Here are couple of pictures of the external wall of extension in a UK home. There are is a small damage to the render.

enter image description here enter image description here

I thought about using the same fillter material that I have used to fill cracks on inside of the house. However, I believe that they will not respond well to the UK rainy season.

What is the proper material to fill in this damage to render of the UK house external wall?

  • 1
    Not what I would call small. All the loose material will need removing before repatching, looks maybe from below top of fence to bottom of window will need checking for looseness.
    – crip659
    Aug 27, 2022 at 15:17
  • Loose, what does it matter if it is "loose"? What is name of specialist in renders? What will happen if this is not fixed?
    – quantum231
    Aug 27, 2022 at 15:56
  • 1
    Any of the rendering that is loose/not bonded to the wall will fall off in time. Might as well get the guy out once and repair everything, than have him come out every month or two. Can look for people that do cement/concrete work or brick layers. They should be able to do the job or know who does. If not fixed it will probably look ugly, it is usually more cosmetic/ to smooth a wall than structural, but can add some water proofing.
    – crip659
    Aug 27, 2022 at 16:07

1 Answer 1


If you don't fix all the loose bits now, you will just have to do each of them as it actually falls off. Once water has got behind it, frost will complete the job.

It looks like a pretty ordinary sand/cement mix, nothing special about it.

If you're intent on doing just a patch-up, something like Exterior Polyfilla will do as good a job as anything. Interior Polyfilla will not.

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