cost of building an extension

[elmsoft]

I want to extend my semi by building a single storey flat roof extension to the rear. The width of the property is about 6 metres and I think I would be allowed 3 metres depth. So 18 square metres is my starting guess.

Is it possible to estimate a "per metre" cost as a rough indicator of the sort of cost?

 

[HERTS P&D]

£18-20 not including decorating.

Andy

 

[DeludedAussie]

I want to extend my semi by building a single storey flat roof extension to the rear. The width of the property is about 6 metres and I think I would be allowed 3 metres depth. So 18 square metres is my starting guess.

Is it possible to estimate a "per metre" cost as a rough indicator of the sort of cost?

It bothers me that people often patronise forum posts - I am also interested in this

You will hear people quote 1K a square metre but I have yet to see a proper breakdown

Personally I woul like to know what the cost to excavate per sq m is, the cost of concrete, the cost of bricks and mortar , the cost of tiles and so on so I can see where savings can be made if I decide to do the work

To date I have yet to see any breakdown at this level

Instead you get people who create spam and give you answers like £18

 

[noseall]

Personally I woul like to know what the cost to excavate per sq m is, the cost of concrete, the cost of bricks and mortar , the cost of tiles and so on so I can see where savings can be made if I decide to do the work

To date I have yet to see any breakdown at this level

So begs the question, why don't you spend the money and get a Q.S. to do it for you.

Once you have paid for a full reg's drawing you can then pay to get a complete breakdown of the building work. No one is going to be able to give you this level of service on an internet forum.

If you want exact answers you are going to have to ask precise questions. Asking "how much is a brick" is like asking how much is a house. Similarly if you were to ask "how much to lay a brick" you will get similar variants in that dentil or feature work on a gable cost more than running in on a line at ground level.

As for costing the labour processes involved, these will be largely dependant upon the vagaries of your particular job. No two jobs are identical.

 

[mikeey84]

HI Deluded, the reason that you (and others) keep getting "spam" posts giving outlandish quotes/prices is that there are so many variables for something as complex as an extension (or loft conversion, or new build etc) that its only possible to give ball park figures.

If you are in a large modern detached house with good access, and clay soil near a river, in Wales, your extension is going to be very different, cost wise, than if you live in a terrace house in Central London next to the DLR.

Level of finish, type of brick, planning considerations, existing dwelling, access, ground type etc are all going to have a massive impact on your job.

Surely if you want more detail than just a ball park (£1kpersqm) then get a builder in to quote, and ask for a breakdown of costs. You dont have to use the builder, but you can see for yourself what the costs are for each aspect.

There is only so much someone can do from descriptions on a DIY forum.

 

[jeds]

I want to extend my semi by building a single storey flat roof extension to the rear. The width of the property is about 6 metres and I think I would be allowed 3 metres depth. So 18 square metres is my starting guess.

Is it possible to estimate a "per metre" cost as a rough indicator of the sort of cost?

It bothers me that people often patronise forum posts - I am also interested in this

You will hear people quote 1K a square metre but I have yet to see a proper breakdown

Personally I woul like to know what the cost to excavate per sq m is, the cost of concrete, the cost of bricks and mortar , the cost of tiles and so on so I can see where savings can be made if I decide to do the work

To date I have yet to see any breakdown at this level

Instead you get people who create spam and give you answers like £18

I recall a lecture with a QS tutor. She had everybody estimate the cost to build a three storey office block with a footprint of 4000 square feet. Everybody offered a cost. Then she added some basic detail. Costs went in again - obviously slightly revised. Then more detail and so on.

The only point she was trying to get across was that your estimate is only as good as the information you've got. It wasn't a bad lesson because It sticks in my mind. People here can use their experience to visualise what the OP is trying to achieve but if you ask very basic questions you can only expect to get very basic answers.

 

[kingandy2nd]

I want to extend my semi by building a single storey flat roof extension to the rear. The width of the property is about 6 metres and I think I would be allowed 3 metres depth. So 18 square metres is my starting guess.

Is it possible to estimate a "per metre" cost as a rough indicator of the sort of cost?

It bothers me that people often patronise forum posts - I am also interested in this

You will hear people quote 1K a square metre but I have yet to see a proper breakdown

Personally I woul like to know what the cost to excavate per sq m is, the cost of concrete, the cost of bricks and mortar , the cost of tiles and so on so I can see where savings can be made if I decide to do the work

To date I have yet to see any breakdown at this level

Instead you get people who create spam and give you answers like £18

Dear DeludedAussie

Please bare in mind that the people on this forum offer their advice and opinions for free. £1k per sq m is a fair estimate based on the information (or lack of it) given. It is certainly not ‘spam’.

If you want details – go pay someone to give them for your specific project.

It’s your posts that are verging on spam or trolling.

 

[elmsoft]

Thank you

I am very happy with an answer of £1k / square metre.

Obviously, I realise that this is only a "ball park figure" and obviously "it depends".
But equally, it didn't strike me as stupid to ask for a ballpark figure as a starting point and if it makes people happy to indulge in sarcasm I am happy to have helped them boost their self esteem.

 

[noseall]

But equally, it didn't strike me as stupid to ask for a ballpark figure as a starting point and if it makes people happy to indulge in sarcasm I am happy to have helped them boost their self esteem.

It wasn't you bud but that plonka Deluded Arsy.

 

[mikeey84]

To echo Nose- all sarcasm was directed entirely at Deluded, who over the past few months has posted some rather hilarious posts, where sarcasm is the only worthy reply.

 

[elmsoft]

£18-20 not including decorating.

Andy

I guess I might have picked this up wrong - a missing "K" made it seem like sarcasm? - and if so,apologies.

 

[HERTS P&D]

Sorry, I did forget the 'K'. But even if I did put the k in place I'm sure other people would still had a go at the price quoted.

Andy

 

[elmsoft]

Sorry for being so touchy.
I am very embarrassed at being so rude to someone who offers help so promptly