November 20, 20178 yr Hey all! It's only a tiny detail but annoys me!. I have to leave a nice gap at the edge of my render board where it meets the soffit. I bought some trim to hide my sins As you can see the render board shows through; it would be a pig to cut in situ - and I ain't taking them off. So!; is it ok to paint with say black external masonry paint? - too hide the whiteness popping through. Just don't want any flaking or anything. Do once; then forget - not sure if render board is 'paintable' ..... Cheers Edited November 20, 20178 yr by pocster
November 26, 20178 yr Hi I'd give the board company a call. I don't know if you are aware but your board gaps must be filled with mastic to stop the render squeezing into the gaps.
November 27, 20178 yr Author 13 hours ago, Luckylad said: Hi I'd give the board company a call. I don't know if you are aware but your board gaps must be filled with mastic to stop the render squeezing into the gaps. No i wasn’t aware . Assume when I get it rendered the guy would tell me that ....
November 28, 20178 yr Yes hopefully he would say ,but it's just better if it's gone hard before he starts. You fill with mastic so the render doesn't get in between the boards when they expand and contract. Helps stop any cracking.
November 28, 20178 yr Author 5 hours ago, Luckylad said: Yes hopefully he would say ,but it's just better if it's gone hard before he starts. You fill with mastic so the render doesn't get in between the boards when they expand and contract. Helps stop any cracking. Thanks !
December 4, 20178 yr Author I guess the mastic has no purpose but to stop the render coming through. So just *any* mastic? Could I not use expanding foam (if careful!); I have lots of this hanging around!! Cheers
December 4, 20178 yr 8 minutes ago, pocster said: I guess the mastic has no purpose but to stop the render coming through. So just *any* mastic? Could I not use expanding foam (if careful!); I have lots of this hanging around!! Cheers The mastic has to stay slightly flexible to deal with expansion and contraction, and I doubt that expanding foam would. I also think that the render would find it's way into the holes in the trimmed foam, rather defeating the purpose.
December 4, 20178 yr Author 5 hours ago, JSHarris said: The mastic has to stay slightly flexible to deal with expansion and contraction, and I doubt that expanding foam would. I also think that the render would find it's way into the holes in the trimmed foam, rather defeating the purpose. Ok so just standard ‘bathroom ‘ mastic is fine ?
December 4, 20178 yr You want standard outdoor building mastic probably. It's not expensive, but to ensure the render people are happy with it, give them a call and ask what they normally use, as you don't want the mastic to have some unwanted reaction with the render.
December 4, 20178 yr I have used moisture resistant render board with a dpc behind on a wooden batten and I do not need to mastic the joints. My boards can be left for at least 12 months according to the makers spec so check with the render people before you go ahead. If exposed for any length of time they need brushing down and left to completely dry out before rendering.
December 8, 20178 yr On 04/12/2017 at 20:44, Pete said: I have used moisture resistant render board with a dpc behind on a wooden batten and I do not need to mastic the joints. My boards can be left for at least 12 months according to the makers spec so check with the render people before you go ahead. If exposed for any length of time they need brushing down and left to completely dry out before rendering. Hi Who is the manufacturer of your board? If the joints don't have to have mastic,then that's one less Job!
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