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How do I prevent damp in my home?

Many people consider installing EWI because they have problems with damp in their homes. External wall insulation is a great method of preventing damp. Nevertheless, we do recommend that the cause of these problems is addressed before you go ahead with installing EWI and that you talk to your installers about ventilation strategies with your EWI to prevent damp in the future. For example, leaking pipes could eventually create huge issues in the long run, and would be extremely detrimental to an EWI system – so these need to be ascertained and addressed first.

However, take for example a property that suffers from problems with damp due to the fact that it has a lack of light. External wall insulation can easily remedy this. Read on to find out more about how external wall insulation can prevent damp in the home.

Breathable EWI Systems help prevent damp

Your EWI system can be totally breathable (vapour permeable), depending upon your choice of products. At EWI store we have designed a totally breathable EWI system with our range of materials, so if you are considering EWI and damp/mould is a concern to you then definitely keep reading. Let’s break down which products are the best for breathability:

Mineral Wool: Mineral wool AKA Rockwool is an excellent insulation material. Rockwool is highly breathable, and the best part is that it’s made up of molten volcanic rocks so it’s non-combustible! To make the boards, the volcanic rock is heated in a furnace to about 3,000 degrees Centigrade, until it melts into a liquid. The lava is then exposed to a high-pressure jet of air or steam, and then spun at super-high speed into long fibre strands (like that of cotton candy). The strands are then compressed into thick, dense mats, which are cut into conveniently-sized boards to be used as insulation.

Because it is a stone wool, Rockwool has a low absorptivity and no nutrient content, so it allows moisture to escape and prevents the build-up of rot or mould, making it a highly breathable insulation material. (An extra benefit is that it’s also a renewable material and can be recycled!).

EWI-225 Premium Adhesive: It’s a slightly more expensive option, but its’ high strength, high elasticity and high breathability makes the EWI-225 a popular option for buyers. It also reduces your total expenditure on materials because it does not require a primer to be applied underneath. This Adhesive is also compatible for use on Rockwool insulation boards.

Silicone render/Silicone Silicate: Our silicone-based renders are our most popular render choice. Silicone renders are thin-coat renders, which mean that they are highly flexible and breathable. This is because water vapour can cross the surface of the render, ensuring that the building can breathe, and reducing the risk of condensation and damp. Silicone renders are also very compatible for use with mineral wool as part of a breathable system.

Installing External Wall Insulation to prevent Damp

Although the materials are a key component in helping to prevent damp in the home, the installation is equally important. For external wall insulation, it is vital that the materials are fitted completely tight to the wall. This is why insulation boards have to be cut to fit to the shape of the wall, and cracks in the wall need dubbing over with mortar to begin with. When using EPS insulation, the back of the insulation board also needs to be completely covered using a 5mm notched trowel to maintain a dispersion layer. Uneven substrates always need to be fixed using a leveling coat before application of external wall insulation as well, so ensure that there is no chance of air pockets behind the system. If there are air pockets behind your solid wall insulation system, then water vapour and moisture can gather here and continue to cause damp internally. 

It’s surprising how disruptive and dangerous a little bit of water and damp can be. Not only can it cause your property even more problems internally, but it can also affect the structural integrity of your EWI system and prevent it from functioning to its optimal capabilities. This is because with the presence of water the insulation cannot slow thermal transfer as effectively. So, although external wall insulation will prevent damp in the long run, it’s important that you choose someone who is qualified and experienced in carrying out installations so that it’s done properly. We have a whole list of approved installers, so do get in touch if you are looking for someone trustworthy.  

Ventilating your home against damp

In most properties, damp and mould commonly occurs behind large pieces of furniture, such as sideboards, so it’s important that your room is well ventilated to prevent this. Ventilation goes hand in hand with insulation. If you install EWI, then you are forming a tight seal of insulation around your house, and tightly sealed houses need proper ventilation. This is to prevent mould and damp, and to allow for the house to change air and breathe. Houses should be able to draw in fresh air and expel stale air for good human health. This happens in a number of ways:

Uncontrolled ventilation comes from places such as the doors and windows. This is a good thing in moderation – windows are the most effective and obvious way to ventilate your home. However, if your house feels drafty even with doors and windows closed, then this is a problem and can be costing you more money on heating bills.

Controlled ventilation comes from vents and fans, situated in different spaces of your house – such as the attic.

Some of these vents include:

A Ridge Vent: the most effective method of ventilating your home. This is a type of vent installed in the roof of your home and effectively allows humid air to escape.

Soffit Vents: create a natural flow of ventilation in the roof cavity.

Foundation vents: these will be situated at the base of the wall and allow for cool air to enter the lower levels of your home and prevent moisture build-up underneath your home.

Turbine Vents: This is a turbine mounted to the top of the roof, and again allows for hot air to escape.

Trickle Vents: meant to provide minimum ventilation requirements for naturally ventilated spaces.

Fans are also a common method of ventilation. You’ll often find extractor fans in bathrooms and oven-top fans in kitchens. These are used to draw out moisture from the air in rooms which have a tendency to be especially humid.

So there you have it! Hopefully this was useful to those of you who are suffering from damp in your homes and are looking for a solution. We would suggest that the take home from this article is that EWI isn’t a cure but it is a prevention. For any more advice about our systems, give us a call – we are always happy to help!

We upload to our blog every Tuesday and Thursday, so tweet us your questions about EWI or leave a comment and we will answer them!


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