One of the biggest issues with old sand and cement renders is that over time they crack. The cracks may start small but before long they can really ruin the look of your home – and they can also lead to water ingress.
We get a lot of people asking us what the best solution is to fix cracked render. Well, you have a few choices, depending on the severity and size of the crack as well as how long it has been there:
1. Fixing completely blown render across the entire property
If the render is falling off the walls everywhere you have two options:
The best solution for fixing cracked render is to start again! It’s probably not what you want to read, but putting any other materials on top of cracked render is akin to adding a plaster – it is only really a temporary fix. Therefore we would always recommend removing the existing render back to the brick work, but we appreciate many people won’t do this due to the time and cost involved.
Fix render by adding a thin layer of EPS insulation
The next best solution is adding a thin layer of insulation (20mm or 30mm) to the wall – this needs to be attached to the wall with adhesive and anchored to the wall using mechanical fixings. Prior to adding the insulation board, do try to remove any very loose render and make good the surface with levelling mortar (EWI-260).
Once the insulation boards are in place, then you carry on the rest of the system as normal, adding a 6mm basecoat layer (with mesh) to the top of the insulation boards and finishing off with a render finish.
2. Fixing cracked render on one panel of wall
If there is just one area of the wall that is cracked, then we recommend applying basecoat and render to just that panel (i.e. a square house would have 4 panels, front back and 2 sides). Hopefully the panel in which the crack has occurred isn’t the whole side of the house, and there is a natural break, for example a downpipe.
By basecoating and re-rendering the entire panel, it should ensure the cracked render does not crack again in future. The flexibility of the base coat, combined with the flexibility of the render top coat, should provide a crack-free solution.
3. Fixing a very small crack or area of impact damage
There are some cases where a very small crack has occurred that needs fixing; for example maybe a bin has blown against the wall, or a car has ‘gently’ reversed into it. In this situation you have a couple of options. Firstly, you can remove a square of render around the affected area and basecoat and render this area. This involves taking an angle grinder and trying to remove a clean square around the impacted area.
Unfortunately, there will always be an issue of scarring where the new render meets the old render because both render layers can be as thin as 1mm in thickness – there is simply no way they can be blended together without scarring. The square (marked out using rendering tape) ensures that despite scarring being visible it is still neat.
The other solution for sorting a small crack in the render is to basecoat the whole panel and re-render the property – again a bit more work but you won’t be able to see where the original crack in the render was, therefore it gives a nice finish than marking out the square (as described above).
We often get people ordering additional buckets of render to make repairs on cracked/damaged render and they simply ‘touch up’ the affected area, but 99% of the time this will result in unsightly visible scarring. We would always recommend following one of the methods described above.
At EWI Store, we are very happy to provide help with cracked render – we recommend sending pictures to us at firstname.lastname@example.org and we can provide expert opinion on the best solution to getting the issue fixed!