penetrating damp on exterior brickwork

Treating Penetrating Damp in 2024: Causes and Symptoms

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Treating common types of damp like condensation typically involves quick fixes like dehumidifiers and air vents. Other forms, however, can be more difficult to diagnose, including penetrating damp. This often leads to the incorrect treatment being administered, which can damage both the interior walls and the overall structure of your property.

Understanding how to spot the key signs of penetrating damp is therefore essential for resolving the root cause of the issue, which is where Advanced Damp comes in. We are a premier damp and waterproofing company with more than 30 years of experience in treating any damp-related problem, from mould removal to internal wall insulation.

Our specialist team is fully qualified to complete damp surveys that help homeowners say goodbye to penetrating damp once and for all. Read on as we share the ins and outs of treating penetrating damp, including signs to look out for and how you can benefit from our professional damp proofing services.

In This Article:

  1. What is Penetrating Damp?

  2. Key Signs of Penetrating Damp

  3. What Causes Penetrating Damp?

  4. Why You Need Penetrating Damp Treatment

  5. How Do We Treat Penetrating Damp Problems?

  6. How Much Does Penetrating Damp Treatment Cost?

  7. FAQs

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What is penetrating damp?

Penetrating damp occurs when moisture, particularly wind-driven rainwater, enters the external walls of a property. It then pierces any protective coatings, passing through the masonry until it reaches the building’s interior. Rain penetration creates damp patches that damage your home’s plastering and wallpaper, while also causing toxic mould spores to grow.

Older buildings with degraded, porous bricks allow large amounts of water to soak in, while properties with cracks in the external walls, faulty pointing, defective masonry, or aging roofs are also vulnerable.

However, modern buildings aren’t exempt from water ingress, especially if they’ve undergone little maintenance or have poorly installed cavity wall insulation, for example.

wall causing penetrating damp and mould
Tips to stop damp and mould

5 Key Signs of Penetrating Damp

Knowing the difference between the effects of condensation, rising, and penetrating damp is the first step to successfully treating the issue. We’d therefore recommend looking out for any of the following signs to identify penetrating damp in your home:

  1. Mould Growth: Black mould is a type of fungi that grows and thrives in damp conditions. You may begin to notice patches of this fungi on the walls and ceilings if your property is poorly ventilated.
  2. Peeling Wallpaper: Wallpaper and paint can start to peel due to moisture, which causes interior walls to expand. You may also notice blistering plaster and swelling plasterboard, which damages the overall finish of your walls.
  3. Damp Patches: Dark spots on anything from walls and ceilings to carpets and cabinets all point to fresh penetrating damp. Brown or chalky patches suggest that the issue is much older, yet still in need of treatment right away. These marks may become even more visible during rainfall.
  4. Musty Smell: Damp odours are often noticeable before any visible signs appear, particularly when it comes to penetrating damp.
  5. Rotting Timbers: Moisture seeping into your property weakens any structures made from wood by making them spongy and unstable. This creates the ideal conditions for wet rot, a type of fungus that causes timber to decay.


Book a professional penetrating damp survey as soon as you spot any of these issues to avoid suffering further damage to your home’s internal walls and floors.

    What Causes Penetrating Damp?

    House bricks are typically built to ensure rainwater evaporates off their surface, therefore keeping properties comfortable and dry. However, various building defects can prevent this process, leaving homes and businesses vulnerable to penetrating damp.

    Here are some of the main reasons that water may be penetrating the walls of your property:

    Damaged Brickwork

    When bricks crack or crumble, their soft inner portion becomes exposed to the elements. Frost damage can also create porous bricks, which makes the perfect point of entry for moisture.

    Repointing may therefore be required to remove the damaged materials and refill the mortar joints with a stronger, more water-repellent mix.

    Faulty Guttering

    Guttering and downpipes designed to carry rainwater away from your home. However, when they are broken, water may instead seep through the building’s exterior walls. Cast iron pipes are particularly problematic as they can become easily corroded, making them susceptible to wind and rain damage.

    Gutters that are blocked with foliage such as moss and leaves can also become inoperable, which leaves them open to water saturation.

    Uneven Ground Levels

    Damp proof courses are designed to keep rising damp problems at bay by preventing the walls from soaking water up from the ground. However, external ground levels that are higher than internal flooring can cause the course to stop working, which allows damp to penetrate the walls.

    Damp proofing treatments such as membranes and injections should therefore always be installed by specialist services to ensure that ground levels remain consistent.

    Cracked Door and Window Frames

    Filling in any door or window frame cracks with a flexible sealant is one of the most simple ways to stop penetrating damp from entering your home. Damaged dip grooves under window sills are another common culprit, as they cause water to run straight from the sill into the walls.

    Defective Roofing

    Water ingress can often occur on the roof if tiles become damaged or missing. Another potential entry point for moisture is through the flashing around your chimney, which is difficult to spot without regular inspections.

      Why You Need Penetrating Damp Treatment?

      signs of penetrating damp in a property


      Get A FREE Quote Now

      Get a no obligation FREE quote now. Our team is here to help. Take the first step towards a guaranteed solution by filling out our form below. 

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      The latest government figures suggest that around 4% of homes in the UK are facing some form of damp issue, which includes penetrating damp. This poses several risks to the safety and comfort of your home when left untreated, including everything from rotting timbers to poor respiratory health.

      Contacting a penetrating damp specialist as soon as you spot any black mould, watermarks, strange smells, or interior damage is therefore crucial. Tackling the issue promptly is the most effective way to prevent penetrating damp from returning and offers several benefits for homeowners:

      • Improves Insulation – Preventing water ingress allows the thermal insulation within your home to work more efficiently, meaning less heat is lost through the walls. This improves your energy consumption and can reduce the cost of your heating bills in the long run.
      • Lowers the Risk of Health Issues – Patches of black mould on the walls make both an unpleasant and dangerous addition to your home., especially for those suffering from respiratory conditions. This is because mould releases toxins that increase the chances of an allergic reaction, encouraging symptoms such as wheezing, nasal congestion, headaches, and eye or throat irritation.
      • Prevents Structural Damage – Penetrating damp can be incredibly dangerous as it encourages the growth of fungus, which you may notice feeding on any wood in your home. Penetrating damp treatments can strengthen wood against wet rot so that the timbers in your property’s structure don’t crumble and retain their durability for many more years.
      • Helps Your Property Maintain its Value Continually painting over damp patches simply won’t cut it when it comes to property valuation. This may clean them up for a while, but eventually they will return with that damp musty smell, which is likely to put potential buyers off. Treating damp problems at the root helps to ensure that your home retains the financial value it deserves if you’re looking to sell.

      How Do We Treat Penetrating Damp Problems?

      Identifying penetrating damp may seem simple, particularly when wet patches on the walls make the source of the issue obvious. However, getting to the root cause is a lot more tricky and often results in misdiagnosis if not carried out by a professional. This can cause even greater damage and may end up costing more money to fix in the long term.

      Hiring a qualified damp specialist to inspect the property is therefore vital for properly treating both minor and severe penetrating damp problems. At Advanced Damp, our expert surveyors follow a comprehensive process to find out exactly where water is getting through the walls, and a penetrating damp survey is the first step.

      We’ll use a damp detector during this survey to correctly diagnose the penetrating damp issue, which will show high readings in areas where water ingress is at its worst. The solutions we recommend will then depend on the specific issue that our specialists have identified.


      how to treat penetrating damp

      The most effective course of action to treat penetrating damp is prevention, which is why we may suggest installing one of the following devices:

      • PIV Unit: Positive Input Ventilation (PIV) systems are typically installed in lofts to push moisture and humid air our of your home. This encourages freshly filtered air to enter your indoor spaces, which reduces surface condensation and therefore keeps the walls dry.
      • Vapour Retarders: This water-resistant material prevents penetrating damp from entering through walls and porous brickwork. It can often be combined with a waterproof brick coating, which provides penetrating damp protection for over 30 years. We may then use specialised equipment to ensure that walls, floors, and ceilings are properly dried out.
      • Damp Proof Course: Injecting a silicone-based cream or installing a thin plastic sheeting is an effective treatment for homes where rising damp is also an issue. These methods create moisture-resistant physical barriers that stop moisture from working its way up the walls of your home.

      The next stage involves treating the damage caused by penetrating damp to protect the structural integrity of your home for many years to come.

      For example, window damage, cracked or missing roof tiles, and blocked guttering will need to be fixed to block water from passing through. We can also apply external rendering to your walls, which acts as a barrier against moisture penetration. This process will improve the durability of the walls and extend their lifespan by up to 20 years.

      You may also need to remove wallpaper affected by moisture ingress and apply a damp-resistant plaster, while also replacing timbers that are crumbling due to wet or dry rot. 

      Mould removal is another important step in keeping your home safe and requires specialised treatment to kill the source of bacteria growth. This may include installing ventilation systems like extractor fans and vents that improve airflow and reduce moisture levels.

      Advanced Damp is an experienced team of penetrating damp treatment experts. Our company have over 30 years’ experience and covers the South East of England and surrounding areas. To contact a Penetrating damp treatment professional and rectify your problem immediately, call us now on 0300 373 7251.


      How Much Does Penetrating Damp Treatment Cost?

      While generally ranging from £400 to £4000 plus redecoration costs, all penetrating damp solutions have different prices. This depends on factors such as the size of the affected area and the severity of the issue, along with the type of repairs that are required.

      Minor jobs such as mending window seals or clearing blockages from gutters are lower in labour and material costs, so will be less expensive than damp proofing exterior walls, for instance.

      At Advanced Damp, our specialist team will inspect your home or commercial property and provide a free quote before starting any penetrating damp treatment. All of our solutions are competitively priced as part of our commitment to affordability, plus every new installation comes with a free 20-year guarantee for your peace of mind.

      Visit our property services page to find out how we can repair any damage to your home caused by penetrating damp, from plastering to painting the exterior walls. Contact the team today on 0300 3737 7251 or book a damp survey online to tackle penetrating damp for good.

      Frequently asked questions

      Check out some of our most frequently asked questions below to find out more on how to stop penetrating damp and properly protect your home.

      Picture of Jake Fitzgerald - Damp Surveyor

      Jake Fitzgerald - Damp Surveyor

      Surveyor of Timber & Dampness in Buildings (CSTDB) & ( MRICS ) Chartered Quantity Surveyor

      Jake is a qualified chartered quantity surveyor and experienced damp specialist with a unique skill set in thermal imaging. With a focus on effective solutions, Jake combines his expertise in quantity surveying and thermal imaging to accurately assess and address damp-related issues. He utilises advanced technology to identify hidden moisture sources and develop targeted strategies, ensuring comprehensive and cost-effective solutions for his clients. With a commitment to open communication and client satisfaction, Jake delivers cutting-edge solutions that tackle damp challenges head-on.

      Connect with him on Linkedin...

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