Loft conversion cost per m2: what the job involves and who is registered to do it

How loft conversion cost per m2 works

1. Settle whether it is permitted development. A great many loft conversion are permitted development, which means no planning application, but the limits on depth, height, materials and how much of the plot is already built on are specific and a designer should read them against your own house before anybody prices anything.
2. Get drawings and a structural design. Existing and proposed drawings, then a structural engineer's calculations for whatever is being opened up or carried. On a loft conversion this is a small share of the total and it is what turns an idea into something three builders can price identically.
3. Serve the party wall notices in time. Work on or near a shared wall, or excavation within three or six metres of a neighbour's foundations, engages the Party Wall etc. Act and the notice periods are set in months rather than weeks. Serving late is the commonest reason a start date slips.
4. Price it against a specification, not a sketch. Ask each builder to price the same written specification, with provisional sums shown as provisional sums. Two quotes that differ by a third almost always differ in what is included: the kitchen, the flooring, the decoration and the drainage diversion are the usual absentees.
5. Agree stages, retention and building control. A staged payment schedule against completed work, a small retention until sign-off, and a clear statement of who is notifying building control. The completion certificate is what a future buyer's solicitor will ask for.

Insurance and paperwork

Common questions

So what should I compare instead?

The four groups: structure, envelope, services and finish, each priced against the same written specification. Two builders pricing the same specification will differ in ways you can see and ask about; two rates per square metre will not.

Is the rate useless?

Not useless, but it is a sanity check rather than a decision. It is most meaningful between two conversions of the same type in the same house, which is exactly the comparison an owner rarely needs to make.

How do I compare a quote that includes an ensuite?

Take it out and price it separately. Bathrooms carry a wide range of specification and they are the single easiest thing to make a total look competitive by trimming.

Registered contractors by region

• Registered roofers in the East Midlands postcode area
• Registered roofers in the East of England postcode area
• Registered roofers in the London postcode area
• Registered roofers in the North East postcode area
• Registered roofers in the North West postcode area
• Registered roofers in the Scotland postcode area
• Registered roofers in the South East postcode area
• Registered roofers in the South West postcode area
• Registered roofers in the Wales postcode area
• Registered roofers in the West Midlands postcode area
• Registered roofers in the Yorkshire and The Humber postcode area