Bradstone Ashbourne vs Stonemarket Trustone for a 25-Square-Metre Rear Garden Terrace

Start with the fall before you compare a single slab

A terrace that sits flat holds water, and water sitting on wet-cast concrete is what drives the white bloom, the surface algae, and the freeze damage that shows up by the second winter. The working target for a patio draining to open ground or a channel is a 1-in-60 fall, which across a 5 metre run away from the house comes to roughly 83 millimetres of drop. Set that with a line level and a length of timber before you order either the Bradstone Ashbourne or the Stonemarket Trustone, because the fall determines your bedding depth at the low edge and whether the finished surface clears the damp-proof course by the required 150 millimetres.

Both products are riven-faced wet-cast slabs, meaning a concrete body with a moulded texture rather than split natural stone. That matters for the fall because wet-cast concrete has a measurable water absorption, and a slab that drains slowly across its face needs the pitch to move water off before it soaks in. Ashbourne runs a slightly more open surface texture than Trustone in its standard finish, so on a shallow fall it sheds surface water marginally faster, though neither is permeable through the body.

The bedding decision splits the two products

Stonemarket Trustone is specified by the manufacturer for a full mortar bed, a 5:1 sharp sand to cement mix laid 30 to 40 millimetres thick over a compacted MOT Type 1 subbase. The slab goes down onto a wet bed and gets tapped level with a rubber maul, and the bed is buttered fully so there are no voids under the slab. Voids are where water collects and freezes, and a Trustone slab lifted after a bad winter almost always shows a hollow bed underneath.

Ashbourne tolerates the same full-bed method but also performs on a slightly leaner 6:1 mix, which gives a longer working time on a warm day when you are laying 25 square metres solo and cannot get through a rich mix before it stiffens. Neither slab should be spot-bedded on five dabs of mortar, a shortcut that persists on domestic jobs and produces drummy slabs and cracked corners within a season.

The subbase is identical for both: 100 to 150 millimetres of MOT Type 1 crushed limestone, compacted in layers with a wacker plate, blinded with angular clean stone bedding grit to bring the surface true before the mortar goes on. Angular grit locks together under load where rounded pea gravel rolls, so the blinding layer stays put while you work across it.

Where a permeable base changes everything

If the terrace has to handle roof runoff or sits in a garden with heavy clay that puddles, a bound bed over Type 1 is the wrong build. A permeable block paving base uses a coarser open-graded stone, typically a 4 to 20 millimetre clean crushed aggregate with no fines, laid over a geotextile so water passes vertically through the joints and the bed into the ground below.

This is the build that Marshalls Priora blocks are designed for. Priora blocks carry a moulded spacer nib on each side that forces a consistent joint width, and that joint is filled with a 2 to 6 millimetre angular grit that stays permeable. Water enters through the joints, not through the block body, so the surface can shed a downpour without a single gully. A gravel grid, a cellular plastic panel filled with 10 millimetre gravel, does the same job on paths and informal areas at a fraction of the slab cost, and it holds the gravel against scuffing so it does not migrate into the borders.

The trade-off is that neither Ashbourne nor Trustone is a permeable-jointed slab. Laying either over a permeable base defeats the point, because the closed mortar joint stops the vertical flow the base was built to allow. On a clay garden that floods, the honest choice is Priora blocks and a permeable build, not a wet-cast slab retrofitted onto an open bed.

Jointing: the resin decision

The joint is where most patios fail visibly. A resin jointing compound patio uses a one-part or two-part polymer slurry brushed into the joints and consolidated, and it resists weed growth and ant excavation far longer than a dry sand-cement brush-in. For Trustone, a full-bed wet-cast slab, a resin joint suits the tight 8 to 10 millimetre gaps the manufacturer specifies, and the resin bonds to the slab edge without the picture-framing stain that some cheaper compounds leave on porous stone.

Ashbourne takes resin equally well, but its slightly more absorbent surface means the joint must be applied to a bone-dry slab and the excess washed off fast, because any resin haze that dries on the face is stubborn to lift. Both products want the joint applied when the slab surface is above 5 degrees and rising, not in the damp of an autumn morning when the resin cures milky.

A point that catches people out: resin jointing needs a joint depth of at least 25 millimetres to hold, so the bedding mortar must not be brought up flush to the slab top. Leave the mortar low, let the resin fill the top 25 millimetres, and the joint has enough body to stay put under thermal movement.

Efflorescence: the white bloom you will see anyway

Expect it. Both Ashbourne and Trustone are cement-based, and free lime migrates to the surface as the slab cures, leaving a white deposit that is worst in the first six months. It is cosmetic, not structural, and on Trustone it tends to appear as a broader haze because of the tighter surface, while Ashbourne shows it more in patches. Lithofin efflorescence remover, an acidic cleaner applied to a pre-wetted slab and rinsed thoroughly, lifts the deposit without etching the surface if you follow the dilution and do not let it dry on. Trying to scrub efflorescence off dry with a wire brush burnishes the concrete and leaves a shine that never matches the rest.

A worked cost and material check for 25 square metres

Run the numbers before the delivery arrives. At 25 square metres, a Bradstone Ashbourne project pack covers the area with the mixed-size format, and you order 10 percent extra for cuts and breakage, so budget for roughly 27.5 square metres of slab. The subbase at 125 millimetres compacted needs about 3.1 cubic metres of MOT Type 1 before compaction, which is close to 5.5 tonnes delivered. The bedding mortar at 35 millimetres over 25 square metres works out near 0.9 cubic metres of mixed mortar, or roughly 18 bags of cement to 0.75 cubic metres of sharp sand.

Stonemarket Trustone lands at a higher slab cost per square metre than Ashbourne across most UK merchants, and the full-bed requirement means you cannot trim the mortar volume the way a leaner Ashbourne mix allows. Against that, Trustone holds its riven detail longer under foot traffic, so the higher spend buys a face that stays crisp past the point where a budget slab has worn smooth at the walked lines.

The resin jointing for 25 square metres with 8 to 10 millimetre joints consumes roughly two to three 12.5 kilogram tubs depending on slab size, since smaller slabs mean more linear metres of joint. Larger-format Trustone units cut the joint length and the resin quantity, which claws back a little of the price gap.

Which one for a rear terrace

On a level garden with soil that drains, laid to a proper 1-in-60 fall, either product gives a terrace that lasts. The real fork is what the ground does with water and how much you spend on the face you look at every day. A garden that puddles pushes you off both slabs and onto a permeable Priora build; a dry, well-drained plot where the crisp riven detail matters justifies the Trustone premium, while Ashbourne on a leaner bed is the pragmatic choice when you are laying it yourself over a long weekend.

What neither comparison settles is the seam where the terrace meets the house wall: whether you run a linear channel drain along that edge or rely on the fall alone depends on how much roof water sheets down onto the paving in a storm, and that is a measurement no slab spec will make for you.