Not least, the flood catastrophes in the Eastern and Southern regions of Germany have shown what damage water can do to flooring constructions. In the cases of standing water or water under pressure - caused, for example, by burst pipes or a rising water table - the question arises, what steps should be taken by the tradesman to renovate the damaged parquet flooring?
First of all, the extent of moisture damage to the fully bonded parquet must be determined. For example, if the parquet flooring is a little swollen and is slightly dished due to ingress of rain, then it can remain and can be renovated. After measuring air humidity and temperature in the affected area, ventilation equipment - for example, an air dehumidifier from the company Wolff in Vaihingen/Enz - must be installed to quickly dry out the damp wood flooring. The moisture content of the wood should be measured as a control using, for example, a Gann hydrometer. As soon as a moisture content of maximum nine percent is reached, sanding of the parquet to be renovated can commence. It should be noted that the maximum material thickness to be removed depends on the thickness of the parquet. For 22 millimetre solid parquet, for example, the maximum is eleven millimetres, for pre-finished parquet, no more than the top wear layer can be sanded off. Then the joints are filled with joint seal paste (for example, with Pall X Kitt from Pallmann) and two coats of seal are applied (Pall X 96).
In the case of extensive water damage, from standing water or water under pressure, the parquet flooring is heavily swollen and warped and is partially detached. Usually in this situation, the only option is to completely remove the fully bonded parquet. For this, the parquet must be removed using suitable equipment. Then the substrate must be tested for full functionality. If there are screed cracks, or if the Ri-Ri scratch-test reveals a soft or crumbling screed surface, the screed construction must be completely removed using compressor-driven tools.
Water damage is also often connected with moisture saturation of the incorporated damp-proof membrane under the screed. Water that collects on the membrane following water damage has difficulty in drying out by natural means, most often not drying out at all. From the effects of moisture, insulation materials lose their thermal and acoustic insulation properties. Wetness in the screed means that static damage is to be expected. Natural drying of the isolating membrane, due to the physical conditions, is not possible. In such cases, special equipment for drying the damp-proof membrane has to be used.
If the screed construction is functional, a moisture measurement must be taken, using CM test equipment. If the value for cement screeds is above two percent, and for calcium sulphate screeds above 0.5 percent, the screed must also be dried with the aid of suitable equipment. To be sure, cement-based screed constructions should have a surface barrier system using Epoxy Primer PE 460 from Uzin. Such a barrier system is not possible for gypsum-based screeds - here, it is recommended that the construction is removed and replaced, since calcium sulphate screeds have a high gypsum content and store moisture for long periods.
After barrier-sealing or replacing the screed construction, new parquet flooring is laid. For this, a smoothing coat of Parquet Levelling Compound NC 174 is recommended, followed by adhesion of the flooring with Parquet Adhesive Uzin MK 92 S. Then, with solid parquet for example, the surface can be treated with lacquer or oil and wax.
Where water damage occurs with floating parquet floor systems, the quickest and most economical option is most often to completely remove the parquet flooring. However, if the floating floor is to be sanded, then wedges must first be fixed along all sides so as to secure the surface for sanding. Sanding of floating floor systems is, however, expensive and the result unsatisfactory, because the parquet is weakened and joints cannot be permanently sealed.
Ulrich Weng, Parquet Master Craftsman, Uzin Installations Technician
As at November 2002