Prices for an extension to a semi detached

BritanniaJaf

Well-known Member
Anybody any ideas of rougly what an extension to my semi detached would cost, am hoping to have a games room and dining room downstairs and 2 bedrooms upstairs,i was thinkng about it would cost about 40k upwards but other people have told me woudn't be any more than 25K
 

mason

Active Member
it depends on the size and finish

I have clients that carry out extensions to residential properties and the vary from between £25-£100k.
 

Pat_C

Novice Member
BMURRAY9 said:
Anybody any ideas of rougly what an extension to my semi detached would cost, am hoping to have a games room and dining room downstairs and 2 bedrooms upstairs,i was thinkng about it would cost about 40k upwards but other people have told me woudn't be any more than 25K
I had a similar sized extension built last year (maybe smaller - 1 new bedroom and bathroom upstairs) and the building work alone was £44k. Obviously there are a lot of variables though, and the final cost including all fixtures, fittings etc was around 1.5 times that.

The first step is to get quotes from architects (which vary wildly - and I suggest you ignore those who include expensive project management). In the meantime establish a list of reputable builders to ask for quotes once you have the plans and planning permission (many will only quote once you have this). The best way to do this is through people you know who have had work done, or even local people that you don't know but noticed them having building work done. It's a good idea to view their previous work. Never pick one who hasn't been recommended by someone you believe you can trust as there are far too many horror stories around.
 

Andy98765

Distinguished Member
I just had an extension done and it cost me £23K for a downstairs expansion (7.2M x 3.2M) of my existing dinning room (Changed to a very nice games/home cinema room). Lessons learnt.
1. Do get a good architect.
2. Plan all your power outlets and lighting requirements up front
3. Plan your heating requirements.
4. Submit with your plans your exact requirements, finish, electricals, heating and get the builder to give a complete cost, querie any vague answers you get back in his quote.

In the end I went for a builder who took all this on board, priced against my specs for ALL, electrical, lighting, new fuse boxes, heating and other requirements. If I did not price this in I estimated it would have cost me a small bundle, as it was from start (ground works) to completely finished took 4 weeks. Shame the council permissions where not quicker.
 

GW43

Well-known Member
For insurance purposes, rebuilding costs are around £60-£110 per square foot (2004 prices).

This obviously does not include the land, as it assumes you will have that already.

This may however include site clearance, whiich you would not need, so it may be best to assume £50-£100 per square foot, for each floor required.

Erring on the high side, a 20'x10' extension on 2 floors would be 400sq ft, therefore £40K.

Obviously then there will need to be taken into account any special materials, extras etc.
 

pave

Banned
Good advice in the posts,

Always have a spec done,get quotes for all items in the spec,also agree a rate at which any extras will be costed...get this in writing,

Do not pay any money up front,agree a timetable of payments,

For example ,every two weeks ......only pay when you are happy with there valuation of works carried out,check work carried out ,

There are good builders out there,just do a bit of research,

Prices can vary alot ,so ,as previous posts,always get 3-4 quotes,
 

Pat_C

Novice Member
pave said:
Do not pay any money up front,agree a timetable of payments,

For example ,every two weeks ......only pay when you are happy with there valuation of works carried out,check work carried out ,
I agree, absolutely no payment in advance. My payment schedule was defined by staged completion of work e.g. footings dug out and passed by the building inspector, building up to the damp course, up to roof level etc. That seems to me to be the best way of doing it. And it is advisable to hold back at least 10% of the total as a final payment once everything is completed. I've heard lots of stories of people paying everything on the basis that the builder will return and finish minor things off - and then never seeing him again.
 

Pat_C

Novice Member
Having an extension built can be quite stressful. However this can be reduced by being ahead of the game in terms of choosing fixtures and fittings. Before my building work had even started we had chosen two bathroom suites with all the fittings, wooden flooring, light fittings, switches and power sockets, floor and wall tiles etc. Don't underestimate the time it takes to choose (and agree on) all of this stuff, or the stress it will cause you if you leave it until just before the builder needs it to fit. Particularly when you find that some stuff has a 4-6 week delivery time.
 

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