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Maintenance for External Wall Insulation

Last modified: 01.09.2024
Step-by-step demonstration of a render repair patch using EWI Pro Basecoat and mesh, then masking with orange tape before topcoat reapplication. EWI Store offers all the essential tools and products needed to carry out professional repairs to insulated render systems, ensuring long-lasting performance and visual consistency.

Maintenance for your External Wall Insulation can present a bit of a challenge for many EWI owners who are keen to maintain the condition of their investment. Most of our content here at the EWI store is focused on installing external wall insulation and using our products. Nevertheless, the lifespan and performance of our systems are of the utmost importance to us—we want our customers to be happy with their external wall insulation system for the duration of its lifespan. Therefore, aftercare and maintenance for external wall insulation are important topics. Customers must know a few things after installing their EWI to ensure it lasts and performs to the highest standards.

Maintaining your EWI means keeping a close eye on your guttering and pipes. Continuous leaking from rain gutters will damage and stain your render finish in that area. If you notice any damage or staining, call a professional to get it fixed ASAP and follow our instructions (further down) on how to clean the system. Leaking can also result in water ingress if the EWI system is improperly sealed.

Unfortunately, climbing plants will eventually stain your render finish. The same goes for low-level plants and shrubs—keep these at a distance from the render and try to keep soil levels as far below the system as possible, as this can cause splashback during wet weather.

Unfortunately, silicone sealant will not last forever and will eventually need replacing. Our approved installers will aim to use as little silicone sealant as possible due to its shorter lifespan. Although silicone sealant is relatively easy to fix, it’s pretty important to get it right, so it’s probably best to call your installer to replace it.

You will inevitably want to fix something to the external walls of your property. This could be items ranging from satellite dishes to clotheslines. Still, the important thing to remember is to use the appropriate fixings and ensure that they pass clean through the EWI and into the original wall surface. This is because it is unsafe for the EWI to carry the weight of the fixing, and it could result in damage and injury. Once installed, the fixings must be sealed using silicone sealant around the openings where they penetrate into the EWI system. We also recommend choosing stainless steel fixings to avoid rust transferring onto your render finish.

At some point in the future, you will most likely want to clean your windows and use a ladder to access them. If you need to use a ladder at any time, then if possible, you should use a free-standing ladder so that it is not leaning directly against the EWI. This is because the pressure that the sharp edges of the ladder will apply to the EWI could damage and puncture the system.

If you need to use a leaning ladder, ensure it has a spreading board at the top to minimise any risk of damage and do not drag the ladder against the system. As the homeowner, it’s essential that you communicate this with anyone who is coming to do work on your home that may require the use of a ladder.

Cleaning your EWI system is a fairly simple step in keeping the facade looking fresh. If your EWI looks dirty on the exterior, you may need to clean it using mild, soapy water, a cloth or sponge, or a very gentle power wash. If this is insufficient and your render finish is experiencing some biological contamination, we recommend using our Fungicidal Wash. Simply apply the wash to the contaminated areas or the entire facade and leave it for 24 hours to work its magic.

You may find that the render finish on your external wall insulation system will show signs of needing a refresh over time. We recommend that you first clean the render, and then if the render still looks like it needs a fresh coat of paint, we suggest that our silicone paint be applied over the top of the existing render finish.

Depending on the level of damage on the wall, you may need to fix the insulation. Diagnosing a crack to check whether it is structural or not is the first step. There are 6 categories to the extent of cracks:

  • Category 0: Hairline Cracks - These are hardly noticeable and very fine cracks, measuring less than 0.1 mm in width.
  • Category 1: Fine Cracks - These are up to 1 mm wide and can appear in plaster and wall finishes. They are often due to slight settlement or seasonal changes in temperature and humidity.
  • Category 2: Visible Cracks - Visible cracks measure between 1 mm and 5 mm in width and might indicate more significant settlement or thermal movement.
  • Category 3: Service-Affecting Cracks - These are more serious and range from 5 mm to 15 mm wide. They can indicate a structural issue that may affect the building’s usability.
  • Category 4: Extensive Damage - Cracks wider than 15 mm fall into this category and often denote significant structural damage, requiring immediate professional intervention.
  • Category 5: Structural Failure - This category is reserved for severe structural damage with a risk of collapse, characterised by wide cracks that can be seen through to the other side.

Once you have assessed the level of damage, you can proceed to repair the wall and potentially the insulation. This is a crucial step in the maintenance of external wall insulation.

  1. Mark the area: Use a carpenter's pencil and spirit level to mark out an area twice the size of the damage.
  2. Remove damaged render: Remove the damaged render with a chisel, multi-tool, or angle grinder, working from the centre outwards.
  3. Re-score and Remove the Mesh: Re-score and remove to ensure a seamless repair.
  4. Cut and Remove Insulation: Use a saw to cut out the same area of insulation, leaving the clip-on profile intact.
  5. Apply New Insulation: Measure the new insulation, cut it to size, and proceed to apply adhesive to at least 40% of the board.
  6. Fix the Insulation in Place: Supplement the adhesive with fixings; you may require more than one.
  7. Apply Basecoat and Mesh: Install mesh layer, ensuring it overlaps by 100mm on all sides for continuous reinforcement, then cover the area with a basecoat.
  8. Prime and Render: Prime the surface and apply render that matches the existing wall’s colour and texture. Use rendering tape to protect the surrounding area and ensure a neat finish.
  9. Blend the Repair: Remove the rendering tape and blend the new render into the existing wall using a damp brush.