MATERIALFOREMAN · SHEET SD-001 · EXTERIOR WORKS
CALC-D-001 · DRAWING NO. SD-001 · REV A

Siding calculator.

Drafted to scale · cited sources · honest numbers

Enter the wall dimensions, gable ends, and openings. The calculator returns vinyl squares, Hardie planks, or wood lap square footage with a material-cost range. Deducts doors, windows, and garage doors from gross wall area.

◈ DRAFTING PANEL · SIDING TAKEOFF · N.T.S. SHEET SD-001 · REV A
Redline · scope notice Material takeoff only. Does not size J-channels, starter strips, corner posts, undersill trim, or frieze boards. Does not evaluate wind-zone fastener schedules (ASCE 7). Assumes rectangular walls; dormers and bay windows need separate takeoffs.
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Note 01 · Field Procedure

How to measure the exterior

  1. Walk the perimeter and record total wall length in feet. Include all sides the siding will cover. Round up to the nearest foot.
  2. Measure wall height from the top of the foundation to the soffit line. For two-story homes, measure each story separately if the siding break is at a band board.
  3. Count gable ends. Measure each gable triangle: base width (eave to eave) and peak height (eave line to ridge). The calculator uses the triangle formula (0.5 x base x height).
  4. Count doors (standard 3x7 ft = 21 sqft each), windows (standard 3x4 ft = 12 sqft each), and garage doors (standard 16x7 ft = 112 sqft each). The calculator deducts these from gross wall area.
Note 02 · Equation

The formula

net  =  ( H × P + gables )  −  openings
Hwall height in feet
Ptotal wall perimeter in feet
gablessum of gable triangle areas (0.5 × base × peak)
openingsdoors (21 sf) + windows (12 sf) + garage doors (112 sf)
Vinyl: order in squares (100 sqft). Hardie: order in 12 ft planks (8.25 in. width, 7 in. reveal after 1.25 in. overlap = 7 sqft each). Wood lap: order by sqft.
Note 03 · Sanity Ranges

Siding by house size

T Use case Notes
~800 sfSmall cottage / garageVinyl: ~10 squares. One-day job for two installers.
~1,300 sfRanch / single-storyVinyl: ~15 squares. Hardie: ~205 planks. Most common residential job.
~2,000 sfTwo-story colonialVinyl: ~22 squares. Budget for scaffold rental.
~3,000+ sfLarge homeVinyl: ~33+ squares. Complex trim and multiple gables add 15% waste.
Note 04 · References

Sources

Authorities cited on this sheet
  1. Polymeric Exterior Products Association (PEPA, formerly Vinyl Siding Institute) · Industry trade association for vinyl siding. Defines the 'square' (100 sqft) as the standard ordering unit. Installation manuals cover thermal expansion float-nail requirements.
  2. James Hardie HardiePlank Lap Siding · Product page for HardiePlank fiber cement lap siding. 12 ft planks, 8.25 in. width, 7 in. reveal after 1.25 in. blind-nail overlap (7 sqft coverage per plank). ASTM E136 noncombustible rating. Basis for the plank count on the spec slip.
  3. James Hardie Pro Resources · Installation instructions, ICC-ES evaluation reports, and best-practice guides for HardiePlank and Hardie trim systems.
  4. IRC 2021 Chapter 7 Wall Covering (R703) · IRC R703 governs exterior wall covering, including minimum lap on wood siding and clearance from grade. Basis for the wood lap 6 in. exposure assumption (nominal 8 in. board with 1 in. minimum lap).
Note 05 · Field Manual

What the sheet count does not tell you

A ranch elevation, worked out

Take a single-story ranch: 140 feet of wall perimeter at 9 feet tall, two gable ends 30 feet wide rising 8 feet to the peak, one entry door, eight windows, and a two-car garage door. The walls are 1,260 square feet. Each gable triangle is half its base times its height, so the two gables add 240 square feet. Gross is 1,500. Subtract 21 for the door, 12 each for the eight windows, and 112 for the garage and the net is 1,271 square feet. Add 10 percent waste and the order is about 1,398 square feet, which is 14 squares of vinyl. Materials land between roughly 1,900 and 4,900 dollars depending on whether it is builder-grade or insulated premium vinyl.

Gables, openings, and the square

Two things drive a siding takeoff past the flat wall. Gables are triangles, not rectangles: measure the base eave to eave and the peak height above the eave line, and the area is half the base times the height. Miss the gables on a steep roof and the order comes up a square or two short. Openings come back the other way: a door is 21 square feet, a window about 12, a two-car garage door 112, and they subtract from gross. On the unit, vinyl is sold by the square, 100 square feet of net coverage, while Hardie comes in 12 foot planks that cover 7 square feet each after the overlap, and wood lap is ordered by the square foot. The calculator converts the net area into whichever unit the material you picked is sold in.

Vinyl, fiber cement, and wood

The three siding types behave differently enough to change the install, not just the price. Vinyl is the cheapest and most forgiving, but it has one hard rule: it must float on the nails to expand and contract with temperature. Nail it tight and it buckles in July and cracks in January. Fiber cement, the Hardie product, is heavier, noncombustible, and holds paint for decades, but it is dense enough to need carbide blades and a respirator for the silica dust when cutting. Wood lap is the traditional look and the highest maintenance: it wants paint or stain on a cycle and a minimum 1 inch lap per IRC R703 to shed water. The calculator counts whichever you pick; the trim, the starter strip, the corner posts, and the fasteners are a separate list the unit count does not show.

Note 06 · Common Questions

Common questions

How much siding do I need?
Measure the wall area (height times perimeter), add the gable triangles (half base times peak height), and subtract the openings. A 140 foot ranch at 9 feet with two gables and normal openings nets about 1,271 square feet, which is 14 squares of vinyl after 10 percent waste. The calculator converts that into squares, planks, or square feet depending on the material.
How many square feet is a square of siding?
One hundred square feet of net coverage. Vinyl is sold and priced by the square. A 1,300 square foot single-story ranch is about 14 to 15 squares before waste. Hardie is sold by the 12 foot plank instead, each covering about 7 square feet after the overlap, and wood lap is ordered by the square foot.
How do you calculate the siding for a gable?
A gable is a triangle: half the base times the height. Measure the base from eave to eave and the height from the eave line up to the ridge. A 30 foot wide gable rising 8 feet is 0.5 times 30 times 8, or 120 square feet. Two of them add 240 square feet to the order. Skipping the gables is the most common reason a siding job runs short.
What is the difference between vinyl and Hardie siding?
Vinyl is PVC, the cheapest option, and must float on its nails to expand with temperature. Hardie is fiber cement: heavier, noncombustible, holds paint for decades, but it needs carbide blades and a respirator for the silica dust when cutting. Vinyl installs faster and costs less; Hardie lasts longer and resists fire and impact. The calculator prices both from the same wall area.
PROJ MATERIALFOREMAN
SHT SD-001 / 014
REV A · 2026-06-07
DRAWN MF