House extension, single double? Builder or project manage?

[Hereward]

Planning a house extension approx. 90m2 it will either be two storey 45m2 a floor or single storey 90m2.

Conflicting views as to if two storey is cheaper per m2 than single.

Most online advice seems to say the second storey only adds 50% to the single storey cost, but having spoken to a builder he says that if you have to cut into an existing roof (which we would) and make new openings on both floors to existing house, plus the scaffolding etc., he says in reality there is very little in it.

Cost per m2 seems to suggest £1500-2500m2, if I worked on £2k/m2 would I be far out.

Secondly get a builder for a turnkey job or project manage it myself? Obviously I'm about all the time and as with most farms have access to telehandler, storage etc., that the average homeowner doesn't. Have a reasonable contact list of tradesmen.

 

[Will Blackburn]

Manage it yourself, otherwise the PM that you pay to work for you, will side with the trades.

 

[Hereward]

Manage it yourself, otherwise the PM that you pay to work for you, will side with the trades.

Sorry by project manage I meant do it myself, I don't want to DIY (want a quality finish!), but could organise all the relevant trade professionals.

 

[Will Blackburn]

Sorry by project manage I meant do it myself, I don't want to DIY (want a quality finish!), but could organise all the relevant trade professionals.

That’s what I thought. If you think you can organise the trades, then you definitely can.

 

[br jones]

Planning a house extension approx. 90m2 it will either be two storey 45m2 a floor or single storey 90m2.

Conflicting views as to if two storey is cheaper per m2 than single.

Most online advice seems to say the second storey only adds 50% to the single storey cost, but having spoken to a builder he says that if you have to cut into an existing roof (which we would) and make new openings on both floors to existing house, plus the scaffolding etc., he says in reality there is very little in it.

Cost per m2 seems to suggest £1500-2500m2, if I worked on £2k/m2 would I be far out.

Secondly get a builder for a turnkey job or project manage it myself? Obviously I'm about all the time and as with most farms have access to telehandler, storage etc., that the average homeowner doesn't. Have a reasonable contact list of tradesmen.

Build an extension with easy access and free spoil tip ,1200 m2,plust floor coverings ,bath suit, kitchen ,so 1200m2 to a plastered stage.
As to single or double ,thats up to you ,footings the same cost , roof the same cost,floor joists and a tad more block work

 

[Wurzeetoo]

We have a single storey extension on our house we’ve recently bought. I spend most days wishing for the small escalated cost they would have gone up a floor as said above most costs have to be incurred your just paying for the middle bit

 

[B R C]

If you have time to manage it then it will considerable cheaper, for one a lot of the self employed tradesmen will not charge you vat, costs will be paid from taxed money so you can save an awful lot using your own time.

 

[Lincs Lass]

Project manage it yourself ,,you dont have to do any work ,you can control the spending ,all the communication with planning building control,materials ordering ,,set up trades accounts with materials suppliers and stick to them , if your trades folks require anything ,let them use only the places you have agreed to and have all invoices signed by said trades and hand over the invoices ,,they have a habit of ordering stuff for their own jobs (weekend back pocket) and you end up paying for it .
The new build I was on 2 years ago ,he ordered and organised everything , trades just did the work

 

[George from SJM Planning]

I would agree with most on here that bein your own PM would be the most cost effective assuming you have the contacts and tools to do so. If you need any help with Building Reg's, CDM Regulations and/or Health and Safety then we have jsut launched a new company SJM Projects that advises on post-planning requirements, please feel free to email Michael Stevens ([email protected]) to see if we may be of service.