Lifting and relaying a flagstone floor

A fortnight, in order

Dates shift for weather and for whatever turns up under the floor. The order never does.

Day one

Chalk, photograph, lift

The floor gets numbered before anything moves and photographed from four corners. Then it comes up with wedges, flag by flag, and goes on edge on battens outside. On a kitchen of twenty square metres that is most of a day and about six barrow loads of soil.

Roughly one flag in fifteen is already cracked through and nobody knew, because the crack was holding together under its own weight.

Days two and three

Dig out and cart away

Everything soft comes out down to firm ground, usually 350 to 400 mm. Old cement, ash, the odd brick floor underneath, and on one job in Mells a Victorian dog burial. The spoil goes in a skip on the drive.

Day four

Hardcore and geotextile

Limestone scalpings in two layers, whacked. Geotextile over the top so the limecrete cannot migrate down into it, which is the bit most people skip and the reason floors settle unevenly in year three.

Days five and six

Limecrete slab

Hydrated lime and light expanded clay aggregate, 100 mm, tamped level. It is warmer underfoot than concrete and it lets water vapour through instead of sending it to the walls.

This is the step that cannot be rushed in winter. Below about five degrees it does not set properly, and we would rather move the week than lay it and hope.

Days seven to nine

Curing, and cleaning the stone

Nothing happens on the floor. Meanwhile the flags get the cement, bitumen and old polish taken off with hand tools and a poultice, which is slow work and the part we are usually still doing in the evening.

Days ten to twelve

Bed, lay and point

Sharp sand and lime bed, flags back in their own order, levels checked across the room and against the door thresholds. Pointed in lime mortar, brushed off, and then left alone for a fortnight before anything heavy goes on it.

Twelve days is a normal kitchen. A hall and a scullery together runs to three weeks, and we say which it is before starting, not halfway through.

What ends up under the stone

Five layers, none of them waterproof. That is deliberate: a floor in a solid-walled house has to let moisture out somewhere, and if it cannot come up through the middle of the room it comes up through the bottom of your walls instead.

Flag, 50 mmYour own stone wherever possible, bedded in a lime and sharp sand mix rather than cement.
Bedding, 25 mmSharp sand and lime. Soft enough to take up the difference in thickness between one old flag and the next.
Limecrete slab, 100 mmLime with light expanded clay aggregate. Insulating, breathable, and considerably warmer to stand on than concrete.
GeotextileOne roll, twenty minutes, and the reason the slab stays where it was laid.
Scalpings, 150–200 mmLimestone, in two whacked layers. Below that, whatever the house has been sitting on for three hundred years.