Project type
CDM principal designer for a loft conversion
The principal designer appointment on a loft conversion, where the two risks worth coordinating are both pre-construction ones: working on an existing roof, and cutting into the structure that is holding it up.
Short answer
A loft conversion normally involves several contractors, often sequentially: the builder, a steel supplier and installer, a roofer for the dormer, an electrician and a plasterer. That is more than one contractor, so regulation 5 of CDM 2015 requires a CDM principal designer appointed in writing before work starts.
What makes a loft different
Two things, and both of them are decided at design stage.
The roof already exists and people have to work on it. Its construction, its condition, whether anything up there is fragile, how the scaffold reaches it and what is directly below when a section comes off are all questions with answers, and the answers belong to the pack rather than to the first morning.
The structure is being cut into while the house stands up. Purlins and rafters are doing a job until the new steels take it over, and the order in which that happens is the engineer's decision with consequences for whoever is standing underneath.
What the pack usually covers
- Roof construction, condition and age, and any survey that exists.
- The asbestos position for a house of the relevant age, including the likely locations: artex, insulating board around flues and boilers, cement sheet in outbuildings.
- What is loadbearing, what is being altered, and the propping and sequencing the engineer has specified.
- Occupation: whether the family is in the house while the roof is open, and what is directly below the work.
- Scaffold: where it stands, what it oversails, and how materials and waste move.
- Services in the roof space: old wiring, tanks, flues and vent pipes.
- The new escape route and the fire strategy, which usually reshapes the whole stair.
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
Does a loft conversion always need a principal designer?
Wherever more than one contractor is involved, which in practice is almost always. The steel, the roof and the electrics are rarely all done by the same firm.
Who deals with the party wall side of it?
A party wall surveyor, appointed separately. It is not part of the CDM appointment, although the party wall position is information the pre-construction information should record.
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.