How to do a siding takeoff (vinyl, wood, fibre cement, brick)

Exterior cladding is mostly measured on the elevations, not on the floor plan. That's where the gables, the real heights and the material changes are. The main calculation is simple; what costs money is what gets left out: gable triangles, trim, corners, soffit. Here's a clear method, material by material, with a complete example.

What you need before you start

• The elevations, to scale, with the materials shown (vinyl, fibre cement, brick…) and where each one stops.
• The cladding height on each wall: often from the top of the foundation up to the soffit.
• The gables: their width and height (or the roof pitch).
• The roof plan for the overhangs (soffit and fascia).
• The openings (doors, windows): not to deduct them, but for the trim around them.
• Your waste factor, often around 10% for lap siding, adjusted to the material, the shape of the house and your crews.

Two ways to measure the area

1. Trace the area on the elevations. This is the most accurate way: you follow the gables, the jogs and the limits of each material. Trace each facade, or each zone of a material.
2. Wall length × height. Faster, and you can reuse the walls already measured for framing. Gables must then be added separately.

Either way, doors and windows are often not deducted: offcuts around openings are rarely reused, and the waste factor accounts for it. Only deduct large glazed areas or zones in another material.

1. Vinyl

Vinyl siding is sold in boxes of 2 squares (one square = 100 sq. ft, so 200 sq. ft per box):

Accessories are counted by length:

• starter strip: at the base of the siding, along the full wall length;
• J-trim: around openings, and where vinyl meets another material or the soffit;
• outside corners: number of corners × height of one corner;
• furring, if needed: area ÷ furring spacing, + waste, in lin. ft.

2. Wood or fibre cement boards

For lap boards, count pieces with the exposure (the visible width), not the actual board width:

A 12 ft board with a 7" exposure covers 7/12 × 12 = 7 sq. ft. Check the exposure the manufacturer calls for: that's what changes the board count. Add corner and trim boards by length, and furring (rainscreen gap), often required behind this type of cladding.

3. Metal siding

Steel or aluminum: keep the area (waste included), then convert it to the manufacturer's format (panels, planks, cut-to-length pieces). Accessories are the same as for vinyl: starter, J-trim, corners, furring.

4. Brick

A modular brick measures 8" × 2 2/3" with its joint, which is 6.75 bricks per sq. ft. Calculate:

Bricks laid per bag and tie spacing depend on the product, the mortar and the project requirements: use those from the specifications and your mason. At the base of the veneer, along its full length: flashing and weep holes (one at each spacing, plus one per wall).

5. Soffit and fascia

Measure the length of the roof overhangs on the roof plan (eaves and gable rakes):

Worked example: a 28' x 40' bungalow

Assumptions: 136 lin. ft of walls, cladding 9 ft high, two 28 ft wide gables with a 6/12 pitch (14 ft × 6/12 = 7 ft high), 4 outside corners, 150 lin. ft of J-trim (around openings, an assumed value for the example), 10% waste.

Area: walls 136 × 9 = 1,224 sq. ft, gables 2 × (28 × 7 ÷ 2) = 196 sq. ft, total 1,420 sq. ft.

Fibre cement option (12 ft boards, 7" exposure, furring at 16" o.c.):

Soffit and fascia (18" overhang; 80 ft of eaves + about 63 ft of rakes, so 143 lin. ft measured):

Brick front facade (one 40 ft × 9 ft wall = 360 sq. ft, modular brick, 5% waste, ties at 16" × 16", weep holes at 24"). The number of bricks laid per bag (140) is an example value, to replace with your mason's.

If the front is brick, take those 360 sq. ft out of the vinyl area: one wall doesn't get two claddings.

Common mistakes

• Forgetting the gables. Measured in plan, they don't exist: 196 sq. ft in the example, about 14% of the area.
• Counting a zone twice where two materials meet (brick below, vinyl above).
• Using the actual board width instead of the exposure.
• Forgetting accessories: starter strip, J-trim, corners, furring. They're ordered by length and often cost more than expected.
• Forgetting soffit and fascia, or counting only the eaves without the gable rakes.
• Rounding facade by facade: add up areas of the same material, then convert to boxes or boards once.

Exterior cladding in KOR

In KOR, the Exterior cladding group has starter templates that follow these rules: "Vinyl siding" (boxes of 2 squares, starter strip, J-trim, corners, optional furring), "Wood or fibre cement siding (boards)" (boards from exposure and length, furring, corner and trim boards), "Metal siding (steel, aluminum)", "Soffit and fascia" and "Air barrier membrane". The Masonry group has brick in two versions: from the area traced on the elevations, or from wall length × brick height (with base flashing and weep holes), as well as adhered stone veneer. You trace areas on the elevations with the Rectangle or Polygon tools; trim lengths and the number of corners are set in the item, and every default value can be changed. The quantities then flow into the estimate, where you enter your prices.

Two more KOR modules are in preparation: bid management and project management.

Summary

1. Measure on the elevations, or wall length × height + gables.
2. Vinyl: area + waste ÷ 200 sq. ft per box, rounded up.
3. Boards: area + waste ÷ (exposure × length), rounded up.
4. Brick: 6.75 modular bricks per sq. ft, + cement, ties, flashing and weep holes.
5. Don't forget trim, corners, soffit and fascia.