Rising Damp … Or Not?

On our timber & damp surveys the most common problem our surveyors come across is misdiagnosis of rising damp since damp proof courses (DPC) were made compulsory in 1875 there has been various methods of installing DPCs in buildings from blue brick DPC to recent plastic DPC.

The blue brick or engineering brick method was a good idea in their day but the only problem with this installation was the mortar joint which is very porous to moisture ingress and could lead to rising damp.

Early 1900s seen a method called poured bitumen this was a good DPC and still is to this day, many properties we survey have the older installations like poured bitumen, slate, rolled bitumen and are working fine. But over the years external ground levels can be elevated through soil build up around the perimeter of your home or within the last 25 years block paving or raised tarmac drives to name a few this will cause problems to the damp proof course of your property.

The DPC in your property should be a minimum of 150mm above the external ground levels and if breached by what I mentioned earlier like soil, block paving etc then the DPC will become bridged and moisture ingress will be inevitable, another misdiagnosis we come across is lateral damp penetration or side damp a I call it this is caused by the solid floor in the adjacent room been at a higher level so creating side damp penetration through the wall. Rain penetration at a low level can also cause misdiagnosis as can leaking water pipes in solid flooring and external drainage damage through cracked clay pipes.

Rising damp can only happen where no damp proof course is present in a building or possibly where it has been damaged by renovation work. Here at Preservit Ltd we pride ourselves on the correct diagnosis on all timber decay and dampness problems our clients might come across.