Cost of small extension

G

Gordon Gekko

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Hi,

I appreciate that these things can be a case of “how long is a piece of string”, but I’m hoping someone can give me a very rough idea.

Very approximately, how much should one expect to pay to add a small extension to a standard 1970s/early 1980s 3 bed? It’s a bedroom with ensuite. No planning would be needed I’m advised. Single story out into a back garden. Say a decent finish, nothing absolutely state of the art, but not rubbish either.

Many thanks,

Gordon
 
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20 sq metres is a decent size for bedroom & ensuite.

What's access like? Is there a side entrance?

Assuming Dublin location?

Assuming since it's a bedroom, there's no requirement to 'open up' the house, you're literally talking about sticking an extension onto the existing house, with a doorway into it?

There are certain fixed costs, so the price per sq metre for a small extension will be higher than a larger one. For anything decent, no structural changes to existing, you're looking at 40k+. I'd add another 5k for the ensuite, plumbing, etc. Costs of ensuite depend very much on fittings, etc. For example if you wanted it to be wheelchair accessible wetroom, or standard toilet & shower.

I think your problem will be finding a recommended builder to take on a smaller job like this.
 
Hi RedOnion,

Thanks for replying.

Yes it’s in Dublin and yes there’s a side entrance. There won’t be a need to ‘open up’ the house but it does need to be a wheelchair accessible wetroom.

I suspect it’ll be less than 20 sq m; that it’d be big enough, wouldn’t it?

Sorry, I know very little about this kind of thing.

Thanks.
 
Gordon Gekko said:
I suspect it’ll be less than 20 sq m; that it’d be big enough, wouldn’t it?
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20 sounds plenty big to me.

Double bedroom standard is about 10 sq metre. I'd go a bit bigger to be more accessible for wheelchair. You'd get away with smaller with a single bed.

Wetroom maybe 5 or 6 sq m to allow room for a 2nd person to assist comfortably.

There isn't going to much difference price wise going up or down 10% in size. There's going to be a minimum cost no matter how small you go.

Not a recommendation, but maybe have a look at the companies that do garden offices and home extensions. They might give an idea of a fixed price as a starting point.
 
Allow about €1200 per sq meter for the building costs so somewhere around 30k bathroom is your “how much is a ball of string stuff” but 5-8k would be a decent en-suite.
 
@Gordon Gekko
Something to watch out for when you talk about size / costs. Check if you're being quoted based on internal floor area, or total footprint.
An internal floor area of 20 sq m would be 22-24 sq m footprint using traditional construction methods.
 
Besides what sort of roof influencing the cost, another thing to consider is, depending on the layout, providing access to your waste/sewerage pipe could make a fair impact on your wallet.
 
I'd agree with the estimate of 40k ish plus the bathroom fittings. I have just built a small kitchen extension, not in Dublin though, and it cost 23k, now it's smaller than OP suggested, I've just had to measure it as I sit here in the freezing cold kitchen as obviously with lockdown I can't progress the rest of the work! It is roughly 10 sq m, 5 m opening of house and rsj plus sloped roof, 2 velux, 1 ordinary kitchen window and one floor length big window. Included electrics/plumbing but no fittings. Poor access, footpath width only around side of house but it only took one day with mini digger and two men to dig out foundation, not as big a deal as some builders made it out to be!
 
Those prices are very saucy. Exclusive of VAT. Another 6-8grand to remove wall and connect to house. Another 5k for a WC.

The original poster would be looking at 52200 euro for 20sq m extension with no access to the existing house. Crazy.
 
PebbleBeach2020 said:
Those prices are very saucy. Exclusive of VAT. Another 6-8grand to remove wall and connect to house. Another 5k for a WC.

The original poster would be looking at 52200 euro for 20sq m extension with no access to the existing house. Crazy.
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I'm not sure they're on the 'crazy' scale. It's not that much higher than I estimated.

Any idea what it should cost?
 
I would have quotes under 2000 per sq metre but that's finished (tiles, painted, fittings etc)

Quotes are they builders finish or final finished?

From experience of quotations, I'd say 1500 per sq metre builders finish.
 
PebbleBeach2020 said:
I would have quotes under 2000 per sq metre but that's finished (tiles, painted, fittings etc)

Quotes are they builders finish or final finished?

From experience of quotations, I'd say 1500 per sq metre builders finish.
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Sounds very cheap for Dublin, 2k - 2.5k seems to be the norm now unfortunately, often more so for small extensions as there's a certain amount of fixed costs that are the same no matter the size.
 
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