Why Do You Need To Build A Base For A Garden Shed?

Building A Base For A Garden Shed?

When constructing a garden shed it’s essential to have an even, firm base made from appropriate material – every building needs a suitable foundation, and garden sheds are no different. A sturdy base will ensure that the shed is easy to assemble and will prevent deterioration in the future.

Where is best?

The first thing to consider when building a base is the shed itself. If the shed has a roof which overhangs its outer walls, you’ll need to account for it and not build immediately next to an edge where it could encroach onto someone else’s property. Placing it directly underneath the branches of a tree could also cause a problem, as the branches may drip sap onto the roof. If left for an extended period of time the branches could come into contact with the roof. Anything coming into contact with the roof could reduce its weatherproofing, creating a leak.

When considering placement, take access and sunlight into account. You’ll want the garden shed to have the most natural sunlight as well as being in an area which is easy to take things to and from – especially if you’re considering fitting electricity to it.

Method For Building A Shed Base

When building the base, consider using a reputable builder or skilled person in your area if you feel uncomfortable constructing the base on your own.

A general rule of thumb is to make your base roughly 30mm-40mm larger on each side.

There are three main methods of creating a base for your shed. The first is the concrete base method.

Concrete base

This method is the most reliable for larger sheds.

  • Remove all detritus and plants from the area.
  • Use string and pegs to mark off the area your base will be occupying. To make sure it’s square and not slanted, measure the difference between opposite pegs. If it’s even, the distances should be the same.
  • Excavate the marked off area so that it’s around 150mm (6 inches) deep.
  • Fill this area with 75mm (3 inches) of compacted hardcore, brick rubble or scalping to create the foundations of the base. You can level this with sand if needs be.
  • Remove the string and pegs. Measure, cut and fit wood rails to the edges of the base. This will help to keep the cement in the right place. Make sure to check it’s even and level by using a tape measure and spirit level.
  • Fill the rest of the base with cement. This should be roughly 75mm (3 inches). You’ll want to spread this evenly, making sure it reaches all corners and flush with the top of the frame. Smooth this using a plastic or wooden float.
  • Cover the concrete with a sheet and allow to dry naturally. If necessary, spray with water in hot or dry conditions to ensure it doesn’t dry too quickly.
  • Once dry and firm, the base is ready to be built on.

Paving Slab Base

  • Follow the same two steps from above, then excavate 63.5mm (2.5 inches) down and remove pegs.
  • Lay a 40mm (1.5 inch) deep mixture of one part cement to eight parts building sand for a dry mix. Level with a rake and spirit level to ensure it is flat.
  • Start in a corner and place the paving slabs in the mixture before tapping them with a rubber mallet to secure them. The slabs should be slightly higher than the ground, as this will help rain drainage. Again, a spirit level should be used to ensure the slabs are evenly distributed and square.
  • Clean off any mixture and begin building.

laying floor joists

Timber Bearers Base

  • Follow the initial two steps, then dig a hole roughly 50mm (2 inches) deep and remove the pegs.
  • Partially fill the hole with soil or gravel, leaving a 10mm (0.5 inches) gap. Level this with a rake and spirit level.
  • Lay either tantalised timber or concrete bearers across the base. Space them equally between 400mm and 600mm, and perpendicular to the joists that came with the building. Use a spirit level to check they’re even.
  • Different sized sheds will need different amounts of bearers. Some examples are;
  • 6×4 garden building – 4 bearers at 1150mm (4ft) long
  • 7×5 garden building – 4 bearers at 1450mm (5ft) long
  • 8×6 garden building – 5 bearers at 1750mm (6ft) long
  • 10×8 garden building – 6 bearers at 2350mm (8ft) long

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