Build a Garage

Build a Garage

If your considering to Build a garage why not go the extra yard and build something that can have multiple uses and look spectacular rather than just ordinary.

build a garage

build a garage – showing rear elevation cedar cladding with solar installation on roof and external decking features

Most garages are built with one thing in mind -shelter for the car but often they end up as storage areas and work- rooms. With this in mind why not build it with additional benefit of insulation a nice ceiling, good lighting, plenty of power outlets and even under -floor heating. After all you don’t have to have it on all the time and can be kept on a reduced setting. With plenty of modern insulation incorporated within the whole structure the heat loss will be minimal- so it wont cost much to run.

Lets assume you have dealt with all the Planning and Building control applications- If not -you will find informative links on these subjects at the bottom of the article.

I’m using a recently completed project for this example. The garage is question is 7.5m x 7.5 m x 3m high  (plenty big enough to house 2 large cars)

Foundations to build a garage

Typically the foundations for the walls will need to be strip type concrete and usually a minimum of 1m deep and 600mm wide. This is assuming the ground conditions are suitable they may have to be deeper in very poor soils and much deeper if you are building near trees. In worse case scenarios ie-really poor soils and close to large trees there is always the option of using a raft foundation- this however will need to be designed by a structural engineer.

Floor slab

150mm thick steel mesh reinforced concrete laid on a consolidated mot type 1 sub base with a pvc damp proof membrane turned up the walls to the height of the Dpc in the walls.

100mm thick  slab insulation and finished with a 75mm thick floor screed with added fibers.

Walls- structural

Build a garage – the walls are constructed using 225mm thermal blocks with a damp proof course set a minimum of 150mm above the finished external ground level.

showing GRP roofing egde trim against cedar cladding

showing GRP roofing egde trim against cedar cladding


Is constructed with 200mm x 50mm pressure treated joist- Solid support noggins of the same dimensions are fitted between the joist at regular 600mm intervals.

The roof decking is in exterior quality 18mm thick plywood with vapour barrier and 120mm of slab insulation.


This roof supports a 3.75 KW  15 panel photovoltaic system mounted on galvanized steel frames

Additional roof support for garages over 3m wide

If you intend to build a garage that is likely to be over 3m wide you will need a steel support beam at the mid point position so the roof support timbers are not over stressed. The steel beam used for this was a UC 254 x 254 x 73kg the 73kg represents the weight of the beam per linear m.  ( So in this case the total weight of the beam was 547.5 kg or just over half a metric ton)  Beams of this weight need to be lifted into place using specialist equipment.

The beam ends should be supported on concrete pad stones 100mm thick x 450mm long and 150mm deep across the wall. The steel has to be supported on the pad stones each end by a minimum of 150mm. 

internal floor insulation before screeding - wall  and ceilings awaiting finishing of plaster

Internal floor insulation before Screeding – wall and ceilings awaiting the finishing of plaster

Internal wall finishes

Are lined using moisture resistant plaster board fitted on timber bearers with an additional 75mm of slab insulation a vapour barrier in PVC is fixed directly to the wall prior to covering all wall surfaces.

Walls are finished in 2 coats of finish plaster

External wall cladding

Is in Western red Cedar fixed on softwood battens that are in turn fixed to the walls using mechanical fixings.

Roof- waterproof covering.

Is glass reinforced plastic (GRP)  with a gray top coat and matching roof edge trim


Main Garage doors 2x standard insulated sprung mounted doors.

Rear -Bi folding- 2x off the shelf double- glazed door sets with stainless steel fittings

Side pedestrian door- solid core external quality door frame.

new rcd protected consumer unit

new rcd protected consumer unit


A new 10mm armored mains supply fed from the existing house supply to a new RCD protected consumer unit and MCB circuit breakers.

The lighting is low energy Led down lighters in 3 circuits

Power circuits are 2 no  2.5mm ring mains.

External decking

Fitted to match the main house complete with planters constructed using  second hand railway sleepers.


Surface water drainage is to a soakaway excavated 1m deep and sited 5m from the building.

Foul water drainage has been fitted and connected to the main drainage system as a toilet my added later.

                                                                                                                                                               That’s how you build a garage