Sealing Drylinng

LivingMan

Hi, I'm about to do Dot and Dab system using Insulated Plasterboards which have an integrated Vapour Barrier. I wish to seal all the perimeters to prevent Vapour leaks. I could use Tape, but it would be visible on the ceiling where it protrude beyond the Skim Coat on the ceiling. Anyone got any suggestions?

10-10-20

Use the adhesive foam in a can which is designed for plasterboard. Gives a good seal around the edges.

Just leave it for 3 to 5 mins as per the instructions before applying the insulated PB to the wall.

https://brooksonline.ie/evo-stik-plasterboard-adhesive-foam-gun-grade-750ml-uq1527

LivingMan

Thanks 10-10-20. I had read about this in my research. But when I held a can of this in a shop the Health warnings put me off ... "May cause cancer", "Keep well ventilated" etc. So I'm thinking that I would breathe in some. What is the safe limit? Also they stressed to use the can upsidedown. So how would I seal the top of the Plasterboard at ceiling level?

However i've seen the guys who put in our windows just using it without any protection. Also I see a guy on YouTube applying it to the back of insulated plasterboards for Dot and Dab.

So that leaves me mulling over the issue. This is no way a criticism of your suggestion, as I do appreciate that you sat down and bothered to answer my query.

MicktheMan

https://www.boards.ie/discussion/2058274284/sealing-drylinng

Imo, you cannot prevent vapour getting past insulated plasterboards regardless of the presence of a vapour check. The only way, in my mind, of doing so is to first apply the insulation, then a continuous and fully sealed vapour barrier and then the plasterboard. Note that any penetrations in the wall such as for electrical switched or sockets will also allow a lot of vapour past the vapour barrier so all pipes and cables should also be sealed to the barrier.

LivingMan

Thanks MicktheMan. First of all I'm glad you said you can't prevent vapour getting past insulated plasterboards. The more I thought about it, I felt the same way. Right from the start I kept thinking how can two boards butted together stop vapour getting through between them. So I read your suggestion with interest and it makes sense. However I have bought some insulated boards but I've still to buy many more. So I will consider to use your approach. Also it would be a lot lighter. I'm using 50mm insulation on 12.5 plasterboard which are dam heavy to haul around. I'll probably be able to move sockets and pipes out of the way as I'm only doing external walls, but I take your point.

GreeBo

Are you doing all walls and ceilings?

How are you going to seal to the floor and window/sockets/pipes etc?

A specific VB and tape is really the only way.

LivingMan

Thanks GreeBo. No Ceilings, only walls. In fact it is only Walls which don't get much or any sun. Sealing to the floor I had intended using Vapour Barrier tape as it would be behind the skirting. But at ceiling level, I had a problem, of the seal being visible, which is why I started this discussion. No sockets. Pipes I can move. Windows I can hide some Vap Barriers but where the Insulated Plasterboard meets the Window frame, there would be the same problem. A vapour barrier tape here would remain visible on the window frame.

All my family are staying over (from abroad) for an extended Christmas period. So I've slackened off. I have some boards cut out and placed in their final position. I'll Dot/Dab later. Meanwhile I can ponder over the situation. I am tempted to use the Expanding foam as a seal as I have bought some Insulated Plasterboards. I've been researching Gas Filters for my Mask, but that's a minefield of varieties of gases.

The sheets were a bit warped/bent. So I've left them braced from across at the far wall in the hope that it will straighten them somewhat. Happy Christmas to all.

10-10-20

I'm still confused about this part:

I am tempted to use the Expanding foam as a seal as I have bought some Insulated Plasterboards. I've been researching Gas Filters for my Mask, but that's a minefield of varieties of gases.

Any of the gasses in either in expanding foam will vent off in gaseous form as they are aerosols. You can't filter them using a mask. The risk from these gasses would be similar to that of hydrocarbons and they are volatile, so will vapourise quickly.

https://www.soudal.co.uk/sites/default/files/soudal_api/document/F0030867_0001.pdf

I'd simply open a window. What risks are you reading and are concerned about?

GreeBo

+1

the gas from expanding foam would be far less of a worry to me (in fact none :)) than the mould forming behind the plasterboard where condensation is forming.

For the ceiling you can always use coving to hide tape, but your problem is more likely to be that you have nothing to tape onto...Unless there is a VB in/above the ceiling?

LivingMan

Thanks 10-10-20 and GeeBo for your contributions. Sorry about the delay in replying.... Christmas hassle! As you've probably guessed I'm a new to Dry-Lining but am into DIY.

You lost me in that paragraph re aerosols and hydrocarbons etc. But i got the gist of it.

I did visit that Website re Soudal Genius Gun. It contains 2 pages of information about the product including a reference to good Ventilation and protective gear. But the very last sentence "For further information on product safety and handling, refer to the information on the container". So I searched for a Safety Data Sheet which contained 8 pages of info. Key points were

That's what scared me off. But I've calmed down and may indeed use it.

(Interesting point was that gas released is heavier than air and so moves along on the groud. So it would take some time to reach the window level for escaping).

But thanks for taking the time and calming me down!

10-10-20

Hi,

You lost me in that paragraph re aerosols and hydrocarbons etc. But i got the gist of it.

My point was that there is inherent risk with many substances - whether they be diesel or talc, but I'd consider many construction materials these days as low enough risk. The risk from radon is probably far higher than a transient off-gassing from expanding foam. But everybody to their own!

(Interesting point was that gas released is heavier than air and so moves along on the groud. So it would take some time to reach the window level for escaping).

I did not know that! What gas is it? It used to be pentane as a propellant as far as I recall.

elgicko

Why not Mechanical fix with mushroom fixings.

Use tape along ceiling and blend in with premix jointing compound. Something like this for corners and ceiling.

https://www.screwfix.ie/p/magnusson-internal-corner-trowel-3-3-4-x-3-1-2/273pr

Personally I would buy good tape and joint tools.

4 inch trowel

9 or 12 inch trowel.

It will take 3 coats to finish with sanding in-between. Higher grit sanding paper between coats. Polybond before painting. Don't forget angle beads for internal reveals of windows.

I would worry about expanding foam gases. This stuff will expand twice to what you use, so go sparingly. Make sure you wear gloves and tape up where you don't want it to go as it will be Paddy's day before you get it off your hands.

GreeBo

https://www.boards.ie/discussion/comment/120001856#Comment_120001856

FYI the foam used for fixing panels like this is very low expansion, its basically just foam glue.

elgicko

I get ya, I was referring to expansion foam for the bit between floor and board, to provide insulation at bottom, usually about 2 inches.

Personally I would mechanical fix with foilback warmboards.

https://www.boards.ie/discussion/comment/120002040#Comment_120002040

GreeBo

Mechanical fix is grand, as long as the thing you are fixing to is flat and solid. Many times I have seen where the bottom of a wall is in bits :(