The term "rising damp" refers to the process by which groundwater (or moisture) is drawn up a building's structure by way of capillary action. Porous building materials like sandstone and brick are most commonly affected by rising damp.
Building materials have complex and varied pore structures, which affect the rate and extent to which moisture rises through a wall. Smaller pores mean the water may rise to a higher level. And it's not just moisture you need to worry about when it comes to rising damp. Along with the moisture rising up your wall comes undesirable substances such as contaminating groundwater salts, which can ruin building decorations. The unsightly effect of these contaminants is often what will bring a rising damp problem to a homeowner's attention. On average, evidence or rising damp can be seen to a height of approximately 3.3 feet.
Rising damp tends to be a fairly slow process, and you may only notice signs of it after a few years. How quickly or slowly the moisture rises up your walls is dependant on a number of factors including the environment inside the home and outside the building, the type of floor or wall construction, and the nature of the earth on which your home stands.
Why is Rising Damp a Problem?
Aside from being unsightly, rising damp can be potentially harmful, and may cause the decay of timber. It can also increase the conductivity of the walls in your house, which can result in the loss of heat.
If you spot any of the tell-tale signs of rising damp, it's best to investigate the issue as soon as possible, as in most cases, the sooner the problem is identified and action is taken, the less damage is caused to the home, and the lower the cost of rectifying the issue.
The most reliable and simplest way to approach a suspected case of rising damp is to call in the experts to survey your home and deal with the rising damp problem is necessary. You can also take steps to investigate the issue yourself, so you're fully aware of the extent of the problem.
How Do I Diagnose Rising Damp?
If you suspect that you have a rising damp problem, your first step towards diagnosing a rising damp problem is to check below your home for evidence of standing water in the crawl space. If you do have standing water, this may be the source of your damp issue. Once you have removed the water in your crawl space and improved your drainage, the dampness may subside. If it does not, you may have a rising damp problem.
Your next step is to check whether your home has a damp-proof course. If you do have a damp-proof course, this should be functional, as these tend to be last a long time. However, damp-proof courses have been known to fail.
Next, you'll need to rule out other forms of damp causing the problem. To do this, inspect your walls for the presence of salts (for example, tell-tale line of salts that is known as a "tide mark" at the highest point of the damp). Damp and salts can enter the walls in many different ways. Therefore, while rising damp is not necessarily the cause, a tide mark is a strong indication that rising damp may be the issue.
If tide marks are not visible above the skirting board, you may notice other common signs such as staining or damp patches. Usually, damp patches are either brown or yellowish in color, and can have a similar appearance to the "tide marks" left by salts.
If you have wallpaper in your home, it's worth inspecting it for signs of peeling or damage caused by moisture. You may see that the wallpaper has started coming away from the skirting board, with either a bottom edge or corner of the wallpaper starting to peel or turn up.
How is Rising Damp Treated?
There are several methods for treating rising damp, and how your rising damp issue is rectified will come down to a number of factors, including the extent of the damage and your home's construction.
The cheapest, easiest and most common method for treating rising damp generally involves injecting a siliconate-type chemical into the affected wall. This chemical can take the form of either a cream or solution. Depending on how thick your walls are, injecting the chemical usually requires drilling holes in the affected wall—or walls. The substance is then injected into the holes.
If for some reason the rising damp problem is too severe for the use of siliconate, a more comprehensive solution may be required. For example, you may need to have a physical rising damp membrane installed to serve as an additional damp proof barrier.
You can also look into using an Electro Osmotic system, which a professional damp proofing specialist will be able to offer.
Once a damp treatment course has been fitted on the property, any plasterwork that has been contaminated with ground salts must be replaced to preserve the integrity of your home. If the plasterwork is not promptly removed and replaced with plaster that is especially formulated to repel salt, the salts that are already present in the existing wall could keep absorbing moisture from the air, despite the presence of a damp proof course.
How Do I Prevent Rising Damp?
By far the best and most cost-effective way to solve rising damp issues is to prevent the problem arising in the first place. Investing in the assistance and expertise of a Damp Proofing Specialist means you're less likely to encounter rising damp down the line. Your damp proofing specialist may install a damp-proof course, a barrier membrane within the walls of your home, typically at about 1.5m above ground. This prevents damp rising up the walls from the foundations.
If you've noticed only a few tell tale signs of a rising damp problem, it's best to call in an expert damp proofing specialist to help you identify and solve the issue before it gets out of hand.