• Joe Bleasdale

Prince Krofa's Guide to Penetrating Damp and How to Prevent It

One of the most common structural problems that turns up in our surveys is damp. Each different type needs to be treated in different ways, and the longer it goes untreated, the more likely our customers will have to pay to remove and repair it. This article explains how to avoid preventative damp in your home.


Before we start…


The most common type of damp is condensation, caused by moist air in poorly-ventilated rooms condensing onto cool walls, usually at its worst in kitchens and bathrooms. PKS wrote an article explaining this in September 2021.


Another theoretical type of damp you may have heard of is “rising damp”, which is said to be more common in older structures, or ones with poor drainage or on uneven, undulating ground. It involves groundwater moving up through the walls and floors, eventually damaging skirting boards, peeling paint and wallpaper, and leaving rising tide marks on walls and floorboards. However, many leading RICS members take the position that “true rising damp” is a myth, and chemically injected damp-proof courses, or DPCs, are a waste of time and money.

Penetrating Damp


Penetrating damp is the type of damp associated with the highest repair costs. It is usually patchier and more reserved to one specific part of a wall or ceiling rather than the whole structure, and is caused by problems with the building. These could include:

  • Air gaps in window frames and doors

  • Badly-designed roofing that lets rainwater gather

  • Cracks in the walls / ceilings that have formed over time

  • Faulty guttering

  • Internal leaks, usually from burst pipes underneath a sink or bath

  • Porous bricks

Houses built since 1920 have needed a cavity wall fitted as standard, meaning that, in more modern houses, wet and moisture penetrating from the outside are usually evaporated before they reach the inner wall. However, where this is “interrupted”, perhaps with a window, pipework or old or faulty insulation, this can allow the moisture to creep in. A “cavity tray” which guides water away from the inner wall may have been, or need to be, fitted to prevent this.


In some parts of the country, penetrating damp is a huge problem where houses are battered by severe levels of wind-driven rain and walls have been poorly constructed, usually hundreds of years prior. However, in London and the Home Counties, where PKS focuses, penetrating damp is more likely to be down to normal wear and tear in a building’s water delivery structures, such as pipes and guttering.


Because penetrating damp is not usually widespread, it can be relatively cheap and easy to repair yourself or with the help of an expert. However, the first job to fixing it is identifying it. If you spot any of the following in an isolated area, you may need to get in contact with a specialist surveyor or builder:


  • Discolouration of interior walls

  • Damp patches

  • Mould (and foul smell where it may have grown)

  • Blistered plaster

  • Water droplets

  • Surface wet to the touch

Preventative measures can include checking your gutters regularly for blockages, cracks and shoddy structural integrity, as well as coating your external walls with a good quality waterproof render and paint. External elements should be checked on a regular basis, and budgeting should be carried out for general maintenance, such as painting, every 3 to 5 years.


If bricks are damaged significantly, or cracks start to become widespread in walls and ceilings, these may need to be repaired and replaced, at a higher and more invasive cost. Again, whether this is appropriate for your structure will depend on the materials, period of the property and recommendations of a surveyor.


One thing to be wary of when looking for a survey is companies that offer so-called “free” damp surveys, as they may have vested interests in the repairs carried out and recommend unnecessary treatments, meaning a greater cost to you, both in money and space invasion. Prince Krofa and Sons’ Condition Reports will provide you with an unbiased solution to the best course of action and the most cost-effective remedial treatments for damp, to preserve your assets and the value of your property.


Visit this page to contact us and book a survey. You can also follow us on Facebook, Instagram and LinkedIn for updates on our findings and further tips.


Source: Which.com / RICS