CARRYING OUT A
SITE EVALUATION Carrying out an accurate site evaluation on a flooring project is vital in order for correct recommendations and prices to be offered.
The first question to answer before conducting any site evaluation is whether it is a new floor or a refurbishment project.
If it is a new build then the major concern is whether the substrates that require flooring products applying are in a fit state to carry out works. This could mean anything from screeds and subfloors being suitably dry, whether boarded floors are mechanically stable, if expansion or stress joints are present and if any underfloor heating systems (UFH) have been commissioned.
The nature of the UFH also needs to be evaluated. Warm water systems in screeds, warm water systems under boarded floors and electrical systems on top of the screed and boards are the three main categories and may all require different approaches.
When it comes to moisture testing there is a range of equipment available to enable assessments to be made. For example, using an encounter meter across a floor is great, but not if only the average figures are given out. The figures of interest are those giving the highest number as these are the “wettest” areas and therefore the most likely to cause issues. Rooms recently plastered are often the best to evaluate as they will have the highest air humidity and potentially have had moisture added from the trades.
When fixing hygrometers, all dust and other materials should be brushed away as they can harbour moisture and give a biased reading. When plugging the floor, the depth of plug should be sufficient to give a reasonable account of the moisture. Typically 40% depth is required, so on a 200mm power float it may not be a good choice. Equipment should also be left to reach equilibrium, which is when a change in moisture content on the test is minimal over a 24 hour period. Some floors release their moisture quickly so an equilibrium of three days may be sufficient, whereas power floated concrete can be seven days plus.
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Also, leaving the equipment itself to reach a steady state during the test is important. An electronic test with both probes in the floor and probes in hygrometer boxes needs approximately 60 minutes until the results stop changing and a true result is attained.
When it comes to refurbishment projects the situation revolves around whether the project is on a ground bearing floor or an upper floor. Upper floors generally don’t have any issues regarding moisture whereas ground and lower floors can be very problematic due to an absence of a base DPM. General ruling in the UK is that before 1970 base DPMs didn’t get incorporated in the building design whereas from 1970 they were; provided the building was designed as a habitable building. With warehouses, factory units etc. it should be assumed that no base DPM is in place and a moisture assessment should be carried out.
The next thing is to assess what floorcoverings are in place and what the new flooring will be. The existing floorcovering can give clues as to the likely adhesive residues and whether these can be smoothed over or not and with what compound. The new floorcovering can dictate the type of compound needed, such as high strength for LVT in an area of variable temperature or a high flowing smoothing compound for thin sheet vinyl, which would show every imperfection. Also, the type of smoothing compound currently in place may need removing if high strength systems are required. The age of the flooring can also give clues as to what is currently hidden beneath, which may include bitumen adhesives possibly containing asbestos fibres. These should not be disturbed and may need to be removed.
Movement joints in older buildings should always be carried through to the surface of any new systems. This is often believed unnecessary as the building will have done all of its movement, which is not the case. Movement is as much a seasonal thing as a settling down thing so it’s important to look out for these.
Obviously there are many more issues to consider on both new build and refurbishment projects but following this guidance can help when putting recommendations forward.
www.bostik.co.uk COVER STORY | 17
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