If you’re looking to damp proof your home, a damp-proof course is an essential protective measure. A damp-proof course is designed to stop water from rising up into a home by creating an impermeable waterproof barrier, and it can protect your home from potentially expensive and dangerous issues that may result from damp.

Modern homes are fitted with a damp-proof course as standard, but older homes may not have ever had one installed. A damp-proof course can fail for any number of reasons, but a damp-proof specialist can help you to identify and fix problems before they can cause damage.

To help you understand the importance of damp proofing your home, the experts at Danford, Brewer & Ives have put together their ultimate guide to damp-proof courses.

What Is a Damp-Proof Course?

A damp-proof course is designed to protect a property against the dangers posed by moisture, damp and excess water. When properly installed, a damp-proof course creates an effective waterproof barrier that prevents moisture from rising up through the brickwork and masonry, and then into the home.

A damp-proof course is generally fitted just above ground level, with the main goal being to protect against rising damp. There are several different types of damp-proof courses that can be installed, with the most common method being to inject a damp-proof cream into the ground floor masonry.

Without a damp-proof course to create a waterproof barrier, excess groundwater and moisture can rise up through the brickwork and cause damage to a property. If left unchecked, this damp problem can lead to structural and health and safety issues within your home.

How Do Damp Proof-Courses Work?

All damp-proof courses are intended to create a protective barrier that stops water from rising from the ground and into the home, but there are different types of damp-proof course and they all work in slightly different ways.

Any damp-proof course needs to be installed at least 150mm above ground level. This is a legal requirement, and it ensures that the waterproof barrier is formed above groundwater level. Because a damp-proof course is intended to protect primarily against rising damp, which enters a building from the ground upwards, they are generally installed in the masonry or brickwork on the bottom floor of a home.

Modern damp-proof courses consist of chemical injections, but they are at their most effective when used in conjunction with other damp-proofing methods, such as a damp-proof membrane. Here are the most common varieties of damp-proof courses that can be installed in your home:

Chemical Damp-Proof Course

A chemical damp-proof course is injected into the masonry and brickwork of a home, and is at its most effective when placed 150mm above ground level. It consists of a specialist damp-proofing cream that forms an effective waterproof barrier once it’s settled into the brickwork.

To be installed, holes are drilled directly into the wall at the intended level, and the chemical damp-proof course is then injected into them.

Mortar Damp-Proof Course

A mortar damp-proof course is also injected directly into holes drilled into a wall, and again it must be injected 150mm above ground level for it to work effectively.

Mortar damp-proof courses consist of a chemically enhanced mortar that can fill any holes in the masonry and brickwork that might be causing damp problems.

The mortar, once injected, creates a waterproof barrier by filling in these holes and removing any chance of rising damp moving through the walls by removing any gaps in the brickwork.

Non-Chemical Damp-Proof Course

Non-chemical damp-proof courses are also available, with the most popular method being an Electro Osmotic damp-proof course. This works differently from a chemical damp-proof course because it involves installing metal wiring to create an electric charge.

Rather than creating a physical, waterproof barrier, this electric charge changes the polarity of the wall itself. This means that rising damp isn’t drawn upwards through the brickwork, but is repelled downwards.

This system isn’t as common, as it’s more difficult and time-consuming to install in comparison to a simpler chemical injection.

Damp-Proof Membrane

A damp-proof course creates an effective barrier against rising damp, but it works best when installed alongside other damp-proofing methods. The most popular damp-proofing method is a damp-proof membrane, which creates a physical impermeable barrier that protects against damp and moisture.

A damp-proof membrane is essentially a thick sheet of waterproof material that’s installed above or below the floor. A damp-proof membrane needs to be at least 1,200-gauge thickness and it needs to be installed so the sheets overlap, and therefore create a continuous barrier.

Why Do I Need a Damp-Proof Course in My Home?

The main goal of a damp-proof course is to protect against different forms of damp and water damage that could cause costly and even dangerous repairs. Damp is caused by excess moisture and water, and the damp-proof course exists to create a waterproof barrier against this.

Damp can cause any number of problems inside your home, including:

  • Structural damage
  • Decaying timbers
  • Damaged plaster and decorating
  • Mould
  • Wet and dry rot
  • Respiratory illness

There are several types of damp that can be found inside a home, including condensation, rising damp and penetrating damp. A damp-proof course is primarily intended to protect against rising damp, which occurs when water rises up through the brickwork from ground level using capillary action to move vertically through bricks and mortar.

If rising damp is left unchecked, it can eventually cause serious structural damage to the foundations of your home. Other unwanted side effects include fungus and mould, which can lead to respiratory illnesses and serious health and safety dangers for anyone who lives in the house.

Lack of a damp-proof course is one cause of rising damp, although it can also result from major leaks, floods or other broken infrastructure, such as drains or pipes. For this reason, it’s important to ensure that your home is fully damp proofed, with an effective damp-proof course in place to protect against excess moisture and water.

How Do I Know If My Home Has a Damp-Proof Course?

Your home should already have some form of damp-proof course installed. Since the late 19th century, it’s been a legal requirement for a property to have a damp-proof course installed. This means that modern homes will have one already in place, and it’s very likely that much older homes will, at some point, have had a damp-proof course installed too.

However, there is a small chance that a Victorian-era house may never have been upgraded with a modern damp-proof course. If this is the case, then it’s important to have a modern damp-proof course installed quickly and to have any other damp-proofing measures updated.

A damp-proof course is also liable to deteriorate over time, in which case you could find your home affected by damp problems. The ground may shift, walls may sink, or brickwork and masonry may crumble after the damp-proof course has been installed. Regular checks and a professional damp and timber survey can help to identify any existing issues with the damp-proof course in your home, or in a property you might be hoping to purchase.

If you are worried that your damp-proof course is failing, there are several key signs to look out for. The following are all big indicators that your home has a damp problem, which could be the result of a damaged damp-proof course:

  • Damp, musty or mushroomy smells
  • Mould and fungal growths
  • Damp patches on the walls
  • Damaged plasterboards or wallpaper
  • Crumbling or damaged masonry or brickwork
  • Tide marks on the walls
  • Unusual growths on the outer walls

You can spot signs of damp on both internal and external walls, but the most noticeable sign of damp is likely to be a strong musty smell drifting through the home. If you spot salty tidemarks on the walls, this is a common sign of rising damp, which as we’ve explained, generally results from a failed damp-proof course.

Of course, a failed damp-proof course isn’t the only cause of damp, and different types of damp can result in different problems and require different fixes. If you are worried about any issues relating to damp, then it’s important to have a professional inspection in order to correctly identify the cause and solution of the problem.

How Do You Fix a Damp-Proof Course?

A broken damp-proof course can either be fixed or replaced entirely. If you notice any of the key signs of damp in your home, then the first stage is to call in a professional for a damp survey.

The professional will identify the cause of the damp and the type of damp before recommending the best way to fix the problem. If the issue is a broken or missing damp-proof course, then they will recommend the best type of damp-proof course to have installed.

Before the damp-proof course is fixed, any damp needs to be removed. Once this has been done, the new damp-proof course can either be injected or fixed in place. This may involve removing brickwork or timbers to gain access, or it could be as simple as drilling holes into the walls and injecting a chemical damp-proof course.

How Much Does a Damp-Proof Course Cost?

The cost of a damp-proof course varies from one home to the next, as multiple factors need to be considered and priced up. The main factors that affect the overall cost are:

  • The size of the home
  • The type of damp-proof course
  • The amount of work needed
  • Damage already caused by damp

Let’s take a look at the above factors in more detail:

The Size of the Home

Broadly speaking, the larger the property is, the more it will cost to have a damp-proof course installed. This breaks down to a higher cost for more supplies and materials, and more time needed to fix the damp-proof course in place.

The Type of Damp-Proof Course

Different types of damp-proof courses have different costs associated with them. The best value damp-proof course is a simple chemical injection, while a physical damp-proof membrane can cost comparatively more per square metre to be installed.

The Amount of Work Needed

The amount of time and work needed to properly install a damp-proof course also has a large effect on price. If your home is older, safe installation could be more difficult and this causes an increase in price. If masonry or brickwork needs to be removed or if access to ground level is difficult, then costs will also rise.

Damage Already Caused by Damp

If your home is already affected by damp, then you need to have any damage repaired before having a new damp-proof course installed. You need to factor in costs to repair any structural damage, such as broken brickwork or decaying timbers, as well as any costs needed for redecoration later on.

Remember, the earlier you catch problems associated with damp, the sooner they can be fixed. If damp is left to fester and spread, then the cost needed to remove it and repair any damage caused is always going to increase the longer it’s left.

For an accurate estimation of costs, you need to speak with a damp-proofing expert. There are several factors to consider, and a damp survey will need to be completed before the total cost of a damp-proofing project can be considered by a professional.

Contact Us for More Information About Damp-Proof Courses

If you’re looking to damp proof your home, then a damp-proof course is essential. From the initial survey through to installation, the expert team at Danford, Brewer & Ives is ready to help with all of your damp-proofing needs.

Contact our team today for more advice on installing a damp-proof course, or to book your initial survey and consultation.