 15 ft. 8″
The starter strips for the front elevation; Figure 10-158, is determined by subtracting the front porch width of 11 feet from the house width of 36 feet. The starter strip for the garage portion of the front wall is added for an additional 20 feet. Finally, the starter strip for the gable end above the front porch is added for an additional 9 feet, 6 inches.
Total Front Starter Strip: (36 ft. – 11 ft.) + 20 ft. + 9 ft. 6in. = 54 ft. 6 in.
The starter strips for the left elevation; Figure 10-159 has no areas where the starter strip is not needed, so the quantity of starter strip is simply the length of the left-side wall of 32 feet.
Total Left Elevation Starter Strip: 32 ft.
The starter strips for the rear wall; Figure 10-160 has starter strip along the total length of the 56-foot wall with the exception where it is cut out for the garage entry door (Door number 4). This will subtract 3 feet from the total length of starter strip.
Total Back Elevation Starter Strip: 56 ft. – 3 ft. = 53 ft.
15 ft. 8 in. + 56 ft. 6 in. + 32 ft. + 53 ft. = 157 ft. 2 in.
Calculating the lineal feet of siding J channel is one of the more challenging items to estimate with siding. Essentially, J channel is used wherever the siding is cut to conceal the ragged cut edge with the exception of cut edges that are concealed by the inside or outside corner trim. Figure 10-161 shows the front elevation view with the vinyl trim elements highlighted.
The J channel is highlighted in bright red. J channel is located along the top of the wall where it intersects with the soffit. This includes both horizontal and angled J channel. J channel is also located around the door and along the side and top of the front porch. The total front elevation J channel working from the top down includes
2 Angled front porch soffit trim pieces: 5 ft. 4 in.
1 Front left wall horizontal soffit piece: 14 ft. 9 in.
1Front Wall horizontal soffit piece: 10 ft. 3 in.
1 Garage Wall horizontal soffit piece: 20 ft. 0 in.
1 Horizontal door top edge piece: 5 ft. 6 in.
2 Vertical door edge pieces: 6 ft. 8 in.
2 Horizontal porch top pieces: 2 ft. 10 in.
2 Vertical porch edge pieces: 6 in.
Total lineal footage of front elevation J channel
(2 × 5 ft. 4 in.) + 14 ft. 9 in. + 10 ft. 3 in. + 20 ft. 0 in. + 5 ft. 6 in. + (2 × 6 ft. 8 in.) + (2 × 2 ft. 10 in.) + (2 × 6 in.) = 81 ft. 2 in.
The J channel for the other elevations would be calculated in the same manner.
The utility trim is identified in Figure 10-161 by a bright blue color. It is placed in the horizontal J channel and in the window trim at the top and the bottom of the windows. Utility trim calculations for the front elevation include
1 Horizontal soffit piece: 14 ft. 9 in.
1 Horizontal soffit piece: 10 ft. 3 in.
1 Horizontal soffit piece: 20 ft. 0 in.
1 Horizontal door top edge piece: 5 ft. 5 in.
2 Horizontal porch top pieces: 2 ft. 10 in.
4 Horizontal window trim pieces: 7 ft. 6 in.
4 Horizontal window trim pieces: 5 ft. 0 in.
Total lineal footage of front elevation utility trim
14 ft. 9 in. + 10 ft. 3 in. + 20 ft. 0 in. + 5 ft. 6 in. + (2 × 2 ft. 10 in.) + (4 × 7 ft. 6 in.) + (4 × 5 ft.) = 100 ft. 8 in.
Outside corner trim is located at each outside corner where vinyl siding is installed. Corner trim is purchased in standard lengths of 8, 10, o r 12 feet long. The trim is usually not seamed unless the corner is longer than the longest length of trim. One standard length piece is purchased for each outside corner. The front elevation view shows three outside corners. Two additional pieces are also shown on the back elevation. 10 foot lengths of corner trim will be purchased. This total of 50 feet is entered into the header section.
Inside corners are calculated in the same fashion as outside corners. The front elevation view shows only one inside corner. This is the only inside corner piece in the project.
The window trim for this project will be decorative three inch-wide window trim. The quantity is calculated by determining the lineal feet of window perimeter. In addition, three inches will be added each end of the window trim piece to allow for the miter cuts at each window corner. This adds six inches of length to each window piece, which would result in a total of two feet per window. The window trim for the front elevation would be
Type Mark E Windows
8 window edge pieces: 5 ft. 6 in. = 44 ft. 0 in.
Type Mark F Windows
4 window edge pieces: 8 ft. 0 in. = 32 ft. 0 in
4 window edge pieces: 5 ft. 6 in. = 22 ft. 0 in.
Total front window trim
44 ft. + 32 ft. + 22 ft. = 98 ft. 0 in.
The window trim for the rear elevation would be
Type Mark D Window
4 Window edge pieces: 3 ft. 6in. = 14 ft.
Type Mark C Window
2 Window edge piece: 3 ft. 6 in. = 7 ft.
2 Window edge pieces: 1 ft. 6 in. = 3 ft.
Type Mark B Window
2 Window edge pieces: 6 ft. 6 in. = 13 ft.
2 Window edge piece: 5 ft. 6 in. = 11 ft.
Total rear window trim
14 ft. + 7 ft. + 3 ft. + 13 ft. + 11 ft. = 48 ft.
The lineal feet of soffits are the amount equal to the lineal feet of roof edge which was one of the basic takeoff quantities. The total of 186 lineal feet is carried forward from the basic takeoffs.
The soffit width can be determined from detail drawing as shown in Figure 10-162. This shows a soffit width of 12 inches.
Figure 10-162 Wall section detail showing soffit construction.
Figure 10-163 shows a view of the front porch soffit area. The dimensions inside of the support beams define the porch soffit area. The front porch soffit area is calculated by the following:
Width 9 ft. 8 in. Depth 5 ft. 7 in = 60 ft.2
Figure 10-163 Front porch soffit area.
Most of the quantities for the vinyl siding materials will be calculated based upon the total in the vinyl siding section and the Excel custom functions used to calculate the totals. A few quantities will need to be manually estimated.
The moisture protection subsection includes house wrap, door and window flashing, and house wrap tape.
The Tyvek house wrap material will be determined using the measurements you have already determined.
A self-adhered flashing tape will be installed around all main floor windows and exterior doors. The perimeter of the windows and doors from the basic takeoffs can be used to estimate the quantity of flashing needed. Excel Figure 10-21 shows the main floor windows and exterior door section of the basic takeoffs. The total perimeter for the windows is listed as 132 lineal feet and the total perimeter for the exterior doors is listed at 68.1 lineal feet. The estimating template calculates the door perimeter for three sides based upon the two sides and top of the door. Flashing will need to be installed at the bottom of the door, so an additional 14 feet, 6 inches will need to be added based upon the total for the width of each door.
Door Widths: 5 ft. 6 in. + 3 ft. + 3 ft. + 3 ft. = 14 ft. 6 in.
Total Window and Door Perimeter: 132 ft. + 68.1 ft. + 14.5 ft. = 214.6 ft.
In addition, flashing material will need to be added to the estimate to account for the lapping requirement. The amount added is dependent upon the width of the flashing material used on the projects. Figure 10-164 shows an exterior window elevation detail with the flashing requirements. The detail identifies the self-adhered flashing as 9 inches wide. 9 inches will need to be added to both the beginning and end of each flashing piece to account for the overlap for an added length 18 inches (2 × 9″). Each window and door would need an additional 72 inches (6 ft. 0 in.) of flashing for the four corner overlaps.
4 pieces’ × 18 in. = 72 in.
Figure 10-164 Exterior window flashing detail drawing.
The basic takeoff lists seven windows and five doors for a total of 11 extra pieces of six-foot-long flashing that will need to be purchased to account for the lapping requirement.
Total Window Flashing Overlap: 11 pcs. × 6 ft. = 66 ft.
The total window flashing that will need to be purchased is
Total Window and Door Flashing: 214.6.6 ft. + 66 ft. = 280.6 ft.
House wrap tape will be needed around the perimeter of all windows and doors to adhere the house wrap to the window or door frame. In addition, it will be needed wherever there is a horizontal seam in the house wrap, such as when a separate piece is installed on the gable ends. Previously, the total window and exterior door perimeter was calculated as 214.6 lineal feet. Additional flashing tape will be needed on each gable end. The two gable ends shown in Figure 10-156 equal a total of 32 feet, and the gable end shown in Figure 10-159 is also 32 feet wide. The two gable ends add a total of 64 feet of additional house wrap tape. The amount for house wrap tape for the project is
Total House Wrap Tape: 214.6 ft. + 60 lf. = 274.6 ft.
The miscellaneous exterior finish material includes electrical and plumbing mounting blocks, gable end vents, and vinyl shutters.
Electrical mounting blocks are used whenever there is an electrical fixture that is mounted on the walls with vinyl siding. Both the elevation views and the floor plan views typically show the location of electrical fixtures. The elevation views shown in Figure 10-156, 10-158, 10-159, and 10-160 show wall mounted light fixtures and outlets.
The elevation views also show one hose bib on the front elevation and one on the rear elevation.
The gable end vents are also taken off from the elevation views which show three gable end vents.
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