Gapfast easy guide on how to lay a patio – in just one weekend!

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How do I lay a patio and make laying patio slabs as easy as possible and achieve a professional finish to my job?

    • How to lay a patio image string pegs areaMark out your new patio using a string line and pegs and check the corners are at right angles, using a builders square.Remove any turf with a spade; clearing an area slightly larger than the area to be paved
    • paving slab layers image GapfastDig out the base to a depth of around 200mm (this will allow for 100mm hardcore, 50mm mortar bed and your paving slab).
      NOTE: if the patio is to be built next to your house, the surface of the paving must be at least 150mm below the damp proof course
    • slab spacers compactor usage imageHammer in wooden pegs to show the finished hardcore level 100 – 120mm above the excavated area, depending on the thickness of your patio slab – allow an adequate fall so rain can run off into the garden. A fall of around 1 in 80 (10 – 15 mm drop in level per meter) is just about right. Then fill up to slightly above the top of the pegs with Type 1 or hardcore; then compact it down, using a vibrating plate compactor (you can hire these almost anywhere).
      NOTE: if you have used hardcore you will need to ‘blind’ it with a thin layer of ballast, levelling off with a rake.Alternatively, as in this example you can lay a concrete base.
      NOTE: For this application you can use a lean mix of 6 parts sharp sand to 1 part cement
    • The base is now prepared!

Ok you have prepared your base and are now ready to learn how to lay a patio. This is where your Gapfast paving spacers will be invaluable, save you time and help you lay paving slabs accurately.

    • flag paving spacers laying slabsMix mortar in an electric concrete mixer (again can be hired anywhere) using 6 part sharp sand to 1 part cement, adding just enough water for a stiff-ish mix.
    • stone spacer level using club hammerPlace mortar to around 50 mm deep onto the prepared base – ‘rippling’ the surface, creating troughs/peaks with a trowel – this will aid tamping/levelling into place. Wet the back of the slab with a brush (this helps it stick and makes it easier to move into position). Then carefully lay the slab on top of the mortar. Use the appropriate Gapfast patio slab spacers (Gapfast Tees are ideal or alternatively Gapfast Crosses can be cut if necessary) to space the slabs away from the house, wall or turf border.
    • paving slabs spacer image pointingUsing a club hammer tap the slab into position. If necessary lift the slab to place a little more mortar underneath. Note here the Gapfast Tee paving spacer is vertically inserted between the first paving slabs as they are being laid tight against the existing turf border.
    • paving flag spacers check levelStarting with your first or corner slab, lay the first row of slabs in the direction of the fall. Fit a Gapfast (Cross or Tees as appropriate) paving spacer at each corner ensuring they are placed down in the mortar. Using your hammer/timber tap the slab firmly up against the Gapfasts.
    • gapfast spacers used row by rowEnsure you check the fall / levels as you work using a spirit level.
    • gapfast spacers used row by rowWhen the first row is complete, lay slabs along the adjacent outer edge. Fill in the central area, working back row by row. Keep checking that the fall is correct and that the slabs are level laterally. Also ensure the slabs are pushed up firmly against the Gapfasts.
    • gapfast spacers used row by rowLeave the mortar to set for a couple of days before walking on the slabs or filling the joints.

Now, how do I lay paving slabs that require cutting?

    • cut paving slabs using bolster imageConcrete patio slabs can be cut with a sharp bolster and club hammer. Mark the proposed cut with a pencil, on all four sides of the slab. Place the slab on a bed of sand and cut a line with the bolster, gradually going deeper until the slab breaks. You could also use an angle grinder (as shown in this example) with the appropriate disc. Remember to wear your safety goggles, protective gloves and dust-mask!
    • cut curved slabs using grinder imageYou can also use a Gapfast paving spacer to re-mark your cutting line to ensure you maintain a 10mm joint / pointing gap. In this example a curve line is marked on an Indian sandstone natural paving slab

Leave the mortar to set for a couple of days before walking on the slabs or filling the joints

    • clean and prepare slabs ready for useThe easiest and quickest way to do this is to fill the joints with kiln dried sand (remember the Gapfast paving spacers stay in the joints) then drench the joints and flags with Resifix. Alternatively, as shown in this example, you can mix relatively dry mortar using four parts soft (builders) sand to one part cement. You could add lime (acts as a plasticizer). Using a builders trowel and brush place the mortar mix between the joints.
    • clean and prepare slabs ready for useCompact the mortar with a pointing trowel or a piece of wood, and repeat (up to 3 to 4 times) until the joints are full and compacted. Carefully brush away any excess mortar and lightly wet the whole surface using a hose – set the nozzle to fine spray – ensure all residue is rinsed from the surface– let it dry.
That’s it – time to fire up the Barbie!
For more detailed construction information on laying paving slabs visit
How to lay a patio with Gapfast, patio laying made easy!