Patios in Blandford Forum, walled town gardens

What comes out first. Nearly every town garden here already has something down: concrete poured in the sixties, quarry tiles off an old scullery, or riven paving bedded on sand. It is broken up and excavated back to a firm formation. Old footings, made ground and tree roots turn up under half of them, so the dig and the muck away are priced by what leaves.

The sub base nobody sees. Under the paving goes MOT Type 1, put in and whacked in thin lifts, and carried past the edge of the slabs on every side. Hardcore raked level by eye is why so many patios rock within three winters. On soft or made up ground a geotextile separator goes under it.

Full mortar bed, never dabs. Each slab goes onto a full wet bed with a slurry primer painted on the back, so there is mortar under all of it. Five dabs leave voids, the voids hold water, and a sharp frost cracks the slab or lifts a corner.

Porcelain, sandstone, limestone and granite. Porcelain is calibrated, so every slab is the same thickness and the joints come out even, and a textured grade keeps its grip in the wet. Indian sandstone is warmer, riven and variable, so the bed is built up under each one. Limestone marks more readily and granite is unforgiving to cut. Travertine and anything polished we would talk you out of on a shaded terrace.

Falls, and the damp proof course. Paving has to fall away from the house and finish at least two courses below the DPC. Where a low threshold leaves no room, you dig down rather than build up, because bridging the damp course puts water into the wall. Approved Document C sets out why that level matters.

Where the water actually goes. A fall is only half of it. A channel across a doorway needs a gully and an outfall. A soakaway only works where the ground will take it. A permeable build up over open graded stone is the other answer, and it keeps the runoff on your own land.

Steps, edging and retaining. Long town plots rarely run flat, so the level change is set out first: generous treads rather than one mean riser, a haunched edging or kerb where paving meets a border, a retaining edge to a raised bed, and coping on a low wall.

Jointing, and the repairs. Joints get a brush in resin compound worked in wet and tooled off, or traditional pointing on an old stone terrace. Open joints are how weeds and water get in. A lifted or rocking slab comes up and goes back on a fresh bed; a corner that has sunk has a base problem under it. Cracked slabs, algae on the shaded side, efflorescence on new sandstone and staining are separate questions.

No rate per square metre, because the slabs are the part you choose and the smallest part of the price.

Getting to it. A Georgian town house with a covered passage, a 1970s semi on the estates north of the town with a side gate, and a terrace with no rear access at all are three different jobs. Everything comes in and goes out through the garden, often through a side gate or the house. A patio you can barrow to directly is a different job from one where every slab is carried. The work at height rules still apply to the dig and the machinery.

What is coming out before anything goes down. An old concrete slab, a raised bed, tree roots or made ground all have to be dug out and taken away, and that is priced by the load rather than by the metre. The dig is where a patio quote is won or lost.

Falls, levels and the damp course. A patio has to fall away from the house and finish at least two courses below the damp proof course, and getting that right often means steps, a retaining edge or a drainage channel. Laying a new patio up against a wall at the wrong level is the single most expensive mistake on this kind of job.

Comparing quotes? Ask how deep the dig goes and what sub base is specified, whether the slabs are laid on a full wet bed or on dabs, what the falls are and where the water goes, whether edgings and steps are included, and what the jointing compound is. Two quotes for the same job are usually two different jobs.

We cover Blandford Forum, Blandford St Mary, Bryanston and the Winterborne villages, broadly DT11, under Dorset Council. You are dealing with Bournemouth Roofing & Building, the trading name of Bournemouth Roofing & Building Ltd, registered in England and Wales, company number 15471719, which you can look up in a minute. Thomas Hannen's business, and he is the one who comes out to price the job, not a salesman. A verified customer's 10 out of 10 on Checkatrade. The visit and the written quote are both free.