Tips On Dealing With Subfloor Problems
What type of problems can I expect to find when I lift my floor covering?
If you have ever experienced problems with your sub floor when you have your old floor covering lifted you are not alone. Most floors have some associated problem when exposed. The types of problem you can expect to encounter are crumbling floor screed, pot holes, uneven surface, loose floor boards, wood blocks and mosaics, broken floor tiles, damp, mildew, mould.
The objective being to ensure the subfloor is sound, smooth, clean and dry before laying commences.
Problems arise for all sorts of reasons. The most common is when uplifting a product previously stuck down to the sub floor. If on a concrete substrate it is common for some of the screed to be lifted. The only solution to this is a new screed. Don’t patch, it will let you down. When the construction is floor boards, depending upon condition, it will most likely have been laid onto a Plywood/hardboard. This will need to be lifted with the floor covering. Again new ply or hardboard is the answer. If on a chipboard base then the product should lift relatively cleanly. Here a wash over screed will suffice. When wood blocks or mosaics are found in all cases a plywood should be over pinned. When a new Plywood base is used it is important that a feather screed is applied to ensure a smooth flat moisture free clean surface is achieved.
Broken floor tiles need to be taken up, it is best to remove all old floor tiles and prepare a new sub floor but if most are sound then a new screed can be applied over these. Similarly uneven floors will require a smoothing compound.
If necessary, repairs to damaged floors should be carried out using products such as STOPGAP 400 REPAIR compound prior to applying smoothing compounds.
When you discover a damp problem, a new floor can not be laid on any surface with a reading of 75RH or above. This can easily be tested for using a ‘protimeter’ damp tester. The readings immediately reveal the moisture content in the sub floor. If the indicator shows ‘Red’ then, a damp proof membrane will be required. This is applied to the surface of the subfloor and then a new floor screed can be laid in preparation. If the reading is inconclusive, then it is wise to employ a hygrometer moisture reader. This is an instrument placed in situation and left overnight. This enables a more accurate reading on moisture content.
Research source: F Ball & Co. NICF