Building an extension - any rule of thumb for costs?

[garycat]

Hello,

We're thinking of buying a bungalow in a really nice area and it has a great garden.

But, the kitchen is too small and will need extending and I also need a study as I work from home sometimes. So, is there any rule of thumb for the cost of building a single storey extension about 2m x 4m (pitched roof) for the kitchen and the study will be about 3m x 2.5 with a flat roof as it will be ajoining the existing rear wall of the garage.

Any ideas appreciated.

[mrmaggit]

£1k-£1.5 per square metre depending on fittings

[Iain328]

garycat said:

Hello,

We're thinking of buying a bungalow in a really nice area and it has a great garden.

But, the kitchen is too small and will need extending and I also need a study as I work from home sometimes. So, is there any rule of thumb for the cost of building a single storey extension about 2m x 4m (pitched roof) for the kitchen and the study will be about 3m x 2.5 with a flat roof as it will be ajoining the existing rear wall of the garage.

Any ideas appreciated.

Rule of thumb always used to be £100-£120 a sq foot so £1000-£1200 per sq metre. For a relatively small project I'd add at least 30-50% to that.

...and then add 10-15 grand for a decent kitchen!

Can't see you getting much change out of £35K but it all depends on the standard to which you build & equip of course.

[Jasandjules]

Yep, budget 2k per m2. Then hope for the best..

[mrmaggit]

Iain328 said:

garycat said:

Hello,

We're thinking of buying a bungalow in a really nice area and it has a great garden.

But, the kitchen is too small and will need extending and I also need a study as I work from home sometimes. So, is there any rule of thumb for the cost of building a single storey extension about 2m x 4m (pitched roof) for the kitchen and the study will be about 3m x 2.5 with a flat roof as it will be ajoining the existing rear wall of the garage.

Any ideas appreciated.

Rule of thumb always used to be £100-£120 a sq foot so £1000-£1200 per sq metre. For a relatively small project I'd add at least 30-50% to that.

...and then add 10-15 grand for a decent kitchen!

Can't see you getting much change out of £35K but it all depends on the standard to which you build & equip of course.

Yes, I agree, especially when you start factoring in all the plumbing, electrics etc. 1-1.5k/m2 is just shell cost.

[s4avant]

I'd go along with iain328's figures but you'll need to add Vat @15% and any professional and Local Authority fees ( Planning and Building Warrant )that might be involved.

[ss64ii]

My neighbour had a quote of £11500 to build a 2.4mx2.4m flat roofed extension. I did it for just under £9k.
HTH.

[garycat]

ss64ii said:

My neighbour had a quote of £11500 to build a 2.4mx2.4m flat roofed extension. I did it for just under £9k.
HTH.

Sounds good, although my extension for the study will only have 2 sides as it will be butted against the back of the garage and the side of the house (if this is OK according to building regs)

[JCW]

Presumably you double that for a two storey extension? Example - 10m2 = £20,000 x 2 storeys = £40,000?

[mrmaggit]

No quite, because you only have one roof, regardless, but it's a good guide to work from. Always better to be surprised if it's cheaper than pee'd off if it's more money.

[Busamav]

garycat said:

ss64ii said:

My neighbour had a quote of £11500 to build a 2.4mx2.4m flat roofed extension. I did it for just under £9k.
HTH.

Sounds good, although my extension for the study will only have 2 sides as it will be butted against the back of the garage and the side of the house (if this is OK according to building regs)

Its ok to back to the house , but the U value thro' the garage wall will need to be upgraded, possibly by either a skin of block or a stud partition against it .

[Incorrigible]

Rule of thumb is "twice the original estimate"

HTH