Repairs: floors and flooring

A magnesite composition floor screed may desiccate (powders and cracks) as it deteriorates with age. This is rapidly accelerated if it becomes damp.

Solution

This type of floor screed inherently has a limited lifespan, so it is usually removed if encountered as part of a refurbishment or alteration project. Certainly, any traces should be removed if a kitchen or bathroom is to be located in an area that previously had this type of flooring. It originally would normally have been kept well away from potentially damp areas, i.e. kept within bedrooms or reception rooms in domestic situations.

Note: Have the floor sampled to establish whether there is any asbestos content before carrying out further works.

Inherently the floor generally triggers a high damp reading if tested with a traditional conductance moisture meter, usually because timber sawdust content holds a large amount of moisture bound within it. This may help you to identify the material in the first place. Testing with a proprietary salts testing kits (for magnesium salts) may assist in interpretation.

This type of floor can be prone to sweating, as it gives out moisture under some atmospheric conditions. If a non-absorbent flooring has been laid over it, this may also assist with confirming the presence of magnesite. So, lifting a vinyl sheet floor covering and noting a heavy condensate would be very suggestive of this type of floor material.