From this site

One project, every trade

Each calculator adds its lines to a single estimate — consolidated BOM, schedule and cash-flow included.

Open My Project →

Backer Board Calculator

Count cement backer boards, screws and joint tape for a tiled wet area.

Computed in your browser — nothing you enter is uploaded. Figures are presented for United States against IRC 2024, and every formula is cited under regulatory standards below.

Last verified 2026-08-26 · v1.0.0

Market
Imperial · sales tax
Who is doing the work?

Waste is set to 15% by hand. Pick a tier above to replace it, or keep your own figure.

Boards required

18 boards

Check your inputs

Fixing counts assume 200 mm centres on a typical board. Follow the manufacturer's pattern, which varies between products and between wall and floor use.

Board coverage
10.33 ft²
Area with waste
185.68 ft²
Backer board screws
278 screws
Alkali-resistant mesh tape
190.29 ft

Running these inputs gives 18 as the boards required. Note that area to board sits at the low end of the range this calculator was checked against, so treat the output as indicative rather than settled. Expect some drift against the real job; the calculation is solid but conditions on site are not. Currently reading for United States under IRC 2024 — pick a different market above and the figures re-cast accordingly.

Estimated cost — your price

This site holds no price list for this material — local prices vary too much to publish honestly. Enter your supplier's price and the result is costed with it.

Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — confirmed fixes become pinned regression tests.

[Schema Verified] Computed in alignment with American Concrete Institute (ACI 318-19) formulas and International Residential Code (IRC 2024) spatial boundaries.

Regulatory standards & verification citations

  • Fastener spacing 200 mm (8 in) on centre through the field and at edges — manufacturer installation instructions and TCNA Handbook
  • Joints taped with alkali-resistant mesh tape and set in the same mortar used to bed the tile

Your workspace

Most jobs need more than one number. Add the calculators you need next and they open right here, underneath this one — your figures stay on screen and nothing is lost to a page change.

Frequently asked questions

Is backer board waterproof?
No, and this is the most consequential misunderstanding in bathroom tiling. Cement backer board is water-resistant — it will not turn to mush like plasterboard — but water passes through it. A shower needs a waterproofing membrane or a liquid-applied system over the board, or the water reaches the timber behind.
Can I use plasterboard instead?
Not in a wet area. Even moisture-resistant plasterboard degrades under sustained wetting and cannot carry the weight of tile once it does. Outside the wet zone, in a dry room, tiling onto plasterboard is normal practice.
Why alkali-resistant tape rather than ordinary mesh?
Because cement-based mortar is strongly alkaline and will degrade standard fibreglass tape over time. Alkali-resistant tape is made for this environment. The joint is also set in the tile mortar itself, not in a drywall compound, which has no place behind tile.