Damp is a common issue for many property owners. Mould, odours, dark spots, and blistering paint are its most revealing signs and can be frustrating to manage. Without damp-proofing, the problem may worsen, impacting your health and your home’s structure.
On the bright side, there are different damp-proofing solutions for all causes of dampness, from condensation to leaking roofs.
In this post, you can discover the different solutions to fix your property. You’ll also learn the causes, costs, processes, and where you can expect to find dampness.
Damp-Proof Course (DPC)
DPC is a waterproof material made of slate, bitumen, or plastic, that prevents moisture from dampening your property.
Consider these situations where you may need to use DPC:
- Preventing rising dampness in walls: DPC is a horizontal barrier that stops moisture from rising on your home’s walls, preventing peeling paint, mould growth, and structural property issues.
- Keeping basements and cellars dry: These areas are below ground level and more susceptible to moisture ingress. Installing DPC around their perimeters keeps them dry and mould-free.
- Preventing dampness in extensions: Extending your property may wick moisture between the new and existing structures, even if there’s no visible water damage. DPC at the junction between the two foundations stops moisture at its tracks before it damages your new structure.
Damp-Proof Membrane (DPM)
This involves using a thin sheet membrane made of polyethene or Polyvinyl chloride (PVC) to stop moisture entering your property from the ground or roofs. DPM is flexible enough to cope with movement in the building structure without cracking and tearing.
Here’s how it’s used:
- Under concrete slabs: Contractors place DPM over a layer of hardcore before pouring the concrete slabs to prevent capillary action.
- Above concrete slabs: The material is laid over the concrete slab before installing the floor covering to protect your floors from swelling, wrapping, or rotting.
- In walls: It’s inserted in your property’s walls 150mm above ground level to prevent rising dampness from entering your home.
- Around foundations: The material is wrapped around the outside of your home’s foundation to prevent moisture from moving into your building.
- In roofs: You can lay DPM over roof decks before the roof tiles or shingles to prevent leaks.
A damp-proof injection is a fast-acting solution for rising dampness where the original damp course is damaged or worn out. The mixture is made of silanes, siloxanes, and other water-resistant chemicals that react with the masonry in walls to create a moisture barrier.
Damp-proof injections are suitable for:
- Treating rising dampness in existing buildings: A DPC injection effectively treats rising dampness in old buildings with damaged or missing DPC.
- Damp-proofing new buildings: DPC injections work well in new buildings built on a low-lying site or in a high-water table area with a risk of rising dampness.
This type of plaster is designed to resist moisture on walls from condensation and rising dampness. It’s made of cement, sand, hydrated lime, and special admixtures, making it more porous and breathable than regular plaster.
Here’s when to use damp-proof plaster:
- To replaster walls affected by rising damp
- For walls damaged by moisture penetrating through cracks or faulty gutters
- To allow condensed air to dry more quickly
Damp-proof paint is used as a primer to protect your interior and exterior walls from moisture. The paint has polymers to prevent moisture from seeping in, and some varieties even contain biocides to stop mould and mildew growth.
Consider these use cases for damp-proof paint in your home:
- Cellars and basements
- Exterior walls to protect them from high rainfall and humidity
- Internal walls to safeguard them from rising and penetrating dampness
- Roofs and terraces, including around vents and along the flashing and gutters
This plastic sheeting resembles a thin carpet made of polyethene (PE) or polypropylene (PP)—moisture-resistant materials with low permeability to water vapour. It’s often laid under a concrete slab to prevent dampness from capillary action.
Here’s where you can use a damp-proof sheet:
- Under concrete floor slabs
- Under insulation material
- Behind cavity walls
- Under sloping roofs
This is concrete treated with special admixtures to make it water-resistant or by coating its surface with a DPM. The concrete protects your property against condensation, and rising and penetrating damps.
Contractors use damp-proof concrete in the following areas:
- Basements and foundations to prevent dampness through capillary action from entering your walls
- Swimming pools to stop water from seeping into the surrounding soil
- Tunnels and underground structures to protect them from underground moisture
Damp-proof cream is a chemical injected into masonry walls to create a barrier against rising and penetrating dampness. Professionals drill holes into your wall’s mortar joints and spread the cream using an injector gun, creating a water-resistant barrier.
You may use damp-proof cream in the following cases:
- Rising damp treatment: The cream blocks the pores in masonry walls, preventing capillary action from occurring.
- Bridged cavity walls: The solution creates a water-repellant barrier between the inner and outer walls to reduce dampness.
- Damp-proof course failure: When DPC fails, contractors inject the cream instead of replacing the entire solution.
An aerosol is applied to masonry surfaces to seal and cover damp stains or add an extra layer of protection on walls. They’re made of acrylic, bitumen, epoxy, polyurethane, and silicone that form a waterproof barrier on your walls.
Here’s where you may use damp-proof sprays:
- Priming masonry surfaces before painting or adding wallpaper
- Sealing damp patches on interior walls and ceilings
Also called cementitious tanking, a tanking slurry is a thick liquid coating applied to masonry surfaces to prevent dampness. The solution is applied in two coats and forms a hard, durable layer resistant to water penetration.
Insoluble crystals formed from the reaction fill the pores and cracks of masonry surfaces, preventing moisture from seeping through.
Taking slurries is common in:
- Basements and cellars
- Retaining walls
- Tunnels and bridges
How Do You Install a Damp-Proof Solution?
It depends on the solution you need. For instance, to install a DPM on a wall, you have to remove the existing plaster and attach it using adhesive. You also need to plaster or render over the membrane to finish the job.
But, for a damp-proof cream, you have to drill holes into the mortar joints and inject the cream using an injection gun. The solution will dictate the installation process.
Should You Hire a Damp-Proof Specialist?
Yes, in most cases, you need a professional because damp proofing is complex and requires specialised knowledge and skills. An experienced contractor will diagnose the problem accurately and recommend the best solution.
Professional damp-proof specialists also use the latest equipment and materials, ensuring high standards in all their projects. They can sometimes also offer a guarantee on their work, providing you with compensation in case of errors and disruption to your property.
Should You Fix Dampness Yourself (DIY)?
Yes, but you should usually hire a professional because DIY damp solutions have many risks.
If you misdiagnose the problem and apply the wrong treatment, you could worsen the state of your home. For instance, if you have rising dampness and apply damp-proof plaster instead of DPC, you’d be trapping moisture in the walls.
You also risk damaging your property during repairs or harming yourself. If you’re treating dampness around electrical wires or gas pipes, you risk electrocution or explosions that could injure you or destroy your property. And if you don’t fix the problem correctly, it may return and damage your property further.
How Much Do Damp-Proof Solutions Cost?
The cost can range between ￡300 – ￡5,000, depending on your wall’s size, the type of proofing solution, and the extent of the damage. It may also vary slightly depending on your location.
Consider these reasons why your contractor may charge less for damp-proofing your home:
- Your property is small, requiring less material and labour to treat for dampness
- You need a simple damp-proofing solution like a DPM for a wall
- The problem is minor, like a leaking pipe, which only needs repairs
- You live in an area with a low cost of living
- Your contractor is offering a discount
If your damp-proofing bills are high, it could be due to:
- You have a large property that needs more material and labour to treat for dampness
- You need a complex damp-proof solution like excavating around your foundation
- The damp problem is severe and requires multiple solutions to fix
- Your property is located in an area with a high cost of living
Where Would You Typically Find Dampness?
Dampness is a common problem in many homes and buildings, causing health issues and damage to property. Here are the common areas where you’ll find it:
These are the walls inside a building that get damp due to condensation, rising and penetrating dampness. You’ll often find dampness in these areas:
- Behind furniture
- Above skirting boards
- Window reveals
- External corners
They’re the walls on the outside of a building and can get damp from rain, rising damp, splashback from downpipes, and penetrating damp.
Here’s where you’ll find dampness on your external walls:
- At the base of the wall
- Around windows and doors
- Cracks in the brickwork
- Underneath downpipes
- In shaded areas
Dampness in residential properties involves excess moisture in the air or building material. You’ll find these conditions in:
- Crawl spaces
- Laundry rooms
Garages are often poorly ventilated, exposing them to moisture from the ground and the elements. Look for signs of dampness in your garage in:
- Underneath appliances
- Near sinks
- Around your cars
- Doors and windows
- Wood or fabric
A basement is the lowest level of a building, often underground and below the water table. Its walls and floors are always cold, increasing condensation and dampness when warm, moist air rises.
You’ll find signs of dampness inside your basement around:
- Window wells
- Around pipes and drains
- Behind furniture and appliances
Commercial properties are buildings used for businesses like offices, restaurants, warehouses, and retail shops. Most of these spaces have an HVAC system to keep staff comfortable, which also increases condensation.
Expect to find dampness in the following areas in any commercial property:
- Air conditioning systems
- Laundry rooms
- Storage rooms
What Are Some Causes of Dampness?
There are several causes of dampness, each with unique characteristics and treatment methods.
Here are some examples:
- Condensation: When warm, moist air settles on a cold surface, it condenses into moisture. Condensation is often caused by poor ventilation through cracks in walls, ceilings, and floors, causing mould growth if left untreated.
- Leaks: Old, corroded pipes may have holes or leak water from the joints, allowing moisture to seep into your walls and floors. When the water builds up, it cracks your home, weakening its structure.
- Rising damp: Groundwater rises through the walls of a building, causing stained wallpaper, blistering paint, or dark patches. Rising dampness is common in old buildings without DPC.
- Penetrating damp: Water from outside penetrates a building through defects in the roof, walls, or windows. Inadequate gutters may also deposit excess water onto your external walls, increasing the dampness.
How Do You Treat Dampness?
DPM is a versatile and effective way to treat dampness and works well alongside other treatments like DPC and damp-proof paint.
For instance, DPC is an ideal waterproof barrier for your wall’s brickwork, while DPM best protects your floors. Combining these treatments protects your property from rising and lateral dampness.
Damp-proof plaster and damp-proof paint will protect your interior walls and ceilings, while DPM covers the exterior side. Together, these treatments protect your home from penetrating dampness.
For your basement and other areas prone to flooding, DPM and tanking slurries protect against capillary action from groundwater.
How Long Does Damp-Proofing Last?
It can last 20 to 30 years, depending on the solution used, the quality of installation, and the severity of the problem.
Consider the following reasons your damp-proofing solution may last longer:
- Using high-quality damp-proofing chemical treatments and coatings
- Proper installation by experienced contractors who follow industry best practices
- Regular property maintenance like clearing gutters, sealing leaks, and ensuring adequate ventilation.
- Dry environmental conditions prevent your damp-proofing from breaking down quickly
Your damp-proofing may break down quickly due to:
- Lack of maintenance allows moisture to seep into your home without you realising
- Poor installation makes your damp-proofing ineffective at stopping moisture.
- Using the wrong damp-proofing solution for your property makes it less durable
- Damage by construction work or invasive root trees
- Extreme weather conditions like heavy rainfall and high humidity strain your damp-proofing solution
Mould grows quickly within 24 – 48 hours of dampness, eating away wood, drywall and other building materials.
With the right damp-proofing solution, you’ll protect yourself and your home from mould exposure and damage to your property.
If you suspect that you have a leak or notice signs of dampness, call us today for property care and preservation services. We’ll check your pipes and keep your walls and floors dry to keep you safe and healthy on your property.