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We tend to notice that a property has a problem with damp when evidence of it is seen on the internal walls. The common signs are fairly easy to spot and are clearly recognisable. Often we notice damp patches emerging on walls that don’t seem to go away. Wallpaper and paint sometimes appears to be a little flaky, and plaster might easily crumble. Ugly black mold spots often appear on walls and ceiling. Along with this, walls will just feel damp to the touch and you may notice a musty smell. All of this is seen on the inside but most damp comes from the outside, so is damp proof paint for external walls the answer?
Why is Exterior Damp Proof Paint Useful?
Well, it is important that you realise the limitations of damp proof paint for external walls. As we’ve already said, damp usually penetrates a property from the outside. The exception to this is condensation, which is caused because there is too much excess moisture within a property and insufficient ventilation. Penetrating damp is usually caused by a structural defect to the building, which allows water to penetrate through from the outside to the inner walls. For example, guttering, usually diverts rain water away from the walls of a building. However, If that guttering becomes cracked, the protection that the walls were previously given is lost and the walls become vulnerable. The same is true with rising damp. Water rises naturally and if the damp proof course fails, the barrier protecting the property from the rise in water is also lost, and damp will rise from the outside and up the inner walls.
So, what this basically means, is that once the usual signals and signs of damp, detailed above, have been spotted on the internal walls it is too late. You can’t just slap on a thick coating of damp proof paint on the external walls and expect all the problems to go away.
But this doesn’t mean that damp proof paint for external walls is a non-starter. As a preventative measure, applying a coat to the external walls of a property is an excellent idea. As we all know prevention is usually better than cure. And, if you have left it too late and penetrating damp and rising damp has occurred, once the damp has been successfully treated, applying damp proof paint on the external walls will offer a good amount of waterproofing protection for years to come.
It stands to reason really. It is the external walls of a property that are most exposed to the elements, particularly rain. Rain water can enter a property through the masonry in a building. For example through cracks to the brickwork or where there is insufficient pointing. Even if the structure of a building is sound and there are no defects, in particularly bad weather or periods of prolonged and heavy rain (which let’s face it, is British weather!), the external walls will not have a real opportunity to adequately dry out and will simply stay damp.
Therefore, applying a protective waterproofing layer to the external surface makes very good sense. So, what is the best damp proof paint for external walls? Below we have listed our opinion of the top products on the market.
NOTE: If you are looking for the best external masonry paints in 2020 Click Here
Stormdry Masonry Protection Cream
For many, the go-to brand when it comes to damp proof paint for external walls is Stormdry. Firstly, their products are BBA approved (the BBA is the leading regulator in the UK of construction industry products), which is an important seal of approval to have.
As with many products that can be classed as ‘damp proof paint for external walls’, actually Stormdry Masonry Protection Cream doesn’t really look like paint – it is colourless once dry to enable masonry to retain its original appearance after application.
This product is cream-based which enables it to penetrate deep into the masonry. It’s also easy to apply, using either a brush or a roller. Many similar products will require two coats, but Stormdry Masonry Protection Cream only needs one.
The combined technology of silane and siloxane allows the external walls to breathe, as it essentially lines the pores of the bricks, which are porous, rather than simply blocking them.
All in all, this is a product that offers fantastic protection against penetrating damp, for as long as 25 years.
Thompson’s One Coat Water Seal
If Stormdry is at the top end of the price range, then One Coat Water Seal from Thompson’s is at the opposite end. Despite its budget price tag, user reviews of Thompson’s One Coat Water Seal are generally very good with most people commenting favorably on the product.
It can be applied onto an already damp surface and will offer water protection for a lengthy period when application instructions and the guidelines for coverage have been strictly adhered to. This is actually a very important point which is relevant to all types of damp proof paint (both internal and external). Remember, that unlike a matt or emulsion, which is primarily applied to a surface as decoration, damp proof paint is applied as a layer of waterproofing protection. Therefore, it is important that the coverage is exactly as the instructions say.
Thompson’s is a useful product as, although it is only intended for external use, it is suitable for use on various types of surface. It can be applied to concrete, brickwork or stone, as well as render and plaster – making it a versatile and adaptable product.
Thompson’s One Coat Water Seal can be applied with a roller or a brush and although its coverage will vary according to the porosity of the external surface, you should be able to achieve a coverage of around 4 square metres per litre. Depending on the temperature conditions, it should be touch dry after just 2 hours. It is a low odour product that has a milky colour. However, this dries clear to enable the original external surface to show through as normal.
Wickes Water Seal for Vertical Exterior Surfaces
This is another inexpensive product, similar in many ways to Thompson’s One Coat Water Seal. It forms a waterproof barrier with single coat and as well as being a good protector against damp, it also guards against frost. It can be applied to a variety of external surfaces including wood, cement, concrete and brick. It can be applied using either a brush or a spray.
Enviroseal Masonry Water Repellent
This product does not form a damp proofing membrane as such but it provides a lining of silicone resin for brick and stone walls. The lining to capillaries repels water, allowing bricks to breathe at the same time, and prevents damp from penetrating through to the inner walls. Enviroseal Masonry Water Repellent uses silicone/siloxane technology.
It can be applied by brush, roller or spray, giving you plenty of options and the guidance is to apply the first coat by whichever method you prefer and then apply a flood coat before the first coat is dry, especially for porous brick surfaces. User reviews are very positive for this product.
Microshield Ultra Masonry Waterproofing Cream
Last but not least, but back to the top end of the price range is Microshield Ultra. It is a water-based masonry waterproofing cream. It offers long-lasting waterproofing as well as additional benefits, such as protection against frost.
It utilises the usual silane and siloxane technology which enables water vapour permeability to be retained. Water simply runs off the surface. Microshield Ultra can be used on all types of bricks and mortar, as well as natural stone and limestone. This product is particularly recommended for repair, renovation and remedial works.
The benefits of damp proof paint for external walls
In conclusion, just as long as you fully appreciate that damp proof paint for external walls will not solve the problems of existing damp in a property, it is still well worth taking the trouble to protect a property for the future with such a product. At the very least, you should consider giving the external walls of a property some protection. A conventional masonry paint will offer a good general level of protection against the elements – but a damp proof paint product will be the best bet. There is plenty of choice and a good selection of prices to choose from.