Damp and mould cause respiratory problems, respiratory infections, allergies, asthma an affect the immune system.


Some people are more sensitive than others, including:

  • elderly people
  • babies and children
  • those with existing skin problems, such as eczema
  • those with a weakened immune system
  • those with respiratory problems, such as allergies and asthma


Moulds produce allergens that cause allergic reactions, irritants and sometimes, toxic substances. Inhaling or touching mould spores may cause sneezing, a runny nose, red eyes, skin rash and asthma attacks.


Excess moisture in buildings caused by leaking pipes, rising damp in basements and ground floors, and rain seepage through damaged windows and roofs.

Water still drying out in newly built buildings for example in plaster on walls.
Condensation also causes excessive moisture.

It is necessary to find out the reasons for excess moisture in your home to ensure you do the house repairs and take steps to limit condensation in the air. Ask for professional help to remove mould if in large amounts. Exposure to damp and mould may have severe reactions. Some people are more sensitive thus may undergo nasal stuffiness, throat irritation, coughing or wheezing, eye irritation or skin irritation.

People with allergies, weak immune systems and those with chronic lung illnesses may have more severe reactions and should stay away from mould infested areas such as; compost piles, cut grass and wooded areas.


Mould accumulates in damp and poorly ventilated buildings. Inhaling the spores or their fragments may inflame airways causing nasal congestion, wheezing, chest tightness, coughing and throat infections. Prolonged exposure to high levels of indoor dampness can reduce lung function and cause chronic health problems such as asthma. Those with asthma and allergies are more likely to have more severe symptoms when exposed.


Black mould, Stachybotrys chartarum, is the most infamous type of fungus which can grow on water-damaged building materials and produce toxic spores. In 1994, it was linked to a severe respiratory illness after ten children experienced idiopathic pulmonary haemosiderosis and one subsequently died. There was no causal link despite significant media interest.

Mould is found both indoor and outdoor. It can enter your home through open doorways, windows, vents, heating air conditioning systems, and by attaching to clothing, shoes, bags and pets,Mould grows well on paper product’s, cardboard, ceiling tiles, wood products, in dust, paints, wallpaper, insulation, drywall, carpet, fabric and upholstery. Mould can be removed from hard surfaces using commercial products, soap and water, or with a bleach solution of no more than 1 cup of laundry bleach in 1 gallon of water.

Mould growth often looks like spots, with many different colours and smells musty. Effects of mould on people vary greatly, and once you see or sniff a fungus, remove it. Good sampling for decay is expensive, and the standard for accepting the appropriate quantity is not yet set, hence not recommended by the CDC.


Damp has become a big problem for many with the average home subject to a lot of rainwater with the high rainfall in the United Kingdom. Damp is unsightly with a bad smell, can cause permanent damage to plaster, paint and finishes, is terrible for our health, aggravating respiratory problems and encouraging the emergence of mites and mould.

Before damp proofing, determine the causes. The traditional moist wall treatment was to cover up with wooden panelling but this tends to dampen over time and rot.

The dry lining evolved into the air gap membrane, damp proof membrane or cavity drain membrane; which is a dimpled plastic sheet which allows air to circulate and flow freely and thus prevents moisture from becoming trapped which can drive dampness sideways and upwards and into other areas of your home and cause further damp and mould problems.

Damp proof membranes are made from high density, impervious polyethylene (HDPE). Fix the films to internal walls after the source of the damp has been resolved. The surface has an egg box-like profile that creates a cavity or an air gap that allows moisture to evaporate from the wall behind. The membranes are easy to install and are extremely flexible; which means that they can cope with movement thus ensures that your damp proofing lasts for decades.


Water and moisture that is allowed to pass through a wall onto its inner surface will maintain a colder temperature than its surroundings and can cause condensation to build up and black mould growth.

When moisture passes it carries salts and minerals with it, which reach the inner decorated surface that is usually covered with plaster or paint ruining it and eventually blowing the plaster off the wall.

Wall surface below damp proof course will always remain damp since its surroundings naturally contain water and moisture.

The traditional method of dealing with this was to batten the inner wall surface out, and panel over the top of it which would be ok for a while till the wooden tablet would become damp and rot.

Technology has advanced and given birth to tanking; which is effectively a liquid coating that bonds to damp masonry and then cures to form a waterproof barrier.


The three principal methods of tanking wet walls include;

Liquid bitumen coating –

Paint the liquid bitumen coating onto the cleaned brickwork, stone, block or render, which is difficult to apply to old damp salt masonry, is prone to separation from the wall and render coats due to incomplete curing and is best for non-critical small jobs or external coating below the damp proof course.

Cement based slurry –

Apply the cement-based slurry by soft brush onto dampened, cleaned brickwork, stone, block or render, which is easier to use because the cement base wants to amalgamate with the masonry and mortar. It is not a vapour barrier so needs to be finished with breathing materials. It is ideal for partial below ground situations or exterior coating on foundation walls.

Air gap membranes –

Air gap membranes are not strictly tanking in the same way as liquids. It is a dimple plastic sheet fixed onto brick, stone, block or render with plastic plugs to form an air gap cavity. These membranes can have a common surface for battening or a mesh surface for direct plastering or plaster boarding. It is ideal for cold, single leaf walls and lining rooms with cold solid 9 inch walls.


As an example project, what is the cost of a chemical injection into the external walls of a 2-bed house in Surrey?

Example 1.
A professional injects a damp proofing chemical liquid into the external walls. This job does not include internal plastering or finishing off work.

  • Small Business £1100.00
  • Larger Business (5+ employees) £2000.00

Example 2.
First the damp proof engineer will remove the extensive damp patches of plaster from internal walls up to a height of 1.5 meters; the chemical is injected into external walls; the walls will then be sealed and replastered.

  • Small business £3250.00
  • Larger business (5+ employees) £4750.00


The plastering and making good of the walls is time consuming unlike wall injection.

Damp proofing is a messy and disruptive project that will require e you to move out of the house for a few days. You might be tempted to paint the interior walls with waterproof paint or sealant to mask signs of damp, if on a tight budget.

It may seem logical and practical but is a bad idea. The damp will spread behind the sealant if moisture is still present and resolve the underlying issues which can lead to further horizontal or vertical damage, the plaster, bricks, floor joists and may fail as it never has the chance to dry out, and damp odours and smells will persist.

Walls should only be coated with a waterproof sealant if 100% sure that there is no damp rising from the ground below to avoid masking the issue by sealing the moisture into o the wall where it will spread and damage the materials used in the construction of the wall.


Cellars are often damp and unstable beyond storing the odd bottle of wine and old tin of paint. If you want to make full use of your cellar or basement then you will need to keep it dry, tanking systems provide an impermeable waterproofing coating to the walls and floors to help keep the basement dry.

When it comes to water-proofing a basement with damp walls, there are two main options;

One, is to install a cavity drain system, or use cellar tanking. Cellar tanking refers to above the damp ground proofing as well as cavity wall membranes as part of a basement drainage system.

Cellar tanking or basement tanking refers to the application of a liquid waterproof coating to the walls and floor of a cellar. It is used to treat damp walls by preventing water ingress, effectively making the walls permanently water-tight.

Damp walls are common in cellars as the walls are below ground. Water from the retaining earth can make its way through the walls and into the cellar moisture passes through the wall carrying salts and minerals with it.

Damp walls are cold which create s issues with condensation and in turn mould. The tanking slurry is designed to deal with these issues. It is applied directly to damp walls. When the tanking slurry cures, it forms an impermeable waterproof barrier thus preventing water ingress and damp.

It is important to point out that unlike a cavity drain system, taking slurry blocks water from entering your cellar rather than allowing it in and controlling it to an evacuation point.


The cost of tanking a cellar depends on the size of your basement, the type of substrate and the extent of the damp. Most tanking costs will be calculated on a meter squared basis and be an estimated range.

For example, PermaSEAL tanking slurry comes in 25kg buckets; this will cover between 8m2 to 12m2 unit depending on the substrate.

The grey slurry is currently available at £31.00 excluding VAT.

If we take the lowest coverage estimate of 8m2 per bucket, then the cost of cellar tanking works out at £7.75 per m2 for two coats.

Now, if you have four walls at 2metres high and 8 metres long then, this would come in at 16 buckets for £496.00 ex VAT for the wall with the floor being a further 16 buckets at £496.00 ex VAT.


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