How much sub base do i need?

Question

Could anyone give me a good rule of thumb for a patio?

Dave · Answer

A good rule of thumb for a patio sub-base is 100–150mm of properly compacted MOT Type 1, depending on the ground conditions.

Typical installation build-up is:

• 100–150mm MOT Type 1 sub-base, compacted in layers
• 30–40mm full mortar bed (sharp sand and cement mix)
• Paving slabs installed on a full bed, not spot bedded

This normally means excavating to around 150–200mm below finished level.

For firm, well-draining ground, 100mm may be sufficient. However, on clay, softer ground, or areas prone to movement, we always recommend 150mm for long-term stability.

The most important factor is that the sub-base is installed in layers and mechanically compacted, as this is what prevents sinking, rocking slabs, and future movement. Also ensure the patio has a slight fall (approx. 1:60) away from the property for drainage.

In our experience installing patios and landscaping projects, the sub-base is the single most important part of the job. If done correctly, the patio will remain solid and level for many years.

Russ · Answer

A good rule of thumb is 150mm heavily compacted type1 stone (MOT) as a sub base and give yourself 30-35mm for bedding (cement) make a paste up ( watery cement and PVA mix) paste the back of the slabs before laying.

How much sub base do i need?

Follow Us

Cookies

Manage Cookies

Essential cookies

Analytics & Tracking

Advertising