Sub-Base for a Garden Path or Shed Base: Depth and How Much to Order
Garden paths and shed bases look like small jobs, but they fail for the same reason as bigger projects: a weak or uneven base. A path with no sub-base sinks and wobbles, and a shed on soft ground twists, so the door sticks and the floor rots. The fix is a compacted layer of MOT Type 1. Here is how deep to make it, and how to work out how much to order.
Garden path sub-base
A path carries foot traffic, wheelbarrows and the occasional mower, which is much lighter than a driveway. A compacted sub-base of roughly 75 to 100mm is a common choice under paving slabs or block paving on firm ground, and 75mm is the figure we have used in the example below. If the ground is soft or boggy, go deeper. Wherever the path might be driven over, treat it as a driveway and follow our driveway sub-base guide instead.
Worked example: a 10m × 1m path at 75mm
- Area: 10 × 1 = 10m²
- Finished volume: 10 × 0.075 = 0.75m³
- With a 25% allowance for compaction and settling: 0.94m³
- At about 1.7 tonnes per m³ loose: about 1.6 tonnes
- Bulk bags (800kg): 1.6 ÷ 0.8 = 2, so 2 bags. It is a close call at just under 2, so if the ground is uneven, order a third.
Shed base sub-base
A shed does not need a huge base, but it does need a flat, firm and level one that does not hold water. There are two popular approaches:
- A compacted MOT Type 1 base with slabs or a timber or plastic grid on top. It is quick, drains freely and is easy to level.
- A concrete slab. This is more work, but gives a permanent, very flat surface. It still sits best on a compacted sub-base.
Whichever you choose, ask what your shed manufacturer recommends. Many give a minimum base size and level tolerance, and some will not honour the warranty if the base is not right. Make the base slightly bigger than the shed footprint so rain running off the walls does not wash away the edges.
Worked example: a 3m × 2.4m shed base at 100mm
- Area: 3 × 2.4 = 7.2m²
- Finished volume: 7.2 × 0.1 = 0.72m³
- With a 25% allowance: 0.9m³
- Weight: about 1.5 tonnes
- Bulk bags: 1.53 ÷ 0.8 = 1.9, so 2 bags
Two bags of MOT Type 1 sub-base cost £97.50 ex VAT at the time of writing. Because aggregates and cement have a £250 ex VAT minimum order, small jobs like this often combine with other items. See the ordering note at the end of this guide.
If you are pouring a concrete shed base
Work out the slab volume the same way: length × width × thickness. The dry materials you buy are bulkier than the wet concrete you pour, and a common rule of thumb is to allow roughly half as much again. You can buy all-in ballast bulk bag (a mix of sand and stone) and cement such as Blue Circle General Purpose cement, and mix them by volume following the bag guidance. For anything structural, ask a builder for the thickness and mix that suits your ground and your shed.
Building a firm path or base
- Mark out and dig down. Remove topsoil, turf and roots to the depth of sub-base, bedding and paving combined.
- Compact the soil. Firm up the exposed ground with a hand rammer or plate compactor.
- Spread the MOT Type 1. Rake it level and keep checking with a spirit level and a straight edge.
- Compact thoroughly. Slightly damp stone compacts better. Small paths can be done with a hand tamper, but a plate compactor gives a much better result.
- Add the surface. Slabs, blocks or a grid go on a thin bed of sharp sand or mortar, as the manufacturer advises.
For the sand layer, see our guide to sand and cement for paving bedding. Allow a slight fall on a path so water runs off the surface, and check that it does not direct rain towards the house or the shed.
Frequently asked questions
Do I need a sub-base for a shed?
It is strongly recommended. Without a firm, level, free-draining base, a shed can rack, sink on one side and rot from damp. Check your manufacturer's base requirements.
How deep should a shed base be?
Around 100mm of compacted sub-base is common for a typical garden shed on firm ground. Soft ground or a heavy workshop may need more.
Can I lay a path without MOT Type 1?
You can, but paving laid straight onto soil tends to sink and tilt. A compacted sub-base keeps it stable for much longer.
Is hardcore suitable for a shed base?
Many people use it, and we sell a hardcore / crusher run bulk bag. For a finer, tighter surface under slabs or a grid, MOT Type 1 is usually easier to level.
How much does a bulk bag cover?
It depends on depth and how well the stone compacts, so work it out from your own measurements using the steps above rather than relying on a single figure.
Ordering and delivery
You can browse the full range in our cement and aggregates collection. Bulk bags are sold at approximately 800kg each (the packed weight can be up to 850kg depending on moisture), and most sands and gravels are also available in 20 to 25kg trade packs for small jobs. Prices on our website are shown excluding VAT, and VAT is added at checkout.
We deliver to addresses in mainland England only; we do not currently deliver to Wales, Scotland, Northern Ireland or the islands. Timber, aggregates and cement have a minimum order of £250 ex VAT, and delivery is £25 ex VAT on orders under £500 ex VAT and free over £500 ex VAT. Bulk bags are delivered by Moffett lorry (truck-mounted forklift) and offloaded at your site, so someone must be there to receive them and you will need a firm, level area with suitable access. We do not offer next-day delivery. Our shipping policy has the full details, or call us on 03330 908479 or email sales@insulationwarehousedirect.co.uk if you would like a hand working out your order.
The quantities in this guide are estimates. Ground levels, how well the material is compacted and how wet it is all change what you need, and densities vary between quarries, so check the amount with your installer or the manufacturer's guidance before you order. Prices and pack sizes are correct at the time of writing.
Working out quantities? See our MOT Type 1 sub-base guide: how much do I need? or go straight to our aggregates calculator.