Where does moisture come from?
Moisture takes no prisoners – if there is an opportunity for moisture to get into a building then it will. There are 2 main sources:
- Residual moisture – This is the moisture that is present in construction materials.
- Subground moisture – This is the moisture that is present in construction materials, it is this moisture that will migrate into the building if a damp proof membrane is not present.
So is a DPM needed?
In 1965 it became mandatory to install a damp proof membrane in all new buildings so it is paramount to test moisture levels in properties built before this date before any floor covering is laid.
Properties built after this date should also be tested. Remember residual moisture can also be present. Subfloors can take time to dry out (in some cases up to 1 year) so it is important to ensure the subfloor is dry enough to receive a covering.
How should a floor be tested?
British Standards are in place and subfloors should be tested in accordance with the British Codes of Practice BS 8203, BS 5325 and BS 8201. A BS hygrometer box should be used. This will provide a Relative Humidity (RH) reading. A reading above 75%RH is higher than is recommended to lay floors without a surface DPM.
What is the reality if I don’t use a DPM?
In one word – failure!
Firstly, it can ‘blow’ the levelling compound and if the levelling compound fails then the finished floor will fail.
Secondly, the adhesives that are being used to apply the finished floor may be affected. Their bond can be reduced or in the worst case, re-emulsify breaking down completely and allowing the floor covering to de-bond.
Customers will often only focus on the finished floor covering and with so many options available, who can blame them?
It is up to you, as their flooring contractor, to consider how to remove the existing floor and then what you might find underneath.
Customers are savvy and understand all about how add-ons are offered to boost the overall project costs but scrimping on this like DPMs will only come back to haunt you.
At UltraFloor we are continually researching and developing materials including our DPM IT Rapid which is a rapid Curing Primer Membrane suitable for use as a surface damp proof membrane and our new Suppress IT, which is ideal for use over a variety of substrates including concrete floors, sand/cement screeds and most absorbent construction materials.
These products provide proven results for our customers allowing them to have confidence and trust in the floor they are laying.
Visit ultra-floor.co.uk or call +44 (0) 1827 254402 for more information.