Extension - is it more cost effective to have one firm to everything inc plans

[EssexMummy123]

Or is it better to get plans done separately and then find a building firm? or separate builders & tradespeople?

any ideas?

Depends on how much time you have to be able to co-ordinate everyone in site. I naively thought I would be ok to manage it myself but when I weighed up everything that needed done I couldn't be bothered with the hassle tbh whilst holding down a busy full time job
Next time I would just get builder to draw up plans as pretty bog standard rear extension, thought our architect was rubbish and bit worth the cost, lesson learned for next time!!
Mind I have sourced a Lot of the internal stuff myself by scouring internet for hours and have saved a fortune even when taking builders discount into account, for example I have just managed to source 2 large 4 column radiators for £260 on ebay when exactly the same ones would have been 398 +VAT through builders supplier.
I'm a bit dad though and enjoy the research part

Bit sad even

A friend got the same firm to design and build a rear kitchen extension and loft conversion for them. It didn't go well - as the build went in, lots of issues came up which you'd have expected to be ironed out before the drawings were signed off. There were also lots of issues where bits of work were not good quality, and they had trouble arguing the point with the builders because there was no-one else on their side.

I suspect SOME design and build firms are inclined to design things to suit themselves rather than the client - though I'm sure many are fine. For our project (extension plus renovating various bits of existing house) we've got an architectural technician to do our drawings and have been very happy with his work. We're also getting him to supervise the project, so that hopefully if problems arise we have more chance of getting a satisfactory outcome.

But if it's a relatively simple project, and you can get good references, I'm guessing design and build would be ok.

PS I personally wouldn't employ the trades directly, I'd always go for a main contractor, just because I don't have the time or inclination to coordinate all the work and deal with unreliable tradesmen derailing the project :-)

Do it properly and get the plans drawn up by a decent architect first, this way you can get accurate quotes from local builders. If you go down the builders designing it how can you compare quotes like for like? We've had 6 builders round and given them drawings and spec to price up against and every single one said its a breath of fresh air having all the information there. I asked one of them how do you price up without this information, all he does it put in a really high price and if he gets it happy days. So really worth spending a little at the start to get correct quotes

We found an architect through recommendations and he designed our extesion. He offered various levels of service, from basic drawings through to detailed design specification with project management and managing of the tendering process. We went with the top level service as we have no idea about building both work full time and don't have the time or skills to manage a build on our scale.

Our two-storey extension started at the end of September and we are just waiting for some final decoration work to be done. We've been really happy with the builder and all the other trades he has used.

We did specify that we wanted the builder to use our gas engineer as he'd fitted the new boiler in July and knew our heating system already. He was quite happy to do this and has been so happy with his work that he's using him to do the plumbing and heating in a new house he is building.

Don't manage the trades yourself unless you are a builder with plenty of experience.

Get an architect to draw up the plans. Get detailed quotes from three builders. Get a Quantity Surveyor or the architect to manage the project and sign off on the interim payments. Make sure your architect and builders are not buddies.

Whenever I see or hear people trying to cut corners I look forward to hearing how the project went. Cheap? Quick? Proper finish standard? Mmmmm, thought not.

Thanks all - think we'll follow what shabby said about getting the plans and spec done first and then start getting quotes rather than going for the one stop solution.

AddtoBasket - just spotted your reply as well, thanks for that.

Does all of this apply if only basic and tiny extension (2m x 3m) required without having to alter the existing house? (opening already exists)

Mm - we are doing a one storey extension. The builder has just done our kitchen / diner extension and we are very happy with the quality of his work and his communication. We intend to get a couple more quotes but would be looking to use our builder.

We got the plans drawn up by an architect and are about to put in for planning.

Meadow, up to you, but if you have to go through planning you might aswell use an architect, they will then sort planning application and sort your building regs aswell, as an indication of cost, we put in planning to re built a lean to conservatory at 4x3 in brick and a first floor extension above another existing extension which is 3x3. Planning and drawings cost £850 then same again after permission granted for full building regs , construction drawings and engineers report. So cost under £2000 in total which I think is worth it to remove all the later problems

The builders use building regs drawings or architects specification to cost & build so this is important to get right.Most of the focus is usually on the planning phase.The guy who did our regs was excellent, he got involved onsite when we needed him during the build and this was invaluable Check what support you will get during the build as some architects charge a fortune.You can definitely save money if you shop around for the fixtures, radiators,doors and windows.

We got an architect to do drawings and a building regs package, we didn't need planning but double checked we didn't with the council anyway.

Our builder does everything, he has all his own workman from electricians to decorators, sorted out windows and doors and just runs everything by us first. We still make all the decisions on what we want. Much easier than finding all the serpents people and coordinating it all ourselves. It's been quite painless.

Serpents? Ha! Separate even. We have no serpents.