The free diy home improvement guide with answers to your questions on a wide range of do it yourself projects.


Preparation for a New Concrete Garage

Concrete Garages are a cheaper alternative to their brick built counterpart. However it is crucial to correctly prepare for the delivery and installation of your new concrete garage to avoid costly and time consuming problems. In order to achieve this simply follow our guide to the requirements for a new concrete garage.

Concrete Base Requirements

Garages should only be erected upon a permanent concrete base of suitable thickness. We recommend a minimum of 4 inch thickness throughout. The base should be FLAT, LEVEL AND SQUARE, and at least 6 inches longer and 6 inches wider than the external dimensions of the garage to be supplied.


The ground surrounding the base should be lower than the base. If not, water will lay on the base and break through the sand and cement fillet and leak into your building. If the driveway slopes down towards the front of your building, you must put in a gulley to take any surface water away.

measuring a 3 4 5 triangleIn order to check that your base will be laid square, measure out a 3-4-5 triangle as per adjacent sketch before securing your timber shutters.

ensuring diagonals are equalIn order to give your timbers a final check prior to concreting, measure the diagonals which should be equal. We would also advise you to use a reputable ready-mix concrete company who will also be able to tell you the amount of concrete required.

allowing for roof overhangIf you are close to an existing building or boundary wall, make sure that you allow for the overhang of the roof, i.e., flat roof garages 6 inch (150mm) on front and rear and 3 inch (75mm) both sides, apex roof 6 inch (150mm) front, rear and both sides. This does not include gutter width.

adding a sand and cement filletAfter your garage has been erected we strongly recommend that a sand & cement fillet be placed on the base to panel joint all around the inside (not outside) of the building to avoid ingress of water. We recommend a 3 part building sand to 1 part cement with Unibond (PVA) added to the mix.

Your concrete base must be LEVEL from front to back and side to side.

digram showing how base must be level

Please Note:
Before placing any goods or items that may be prone to damage from moisture, ensure your building is fully dried out and watertight before you proceed..

Up and Over Garage Doors:

When operating your up and over door remember to take into consideration the door swing as you will require a minimum of 3’ 2” for the door to close.

Clear Passage (drive through sizes) are:-
Width: Door width less 4” (100mm)
Height: Door height less 5” (125mm)

However, this does not mean that your building does not need planning or building regulations. In all cases, we recommend that you consult your local planning office to find out what permissions, if any, are required.

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