Rising Damp Explained - What It Is And How To Treat It







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Finding your dream home and discovering that it has signs of damp can be devastating. Rising damp is one of the most controversial types of damp, and if it’s left untreated, it can lead to structural decay and rot infestations which can be far more costly to repair. 

Knowing how to correctly identify rising damp in a property, and how to treat it effectively, are essential to preventing this type of damp from destroying your home. 

What is rising damp?

Rising damp is a general term for water which rises up through the structure of a building from the ground. It does this through a process known as capillary action and it’s normally caused by:

  • failed damp proofing course
  • bridged damp proofing course, or
  • complete lack of a damp proofing course. 

A damp proof course (DPC) is made from non-absorbent, water-resistant materials such as bitumen, plastic or slate, and the material used will depend on the age of the property and when it was built. DPCs can fail with age but older properties may not have them at all. 

Most people spot rising damp by noticing the damage it causes to the internal walls of the property, such as water stains and tide marks, wallpaper peeling off the wall or plaster and paint deteriorating. Another sign of rising damp is salts blooming on the internal walls which will exacerbate the debonding of paint and plaster, or white salt stains on the exterior mortar. 

Will a property survey always pick up damp?

One of the many defects that a homebuyer’s survey will look for is signs of damp, not just with visual inspections but also with damp metre readings throughout the property. 

If you’re in the process of buying a property and your surveyor suggests there could be an issue with rising damp, or you’re renovating and stumble across signs of a problem, it’s worth investigating the problem further as soon as possible. An in-depth, damp-specific survey will assess the extent of the issue and suggest the best course of action for treating it. 

“The assessment of how the building envelope and its internal environment are affected by moisture will take into account building materials and construction methods, including any alterations, as well as the ground and surface drainage”, explains building surveyors Hutton + Rostron. Damp surveys are carried out using minimally invasive techniques, such as electronic monitoring and fibre optics, so you have a clear overview of the extent of the problem and how to proceed with your purchase. 

Can I get a mortgage with rising damp?

It’s relatively common for older properties or homes which need to be renovated to have signs of rising damp. “Most mortgage lenders don’t retain mortgages in the event of dampness and mould, unless the problem is severe, to the extent that it makes the property uninhabitable. For example, rotten building timbers that affect the structural integrity of the property could be a reason for a lender to retain some or all of the mortgage”, explains the team at The Mortgage Hut

If rising damp is found on your survey or in the home report for a property you’re interested in, contact a damp proofing specialist to receive a detailed treatment plan so you can deal with the problem and move forward with a smoother sale or receive a secure mortgage offer. 

Who can help me if I come across rising damp during a renovation?

If you are renovating a property and spot signs of rising damp, you should contact a damp proofing specialist as soon as possible to have the issue assessed and to determine the best way to move forward with treating it. They’ll be able to check the DPC in your property and determine what’s causing the problem. 

When left to develop, rising damp can cause serious structural issues, with wet and dry rot infestations developing, so it needs to be treated fully before you proceed with your renovations. 

You don’t want to spend time and money doing up a property, only to find that the damp undoes all your hard work, or that it needs to be ripped out again to deal with the problem. 

What are the main ways to treat rising damp?

One of the most effective and affordable ways to treat rising damp is with a damp proofing injection cream, which is injected or hand-pumped into holes in the mortar, reverting to a liquid which then penetrates the bricks until it’s fully absorbed. This liquid then cures and serves as a water-resistant barrier to stop water rising up through the wall. 

Another option is to install a new damp proofing membrane to the property which involves taking out the bricks in the wall where the mortar has become damaged and installing a new DPC. Naturally, this is more time consuming and labour-intensive, and far more expensive as a result. 

The way to treat rising damp will depend on whether you’re treating it on internal walls or external masonry. If you find evidence of rising damp on internal walls, the first step is to remove all wallpaper and plaster so you’re back to the brick or substrate. You can then check that the DPC hasn’t been bridged before moving ahead with the damp proof injection. 

When you’ve dealt with the damp issue, you’ll need to replaster the areas which have been affected, since the existing plasterwork is likely to be affected by salts which will continue to attract moisture until they’re removed. This replastering needs to be dealt with to certain specifications to prevent issues with salt contamination, so make sure you work with a professional who has experience of this. 

What does it cost to fix a rising damp issue?

The cost of fixing rising damp in your property varies depending on the severity of the problem, the size of the area affected, and the method of treatment you choose. You’ll also need to redecorate the area affected once the problem has been treated, which will increase costs depending on the extent of renovation you’re carrying out. 

The average cost of damp proofing is around £60 per metre, on average, with injection damp proofing costing an average of £3,500 and damp proofing for external walls costing around £1,500. 

Rising damp is a problem that needs to be resolved fully to prevent it from causing further issues, but the good news is that it doesn’t have to mean complete disaster. As long as you work with experienced professionals, both in assessing the problem and treating it, as soon as possible, you can ensure your property remains in good condition. 

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