Loft and extension - how to get confidence in design and price

[MollyVanDer]

Hi everyone
I’m looking for advice as I really don’t know where to go next. I’ve had an architect do drawings and getting planning for a first floor bedroom extension and loft conversion but he said the stairs to the loft had to eat into our box (third) bedroom as building the staircase on top of the current staircase wouldn’t leave enough height for people coming up from ground to first floor. I got another company who specialises in lofts round and they said it was fine to put the staircase to the loft running from our existing staircase just bend around and no rooms need to be effected. So now I don’t know who to believe!
Ive also got a builder who works with my architect telling me £100k for the job and the loft specialists are saying £150k so a massive difference.
What I’d like to do is appoint someone who can do the detailed design that I have confidence works and meets building standards and lists out all the materials needed so that everyone is working from the same scope I can then to go out to different companies and get final quotes.

What type of professional does all this documentation I.e. a full design and build specification? Is it a structural engineer, quantity surveyor, architect- or a mix? I’ve no idea what professional to go to as I don’t really get what they do and don’t do. I also would prefer to go to one company who do it all rather than different professionals. I’m in Cardiff area.

thanks x

DH is an Architect and is in the process of designing a loft extension for our DS. There are many factors involved. The strength of the main roof beams to start with. DH employs a structural engineer to do the calculations, they have got to be spot on. The next important consideration is fire safety, the building regs are very strict on being able to evacuate from the top floor, this may involve fire doors and other fire proofing of the main exit. DS has to have the ground floor under stairs fire proofed.
Then of course there are the aesthetics, do you want a bathroom up there, a full dormer window, or a Velux. These all add to the cost.
There is a book by Ian Rock called Loft Conversion Manual, publish by Haynes.
im not suggesting DIY, but it will explain a lot.
Hope all goes well.

Argh we are in that neck of the woods and I was hoping more like 70-80k 😬.
We haven’t started the process yet (clearly) but someone did suggest using teams based in the Valleys who cover Cardiff rather than Cardiff based folk.