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External Wall Insulation on a Semi-Detached House?

It’s pretty common to install external insulation on a semi-detached property, but the fact that the insulation cannot wrap around the entire building presents a bit of an issue in terms of sealing the system. So how do you externally insulate a semi-detached property without risking damage from water ingress?

Use High-Quality uPVC Corner Beads

Using high-quality uPVC corner bead with mesh around the insulation where it meets with the boundary to the neighbouring house will mean that the insulation is fully protected against impacts.

The insulation (let’s say you’re using EPS on this project) is secured to the wall using the EWI-220 Basecoat Adhesive and plastic mechanical fixings. Then, once the adhesive has set you can rasp the insulation before applying your basecoat layer. This should be taken right the way around the edge of the insulation boards that meet the boundary line so that no EPS is exposed. The corner bead should be embedded within the basecoat.

Once the basecoat has set, you can prime the basecoat and once this is dry you are ready to apply your render topcoat. We strongly recommend using the EWI-075 Silicone Render as it is highly hydrophobic so will repel any water from its surface.

Using Silicone Sealant for Externally Insulating a Semi-Detached House

As we know, water ingress is one of the biggest issues that installers need to protect the EWI system against. It’s imperative that any gaps between the insulation and the underlying substrate are sealed against water.

On a detached property, this is only an issue at the top and bottom of the system, but with a semi-detached property, you will need to use a silicone sealant in the area that is exposed at the boundary line. This will stop water from seeping behind the system and causing the adhesive to wear away. We stock a range of Silicone Sealants in a variety of colours including transparent.

There is a slight issue also that silicone sealant can wear away quite easily, so you may find that this will need to be reapplied every few years.

Verge Trim for insulating Semi-Detached Houses

As we know, sealing the EWI system against water ingress is important for any type of property. However this is especially important in a semi-detached property, so if the roof doesn’t properly overhang the insulation then Verge Trim will need to be installed.

Verge Trim basically works to extend the roofline and cap the top of the insulation boards so that water will run straight off the front of the system rather than down the back. Even better in a semi-detached property is the use Verge Trim End Caps to round off the edge of the system and ensure further protection.

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