A Guide to Drying Cavity Walls
Considerations and Processes
Restoration companies that have been called out to a property where there is water damage and that requires insurance reinstatement, will often be faced with the prospect of having to dry out cavity walls as part of the process. Dampness in buildings that isn’t fully expelled and residual moisture that isn’t properly dried out can cause all sorts of continuing problems such as mould on walls, wet and dry rot. This can require additional flood damage repair with increased costs many months later. If not treated effectively at the time, then additional building restoration carried out later on may not be covered within the original insurance repair quotes.
The effective drying of cavity walls requires special equipment and expertise on the part of the building restoration company team and the first task will be to carry out a damp survey to investigate the extent of water damage repair required.
The building reinstatement contractor will need to look at the construction of both the exterior and interior walls. If there is a need to dry internal walls that are constructed with insulation materials there will be a need to deploy more drying equipment and systems than if there is no insulation present. This consideration also applies to external walls which are usually thicker and more substantial.
The building plan and room layout needs to be carefully considered so that the drying equipment can be properly vented to the outside. Windows, extractor fan outlets and even letterboxes can be used to assist the venting process, expelling mist damp air out to the exterior of the building for dissipation into the atmosphere.
Once the contractor knows how many drying systems are required, the next consideration is how many holes will be needed to be drilled into the walls to present the drying pipes into the cavities to start the drying process itself.
Dense Insulation & Drilling
These holes are normally 16mm drill holes and consideration is needed when drilling into any cavity to ensure the penetration and removal of any loose insulation that may block the hole. Dense insulation (eg Celotex, Kingspan or compacted Rockwool) will require drilling deeper until the rear wall surface is reached or there is a risk that the insulating layers act as a barrier to the trapped water. This would adversely affect the efficiency of the drying process.
Between three and four holes per meter is recommended and it is also recommended to drill low down on the wall, removing undamaged skirting boards if necessary. This not only ensures a more efficient dampness removal during the process but it is also a key factor in the prevention of mould on walls developing in the future. If the skirting boards are flood damaged anyway, then their entire removal is recommended prior to the drilling of the holes.
The drying pipes are placed into half of the holes drilled into the walls with every second hole being used as vent holes. The way it works is that dry air is forced into the cavity by special turbine equipment and this dry air equalises with the moist air in the cavity. This combined air is then expelled via the vent holes.
As every school pupil knows when studying physics; when the same quantities of dry and damp air are mixed, the overall moisture content halves. When this reduced moisture laden air is expelled and more dry air is introduced, the overall air becomes dryer and dryer until it is equivalent in moisture to the ambient background moisture. Damp meters and testing is carried out regularly until the moisture is cleared, so building restoration can being in earnest.
Scotland's Water Damage Specialists
Water Damage Specialists is one of the leading specialist building restoration companies based in Scotland. They deal with many types of building restoration projects including the drying out flood and water damaged buildings of all types and sizes. They own and deploy a wide range of water damage drying equipment to ensure efficient drying out of cavity walls and can help with your water damage problems, call Paradigm or request a free quote online.
