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Corrections, questions about a figure, or anything else about the site.
Corrections are the most useful thing you can send
If a waste factor does not match what you see on site, or a coverage rate contradicts the data sheet for a product you use, that is worth more to this site than almost anything else. Please include:
- Which page and which figure
- What you believe the correct value is
- Where it comes from — a data sheet, a standard, or your own experience fitting the material
We check it, change it if you are right, and note the correction and the date on the page.
Requests for a new calculator
Tell us what you are trying to work out and what makes it awkward at the moment. The useful ones are usually where the arithmetic is simple but knowing which numbers to use is not — that is the gap these tools are meant to fill.
What we cannot help with
- Specification and structural advice. We cannot tell you what thickness your slab should be, whether a wall is load-bearing, or what your local regulations require. Those need someone who can see the building.
- Disputes with a contractor or supplier. We are not able to act as an expert opinion on a quantity dispute.
- Product recommendations. We do not rank or review brands.
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Advertising on this site is served through Google AdSense; we do not sell placements directly, and we do not accept paid links, sponsored posts or guest articles. Please do not send outreach about those — the answer is no in every case.
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Last updated 2026-09-18.