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Cost per square metre for single story vs 2 story dwelling


smart51

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I'm currently putting thoughts together for a future (hopefully soon) self build.  I often see  figures like £2000 per square metre as a guide.  I assume that's for a 2 story house.  How does it vary for a single story house of otherwise the same construction.

 

So a 200m2 2 story house has a foot print of 100m2 and at £2k per m2, the build cost would be £200k.

If that were a 200m2 single story house, with a 200m2 footprint built to the same standard, would would be a good cost estimate?

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Crikey, it's a matter of determining how long a piece of string is...

 

Broadly, the larger the floor area the more floors it justifies. 

 

At a guess, from viewing developers catalogues for one off houses with prices, < 120m2 for a single story, 120-240m2 for 2 story etc etc. 

 

Obviously if you get a superb price for foundations and roofing it sways the deal. 

 

 

 

 

 

 

 

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General rule I've heard before is an additional floor to the ground floor costs approx 50% less than the ground. 

 

A bigger factor tho is economy of scale, I.e. the bigger and simpler, the cheaper. And how quickly to can build it so inflation and increasing costs don't drive it up too much.

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Cost per m2 will always be more for a single story compared to two story 

Apart from taking up more ground 

You are increasing the size of your foundations One of the more expensive parts of many builds 

We spent more than a quarter of our entire budget getting out of the ground on our previous build 

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I would add that design is the bigger factor to cost rather than size. 

I think if I had changed my design, different roof, less weird angles, different materials. 

I think I could build my place for £100,000 less than it’s going to cost. 

 

Square box, red tiled roof, plastic facia and gutters. 

Probably why the developers stick to a certain design. 

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There is a plot of land up for auction that we have our eye on.  It is between back gardens and allotments.  My concern is that the council might impose a height limit on any development which would mean a single story building.  Before we get in too deep, I want to know what that might cost.  There is enough room to do what we want with a single story building  but I'd prefer 2 stories and a bit more space between the house and the boundaries.

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It could be the design allows for a single story construction on the allotment side and a 2 story construction on the housing side..  

 

With a big sloping roof...

Edited by Marvin
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18 hours ago, nod said:

If you budget at around £1500-2000
m2 build cost on good ground 

Plus all the usual fees Buying - Surveys Conections etc

 

I think you'd be very lucky there! 

 

We are building a mid-high ish spec bungalow, 250sqm and when we got quotes last August we received 5 detailed quotes all for around £2500 - 3000psqm.

 

That's for ASHP, MVHR, lots of big aluminium windows, big posh slidding doors, upgraded insulation  etc etc. Turn key build though not inc usual fees & paperwork. 

 

We managed to get that down to around £2100 when our favourite builder (but also one of the more expensive ones) had a commercial cancellation that overlapped perfectly with our needs, so got a good deal off him, if we fitted to his time framen (which itself caused plenty of headaches) . 

 

 

Edit: we also assumed around 15-20% extra for single story vs 2 story. 

Edited by Andehh
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It depends on how you go about your build 

For arguments sake If the total brickwork cost was 20k your builder will nearly double that 

Everything will come with a very large mark up 

 

Some friends of ours have even been charged vat on some of the work they had done while using a main contractor 

 

Our build is 416 m2 and we will complete it to a very high spec within the 350k that we have budgeted 

 

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On 11/03/2022 at 23:19, smart51 said:

I'm currently putting thoughts together for a future (hopefully soon) self build.  I often see  figures like £2000 per square metre as a guide.  I assume that's for a 2 story house.  How does it vary for a single story house of otherwise the same construction.

 

So a 200m2 2 story house has a foot print of 100m2 and at £2k per m2, the build cost would be £200k.

If that were a 200m2 single story house, with a 200m2 footprint built to the same standard, would would be a good cost estimate?

someone correct me if im wrong but its not the footprint you work costings on its the internal floorspace so if its 200m2 then at 2k/m2  thats 400k??

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On 13/03/2022 at 08:17, nod said:

It depends on how you go about your build 

For arguments sake If the total brickwork cost was 20k your builder will nearly double that 

Everything will come with a very large mark up 

 

Some friends of ours have even been charged vat on some of the work they had done while using a main contractor 

 

Our build is 416 m2 and we will complete it to a very high spec within the 350k that we have budgeted 

 

 

With the greatest of respect though -and please correct me if I'm wrong-but I believe you are undertaking some of the work yourself? Thus giving you a greater saving on psqm cost. 

 

Most self-builders will be in the same boat as me, not able to do any work Inc project management so will need to assume full builder fees. :)

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10 hours ago, Amateur bob said:

someone correct me if im wrong but its not the footprint you work costings on its the internal floorspace so if its 200m2 then at 2k/m2  thats 400k??

That's correct.

 

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15 hours ago, Amateur bob said:

someone correct me if im wrong but its not the footprint you work costings on its the internal floorspace so if its 200m2 then at 2k/m2  thats 400k??

Internal floor space?  I'd assumed external foot print, so including the external walls.   If I have to build a single storey, there's about 10% difference, slightly more at two stories.  I like errors in my favour.

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50 minutes ago, smart51 said:

Internal floor space?  I'd assumed external foot print, so including the external walls.   If I have to build a single storey, there's about 10% difference, slightly more at two stories.  I like errors in my favour.

But they are all estimated, the estimate will change hugely, based on building shape, size, build type, external and internal finish, flat roof, pitch roof, insulation levels, ventilation/ airtightness, heating type (gas, ASHP,gshp, UFH radiators) etc etc.

 

Two different kitchen designs can change a build budget by £50k, the amount windows can change it again by £20 to 30k with ease, uPVC or Ali clad can change it again by the same amount.

 

My thoughts are for a basic start point.

 

£2k to £2.5k per M2 with someone else doing all the work will be a basic ok performance house, so 400k for 200m2 two storey.  Add a good 10 to 15% on for single storey but depends on roof complexity (our roof added about 25% to m2 cost).  The more bells and whistles and any changes you make along the way will add quite quickly.  The above assumes limited or no landscaping, painted internally a single colour.

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20 minutes ago, JohnMo said:

But they are all estimated, the estimate will change hugely, based on building shape, size, build type, external and internal finish, flat roof, pitch roof, insulation levels, ventilation/ airtightness, heating type (gas, ASHP,gshp, UFH radiators) etc etc.

 

Two different kitchen designs can change a build budget by £50k, the amount windows can change it again by £20 to 30k with ease, uPVC or Ali clad can change it again by the same amount.

 

My thoughts are for a basic start point.

 

£2k to £2.5k per M2 with someone else doing all the work will be a basic ok performance house, so 400k for 200m2 two storey.  Add a good 10 to 15% on for single storey but depends on roof complexity (our roof added about 25% to m2 cost).  The more bells and whistles and any changes you make along the way will add quite quickly.  The above assumes limited or no landscaping, painted internally a single colour.

Good point 

The amount of work that you do yourself will have a massive impact on your costings 

It seams a long time since we came in at 815m2 At a very good standard 


Something I have notice this time 

Planners have included our detached garage - workshop 

Last time while we included the material We didn’t add any m2 for the garages 

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  • 2 weeks later...
On 12/03/2022 at 08:09, nod said:

Cost per m2 will always be more for a single story compared to two storey

Ahhh, I don't think it is quite that simple.

It is that word 'always'. I would agree with nearly always.

 

For a conventionally designed house yes.

When open plan or large rooms are designed then that changes because everything gets technical and heavy.

 

Plus when you allow for the loss of useful space for the stair and the stair approaches x both floors, the useful space is reduced. This applies much more proportionally to a small house.

 

For non-domestic, which is my thing, I would tell a client at first meeting that it was much the same cost £m2 of useful space, and the use of valuable ground might be more important. Lifts also add to the cost and loss of space. Single storey easier and safer too, as there are no holes in the floor and don't have to carry plasterboard up. 

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  • 1 year later...
On 11/03/2022 at 23:19, smart51 said:

So a 200m2 2 story house has a foot print of 100m2 and at £2k per m2, the build cost would be £200k.

 

It's total floor space and not just the ground floor space.  You got my hopes up for a moment that I could halve the project costs!

Edited by flanagaj
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12 minutes ago, nod said:

We are over 400 m2 total floor space including the garage and look set to complete within our 350k budget 

 

Be wary taking notice of this, this is not a standard build. It's like buying a car and not including the engine as you made it yourself.

 

Normal costs are an absolute minimum of £2.5k m2 NOT including groundworks.

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3 hours ago, Dave Jones said:

 

Be wary taking notice of this, this is not a standard build. It's like buying a car and not including the engine as you made it yourself.

 

Normal costs are an absolute minimum of £2.5k m2 NOT including groundworks.

What’s not standard about it 

It’s as self build as your going to get 

 

How your build going Dave ?

Post some figures up

 

There a full spreadsheet of our previous build on her 815m2 

Bit before your time on here 😁

Edited by nod
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