Building a base for your Garden Building

It is essential that all garden buildings are assembled on a solid level base. This will ensure that the construction of your building goes smoothly and will deter any future issues such as doors / windows dropping out of alignment and becoming difficult to operate. It can also become a source of water leakage.

Assembling a garden building on an incorrect base is also likely to invalidate any warranty provided with your building.

Where to Place a Base for Your Building

When determining where to locate your garden building, there are a few areas you will need to pay attention to.

Boundary walls, fences and/or other buildings – Make sure to allow for any roof overhang your building may have as this may overhang the base. Furthermore you will need to be able to access all points of the building to apply wood treatments/preservatives.

Installing the base close to trees or large bushes could also cause problems from overhanging branches. If these are in the area you plan to use it may be worth removing or cutting these back prior to the assembly of your building. Furthermore when the garden building has been assembled, you will need to regularly check overhanging foliage regularly as any rubbing on the roofing material may cause damage, causing water leakage and voiding any guarantees.

When choosing the best location for your base, take into consideration what access is going to be required and what the building will be used for.

• Try to visualise what the garden building will look like in the position selected – you may not want to transport large or heavy items into areas of your garden that may be hard to reach.
• You may also want to consider an area of the garden where the building is most likely to receive natural light or have a nice view, especially for buildings such summer houses.
• If you intend to fit electricity or water supplies to your building, you may need to consider locations that will be suitable for this. Taking into account where the mains supplies are.

How to Construct a Base for your Garden Building

We recommend using a reputable local builder or handyman to complete the construction of your base, However, if you feel confident enough to complete the task, then it is relatively straightforward to construct your own base.

The following guide will help you to prepare and complete a base for your garden building using the suitable material of your choice.

Please note: It is strongly advised that you build your base slightly larger than the dimensions of the garden building (add approx. 30-40mm to each side).

Concrete Base Method

This method is strongly recommended for larger garden buildings.

• Remove any vegetation from the area where you have chosen to construct your base
• Use pegs and string to mark out an area for your base. Measure the lengths between opposite angles to ensure the area is square and not slanted. These lengths will be equal if the base is square.
• Excavate the ground in the marked out area to around 6” (150mm) deep.
• Within the excavated area, lay approximately 3” (75mm) of firmly compacted hardcore, scalping or brick rubble to act as a sound foundation and level with compacted sand if appropriate. You may wish to use a rake to aid with the levelling process. Remove the pegs and string.
• By measuring, cutting and fitting timber rails or steel shuttering to the shape of the base, board up the base as portrayed in the diagram. Use a tape measure, spirit level, and tri-square to ensure the base with shuttering is 100% level and square.
• You should then lay approximately 3” (75mm) of concrete. Concrete can be produced using either bags of dry mixed concrete with small amounts of water added at a time, or making a mixture of ‘all-in’ ballast, cement and water. For this second alternative, it is mixed in the ratio of 1 part of cement for 5 parts ‘all-in’ ballast. ‘All-in’ ballast is sold in 40kg bags at most building merchants or DIY stores (Note approx 1.25 will be required to produce around 1 cubic foot of concrete). Do not allow the mix to become too wet as this will weaken the concrete.
• Spread the concrete evenly in the shuttering, taking particular care to push the concrete into the corners and edges. Arguably the best method to lay the concrete is to do it a layer at a time and compact it until the shuttering frame is full. Leave the concrete flush with the top of the framework and smooth it out using either wooden or plastic float.
• The concrete must then be covered over with sheets to allow it to dry naturally. Please note however that the concrete must not be allowed to dry out too quickly and so spraying it with water may be necessary, particularly in warm and dry weather conditions.
• Once firm and dry the base is now ready for you to begin assembly of your garden building.

Paving Slab Method

• Remove any vegetation from the area where you have chosen to construct your base.
• Use pegs and string to mark out an area for your base. Measure the lengths between opposite angles to ensure the area is square and not slanted. These lengths will be equal if the base is square.
• Excavate the ground in the marked out area to around 2.5″ (63.5mm) deep. Remove the pegs and string.
• Within the excavated area, lay approximately 1.5″ (40mm) mix of one part cement to eight parts building sand. This will create a dry sand and cement mix. Level this mix – you may wish to use a rake and a spirit level to aid with the levelling process.
• Starting from a corner lay the paving slabs and tap down with a rubber mallet. The surface of the paving slabs should be slightly higher than the surrounding ground to encourage rain water drainage. Use a spirit level to make sure all the slabs are square, level and firmly butted together.
• Brush off any excess sand and cement mix – the base is now ready for you to begin assembly of your garden building.

Timber Bearers Method

• Remove any vegetation from the area where you have chosen to contrast your base.
• Use pegs and string to mark out an area for your base. Measure the lengths between opposite angles to ensure the area is square and not slanted. These lengths will be equal if the base is square.
• Excavate the ground in the marked out area to around 2″ (50mm) deep. Remove the pegs and string.
• Within the excavated area, lay approximately 1.5″ (40mm) gravel or soil. Level this mix – you may wish to use a rake and a spirit level to aid with the levelling process..
• Lay either concrete floor bearers or pressure treated (tanalised) timber bearers across the gravel/soil. These should be equally spaced at intervals of approx 400-600mm ensuring they are to run perpendicular to any floor joists which already come built in to your garden building. If you are installing your base prior to receiving your building please speak to one of our team members who can advise which direct the bearers will run.
• Make certain that all floor bearers are level with one another by using a spirit level. Use a rubber mallet to tap down the bearers if necessary.
• How many floor bearers will I need? This is dependent completely on the size of your building. All of our buildings come with bearers attached to the floor panels. Please review the instructions to see the floor plans for your building or alternatively give us a call and we can advise where the bearers will run.

Need more information about the assembly of your garden building or base?

If you need further advice about constructing or installing your new garden building, please give us a call on 01777 802300 where one of our friendly team will be happy to assist.