Whether you are dealing with a new construction or renovation project, commercial or residential, the drained cavity basement waterproofing approach is extremely popular and has become the weapon of choice for professional specifiers and waterproofing contractors when protecting underground structures.
The Cavity Drainage System is an internally applied basement waterproofing system consisting of a series of high density polyethylene membranes (studded profiles) mechanically attached to the basement walls, creating an air gap (usually 8mm) in the vertical plane. The air void created by the membrane ends at the wall/floor connection in a box duct, a Basedrain, which then carries all the water entering the basement (usually entering at the wall/floor connection or the joints in the concrete) leads to an open space. height or to a sump pump.) This basement waterproofing technique, in short, creates a sustainable air void in the basement, displacing any water that pushes into the gap before it damages internal fixtures.
The advantages of this approach are that you can apply the system in all weather conditions which can be a real problem when using externally applied or bonded membrane products that have limitations on when you can apply them i.e. the structure must be dry or the temperature is too low to achieve 100% binding.
Other key benefits include: minimal surface preparation – so no sandblasting or hammering, which is messy and can damage structures; the cavity drainage system is reversible, so it can be used on monumental and monumental buildings (refueling is not possible!); and most importantly, it is easy to maintain and repair if necessary. The same cannot be said of any form of external waterproofing which, once installed, is very difficult to remedy in the event of a problem; and in many cases a failed external basement waterproofing is remedied by retrofitting an internal cavity drainage system.
When using the cavity drainage system for your basement waterproofing project, the key is to remove any water that enters the system. As described above, the wall-floor connection drain, or Basedrain, is a very effective way to achieve this. The Basedrain should either drain into an open area, if you have one in your development (such as a property built against a hill), where water removal can be achieved by gravity or if this is not possible, a collection and pumping unit.
The specification of the sump and pumping unit for cavity drainage systems should be carried out by a specialist waterproofing contractor as part of the design and installation of the full basement waterproofing. In this way, the basement waterproofing contractor can guarantee the installation and offer maintenance contracts for the pumps themselves. Since people use their basement rooms for living space, the pump and sump systems can also be designed for sinks, condensate overflows, showers and even toilets. In many cases, the sump and pump can also be housed in the light well (if equipped) and can drain surface water.
Without a doubt, the key to using a cavity drainage membrane system is the drainage aspect, as the system is not like a traditional tank system, where you are trying to hold back water. It’s more of a water management system, so the principle is to make your structure as watertight as possible and still accept that it can leak. This is where the cavity drainage membrane “mops up” and removes the intrusion.
If you are using a sump and pump to remove water from the cavity drainage system, you should also consider what will happen in the event of a power failure. Answer: Your pump is not working! So if you are getting advice on the right kind of pumping system for your basement sealing project, you will need a backup battery and at least two pumps. You can be protected against power failures for a minimal additional charge. A tip when looking for such systems is to make sure that the backup pump has the same job and capacity as the primary pump, otherwise you will just be wasting your money. The recognition of cavity drainage systems is now undisputed as the most reliable and maintainable form of structural waterproofing and has been embraced by professional contractors and specifiers alike.
Even insurance companies now prefer the use of cavity drainage systems and offer longer periods of protection compared to conventional fueling in the UK.