How Long Does Damp Proofing Last?

How Long Does Damp Proofing Last?

If your home needs damp proofing, you might be wondering: how long will this actually last?

It’s a fair question,  and the good news is that a professionally installed damp proof course should last at least 20 years, and often much longer. Some methods can protect your home for the entire lifetime of the building.

The emphasis here is on “professionally.” The method used, the quality of the installation, and the condition of your property all play a role in how long your damp proofing will last. Let’s walk through what you need to know so you can feel confident about what you’re paying for.

How Long Do Different Damp Proofing Methods Last?

There are several ways to damp-proof a property. The method your surveyor recommends will depend on the type of damp, your property’s construction, and the severity of the problem.

Here’s what you can expect from each.

Chemical Damp Proof Course Injection

This is the most common method for treating rising damp in the UK. A specialist drills into the mortar course at the base of your walls and injects a damp-proofing cream, creating a new waterproof barrier. When done properly, this treatment lasts 20 years or more, and most reputable companies will guarantee it for that long.

Physical Membrane Systems

Sometimes injection isn’t the right option, for example, in older properties with thick stone walls. In these cases, a specialist can fit a waterproof sheet (also called a membrane) directly onto the inside of your wall to prevent moisture from entering.

Membranes are extremely durable and can last the lifetime of the building, provided they’re installed correctly with drainage in place.

Tanking and Structural Waterproofing

If you have a basement or below-ground space, your specialist will likely recommend tanking or structural waterproofing. How long these last depends on the system your contractor uses.

Cementitious tanking systems, when properly applied, typically last 10 years or more. Some cavity drain membrane systems can last longer, but they often require ongoing maintenance and a sump pump, which may make the guarantee conditional on regular servicing.

What Affects How Long Damp Proofing Lasts?

Even the best damp proofing method won’t last if the underlying causes aren’t addressed. A few things can shorten or extend the lifespan of your treatment.

Quality of Installation

This is the most important part. Damp proofing is specialist work, and it needs to be carried out by trained, experienced operatives who understand the specific challenges of your property.

Poorly mixed chemicals, incorrect drilling depth, or missed sections can all lead to early failure. It’s one of those jobs where cutting corners to save a few hundred pounds can cost you thousands down the line.

Property Condition

If external issues like faulty guttering, raised ground levels, or bridged damp proof courses aren’t sorted at the same time, moisture will continue to find its way in, regardless of how good the internal treatment is.

A thorough survey should identify all contributing factors before any work begins.

Replastering

Replastering is often overlooked. After a chemical damp proof course is injected, the old contaminated plaster below the treatment line needs to be removed and replaced with a specialist renovating plaster.

If you skip this step or use the wrong materials, dampness can persist on the wall surface even though the treatment itself is working perfectly.

What Guarantees Should You Look For?

A guarantee is only as good as the company standing behind it. When you’re comparing quotes, there are five things worth checking.

Length of Guarantee

A 20-year guarantee is the industry benchmark for damp proofing and rising damp treatment. For basement tanking and structural waterproofing, 10 years is standard. Anything significantly shorter should raise questions.

Insurance-Backed Protection

An insurance-backed guarantee means that, even if the company were to cease trading, your guarantee would be protected by an independent insurer. It’s a sign that the company is confident in its work, and it gives you peace of mind for the full term.

Conditions and Ongoing Costs

Some guarantees (particularly for cavity drain membrane systems) are conditional on you maintaining a sump pump or paying for annual servicing. Others, like those for cementitious tanking systems, have no ongoing maintenance requirements, which means lower costs and fewer things to worry about over the years.

Who Does the Work

Ask whether the company uses their own trained operatives or outsources to subcontractors. When subcontractors are involved, quality control is harder to maintain, and if something goes wrong, chasing up a guarantee claim can become a headache. A company that employs its own team is directly accountable for every job.

What’s Actually Covered

Not all guarantees cover the same things. Some only cover the treatment itself, while others include labour, materials, and making good any damage. Before you sign, make sure you understand exactly what’s included.

Kenwood’s Damp Proofing Guarantees

At Kenwood, our damp proofing, woodworm treatment, and dry rot treatments are guaranteed for 20 years. Our tanking and structural waterproofing are guaranteed for 10 years, and our condensation systems for 2 years.

Unlike many waterproofing systems, our SWS tanking system doesn’t require a sump pump. That means the guarantee isn’t conditional on ongoing maintenance contracts or servicing arrangements; it’s straightforward protection, with nothing extra to pay.

We have our own skilled operatives who carry out all our work, never subcontractors, and we’ve been doing this for over forty years. We also offer insurance-backed guarantee options for additional peace of mind.

That experience and that confidence in our work allow us to offer genuine long-term guarantees.

Not sure what treatment your property needs? Book a next day survey, and we’ll give you an honest assessment. No obligation.

Frequently Asked Questions

How long does a damp proof course last?

A professionally installed chemical damp proof course typically lasts 20 years or more. Many damp proofing companies, including Kenwood, guarantee their work for 20 years.

Does damp proofing need to be redone?

In most cases, no.  A damp-proof course, when installed correctly, should not require replacement or redoing within its guaranteed lifespan. If damp reappears, it’s more often caused by a separate issue, such as faulty guttering or raised external ground levels, rather than a failure of the treatment itself.

Is damp proofing guaranteed?

Any reputable damp proofing company will guarantee their work. For rising damp treatment, you should expect a minimum of 20 years, and it’s always worth checking whether the guarantee is insurance-backed.

How long does basement tanking last?

This depends on the system used. Cementitious tanking systems typically last 10 years or more. Cavity drain membrane systems can last longer but may require ongoing pump maintenance. Kenwood’s SWS Tanking System is guaranteed for 10 years with no ongoing maintenance required.

How do I know if my damp proofing has failed?

Common signs that damp proofing may have failed are damp patches returning to walls, peeling or bubbling plaster, a musty smell, or visible tide marks at low level. If you notice any of these signs, it’s worth having a specialist take a look. The cause may not be a failure of the treatment but a new or separate source of moisture.

Worried about damp in your home? Our surveyors cover over 20,000 properties a year, so we’ve seen it all.  Book your free survey today.