Flagstone Restoration

Earlier this year I was asked to improve this tired looking Black Flagstone floor which was at a house in Kendal that dates back over 200 years. The property used to be the Prison Wardens house and was part of the House of Corrections which was situated in Kendal on the Hill on the road up towards Windermere. The old Stone walls, in what is now the car park, are still present but the Gaol has long gone with new houses built in its place around 120 years ago.

The flagstones formed the floor of what is now a Kitchen and Pantry and sometime in the past a red cement base was put on top of the stone to level it and was then covered in a wooden Parquet floor. The trouble with this was that it stopped the stone from breathing leading to damp spreading into the walls which in turn encouraged mould to grow. Certainly not what you want in a house and certainly not in the Kitchen.

The customer had removed all the old Parquet floor which was rotten anyway and knocked out a lot of the leveller but the stone was very rough and he was unable to get it clean as it would shred mops and the dirt would get trapped in the pits and build-up.

I went over to look at the Flagstones and recommended that we mill the stone which would remove what remained of the levelling compound allowing the stone to breathe again and remove the roughness of the stone allowing it to be cleaned easily. I came up with a restoration plan to do that, address the pointing and then seal the stone with a breathable sealer. Happy with the quote and relieved they now had a practical solution we were given the go ahead to do the work.

Milling a 200-Year-Old Black Flagstone Floor

We used a series of coarse DRB milling pads to grind off a thin layer of stone off the flagstones. This exposes new stone underneath and removes the contaminates in the process. The work starts with the very coarse 50-grit DRB milling pad and is applied to the floor using a heavy-duty buffing machine that has weights added to improve traction. Water is used to lubricate the process and this slowly turns to a slurry as work progresses. The slurry is then rinsed and extracted from the floor and the process repeated with the 100 and then 200-grit DRB milling pads.

Once done we moved onto the pointing which was knocked out with a Hammer Drill and replaced with a breathable pointing product called VDW in a stone-grey colour. Work continued into the next day where the sandstone was cleaned again with the 200-Grit milling pad and focus turned to cleaning all the edges and corners where the pads struggle to reach. Once done the floor was given another rinse and extraction and left it to dry overnight.

Sealing a Black Flagstone Tiled Basement Floor

To return the dark Black colour to the stone I decided to use a breathable oil-based sealer called Tile Doctor X-Tra seal that leaves a low satin finish. This product is rated for internal and external use and being breathable it will allow moisture to rise through the floor and evaporate at the surface. Old floors like this don’t have a damp proof membrane so it is important to choose a sealer that can allow the floor to breath and this will resolve the damp issues the property was experiencing previously.

This was not an easy job for us, but luckily it was quite a small floor. I’m not sure the photographs really do it justice but our work certainly made a difference and my customer was very happy with the result. They even left the following 5-star feedback on our website.

For aftercare I recommended Tile Doctor Neutral Tile Cleaner which will clean the floor without impacting the sealer which can be a problem with many of the stronger products you find in supermarkets.

Professional Restoration of a Black Flagstone Basement in Cumbria