Sealing Flagstones

The client said when he moved into this house in Lytham St Annes late last year that this room had a really bad smell of damp. The Flagstone floor was covered in carpet and he had the impression that the previous owner’s cat had been known to use it as place to pee!

The smell was rank and probably bad for your health so he decided to remove the carpet and the thick underlay underneath. Under that there was some old Vinyl flooring which all came out to reveal the original flagstone floor. As you can see from the pictures it was in a poor state covered in red and white paint, bits of bitumen here and there and the pointing had been lost in several areas of the floor. Additionally, all those layers over the stone would have prevented any moisture from naturally evaporating at the surface thereby resulting in damp.

The client had seen what we could do on our website and sent us some pictures of his floor which covered approximately 16m2. I priced for milling the flagstone as a deep clean would not resolve the shaling issues on its own and only a good mill of the stone would do that. Also, it needed all the pointing that was still in place knocking out and new flexible breathable pointing put back in place.

Cleaning and Repairing a Flagstone Tiled Hallway Floor

Milling stone is not a low-cost option, but it is a lot more cost effective than pulling up the whole floor and putting in a modern subfloor. Milling involves using a weighted buffing machine fitted with different grits and grades of coarse Diamond encrusted pads which cut into the surface of the stone to reveal new stone underneath, you then apply finer pads to hone and refine the surface.

In this case I used a set of Tile Doctor Milling Pads applied in sequence starting with 50-grit, 100-grit and then 200-grit. Water is used to lubricate the process and keep the dust down, it’s also important to rinse the stone off after each pad and extract the slurry that is generated with a wet vacuum.

The floor was then cleaned with Tile Doctor Remove and Go allowing the product to soak in for ten minutes to loosen deep seated paint staining. The Tile Doctor Remove and Go was then worked in with another 200-grit pad before another rinse and extract again with the wet vacuum.

Older floors like this were installed before the invention of the damp proof membrane so moisture is always a concern. To counter any issues that might develop later such as Efflorescence the last step in the cleaning process was to give the floor an acid rinse using Tile Doctor Grout Clean-up, this neutralises any latent salts trapped in the subfloor.

Sealing a Flagstone Tiled Hallway Floor

The milling, re-pointing and cleaning work took two days and we returned for a third day to apply a breathable sealer called Tile Doctor X-Tra Seal. This product is fully breathable and a great choice for any floors where damp can be a problem as it will allow for moisture to rise through the stone and evaporate at the surface. Being oil-based it also adds character to natural stone and adds an appealing low satin finish.

The whole process completely transformed the appearance of the flagstone floor and really suits the property which was a late Victorian four-story house with a basement. Original features like this are very sought after so it makes sense to restore them as it will add value.

An additional advantage of the milling process is it also reduces the roughness of the stone surface makes it smoother and easier to clean. On the topic of cleaning its worth mentioning that you should never use a strong bleach-based tile cleaning product on a sealed floor as it will erode the sealer prematurely. For a floor like this you need to use a product like Tile Doctor Neutral Cleaner which is a mild but effective cleaning product designed for use on sealed tile and stone.

Professional Restoration of a Flagstone Floor in Lancashire