Gritstone or limestone

Millstone Grit on the western hills

The stone that builds the western side of Harrogate is Millstone Grit, a Carboniferous sandstone laid down by ancient rivers. You can see it in the villa walls climbing towards Harlow Hill, in the copings of the south-western lanes, and in the Killinghall stone of which St Michael and All Angels at Beckwithshaw was built in 1886. The British Geological Survey's names include the Almscliff Grit, exposed in the Harlow Carr valley, and a Harlow Hill Sandstone in the local succession. For a patio, this country asks for a flag that can stand in the same light as those walls. Yorkstone and other sandstones, in buffs, soft greys and quiet browns, are the natural stone we lay against a villa or a cottage whose masonry is already that rock.

Magnesian limestone around Knaresborough

Travel east and the rock changes. Around Knaresborough the solid geology becomes the Magnesian limestone of the Permian, a dolomitic limestone, often pale cream to warm buff, which forms the edge the castle stands on and the stone of many older walls. The Nidd has cut a gorge through it, which is why garden walls on the old streets often read as a pale masonry. A flag chosen as if the house were still on the western grit can look carried in from another part of the county, so against these walls we look for a lighter sandstone, or a limestone surface in the same colour range. Ripley lies between the two, with Millstone Grit and till still in the picture and the limestone strengthening towards the gorge, so the geology viewer and the dig both matter.

How the wall should guide the flag

Stand at the back door, look at the wall beyond the terrace, and choose a paving that can share that company. A coarse gritstone wall, with its sandy grain and buff-grey range, is at home with a sandstone flag of a similar grain. A pale Magnesian limestone wall, common in Knaresborough, is at home with a lighter flag. Where the garden contains an old stone wall and a new extension in render, each part of the paving can answer the elevation it sits against, with a sett band or a change of direction to make the join intentional. Block paving is the usual tool for that band, and for a path that has to curve along a wall which was never straight.

When porcelain is the practical choice

A rendered extension, a brick house of the middle of the last century, wide rear doors and a level threshold, and a garden where an even grid will look intentional, are all moments for a porcelain slab. It is made to a precise size, so the joints can be narrow and the lines can run true to the doors. It takes up very little water, which means a Harrogate frost has almost nothing inside the slab to expand, provided the slabs are bedded solidly on a firm build-up. In a shaded side garden, where a riven sandstone can hold a green film in the grain, porcelain gives that film less to grip. The porcelain page sets out the formats. On a listed gritstone cottage, whose wall is the point of the view, we stay with real sandstone.

Laying either rock, and where we work

Soft topsoil comes out, a separating sheet goes down where clay would work up into the stone, and crushed rock is firmed in layers. Slabs, whether stone or porcelain, are set on mortar across the whole underside. On a slope the same materials become the steps and the low edges, so the paving and the walls stay in one conversation from the door to the lawn. The steps guide covers risers and landings, and once a terrace stands more than about 300 millimetres above the lower ground the height is a planning question we draw before we build. We lay these surfaces across Harrogate, Knaresborough and the villages on the areas page. The quote form asks for the postcode and a note about the house and the garden.

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