How to Remove Bitumen and Cement from Stone Flooring

Late last year I was asked to survey a Flagstone floor in Morecambe which appeared to be beyond restoration. The floor had a long history and at some point in its past was covered with carpet which had been secured onto self-levelling cement with bitumen. All the companies that had visited before we got there said nothing could be done with it and recommended replacing the carpet or covering it with vinyl. As mentioned, it had been previously covered with carpet however this is an old floor and damp had been rising though the floor causing the carpet to rot. My client didn't want to entertain that as a solution and so kept on looking for a company that could restore the stone.


Old houses like this one do not have a damp proof membrane installed under the floor and moisture rising through the stone needs to be allowed to evaporate or you will find damp spreads outwards towards the walls leading to rising damp. In this case I suspect the bitumen which acts as a water barrier had either failed or damp was coming up the wall and into the carpet and underlay. Certainly, in our experience, if you have an old natural stone floor like this it is best not to cover it with anything more than a rug.

 Having inspected the floor, I recommended restoring the appearance of the flagstones by grinding the surface down a few millimetres to reveal new stone. We can do this using several different grades of coarse diamond encrusted diamond pads, a process we call Milling.

Cleaning/Repairing a Flagstone Tiled Hallway Floor

After being given instructions to restore the floor we returned on the schedule date and began by removing as much of the loose cement and bitumen by hand using hand tools.


Milling the floor using a very coarse 50-Grit pad fitted with DRB segments (Diamond Resin Blocks). Cutting the surface of the stone like this is hard work and requires the use of a weighted floor buffer to apply the pads. The process is lubricated with water and generates a lot of slurry which is extracted off the floor with a wet vacuum. The 50-grit pad was followed with a 100-grit DRB pad and then 200-grit DRB pad which start the slow process of refining the surface. It’s a two-man job so I brought a colleague along, whilst one was milling the other could take a rest and help with the clean-up.

The milling did a great job of removing the Black Bitumen, Self-Levelling compound and old paint revealing the true beauty ` and colour of the Flagstones, in fact the stone had quite a variance of colour which was lovely to see coming through. Half the pointing was missing so after milling the stone we moved onto replacing what was left of the old pointing and replacing with a modern breathable product.

We called back the next day to finish the stone cleaning by further renovating the stone surface using finer grades of diamond encrusted burnishing pads of 400 and 800-grit. Again, you need to water to lubricate the process and rinse the slurry of the floor with water after each pad, then extract with a wet vacuum. This does leave the floor damp, so once we had finished it was left to dry out for a few days, old floors without a damp proof membrane can take longer to dry and especially so in the Winter months.

Sealing a Flagstone Tiled Hallway Floor

Returning a few days later the stone was first checked with a damp meter to check it had dried out before sealing. The moisture readings were fine, so it was then sealed with a couple of coats of Tile Doctor Colour Grow which penetrates deep into the stone protecting it from within and enhancing the natural colours in the process.


The flagstone floor was completely transformed by the process and our client was over the moon with the result. In fact, they have asked us back to do the same in the Kitchen as the vinyl in there has since been torn up and revealed the same stone.


Source: Stone Floor Cleaning and Restoration Service in Lancashire