Phone: 01709 881844

Concrete Garage Base Construction

There is a saying in the garage industry ‘a concrete garage is only as good as the base it sits on’. It’s an old adage but it’s certainly true. Preparing a concrete garage base correctly is vital to the stability of any sectional concrete building. It may not be the most glamorous side of concrete garages but it is still important. So this week we will be looking at the do’s and don’t’s of laying the perfect concrete base. 

It’s all about the weight! 

Concrete garages are heavy beasts. In fact the average single pent garage weighs in excess of two tonnes. If it’s anapex garage it will probably weigh over three, and that’s before you start with double garages or extra high buildings! For that reason alone we need to have a strong stable base to build our garages on. 

Concrete base

Good Base Position

Here the base is positioned nice and centrally, the corners are at right angles so the base will be square

Concrete base

Poor Base Positioning

Here the corners of the base are not at right angles so the base is offset

Concrete base

Checking For Square

If the distance between A-B is equal the distance between C-D, the base is square

There are some very important factors to take into account when considering a concrete building. 

  • We cannot build on tarmac, paving blocks or slabs as they are inherently unstable. 
  • Your base will need to be square (meaning all the corners are 90°) flat and level. 
  • It should be above surrounding ground level by a minimum of 1”. 
  • A 3” trowelled or floated edge to the base should be provided all the way around the base to ensure that there is a slight fall away from the footprint of the building, 3mm or 1/8th of an inch is ideal. This will encourage water to runaway from the building. 
  • If your drive slopes down to the garage, you will need to put in a gulley to take away the water, if there is a wall or bank around the building, you need to ensure adequate drainage. 
  • Where a ramp is added to the front of the base make sure this does not end up with a slightly higher level than that of the main base as this will encourage water to enter under the door. The ramp should obviously always be sloping away at a lower level than that of the main base. 
  • It’s not just the base itself that is important but also the preparation. Laying a damp proof membrane underneath the concrete will prevent damp from rising up through the base causing problems with the building. It is also good practice, especially on larger bases to add reinforcing mesh to give the base extra strength and help prevent any cracking in the future. 
Concrete Base

Base Recommendations

This cross section of a concrete base shows the correct method of construction. 

The base should be 4 thick concrete. 

Underneath the concrete should be a minimum of 4 compacted hardcore. 

Edges should be chamfered to aid drainage. 

Around the edges the concrete should be 6 thick. 

The base should be 3 bigger than the building all the way round the perimeter. 

It should also be flat, square and level throughout. 

Laying a good base for a concrete garage is mainly common sense. But following these simple rules will help to ensure the perfect concrete garage base.

Our sales team are available here to answer any questions about concrete bases. We also have Lidget Compton Building Specialists all over the UK who can provide a concrete base laying service

Get brochure and price list