Wed, 29 Apr 2026 12:05:42 +0100 https://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18251&Focus=307500#Comment_307500 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18251&Focus=307500#Comment_307500 Sun, 15 Dec 2024 16:54:49 +0000 Osprey
What is the best render make to avoid this staining?

I will be having a new extension smooth rendered, as well as part of the old (pebble-dashed) house: PD removal TBD. At some time in the future, I plan to have EWI applied to the rest of the house, and so ideally use the same render.

Thanks

Any thoughts or suggestions?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18251&Focus=307506#Comment_307506 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18251&Focus=307506#Comment_307506 Mon, 16 Dec 2024 18:08:04 +0000 tychwarel https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18251&Focus=307507#Comment_307507 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18251&Focus=307507#Comment_307507 Mon, 16 Dec 2024 18:24:12 +0000 djh Posted By: tychwarelThey all get algal growth. ultimately the only thing that stops it is paint and that is only because there are algicides in the paint.I'm not sure I believe that. My exterior walls are painted with Beeckosil and show no signs of algal or other growth after ten years. The data sheet specifically says "Free from solvents, biocides and preservatives". I believe algicides are one type of biocide. FWIW my mill-finish aluminium roof (i.e. shiny) has a matt grey-brown appearance on the north-facing part the sun never shines on. I've never investigated what that is.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18251&Focus=307508#Comment_307508 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18251&Focus=307508#Comment_307508 Tue, 17 Dec 2024 08:01:36 +0000 GreenPaddy
The first project was over 10 years ago, and I drive past the gable often, which is still looks as good as when it was applied. Actually, about 2 months after we applied it, an idiot roofer did some shoddy work to the chimney at the top of the gable, resulting in soot/tar running down over the new render. I told the distraught client to leave it over the winter, as there was nothing I could do till the better weather. He called me a month later to tell me no to worry, it had all washed off with the rain. Anyone who has experience tar on cement renders or plasters will know that it's almost impossible to get rid of the staining, which just keeps seeping though. That convinced me of the performance of Jub Unixil.

I've used KRend silicone render recently, because that's what the EWI company would supply. Seems ok, but no longterm experience to report back on yet.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18251&Focus=307509#Comment_307509 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18251&Focus=307509#Comment_307509 Tue, 17 Dec 2024 08:15:45 +0000 Peter_in_Hungary https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18251&Focus=307513#Comment_307513 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18251&Focus=307513#Comment_307513 Tue, 17 Dec 2024 17:13:35 +0000 Osprey
Yes all render gets staining, but some seem to suffer much more than others (of course it could be location, lack of cleaning or other factors, but not obviously).

Some of the buildings I have seen are appalling, due to bio growth I believe.

Current default plan is for K Rend, but over time I have seen people recommend 'better' alternatives, but without consistency. So I am looking for latest thoughts/experience.

(House has pretty good soffits - 500+mm - one one wall is north facing and see no sun.)]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18251&Focus=307514#Comment_307514 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18251&Focus=307514#Comment_307514 Tue, 17 Dec 2024 18:56:28 +0000 Cliff Pope