Groundworks and Base for your building

All our timber buildings require a prepared base which needs to be flat and level.

Base Size

For a base built specifically for the building purchased from us, the size of the base should be no less than 25mm (1″) smaller than the building in both length and width. This is to prevent excess water sitting on the base and also the splash back effect of the rain falling from the roof. For example:

An 8′ x 6′ building would require a base minimum base of 7’11” x 5’11”.


The ground must be prepared correctly for each of the base types below. Particular care is needed with ground that retains water, or is often flooded in wet weather. Drainage may need to be sorted out before a base is built. Don’t forget that access to your building may cross wet or waterlooged ground, again this needs to be addressed before a base is built. A specialist groundworks contractor may be required for the initial work.

Failure with the groundworks can lead to an unstable and unsupported timber building, putting strain on the panels, floor and roof.

Recommended base types:

  • Concrete base – the strongest and most stable method provided that it’s correctly carried out. However, a concrete base is the most expensive and can hold water if water gets on it.
  • Paving slabs – a cheaper yet successful alternative.  Always allow a good space between the slabs to allow any water dispense quickly.
  • Gravel or Quary Waste – The cheapest and possibly the most effective way of doing a sound foundation.  This is quick and esay to do, allows plenty of drainage under the building and doesn’t spoil the area if you decide to move the building in years to come.
  • Timber framed base – by far the most straight forward solution! Make a timber frame out of 4″x2″ pressure treated timbers and set this up level.  You can you suitable packings such as slate, damproofing etc and also use timber stakes to stop any movement.  The disadvantage is that it creates quite a large step into the building.

Alternative base types:

  • House brick – probably one of the cheaper options. However very time consuming and needs care with accurately positioning and levelling of bricks.
  • Timber or concrete support joists -an economical and effective option.
  • Decking – An area can be set up using decking.  The building can also be fixed down to the decking to stop any movement.

Note: This information is to be used as a guide. Heritage Garden Buildings Ltd will not be liable for any issue due to inappropriate ground preparation.