extension rough costs

stuart888

Hi all

Looking at buying a house and am considering adding a 2 storey extension and am trying to work out what this is likely to cost and see if its viable.

Is need a builder to build the structure but being in the trade I can install windows, run basic wiring, board and plaster and decorate. All prices online only give rough figures for the entire thing per metre.

How exactly do costs breakdown

-surveys and plans (are these allways neccessary or are builders and planning happy to work from amateur sketches?

-planning permission and building control fees ( would it be best for me to arrange to have all work inspected both the builders and my own by one building inspector?

-any potential costs such as moving drains or adding inspection chambers that people can think off?

-cost per square metre of structure in single skin blockwork (to be externally insulated and render by myself.) + roof

-cost per square metre cavity wall with outer skin blockwork ( to be rendered by myself ) + roof

-cost per square metre cavity wall with facing bricks (appreciate the price of these can vary somewhat) + roof

-can work out all electrical, plastering, flooring costs ect by myself as it mainly just materials

KennyH1

stuart888 wrote: »

Hi all

Looking at buying a house and am considering adding a 2 storey extension and am trying to work out what this is likely to cost and see if its viable.

Is need a builder to build the structure but being in the trade I can install windows, run basic wiring, board and plaster and decorate. All prices online only give rough figures for the entire thing per metre.

How exactly do costs breakdown

-surveys and plans (are these allways neccessary or are builders and planning happy to work from amateur sketches? Yes these are necessary. You need scaled plans for planning permission, building regs and for the builder to work from.


-planning permission and building control fees ( would it be best for me to arrange to have all work inspected both the builders and my own by one building inspector?
You could get an approved inspector to undertake the visits rather than building control so you can talk to them directly about works / visits.

Cost of the actual plans will vary depending if you use an architects, do it yourself or use a CAD technician.

I would charge -

Survey £150
Planning application drawings £350
Building Regs Drawings £500

Planning Fee £150
Building Regs Fee approx. £500

-any potential costs such as moving drains or adding inspection chambers that people can think off?

-cost per square metre of structure in single skin blockwork (to be externally insulated and render by myself.) + roof
£1000/£1500/m2 gives a fully finished extension, so i'd work on the lower figure if you're doing some of the work yourself.

-cost per square metre cavity wall with outer skin blockwork ( to be rendered by myself ) + roof

-cost per square metre cavity wall with facing bricks (appreciate the price of these can vary somewhat) + roof

-can work out all electrical, plastering, flooring costs ect by myself as it mainly just materials

If you can get your hands on a Spons Directory that has a breakdown of costs / m2 and should have all these costs in there.