New CIOB Guide Spells Out Who's Responsible When Building Regs Go Wrong — Worth Knowing Before Your Extension Starts

A homeowner off the High Street in Newport Pagnell came to us last week wanting a two-storey side extension, and the first question was who's actually responsible if building control picks something up once the walls are up. It's a fair question, and one more people are asking these days.

The Chartered Institute of Building has just published a free guide setting out exactly that — who's responsible for what under Building Regulations and the Building Safety Act. It's aimed mainly at commercial clients, but the same principle holds for anyone commissioning work on their own home: you don't need to be a technical expert, but you do need to know what your builder is doing and why, and check they're competent before signing anything.

On a domestic job that starts with the foundations. Depending on ground conditions and whether there are trees nearby drawing moisture out of the clay, we'll go trench-fill or traditional strip — the clay round Newport Pagnell can shift more than people expect. From there it's a standard cavity wall with wall ties at 900mm centres, DPC a clear 150mm above ground level, and lintels sized properly for the span rather than whatever's left lying in the yard.

Insulation's where Part L tends to catch people out. We're using Celotex or Kingspan PIR board in the cavity now rather than the old fibre batts, finishing internally with British Gypsum Thistle MultiFinish for a proper smooth skim. If you're close to next door's wall, a party wall notice needs sorting before anyone breaks ground — skip that and you can end up with a stopped job. We've been building extensions, conversions and driveways around Milton Keynes and Newport Pagnell for decades, and we always walk clients through building control before quoting. Have a look at masonpropertyservicesltd.co.uk or give us a call.

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