If you have a Victorian house you will almost certainly have experienced "rising damp". The cure to damp in walls is, in many ways easy, but the diagnosis is not as straight forward as some would have you believe. There are plenty of things you can do before you call a "damp proof expert". The first interesting thing to note is that in all the years I have been surveying I have never come across a pure case of rising damp. It is rarer than you think. What is common are Victorian walls injected with a chemical DPC that didn?t need it.
DPC stands for Damp proof course which is a thin waterproof layer at the bottom of a wall about 3 courses up. Why is it there? All bricks absorb water and in theory can pass it on to the other bricks around it. This way water can appear to "rise" up a wall. When water rises up from the ground through bricks we call it "rising damp". By placing a waterproof layer (DPC) at the bottom of the wall the theory goes that water cannot rise up and therefore the inside stays dry. If the wall has no DPC one possible remedy is to inject a chemical into one layer of bricks to make them water resistant and make them into a DPC layer. This is called a chemical DPC. In practice you actually need quite a high water level in the ground to create rising damp that occupants notice and complain about.
Bricks can get wet in a number of ways, the most obvious is when it rains. Basically every time it rains walls get wet and when it is sunny walls dry out. If the wall is made of solid brick then as long as the wall dries out before the water reaches the inside no one need worry. Basically solid walls work because they are thick enough to prevent water getting in. Modern walls stop water getting to the inside because they are in fact two walls separated by a gap (cavity). The outside wall can get as wet as it likes because the inside one will stay dry.
If a solid wall gets wet from rain and cannot dry out then this is called penetrating damp not rising damp. An introduction of a DPC at the bottom of the wall will not cure it.
The next biggest cause of water getting into the walls is you- or more precisely, your breath. Other sources of moist air are baths, sinks, kettles and tumble dryers. You cannot see this moisture but as it passes through a cold wall it can convert to water and soak into the bricks making the wall appear wet. This is not rising damp.
If the wall is exposed to more rain than sunshine then a solid wall may simply not cope. Walls soaked by leaking gutters, road spray, parapets or rainwater pipes will become deluged and stay damp but this is not rising damp.
So there is more than one way to get a wall damp and any one or all of them could be at work (there are other ways but I have covered the main ones). A wall does not become damp because it is Victorian it is simply a wall that has become compromised. Removing one cause is usually straightforward but dealing with multiple causes requires careful diagnosis. Troublesome walls rarely have just one problem so calling in a surveyor who only has one remedy will not be enough. Geoffrey Hunt Building Surveying Services analyse all the potential causes and devise careful re balancing with the minimum of disruption.
Here are some top tips for keeping your walls dry before you start looking for cures. If symptoms persist then call 07841 488636.