Converting a Single Detached Garage

Ok, there are a few more considerations now our little garage has finally separated itself from the “mothership”.

Firstly we are only going to deal with brick built garages with “proper roofs”, not corrugated asbestos or prefabricated ones.

Secondly, there are now 4 external walls to deal with and there may be no electricity.

Let’s start as always, with the most basic job possible. You probably noted the “as always”,….. that’s because we are assuming you have at least read the article entitled “Job 1”.

The basic job (assuming a pitched roof)

A damp proof membrane, insulation and screed, to create a new floor on top of the existing concrete one.

A vapour barrier, insulation and dry lining to convert the 3 existing exterior brick walls. This assumes there is an existing back door and window.

A timber, insulated, plasterboarded stud wall, directly behind the up and over door.

An insulated, plasterboarded ceiling, with ventilation above.

Assuming an adequate legal electric supply exists, fit one electric heater, two electrical sockets, one central light and switch, skirting boards and architraving around the door and window.

No plastering, just tape and fill the joints between the plasterboards and paint the room.

That will take two blokes on £150 and £100 per day respectively, 10 days, plus a sparks for a day.

Labour £2700.00
Materials £1400.00
Building control £350

Basic Job Total £4475.00

The following prices are in addition to this basic job.
Maybe you also have to

Cut out for and fit a new PVCu door £1000.00

Or replace the existing one …………£750.00

Cut out for and fit a new PVCu side window…………£700.00

Or replace the existing one ……………£400.00

Actually dig out the old floor (because it's too high possibly), and lay a new concrete "base slab" before undertaking the above, "basic job" floor work £1000.00

Convert an existing flat roof to a warm roof (see “Job 4”)…………..£1100.00

This price takes into account the ceiling and insulation included in the “basic job” price.

Take an electricity supply to the garage…………£500.00


Or, if you want to spend a bit more, how about.

Brick up the existing “up and over” door (on a new foundation), to comply with current regulations.

This price is minus the amount previously included in the basic job for masking the door.£750.00

Converting the 3 existing exterior walls to cavity walls.

This price includes laying a foundation (which would be done during the floor slab conversion).

We have also deducted from this price, the amount previously included in the basic job for dry lining these walls £500.00

Plastering all the walls and ceiling £400.00