Project type
CDM principal designer for a house extension
The statutory principal designer appointment on a domestic extension, taken as a fixed fee service. Short forms, one site visit, and the information pack out to your builder before work starts.
Short answer
Almost every house extension involves more than one contractor once the electrician, the groundworker or the roofer is counted, and that is the test regulation 5 of CDM 2015 applies. Where it is met, you must appoint a CDM principal designer in writing before work starts. ClearCDM takes that appointment from £750 plus VAT.
What the appointment covers on an extension
- The appointment in writing
Which is the part regulation 5 actually requires, and the part most domestic projects never get round to.
- Information from the people who hold it
A short form for you about the house, the access and how you will be living in it. A short form for your designer and your engineer about the risks their design leaves behind.
- One site visit
To record the building as it is: the meter positions, the neighbour's side return, the condition of what is being cut into.
- Design risk coordination
Making sure the propping sequence, the opening and the services are dealt with by the people designing them rather than discovered on site.
- The pre-construction information pack
Out to whoever is pricing and whoever is building, with the gaps named.
- The health and safety file
Where the appointment runs to completion, handed over as a single PDF at the end.
The four things that actually matter on an extension
Extensions are not complicated projects, and a good pack for one is short. What earns its place is usually the same short list.
| Question | Why it changes what the builder does |
|---|---|
| Is the house occupied during the works? | Separation, protection, dust, hours and escape all follow from the answer |
| What is the asbestos position? | For a house of the right age, this needs establishing before the fabric is disturbed, not afterwards |
| What has to be propped, and in what order? | The engineer's sequence is a design decision. In the pack it is information; in somebody's head it is not |
| How does everything get to the back of the house? | Access is the constraint that governs the programme on most terraced and semi-detached sites |
Your builder gets something out of it too
The reason to do this properly is not the appointment, it is what the appointment produces. A builder pricing an extension with the asbestos position established, the propping sequence written down and the access constraint stated is pricing the actual job. One pricing without any of that is guessing, and the guess is usually corrected mid build at the client's expense.
What it costs
From £750 plus VAT for the pre-construction service, with the construction phase service from £450 plus VAT if you want the appointment to run to completion and the health and safety file handed over at the end. The published fee schedule, or price your own project.
Common questions
My builder says he does not need any of this. Is he right?
He is right only if he is doing every part of the work himself with his own staff. One subcontracted trade makes it a project with more than one contractor and the appointment is required.
Is this the same as building control?
No. Building control checks the work against the Building Regulations. CDM is separate law about health and safety in construction, with its own appointments and its own documents.
Does it hold up my start on site?
It should not, if the appointment is made while the design is still moving. It sometimes reveals something that should hold up a start, such as an asbestos survey that has not been done, and that is the system working rather than failing.
Price it in about two minutes
Answer a few questions about the works and see the fixed fee. Nothing is contracted and no money is taken online.
Get an instant quote →Not sure yet? check whether the appointment is required at all.