My property has damp walls when it rains – what’s happening?
If during or following rain, your property is experiencing damp patches, condensation that doesn’t disappear or more serious symptoms such as mould growth – then your property may be suffering from penetrating or rising damp.
If your property hasn’t previously had this issue, then it’s vital to get this inspected as soon as possible. Whilst a small amount of damp can be handled through proper temperature control and ventilation, causes of damp will not resolve on its own and will only worsen over time.
Unfortunately, once moisture is inside the cavity of a building, it often cannot escape, causing damp patches, aesthetic degradation, and eventually structural defects if left too long.
Being proactive is the only way to ensure your property is protected from damp and associated property defects. You can do this by getting a professional damp survey & remedial works from Biocraft South West’s PCA accredited operatives.
How do damp problems start?
There are several causes for penetrating and rising damp. Damp problems occur when the waterproofing designed to protect your property fails, and moisture has been allowed to enter the fabric of the building.
For penetrating damp, moisture can be introduced due to simple wear and tear of building materials over time, poor workmanship during repairs or renovations, or damage caused by weather such as storms, drought, or extremes of temperatures. A broken roof tile, or a worn-out plumbing joint could very well allow water ingress, leading to penetrating damp.
In terms of extreme weather – building materials are designed to work within certain parameters, and to protect the structure of a building, they are designed to shrink or expand as necessary. In some instances, they can shift beyond their typical amount, introducing damage such as failed seals or cracked pointing.
During drier weather, these defects don’t present any symptoms. However, once rain returns, penetrating damp can quickly develop if enough moisture is able to enter the internal structure.
Rising damp, however, is a bit more complicated. When rising damp is identified, it’s normally associated with damp caused by defects or bridging of the property’s Damp Proof Course (DPC)
The most common issues with DPCs are bridging, as opposed to them failing. This happens when the ground level is raised above the DPC, or the DPC is built up against without being correctly accounted for. This allows moisture to bypass the damp proofing measures and enter the structure.
Legitimate rising damp is incredibly rare, but if you had renovations completed during a dry summer, for example, you may not notice that your DPC is bridged until it rains and groundwater levels are higher than usual.
What to do if my walls are damp during or after rain?
If you’re noticing damp patches during or after rain, then the best way forward is to treat the immediate symptoms whilst ensuring you get a damp survey completed by a professional, PCA-accredited surveyor who can then advise on the best solution to solve the problem.
Keep a look out for the following:
✅ Damp patches that get worse after rainfall
✅ Paint or wallpaper peeling
✅ Musty smells
✅ Mould that returns after cleaning
✅ Tide marks appearing near the base of walls
If any of the symptoms are consistently present during and after rain, you can manage them by doing the following:
- Ensure your property maintains a steady, warm temperature.
- Provide the affected area with adequate ventilation
- Avoid introducing extra moisture unless there’s ventilation
For mould, you can treat the spores with bleach or cleaning solutions – just be aware this won’t stop it from coming back.
Whilst managing these symptoms, contact a damp & waterproofing specialist, such as Biocraft South West, who can provide a detailed damp survey to find the root cause of the issue.
What happens during a damp survey?
During a damp survey, an engineer will inspect both the exterior and interior of the property to identify the source of any moisture and assess all affected areas. As some signs of damp may not be immediately visible, a thorough inspection is essential to ensure no underlying causes are overlooked.
Typically, this means:
- Checking for internal and external building defects – including masonry and timber condition.
- Checking ventilation levels
- Assessing moisture distribution
- Investigating damp proof course performance
- Looking for evidence of mould, wet rot and dry rot
When you get a damp survey with Biocraft South West, our CSRT & CSSW-certified engineers can then provide remedial treatments that will resolve the root cause of the damp for good. By working with us, the solution provided will be tailored to your property’s needs, and may include:
- Repairs to brickwork & masonry
- Repairs to guttering
- Window & door sealing
- Repairing or replacing a DPC or using a chemical injection that creates a water-repellent barrier in its place.
- Once the damp is treated, and the building has had time to dry out, you’re then free to redecorate to remove staining, peeling paint/wallpaper, etc.
Speak to Biocraft South West about your damp problem
Damp rarely resolves itself. In most cases, the sooner the source of moisture is identified, the simpler and less expensive the repair will be. If you’ve noticed damp patches appearing during or after rainfall, our experienced surveyors can identify the cause and recommend the most effective solution for your property.
If you have concerns or queries about damp appearing in your property, contact our expert team today. Biocraft South West is one of the leading damp & waterproofing experts across the South West, serving Swindon, Bath, Bristol, Gloucester, Oxford, and surrounding areas. Our friendly damp specialists are here to help.