PVA on top of Stain Block / Damp Seal

and_the_noobie · Post by **and_the_noobie** » Sat Oct 28, 2023 11:31 am

Hello folks - searched for an answer, but no joy

I’ve got a chimney that leaked (but this is now resolved)

After it was fixed, I coated with “Thompsons Stain Block Damp Seal” —> https://www.amazon.co.uk/TDS250-250ml-T ... 001GU4BEE/

I now need to dot and dab, but I’m not 100% sure if I can / should PVA first (how will it interact with Stain Block? Will it adhere?)

Very new to this. Any advice welcome.

Picture attached in case it helps.

: IMG_1351.jpeg (397.88 KiB) Viewed 1821 times

dewaltdisney · Post by **dewaltdisney** » Sat Oct 28, 2023 11:50 am

PVA is the last thing in a damp situation as it is water based and reactivates when wet. It looks like you are dry lining plasterboard onto studs so I really do not see any need for further wall sealants as long as it is dry. I may have read this wrong?

DWD

aeromech3 · Post by **aeromech3** » Sat Oct 28, 2023 12:00 pm

As DWD.
Well if it states you can paint and paper over so dot and dab should adhere, would avoid PVA, it is more of a sealer.

and_the_noobie · Post by **and_the_noobie** » Sat Oct 28, 2023 12:13 pm

dewaltdisney wrote: ↑Sat Oct 28, 2023 11:50 am PVA is the last thing in a damp situation as it is water based and reactivates when wet. It looks like you are dry lining plasterboard onto studs so I really do not see any need for further wall sealants as long as it is dry. I may have read this wrong?

DWD

thanks - yes, the issue was fixed last year, so I can confirm that the wall is definitely not getting wet now - though I did the seal as a precaution as there were still some low damp readings on it from where it hadn't fully dried out

I've not done plasterboard before but had read from this about using PVA to ensure the wall doesn't take damp from my adhesive: https://www.buyinsulationonline.co.uk/b ... lete-guide

my thought was that the damp seal / stain block is already doing that, so was trying to figure out if I can skip the PVA step, or if I should still do it :)

thanks to you and @aeromech3 for confirming PVA isn't necessary :)

would you know if the above website is correct in stating that PVA should be used on other (non damp seal stain blocked) walls before dot and dab? :)

wine~o · Post by **wine~o** » Sat Oct 28, 2023 5:09 pm

and_the_noobie, A mix of PVA and water is usually used when applying a finish coat of plaster to control suction and stop the plaster drying too quickly. I've never heard of PVA being used for dot n dab.

and_the_noobie · Post by **and_the_noobie** » Tue Oct 31, 2023 11:23 am

wine~o wrote: ↑Sat Oct 28, 2023 5:09 pm and_the_noobie, A mix of PVA and water is usually used when applying a finish coat of plaster to control suction and stop the plaster drying too quickly. I've never heard of PVA being used for dot n dab.

thanks - sounds like I'd best go off and look at a few more guides / "how-to's" :)