How to Build a Patio from Scratch
Planning a patio is more than just choosing the right paving slabs. A professional patio requires a solid foundation built in layers. Our Patio Material Estimator calculates the complete shopping list for all three essential layers.
Layer 1: The Sub-Base (MOT Type 1)
The foundation of any good patio is the sub-base. In the UK, this is almost exclusively built using MOT Type 1 crushed aggregate. This material contains stones ranging from 40mm down to dust, allowing it to interlock and compact into a rock-hard layer.
For a pedestrian patio, a compacted depth of 100mm is standard. You will need a heavy Wacker plate (compactor) to consolidate this layer properly.
Layer 2: The Laying Bed (Sharp Sand & Cement)
Never lay patio slabs directly onto MOT Type 1, and avoid the outdated "dot and dab" method where mortar is placed in five spots under the slab. Dot and dab creates voids that hold water, leading to loose slabs and frost damage in winter.
Instead, professionals use a Full Wet Bed. This requires a mix of Sharp Sand and Cement (typically a 4:1 ratio) laid at roughly 40mm deep. The slab is then tapped down into this solid bed.
Layer 3: Paving Slabs & Pointing
Our calculator determines the exact number of slabs required based on your dimensions. It automatically factors in a standard 10mm mortar joint gap between each slab. Always order a 10% waste allowance for your slabs to cover cuts and breakages.
The final step is Pointing (filling the gaps between slabs). Modern projects usually use a Brush-in Jointing Compound which is permeable and incredibly fast to apply. Traditional mortar pointing (a 3:1 sand / cement mix) is also common but requires more skill to ensure a clean, long-lasting finish that won't crack or pop out.