fitting plasterboard with foam: never again!

[Fred]

Hi,

I've tried fitting plasterboard to the wall using foam. Call me old fashioned but I think in the future I'll stick to screwing it to wooden battens!

I bought 8x4 sheets of plasterboard so that I didn't need to worry about joins and perhaps this added to the problem that the boards were too big and too heavy to manoeuvre.

I tried to spray foam to the back of the plasterboard but it just fell off, wasting foam. I had slightly better success applying the foam to the wall.

Even so, I could see the plasterboard was coming away from the wall in places, so I drilled 10mm holes along the edge to squirt foam through.

I supported the plasterboard with a pair of plasterboard props but I think I needed more of them to evenly support the whole board.

I have noticed now that there is a bulge. I don't know whether the wall beneath was not smooth or whether a pocket of foam has caused the plasterboard to bulge. It's very obvious now because it's in a corner and you can see the wall is not square.

I'm thinking I will remove the plasterboard and try again. I assume that this means chiseling and lots of noise, swearing, and dust.

It seems to me that a big problem using foam is that the wall might not be flat, with odd bricks sticking out, and with battens you can get the plasterboard right without getting into a sticky mess. How do you do this with foam?

I did think about using grab adhesive and I wish I had now. It would have been less sticky than foam and easier to wash off your fingers (I was wearing gloves but even so managed to get foam all over me). I also think that even if you used once cartridge per sheet, grab adhesive would work out cheaper than foam.

TIA

[polygonum]

Never thought about the practicalities before. But perhaps you need to create several "high points" as spacers which the plasterboard will touch? More or less like "dabs"!

[harry]

I don't think it's possible to fix plaster board that way with foam. The conventional way is to use "dot and dab", ie plaster blobs put on the wall & the Pb pushed against them while soft. Harder to do than it looks.

I think the only way you could use foam would be to secure the Pb to the wall with screws & spacers and squirt the foam in small holes afterwards. I think you would need lots of screws as the Pb would bow out as the foam expanded, esp. if you put a bit too much in.

[Jim K]

Low expansion foam?

Jim K

[David.WE.Roberts]

Not really sure why you would want to use expanding foam to fix plasterboard.

For 'dot and dab' you can get a special version of plaster to use as an adhesive - plasterers make it look easy but then they make plastering look easy as well.

If you want insulation then use PIR foam sheets behind the plasterboard and screw through.

Cheers

Dave R

[Bert Coules]

I've never tried to fix plasterboard with it, but whenever and wherever I have used - or tried to use - expanding foam it's never been a success. It's wasteful, messy and next to impossible to clean up, and I heartily dislike it. Or perhaps it heartily dislikes me.

[Tim Watts]

On Tuesday 21 May 2013 10:58 David.WE.Roberts wrote in uk.d-i-y:

There is a specific drywall foam - low exapnsion.

However, I would be a little wary of this. Having used foam to hold in celotex *between* rafters (where a tight fit was impossible) it is sort of OK there, but as the OP noted, it does not hold at all until it's gone off. No grab.

Used in conjuction with edge battens it may make sense. You get the basic positioning sorted and the edge battens hold it while it sets. The foam them makes the fit firm. Low expansion foam is unlikely to bulge the PB.

+1.

[Tim Watts]

On Tuesday 21 May 2013 08:42 harry wrote in uk.d-i-y:

You can (becaus ethey make a foam for specifically this - the OP did not go insane) - *but* I don't think it's the easiest way... Can be useful in conjunction with another method.

No - if you use the correct foam and don;t go mad with it. Most of the expansion happens wet, so as long as the foam can extrude sideways it's fine.

[John Williamson]

It *is* easy, once you've signed the contract for your first born's soul with the Devil.

[sm_jamieson]

I've used it with excellent results (with a proper gun). On various walls including tiles. What did you use - normal expanding foam ? Did you use a proper gun, or the tube on the can ? The proper stuff is low expansion and the cured foam is more dense. And its more sticky than the normal stuff. On the main wall I used a few battens and screws to level it, but on the other wall just a couple of screws at the top to be sure.

You have to leave it until the initial expansion has occurred, and hold it in place somehow until it cures. I just kept pushing it flat with a long level every 30 seconds and it became firmer each time and suddenly it was done.

I cannot see how you got in a mess if you had the correct foam. You can add a little at the edges after it is done to firm those up if required. It saves mixing up plasterboard adhesive and avoids cold spots that dot and dab can produce.

You have to be aware of the "high points" as you do with dot and dab, and whack off any too proud. But I found it very useful stuff.

Simon.

[sm_jamieson]

I found it quite easy once I was using enough adhesive. The blobs need to b e pretty big and the "suction" holds the board once it is up (support the b ottom edge !). To get it on the wall just flick it off a trowel.

The proper low expansion stuff works fine. The "normal" foam would be usele ss though. Simon.

[sm_jamieson]

including tiles. What did you use - normal expanding foam ?

more sticky than the normal stuff.

wall just a couple of screws at the top to be sure.

place somehow until it cures. I just kept pushing it flat with a long level every 30 seconds and it became firmer each time and suddenly it was done.

little at the edges after it is done to firm those up if required.

dab can produce.

whack off any too proud. But I found it very useful stuff.

I used this (a toolstation link):

Simon.

[Tim Watts]

On Tuesday 21 May 2013 13:37 sm_jamieson wrote in uk.d-i-y:

I've used that - sticks like a bastard.

[sm_jamieson]

I didn't finish the can, and have been using the rest for general foam applications. I suspect its pretty much the same thing as window fix foam. I'm not usually trying to fill in a huge hole (add your own comments ...)

Simon.

[John Rumm]

Not only is it possible, there is even a special low expansion foam for doing it...

The right way is:

give the back of the board and the wall a quick light spray with water to aid adhesion (optional, but worthwhile if the wall is dusty or flaky). Lay the board flat, and apply a bead of foam about an inch thick around the periphery - but a couple of inches in from the edge. Add another couple of beads at approx 400mm spacings either vertically or horizontally. Now offer the board up to the wall, and using a level, push onto the wall. I normally stick a couple of pins into the floor / ceiling just to lock the position as if you were fitting a cove. If doing lots of sheets, you can fit temp battens on the ceiling and floor to trap it in place. These can be removed after 10 - 15 mins or so.

Its a handy technique for fixing to particularly uneven walls where you would otherwise need huge dabs of conventional adhesive to make up the low points.

[Rick Hughes]

If someone had asked me how to dry-line, using foam would not be one of the ways. Its' expansion is unpredictable, it's messy, and it's holding power (to me) is undetermined.

Dot & dab or batten out and screw fix.

>

[harry]

That method sounds good to me.

[John Rumm]

The two times I have found it very useful were once when boarding out what was once a garage with some very rough brick and blockwork that was all over the place level wise. The other time was for fitting lots of fiddly bits into cupboards in the eves space in the loft conversion. Much easier than trying to cut out odd sized battens, or work out how to get a fixing on to the sawtooth profile of the underside of some brickwork on a chimney stack etc. You could just cut whatever weird shapes and sizes required and quickly glue them where you want them regardless of the actual shape of the substrate. Taping bits in place with gaffer tape, and letting the foam fill the gaps works well there.

[John Rumm]

How to master the way of the foam:

1) Buy the proper applicator gun and use gun grade foam rather than the cans with built in applicator. (you can (generally) leave a part used can on the gun for some time without it de-pressurising) 2) Get a can of foam cleaner for washing off uncured foam 3) Buy in quantity (i.e. a few cans more than you think you need) - and if you get the odd can that misbehaves you can skip it 4) dampen surfaces for better adhesion and expansion. 5) Fill holes with far less than you think they need. 6) Wear gloves and old clothes.

[sm_jamieson]

As other posters have said, the proper stuff works fine. I'd trust the holding power over dot and dab. Not sure how it would be in a fire though. I think with all these adhesive methods, a few mechanical fixings at the top are recommended.

Simon.