Built Simple for UK builders
Free calculators and plain English guides to the Building Regulations for England, plus construction management software that runs the whole job from your phone. Nothing here needs an account.
How the rules fit together in England
The Building Regulations 2010 are the law. The Approved Documents are the government’s published guidance on ways of meeting them, and following one is not the only route to compliance, but it is the route a building control body will accept without argument, which for domestic work makes it the practical one. They are published for England under the Open Government Licence, so these pages quote them directly and name the edition each figure came from.
Building regulations approval and planning permission are separate processes, and having one tells you nothing about the other. A loft conversion can be permitted development and still need a full plans or building notice application. An extension that goes through the Larger Home Extension route, where the council has 42 days to decide once the neighbours’ 21 day objection window has closed, still has to satisfy the regulations in full.
Where to start
- Pricing an extension. The extension cost calculator takes your own rate per square metre and adds what the headline rate leaves out: fees, the party wall surveyor, contingency and VAT at 20 per cent. It deliberately publishes no average rate, because the free estimates span more than two to one for the same description.
- Setting out a stair. The stairs calculator checks rise, going, pitch and 2R+G against Approved Document K, and the Part K guide has the guarding heights, including the 900mm figure at the edge of an internal floor in a dwelling that most sites replace with the 1100mm commercial number.
- Building a ramp. The ramp calculator works out gradient, flights and landings against the right volume of Approved Document M. Volume 1 is dwellings, Volume 2 is everything else, and the two set different limits.
- Framing a floor or deck. The joist calculator gives you the count, centres, lineal metres and noggins. It is a take-off, not a span check, and the page says so.
Three things this section corrects
Writing these pages from the source documents rather than from other websites turned up three points where the common advice is wrong. No Approved Document sets a minimum roof pitch; the minimums are manufacturer figures governed by BS 5534. The guarding height at the edge of an internal floor in a dwelling is 900mm, not 1100mm. And party wall notice periods are statutory, one month for a line of junction or adjacent excavation notice and two months for work to the party structure itself, not a courtesy to be negotiated on the day.
Built to British standards, not translated from somewhere else
Every guide and calculator in this section is written to the Approved Documents published for England. The maths in a calculator does not change between countries, but the rules it has to satisfy absolutely do, so these are separate pages with separate figures rather than an Australian page with the currency swapped.
| Calculators | Check against the Approved Documents, not the National Construction Code. |
| Guides | Written from the current Approved Documents, with the edition named and the source linked. |
| Coverage | England. Wales, Scotland and Northern Ireland have separate documents and we do not quote their figures. |
| The app | Scheduling, estimating, team tracking and defects. Not localised to UK tax or payroll, and billed in Australian dollars. |
Run the whole job, not just the numbers
Built Simple handles scheduling, estimating, team tracking and defects in one place. The calculators are free forever on the starter plan.
Frequently Asked Questions
Are these calculators written for UK building regulations? Yes. Every figure is checked against the current Approved Document, and the edition is named on the page. They cover England.
Do I need an account to use the calculators? No. Every calculator on this site is free and runs in the browser with no signup.
Is Built Simple a UK company? No. Built Simple is Australian. The app is used internationally and the guides here are written specifically for England, but billing is in Australian dollars, converted at checkout.
Do you cover Scotland, Wales and Northern Ireland? Not yet. Those are separate regulatory systems with different documents and different figures, and publishing English numbers under a Scottish heading would be wrong. We would rather say so than guess.
