A damp basement can be a nightmare to deal with and can be an expensive fix if left without treatment. If you’re dealing with musty odours, mould growth, or even structural damage, excess moisture can pose serious risks.
The good news is that with the right actions, you can treat and prevent basement dampness effectively. From basement waterproofing to basement tanking systems, we take a look through the various actions and treatments to keep your basement dry and usable.
Understanding the causes of basement dampness
Before jumping into the various fixes, it’s important to take a look at what causes basement dampness.
Common culprits include:
Poor drainage around the foundation: If rainwater or groundwater isn’t directed away from your home, it can seep into the basement through walls and floors. This issue is common in homes without proper grading or with clogged or missing gutters.
Cracks in the basement walls or floor: Even small cracks in the concrete can allow moisture to enter, leading to dampness and potentially even structural problems over time.
High groundwater levels: In areas with a high-water table, hydrostatic pressure can force water through even the smallest gaps in the basement structure.
Condensation due to poor ventilation: Warm, humid air meeting the cool basement walls can lead to condensation buildup, creating a perfect environment for mould growth.
Identifying the root cause will help you choose the right basement waterproofing methods to address the issue permanently.
Mould and mildew growth
These can harm air quality and trigger health issues, especially respiratory problems.
Damage to walls and plaster
Damp can lead to bubbling paint, peeling wallpaper, and deterioration of wall materials.
Structural weakening
Persistent moisture can weaken a building’s structure, which may lead to costly repairs in the long run.
Basement waterproofing: Key approaches
There are several basement waterproofing types available, each suited for different situations. Here are the most effective methods:
1. Basement tanking
Basement tanking involves applying a waterproof coating or membrane to the interior walls and floors of your basement to create a watertight barrier. There are two main basement tanking types:
Cementitious tanking:
Uses a cement-based slurry applied directly to walls, ideal for minor damp issues. This method is commonly used in existing basements where external waterproofing is not feasible.
Liquid membrane tanking: A more flexible option that prevents cracks and seepage over time. This method is especially useful for older basements where movement in the structure might cause rigid coatings to crack.
2. Drained cavity basement construction
For basements prone to persistent water ingress, a drained cavity basement construction system is a reliable option. This system allows water to enter a controlled drainage space behind the walls, where it is collected and pumped away, preventing it from reaching your interior space. This method is often combined with sump pumps and drainage channels to provide a full waterproofing option.
3. External basement waterproofing
One of the most effective long-term options, external basement waterproofing, involves excavating around the foundation and applying a waterproof membrane to the exterior walls. This prevents water from penetrating the basement structure in the first place. However, it is more labor-intensive and expensive. This method is best suited for new constructions or during major renovations
Choosing the right basement waterproofing system
There are different basement waterproofing systems to suit various needs.
The three main types are:
Type A (Barrier protection): Uses basement tanking detail to form a waterproof barrier inside the basement walls and floors. This method is suitable for basements that do not experience significant water pressure from the surrounding soil.
Type B (Integral protection): Involves using waterproof concrete in the building structure itself. This is often used in new constructions where waterproofing is built into the basement walls and floor.
Type C (Drained protection): Incorporates drainage channels and sump pumps to manage water ingress. This is the most effective option for basements in areas with high groundwater levels.
Preventing future basement dampness
Once your basement is dry, take these preventative measures to keep moisture at bay:
Improve drainage: Make sure your home’s gutters and downspouts direct water away from the foundation. Consider installing a French drain if surface water pooling is an issue.
Seal cracks: Regularly inspect and seal any foundation cracks with appropriate sealants to prevent water ingress.
Use dehumidifiers: Keep humidity levels low to prevent condensation. This is particularly important in basements used as living spaces.
Regular maintenance: Check sump pumps and drainage systems regularly to make sure they are working correctly. Clean out gutters and downspouts regularly to prevent blockages.
Other things to consider for basement waterproofing
If you’re planning a basement renovation or conversion, look at adding waterproofing options from the beginning. Proper planning can save time and money in the long run. Some other factors to include:
Flooring choices: Choose moisture-resistant flooring options such as ceramic tiles, vinyl, or specially treated wood to prevent damage in case of unexpected moisture buildup.
Wall treatments: Using moisture-resistant drywall or insulation can help prevent condensation and mould growth on finished basement walls.
Ventilation: Improving airflow with mechanical ventilation or an HVAC system can help regulate humidity levels and reduce condensation risk.
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Damp proof membrane
A damp proof membrane is a plastic sheet or film applied to walls, floors, or ceilings to stop moisture from penetrating surfaces.
Membranes can be used internally or externally, providing flexibility for various building structures.
Example of basement waterproofing
Clients who recently purchased a home with a damp basement. They noticed a musty odor and water stains on the walls. After an inspection, they found that their home had poor external drainage and cracks in the foundation walls. They opted for a combination of external basement waterproofing and basement tanking. Excavating around the house and applying a waterproof membrane helped prevent further water ingress, while cementitious tanking sealed minor cracks inside. Now, their basement remains dry, and they have turned it into a cosy living space.
Cost of basement waterproofing
They cost of waterproofing a basement varies depending on the method chosen and the severity of the problem. At Damp HQ, we know one of the most common culprits of basement damp is water seeping through the joint where floors meet walls. Rainwater and melting snow can sneak into small cracks, leading to serious issues if left untreated.
Based on insights from professional estimators from Checkatrade, here’s what you need to know:
Average waterproofing costs
Per m²: £40 – £250 (avg. £120)
4m x 5m basement: £2,960 – £18,500 (avg. £8,000)
5m x 6m basement: £3,840 – £24,000 (avg. £10,500)
6m x 7m basement: £6,480 – £40,500 (avg. £17,500)
What affects the price?
Several factors will influence the overall cost of waterproofing a basement. The size and layout of the space play a major role, as larger or awkwardly shaped basements typically require more work. Any necessary structural or preparatory work can also increase costs, especially if the basement is being converted into a habitable living area. The quality of materials and finishes you choose will impact the price, as will your location and how easily the basement can be accessed. Finally, the time needed, and the complexity of the job are key considerations that can affect your final quote.
You may also need to budget for:
Dehumidifier hire: £65–£85/week
Proprietary filler: £65–£75 per 25kg
Waterproof sealers: £25–£85 per 5L
Survey fees (if not free): £100–£200
Tips for successful waterproofing
Only waterproof when surfaces are dry
Avoid sealing over painted walls or efflorescence
Fix cracks before applying any product
Use sealers specifically made for masonry
External solutions are often more effective, though pricier
Get multiple quotes and always check reviews
While some DIY waterproofing solutions exist, professional installation is often recommended for lasting results.
Keeping your basement dry
A damp basement doesn’t have to be a persistent problem. Whether you go for basement tanking systems, drained cavity basement construction, or external basement waterproofing, choosing the right basement waterproofing system is crucial. By addressing the root cause and taking preventative measures, you can enjoy a dry, healthy basement for years to come. Investing in waterproofing now can also increase your home’s value and prevent costly repairs in the future.
FAQs
1. What causes damp in a basement?
Damp in basements is usually caused by water penetrating through walls or floors due to poor drainage, high groundwater levels, leaking pipes, or ineffective waterproofing. The joint between walls and floors is a particularly common weak point.
2. How do I know if my basement needs damp proofing?
Signs include a musty smell, discoloured or flaking walls, mould growth, pooling water, or condensation. If you notice any of these, it’s worth getting a professional survey to assess the extent of the problem.
3. What is the difference between damp proofing and waterproofing?
Damp proofing typically controls moisture but may not stop water ingress under pressure. Waterproofing is a more comprehensive solution designed to completely block water from entering, ideal for basements below ground level.
4. How long does damp proofing last?
A professionally installed damp proofing system can last 20 to 30 years or more, depending on the materials used and ongoing maintenance. Many installers offer guarantees for added peace of mind.
5. What type of damp proofing system is best for basements?
There are several options including tanking (coating the walls with a waterproof barrier), installing a cavity drainage membrane system, or external waterproofing. The best method depends on the condition and layout of your basement, as well as your budget and intended use.
6. Is a survey necessary before damp proofing?
Yes – a professional survey can identify the source of the damp and help determine the most effective treatment. Some companies offer free surveys, while others may charge a small fee.
7. Do I need planning permission to damp proof a basement?
Generally, no. However, if you’re converting the basement into a living space, you may need to comply with building regulations, especially around ventilation, insulation, and fire safety.
8. How can I prevent damp returning after treatment?
Ongoing maintenance is key. Ensure gutters and drains are working properly, keep ventilation consistent, and avoid storing items directly against walls. It’s also important to monitor for any new signs of water ingress and deal with them promptly.
Flood Damage
With decades of experience, Damp HQ has supported countless homeowners in getting their homes back to liveable conditions.
Water Damage
Structural waterproofing acts as a preventive measure, ensuring that water is kept out and your property stays strong and secure.
Mould Removal
At Damp HQ, we specialise in providing full mould removal & prevention services that ensure your home remains mould free
Basement and cellar services
At Damp HQ, we provide expert waterproofing services to protect your property from water.
If you’re not sure what to do about your basement damp it’s always best to consult professional help. The best treatment really depends on your home and how bad the damp problem is. In places like Bournemouth and Poole, where damp is quite common, methods like tanking or using a damp-proof membrane can work really well. Whether you need a quick fix or a more long-term solution, choosing the right approach can make a big difference.
By taking steps to sort out basement damp, you’re not just protecting your home—you’re also making it more comfortable and adding value in the long run.
Get in touch today for our help and advice – and say goodbye to your damp problems.
