Rising Damp in Basements: Waterproofing Techniques for Below-Ground Areas

The basement is an important part of a house but is often overlooked. Doing this is costly because damp issues can cause problems across the home. The main issue with basements is that they are susceptible to moisture buildup and water leaks. Rising damp is a particularly serious concern because it can weaken the home’s structure in addition to doing other damage.

Understanding Rising Damp

Moisture can travel up a wall through capillary action. This happens when the wall is porous enough, with the best example being brick walls. These pores act like a series of many straws, transporting water upwards, which then causes damage.

Since basements are in direct contact with the ground, they are one of the places this issue starts. Basement waterproofing can help address this issue. Because every home and its basement is different, the right solution will depend on the type of foundation, the home’s location, and the issue causing rising damp. This article looks at the most common waterproofing techniques that ensure the basement and the surrounding area remain dry.

Use Epoxy Injections and Sealants

Both techniques are considered short-term solutions that are only used before a homeowner instals a more robust solution. They are best used when the cause of damp is cracks in the basement walls, such as cracks in the masonry that hold everything together.

A contractor will apply the epoxy or sealant into the wall, so it fills the whole crack and flows to the exterior, effectively sealing the crack. Doing this stops water from ingress through the cracks, helping eliminate one of the causes of rising damp.

Although they work well, there are certain things homeowners should know before using them. First, you should not use them on painted walls or where there is efflorescence. Efflorescence is mineral deposits that form on concrete walls. Paint and salt deposits make the epoxy and sealants adhere poorly, which means you will not have great results and will likely be damp again after a short while.

Second, they can crack and become ineffective. Basement walls expand and contract depending on factors like temperature, moisture content, outside water pressure, and the natural movement and settlement of a house as it ages. When any of this happens, the mortar will crack alongside the sealants and epoxy used to prevent water seepage.

Solutions that work well without cracking include porous foams, flexible sealants, and impermeable membranes that also waterproof a basement well without cracking due to expansion and contraction cycles.

Use Tanking to Prevent Rising Damp

Tanking uses a slurry to make a wall impenetrable to water and is a great solution for basements with a rising damp problem. Once it has been applied to the wall and dried, it creates a waterproof coating that stops water ingress.

One critical thing to know about tanking is that it does not solve any underlying causes of damp. For example, it cannot solve the issue of a leaking pipe that makes the basement walls wet or condensation that does the same.

The slurry used in tanking contains Portland cement and other constituents that ensure adherence to the basement walls. Because of how these additives work, proper preparation is crucial to prevent tanking failure in the future.

Once the tanking mixture is ready (it also comes premixed), you or the contractor will apply two to three coats to your walls, waiting for each to dry before applying the next. Once dry, you can paint over it and then decorate the basement as you like.

You can also use tanking before applying plaster if you have been renovating or converting the basement. The underlying tanking layer will provide additional protection to the wall behind it and the plaster in front of it.

Use Cavity Wall Waterproofing Systems

Cavity drain systems are a popular option for new construction, basement conversions, and retrofitting cellars. They are often installed to counteract hydrostatic pressure, which occurs when water pressure exerts forces on the basement’s retaining walls. While the walls will provide some resistance, any weaknesses in them will cause water ingress into the basement, rising damp, and other issues.

Cavity drain systems use cavity membranes and a drainage system to channel water safely out of a property, protecting the basement and any possessions in it. The contractor instals the cavity membranes to the floor and walls, ensuring all surfaces are covered.

Once installed, the membranes leave a small gap between themselves and the underlying surface due to their studs. This gap allows excess water to flow down the cavity between the membrane and the underlying surface, relieving water pressure.

All water that enters the basement and travels behind the membrane is channelled into a drainage system. It is then directed to a sump pump chamber that the contractor installed below the floor slab, which pumps the water out of the property and into an external drainage system.

Some designs also allow the water to be diverted to the external drainage system without using a sump pump. These options allow you to keep your basement dry whether you have power or not because they do not rely on it. However, systems using a sump pump can have optional battery backups.

Installing these systems is never a DIY task, so you should hire a contractor to ensure it is done right. Doing it yourself means you might not be able to meet the required specifications, and you might cause weak patches that will cause damp and flooding issues in the future. The risk of damage to your property, the cost of the subsequent repair, and the cost of installing the waterproofing solution again are not worth doing this yourself.

Ensuring your basement is waterproof can help prevent many issues, including rising damp. The solutions you pick will depend on your preferences, budget, and how serious the issue is. It is also best to let a specialist company like us waterproof your basement because doing so can involve extensive work and a significant risk of damaging the home.