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Foundation Guidlines


It is very difficult for us to confirm what is required for your building as there are a couple of different options and several different schools of thought.

Depth of your base will depened on the size of your building and most importantly what you will be storing in your building, we would always suggest checking with a local builder if you are unsure, please note local soil conditions may also affect your requirments.

Size of your foundation will depend on your own personal preference, as a general rule we suggest adding at least 6 inches each way, this means the base does not need to be millermeter perfect.

Your building is supplied with a basic ingress system. If we are installing your building this will include a sealant to the base beams, if you are purchasing the building supply only then you can find a similar product readily available at a local builders merchants or online (please contact us for pictures).  

Below is a guide written by a third party contractor as advise on installing your base.

The base

Materials and Tools Needed


4 pound Lump or Club hammer


2 x 2 by 18 inch stakes

5mm reinforcing mesh

DPC membrane

Sharp Sand



Float Trowel

As a general guide: one cubic metre of concrete will make 9 square metres 4 inches thick, or 6 square meters 6 inches thick. One ton of sand is approximately 2/5ths of a cubic yard and will cover about 7-12 square metres of hardcore (because you lose about half to a third between the cracks).

Bonds do not supply the base for your building.

Prepare your base at least 2 weeks before you start errecting your building to give the concrete time to cure, or it will crack when you try drilling it for the masonary bolts, or if you put weight on it.

We strongly recommend that you construct a concrete base sufficiently strong to do the job required of it. In most cases this will be four inches thick, contain reinforcing wire mesh and be constructed slightly larger than the garage or shed building. We would recommend it protrudes six inches out around the base of the building if possible. For larger buildings, where the base could be asked to support loads greater than a standard family car, we would recommend the concrete is at least six inches thick.

If you are building your own base, then you should remove all topsoil from the area where your garages is to be errected.

Excavate the soil down to good firm ground or 12 inches depth keeping the surface level and reasonably smooth. The sides of your excavation will usually suffice as your shuttering to retain the concrete when poured.

If you are building straight on to already firm hard ground, you will need to errect a shutter around where your base is to stand to hold in the concrete. Your shutter should be of good strong material and preferably finish level with your base surface when finished. 18mm shuttering ply, or purpose made steel shutters will be fine. Check all your levels with a good spirit level, or laser level.

For large areas it is recommended that you pour the base in sections (bays) about two meters wide on different days, so you can put an expansion joint between the bays to avoid cracking as the concrete cures. The shutter should be retained with some good stout pegs spaced about two feet apart. Steel pegs are best, 2x2 timber pegs about 18 inches long will also do the job. Make sure the pegs are driven deep enough into the ground. There is nothing worse than having your shutter collapse just as you are pouring your concrete.

Place approximately 6 inches of good quality hardcore (brocken brick rubble or 2-4 inch stones). Vibrate this level with a wacker plate (you can hire one from any good tool hire shop).

Cover the hardcore with a 2 inch layer of sharp sand.

If you require your building to be dry, (recommended) you will need to cover the sand with a damp proof membrane (Blue Plastic Sheet from any builders merchants).

If you require your building to be insulated, cover the damp proof membrane with polystyrene sheet, this comes in varying thicknesses between 1 inch and 6 inches. For a garage or shed it normally isn't needed, but if you use it the two inch will usually suffice for most purposes. If you intend using your building as a worshop we would recommend you insulate the base.

You can mix your own concrete if you like, though there is little point unless you like to work up a sweat, or you're a fitness fanatic. It usually isn't much cheaper to mix your own, than it would be to buy ready mixed concrete from you local supplier, which will be accurately mixed for the job and it will save you a lot of hard work if they deliver it.

If you mix your own, be sure to make the mix 1 part cement to 3 parts 3/4 inch concrete ballast. The ballast will come ready mixed in the right proportions of sand and stones. Also, be sure to mix in some water proofing agent, and if its winter, some anti freeze. Both can be purchased from your builders merchants, and will have mixing instructions on the cans.

Pour the concrete to to a depth of about one inch then place your reinforcing mesh on this. Once the mesh is in place (it doesn't matter if it overlaps, in fact it helps if it does) finish pouring your concrete up to the desired level for the base. This will usually be the top of your shuttering, or ground level. Smooth the concrete off with a float trowel.

If it is a hot sunny day, allow the concrete to cure for about three hours, then cover it with some old sacking. This will help reduce surface cracks from hot sunlight. If it looks like it will rain before the concrete is properly cured you should cover it with something to help shed the water off the surface.

Now go and have a cup of tea, you've probably earned it.

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