Tile over asbestos floor tiles

Short answer yes. But you'd be raising the floor level. Would that propose an issue with your doors?

Best to leave the Bitumen tiles well alone. Major asbestos safety concerns see Domestic Bitumen Removal: Tiling on tile is only as good as the substrate underneath also the increased height has to be considered but there are other mitigation’s that need to be taken into account see below. Bitumen is frequently used in commercial construction projects but is lesser known for domestic use. However, if you plan to renovate your home, need to rip up a floor or remove Wall or floor tile coverings, you may potentially find Bitumen lurking under the surface. Bitumen was used to glue tiles in place and can be found in many homes constructed pre-2000. Whilst harmless, the substance is tacky, hardwearing and tough to remove. Over time Bitumen can dry and become brittle but if a thick layer has been applied it may still be wet and sticky beneath the surface. It may be tempting to leave the Bitumen and cover it with a new floor but the application of the tar-like substance is often found to be irregular. As a consequence, flooring, ceilings and walls are left with an uneven surface. Modern adhesives and cleaning chemicals can also react with Bitumen. Bitumen isn’t a hazardous substance, except when in liquid form due to its intense heat, but care is required when found as a tile or floor adhesive because it may contain traces of asbestos. Attempting to break up materials, sanding and aggressive removal techniques can crack and damage exposing the asbestos fibres. Now if you have tiled on top and the tiles are solid with no lose tiles then tiling on tiles can be done as I said previously height can be an issue. If you want to start from scratch removing both the old tiles and bitumen then you will need to contact a reputable company for them to conduct an asbestos survey and inspect the materials that need removing. An asbestos sample may be taken to determine the risk prior to removal if removal is advised. If best left alone and the floor if wooden may be covered using a Hardie backer board substrate prior to tiling. PPE is advised prior to working on top of bitumen. But to mask this material my be a risk for future persons trying to remove the tiles that were placed on top. So to be safe get a company who are registered to remove hazardous materials of this nature. Do not attempt this yourself. Be safe act safe

Although tiling over original tiles is financially attractive is it unfortunately not the best solution. If a couple of the ceramic tiles have already cracked there could be other issues. The original tiles might not be bedded securely, there could be damp issues or movement caused by the substrate underneath. Also there is the issue of the original substrate being able to cope with the extra weight of tile on tile if it’s a suspended floor. My advice would be to remove all the current tiles and investigate why the cracks have appeared. There are products available such as Ardex NA self levelling compounds that can be used to screed over the bitumen 1st, then lay your new tiles on top. This would also help keep you height to a minimum as well as insuring any money you investment in your floor is not wasted. Tiling on top of old tiles that aren’t 100% secure could very well come back and financially bite you at a later date. Hope this helps...

My advice is always where possible lift the existing tiles so that you can be sure of a perfect foundation for the new tiles. It would only take an existing tile to de-bond with the existing substrate and your new tiles are coming up with it. For encapsulating a bitumen substrate, you must use a self levelling compound that does not contain ammonia. I would recommend Mapei Latexplan No Ammonia which is a two part SLC designed to go over bitumen. Hope this helps Shaun