Monitoring The Drying of Cavity Walls
Restoration companies use specialised turbine equipment for drying out cavity walls. Dampness in buildings can cause many ongoing problems including mould on walls, wet and dry rot. If not treated professionally then additional flood damage repair costs may be incurred many weeks, months or even years later. These additional building restoration costs may not be covered within the original insurance repair quotes.
In a previous article we discussed the damp survey process involved in the effective methods of preparing the drying out of cavity walls. This is where holes are drilled and pies are presented into the cavities to introduce warm dry air to assist drying, mixing with the moist air and then vented to the building exterior.
Once the turbine drying equipment is set up, the holes are drilled and the pipes are in place how does the building reinstatement contractor know when the drying process has been completed satisfactorily?
The Drying Process and Timings
The process is as follows: The specialist connects the turbine manifolds to the machine outlets and turns the drying systems on. The flow-meter is checked on the system to ensure it is not indicating in the amber or red zones. If that is what is showing, then there is insufficient air flow. In that case a few more holes will need to be drilled. If it indicates in the amber sector, then turbine can be left running for up to half an hour after which it should be moving out of amber and indicating in the green sector in which case all is working well and the system can be left to carry on drying out the cavity walls.
The pipes introducing the dry air should be sealed so there is no air coming out as seepage. If that is the case then the drying job will take longer and will not be as efficient and so they should be resealed. If a good seal cannot be achieved then new holes should be drilled and the pipes moved into these new holes and resealed. An anemometer should be used to check the air flow from the vent holes that are venting moist air to the outside.
The reinstatement contractor should remain on site for around half an hour to an hour to ensure the turbine equipment is working efficiently and that the meters are remaining to operate in the green sector. As long as the systems are working properly the contractor may leave the equipment working on site, checking back every two days to ensure all is still working as it should.
As the air being introduced into the cavity walls is pressurised it will also be generating heat. Anyone who has every pumped up a bicycle tyre will know that the pump valve can get very hot when forcing pressurised air from the pump into the tyre. This is a natural attribute of the physics of air pressure. In the same way, if the air drying turbine equipment has switched itself off, it is probably because it has become too hot and the heat sensor has switched the equipment off. This is a safety feature and should never be manually overridden. If this occurs the vent holes need to be checked and the system restarted. All this can affect drying times and should be taken into consideration when planning the next phases of building reinstatement.
Turbine drying machines are designed to operate on a 24/7 basis and should be kept running, with the flow-meter in the green section, until the drying process has been fully completed.
Monitoring the Drying Process
Regular visits to site should be made when grams per kilogram (g/kg) of moisture readings should be taken from both a dry air pipe and also the vent holes. By making comparison calculations it can be easily assessed and measured how well the cavity walls are drying. As part of the process, the damp proofing contractor may need to drill new holes and move the pipes into areas that are not drying so well. Once the dry air and the vented air are measured as being in balance the process is complete and the turbine drying systems may be shut down and pipes removed.
Humidity sleeves should then be placed in some vent holes, coupled with a hygrostat. Moisture readings should be taken from these after a further three days. If the readings have increased from the surrounding ambient moisture then further drying will be required and the pipes reintroduced and the equipment should be turned on again for another week.
The overall drying time can be generally as broad as between one and four weeks. These timescales are dependent on many factors including the extent of saturation that has occurred, the presence of insulation, weather conditions and also humidity. However the experts in this sector know how to cure dampness in buildings in the most efficient way, before the building restoration process commences.
Scotland's Water Damage Specialists
Paradigm Reinstatements is one of the leading specialist building restoration companies based in the UK. They are regularly appointed by several of the UK’s leading insurance companies to deal with 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 such as the turbine drying systems described above.
