Front Room, Full Regulations: A Builder's CDM Checklist for Domestic Extensions and Lofts

Most builders clock that CDM paperwork scales with the size of the job. Fewer clock that it can land on them just as heavily on a two-storey side return in Surbiton as on a distribution centre in Wakefield — not because the regulations change, but because of who's paying the invoice.

A domestic job still sits inside CDM 2015. What shifts is who carries the duties. Get that muddled at the quoting stage and you can find yourself as the de facto principal contractor on someone's house, with none of the arrangements in place that the role expects.

Start with the client, not the drawings

A domestic client is a person having work done on domestic premises, where the work isn't in connection with a business. Mrs Patel's loft conversion: domestic. A developer flipping a terrace: not. A landlord refurbishing a rental flat can go either way — if the property is run as part of a letting business, treat it as commercial and don't take the shortcut.

That distinction matters because of a single regulation that most small builders have never read.

Regulation 7: the handover nobody mentions

Under regulation 7 of CDM 2015, a domestic client's duties transfer. If the project is notifiable and there's more than one contractor, they go to the principal contractor. If it isn't notifiable, or there's only one contractor, they go to the contractor in control of the work.

On a typical house extension, that's you. The bloke who quoted for the knockdown, the steels and the roof lantern.

The bit people miss: 'more than one contractor' includes your own subcontractors. The moment the electrician and the plasterer are on the same programme as you, you're in multi-contractor territory. It doesn't matter that they're on your books, day rate, or a handshake. They're contractors under the regs, and the duty lands on whoever is coordinating.

In practical terms, the transferred duties mean you're the one responsible for making sure:

• a construction phase plan exists before work starts, where one is required;
• welfare facilities are on site from day one;
• an F10 gets submitted if the project crosses the notification threshold;
• relevant information is shared between the trades on site.

The homeowner hasn't been let off the hook entirely — they still have to cooperate and give you what they know about the property — but they're not the one an inspector will be talking to.

Written arrangements that fit in a folder, not a filing cabinet

Nothing in the regs says domestic arrangements have to be a lever-arch file. Proportionate is the watchword. Two sides of A4 agreed at the pre-start meeting will do the job on most extensions, provided it actually says something.

What it should cover:

1. Who's coordinating what, and who the trades take instruction from. Be explicit that the homeowner doesn't instruct other trades directly.
2. Site rules — hours, deliveries, parking, where materials get stored, where waste goes.
3. Emergency information — nearest A&E, first aider on site, muster point, and how the crew gets out if the stairs are out of action.
4. Welfare arrangements, and where they are.
5. How changes get raised — in writing, priced, signed off, before anyone picks up a tool.

Get the client's signature on it. Not because a signature magically discharges a duty, but because it forces the conversation before the first day rather than in week six when the neighbour's complaining about the skip.

Welfare on a domestic job: the skip doesn't count

Schedule 2 of CDM 2015 sets the minimum, and 'it's only a house' is not an exemption. Sanitary conveniences, washing facilities with soap and a means of drying, drinking water, somewhere to change and dry wet gear, and a place to sit and eat that isn't the client's sofa.

On a domestic site, that usually means a serviced portaloo plus a hand-wash station with soap and paper towels, positioned before the first delivery lands. Don't plan on using the kitchen sink — it's the client's house, not a site facility, and if someone gets a dose of something nasty the arrangements will be the first thing anyone asks about.

F10: the notification that catches people out

The trigger is often misremembered, so here it is plainly. A project is notifiable if construction work lasts more than 30 working days and involves more than 20 workers simultaneously at any point, or exceeds 500 person-days in total.

And, not or, on that first limb. A loft conversion with a small crew will almost never get near it. A substantial extension with a big crew, or a long refurbishment with a full house of trades, can creep over the 500 person-day mark without anyone adding it up.

Person-days means everyone — your lads, the electrician's mate, the scaffold crew, the client's cousin who's helping out. If you're anywhere near the line, notify. The form takes minutes online and costs nothing. Skipping it costs rather more.

The pre-start pack: five things before day one

• A one-page project summary — client, address, scope, start and finish dates, who's on site when.
• The construction phase plan, scaled to the job. On a single-contractor, non-notifiable job that can be a short set of arrangements; once you've got multiple trades, write the plan properly.
• Welfare confirmed — booked, delivered, and positioned.
• An asbestos check before anything gets stripped, especially on pre-2000 housing. Note who holds the duty to manage, and don't disturb anything you can't identify.
• A signed arrangements sheet and a short client briefing on how changes and access get handled.

Where it goes wrong

Three recurring ones. The homeowner instructs a tiler directly and now you've got an uncoordinated trade on your programme. The scaffold gets 'sorted by a mate' and nobody has recorded the handover. And the pre-start chat happens in the van, verbally, with nothing written down — which is fine right up until the point it isn't.

The short version

Domestic work is still CDM work. The client's duties transfer to you under regulation 7, and on most extensions that means you're running the show. Write the arrangements down, get welfare on site before the first delivery, work out whether you're notifiable before rather than after, and treat your own subcontractors as what they are — other contractors. Do that and the job stays domestic. Skip it and you've taken on commercial risk for a domestic fee.