Rough costs to extend an extension!?!?

R.O.S.S.I

R.O.S.S.I

R.O.S.S.I

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Bit of a long shot this really but just wondering if anyone can help me out with a couple of ball park figures.

Been looking at some houses recently and spotted one today which is a bit of a do'er up'er. Its a 2 up 2 down semi detached house but with a fairly large garden and has recently had a utility room extension (9ft by 8ft) built onto the back of the house behind the kitchen.

The utility extension doesn't span the whole width of the house at the back so I was wondering that the costs might be to extend the current extension by about 5ft so that it does run the full width of the house. This will enable us to knock through from the kitchen to make a sizeable kitchen/diner and make the house a whole lot more appealing.

Is there any way of working out the rough costings? And are there any other considerations to make other than the fact that it will need the roof extending by about 5 ft and 2 walls rebuilding again (with appropriate footings)?
 
A lot depends on how the original extension was built. Is it flat roofed or tiled. What sort of floor does it have, suspended boards or concrete?

Sounds silly but lots of the cost will depend on the above.
 
Its a concrete floored extension and has a pitched tiled roof. All built within past 3 years or so as it all looks in very new condition.

I'm thinking I could do a lot of the manual labour of digging out the footings for the extra bit myself so it would just need some labourers to come and put the new walls in and extend the current roof.
 
You can work out the sq mtr area of the additional walls, & get some idea of cost for them, it's 60 bricks & 10 blocks to one square metre.

Some builder merchants offer cash accounts, I have several, one gives me around 30% discount, so it might work out cheaper sourcing brick/ blocks, etc yourself.
 
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Have you checked to see if you will need planning permission to extend the existing building, some smaller extensions don't need permission. As what you want to do would make it full width then it may need permission.
 
maccapacca said:
£2000 a sq m
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Got a few too many noughts Macca.:eek:

Don't know the actual width, length, depth of footings, whether it's a simple lean too roof with half gable end, etc,etc, but around £2k, maybe 2.5k depending on area, work involved.

You also have the work for removing the wall for the opening, there will be a rsj need to support the load from above.

Rough calculation from your dimensions, blockwork 12-13sq mtrs 130-150 blocks, 777 bricks, allow extra for 10% for breakages.

Roof tiles inter locking say Marley Ludlow 16 tiles per sq mtr, so it's fairly easy to work out your roof area & cost it, again allow 5% for breakages.
 
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Thanks for those figures Nightglow, starting to get a better idea of whats involved. Stuff like the footings I can dig out and do myself really as its not a huge area.

Its just the rest that'll need someone proper to come in. Will need someone to take out the left hand wall and then build the new walls to make the room bigger. The roof is a simple lean too roof with half gable ends so will just need to be extended.

29blzeb.png


That's a very crude drawing of the layout of the house atm (based on dimensions on property listing and from memory).

The grey area top left is what I'm referring to being extended. So the extension will run the full way across instead of stopping where it does. We want to remove the downstairs WC then we'd like to knock through in the kitchen to open it right up.
 
With all due respect theres more to it than blocks, bricks and roof tiles.
£2k / sq metre isnt many miles away from an all in figure.
Assuming you dont need planning permission, you will still need building regs which round here is best part of £500.
Then theres all the things that havnt been mentioned such as wall ties, wall insulation, floor slab, floor subbase, floor insulation, roof truuses, roof battens, roof felt, roof insulation, fascias, gutters, drainage if required, plaster boards, plastering, floor and wall finishes, window if required, electrics, electric testing and certification, heating, skips for waste etc.

And I've probably missed some stuff as well.
 
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Possibly need structural re enforcement to support the main house wall if you intend to knock through a large part of it. By that I don't just mean a big RSJ!
 
dholdi said:
With all due respect theres more to it than blocks, bricks and roof tiles.
£2k / sq metre isnt many miles away from an all in figure.
Assuming you dont need planning permission, you will still need building regs which round here is best part of £500.
Then theres all the things that havnt been mentioned such as wall ties, wall insulation, floor slab, floor subbase, floor insulation, roof truuses, roof battens, roof felt, roof insulation, fascias, gutters, drainage if required, plaster boards, plastering, floor and wall finishes, window if required, electrics, electric testing and certification, heating, skips for waste etc.

And I've probably missed some stuff as well.
Click to expand...

I don't think anyone is saying it is just bricks, blocks and roof tiles. It was just a general musing really, I was just after some rough prices which I've now got and I'm a bit more aware of what's involved!
 
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dholdi said:
With all due respect theres more to it than blocks, bricks and roof tiles.
£2k / sq metre isnt many miles away from an all in figure.
Assuming you dont need planning permission, you will still need building regs which round here is best part of £500.
Then theres all the things that havnt been mentioned such as wall ties, wall insulation, floor slab, floor subbase, floor insulation, roof truuses, roof battens, roof felt, roof insulation, fascias, gutters, drainage if required, plaster boards, plastering, floor and wall finishes, window if required, electrics, electric testing and certification, heating, skips for waste etc.

And I've probably missed some stuff as well.
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It's only 8'x 4' 3", roughly 34sq ft, so around 3.3 cubic metres of concrete for a floor, plus footings 1.4 cubic metres (estimate, don't know ground conditions)
Concrete 100mm Dense 7n blocks, last lot I bought was £58 inc vat for a pallet of 72 with my discount, usually around £75 per pallet.

There isn't too much timber, your looking at C16 grade at 400-600mm spacing, plus wall plate.

Did forget building regs costs, but you might get away with 'Permitted Development Rights' not requiring an application for planning permission, but it still has to conform to building regs.

http://www.planningportal.gov.uk/permission/commonprojects/extensions/
 
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Nightglow said:
It's only 5'x 4' 3", roughly 21 sq ft, so around 3.3 cubic metres of concrete for a floor, plus footings 1.4 cubic metres (estimate, don't know ground conditions)
Concrete 100mm Dense 7n blocks, last lot I bought was £58 inc vat for a pallet of 72.

Did forget building regs costs, but you might get away with 'Permitted Development Rights' not requiring an application for planning permission, but it still has to conform to building regs.

http://www.planningportal.gov.uk/permission/commonprojects/extensions/
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Hmmm not sure if im reading that web page correctly but sounds like I don't need to seek for planning permission for and I just need to adhere to building regs?

I did a search online to see if I could find the planning application for the current extension (if there was one) but there is nothing online. I thought any sort of extension like that you needed to get plans and planning permission from council? Or am I completely wrong?

With me not being able to find the extension on our councils planning permission portal I'm thinking it may come under the 'Permitted Development rights' which is a bonus.
 
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R.O.S.S.I said:
Hmmm not sure if im reading that web page correctly but sounds like I don't need to seek for planning permission for and I just need to adhere to building regs?

I did a search online to see if I could find the planning application for the current extension (if there was one) but there is nothing online. I thought any sort of extension like that you needed to get plans and planning permission from council? Or am I completely wrong?

With me not being able to find the extension on our councils planning permission portal I'm thinking it may come under the 'Permitted Development rights' which is a bonus.
Click to expand...

Your extension might have been built as a 'Permitted Development' maximum area 15m2 if my memory is correct, therefore you won't find the planning permission your searching for.
 
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As a general rule of thumb we advise clients to allow in the region of about £1500/m2 based on a shell out. Would include for plastering and wiring with basic light fittings etc but not kitchen / bathroom fittings (although you might get them fitted for that). There are obvious regional variations but 2K/m2 certainly isn't unheard of, also the smaller the project the higher then m2 rate will be as building doesn't really "scale" that well at micro levels.

Its a little bit of a "how big is a shed" question though as you can spend vast amounts on finishes.
 
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Thanks for all the info peeps, I know it was a bit of a vague "how longs a piece of string" sort of question but appreciate the responses no less.
It might be something that we do a few years down the line really if we decide to go for the house because on reflection it would still be a very decent sized kitchen diner if we opened up what is there already.

Might make more financial sense to save opening it up fully until we want to add in a new kitchen, would be more viable to do an upstairs extension too at the same time.
 
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