Sources we use
We rely on primary sources: the official read-only text of the building codes (ICC, gov.uk, NRC Canada, ABCB), standards and design data (NIST PS 20, the AWC National Design Specification and span tables, AWC DCA 6), US government research (USDA Forest Products Laboratory, DOE Building America) and manufacturer technical documents. We do not use retailer guides, forums or social media as sources of fact.
How calculators are checked
Every calculator uses published, standard formulas. The code is covered by automated tests that check known answers (for example, a 2x6 board 8 ft long is 8 board feet, a 105 in rise under the IRC takes 14 risers of 7-1/2 in, and a No. 2 Douglas fir-larch 2x10 at 16 in centres spans 15 ft 7 in, matching the IRC table). We show the formula next to each tool so anyone can verify the result by hand.
What we will not publish
- Paid placements, supplier price lists or reviews written for a seller.
- Links to retailers or "where to buy" recommendations.
- Structural designs presented as engineering; our span and code checks are planning aids.
- Claims we cannot support with a source.
Updates and corrections
Each page shows the date it was last updated. When a new code edition, standard or design-value table is published, we update the affected pages and note the edition. If you find an error, tell us through the contact page and we will review it and correct it.