thermal board - glueing to wall

[osie]

Hi All

I have bought some thermal board (polystyrene with a board attached to it).  Each one is 1.20 high x 2m~ wide and 10cm thick.  I also have some mortir adhesif.  This was purchased based on advice not experience.

My very basic questions are:-

Do I just mix the adhesive with water to produce a cement type paste, put it all over the polystyrene side of the boards and stick em to the wall.

Is it okay to stick it on whole or is it better to cut them into smaller pieces.

What consistency should the adhesive be.

Are there any pitfalls/tips I should know about.

I have some tape to join the pieces... should I just stick this on.

I dont want it falling off after a few days especially after I have put some tiles on it.

thanks

osie

[BIG MAC]

If wall and floor are damp then misture can track through the board what I do is to cut the board 25mm..ish short of what I want height wise then hang fasten breather membrane or DPM to battens loosely affixed to ceiling (Imagine hanging like a curtain about 100mm out from the wall to be covered. I then place a strip  of 18mm flooring on top of the membrane and push it up to the wall so that the membrane isn't too crumpled but is slack enough to allow the placo to be placed against the membrane all the way up the wall (Fiddly but I think worth it). I then drill and plug through the board using long drywall screws but pumping silicone sealant into the screwhole (I use 2" tape to mask the area to be drilled and sealed this way silicone doesn't get on the face of the board). Once sufficient screws are in then the board on which the placo was stood can be wiggled out of position leaving a small gap I trim the mebrane to allow it to be turned up the face of the board by about 1" or so and staple it there ditto at the top. I then tape and joint the board junctions (That's what the fillers best used for  IMHO although some stick the boards up with it I believe) once sanded back carefully wall can be decorated and coving (Timber or plaster ..I like timber as its handy to use as a conduit hider! ) I fit skirtings but I prime and gloss the rear of them before fitting and I sit them up on thin strips of plastic creating a slight shadow gap which allows any moisture running down behind to escape under the board without getting into the timber.If tiling I would tile down on to sections of tile laid flat (Off cuts) in a few inconspicuous areas  then when grouted etc pull out the tile pieces and run a bead of silicone around the floor wall junction you can insert little plastic weep holes quite tidily or yo may take the view that as its a wet area you don't want any gaps, personal preference really but this gives you at least a start. I prefer to use studded membrane and insulated metal frame but accept sometimes there just isn't the room.

PS. Dont forget to channel your gaine into back of boards and through at lightswitch / socket locations and don't drill through the gaine when fitting boards! ditto plumbing for showers / taps but make sure this is tested for soundness, well lagged also well supported as to take the whole thing apart due to a later leak is soul destroying and expensive!

Bon Chance!

 

[osie]

Hi Big Mac

auch.. that gave me a headache and has increased my diy dictionary knowledge...

My wall is only 1.2m high as it is windowed above that and there is no need for electricity wires.  I have a few water pipes poking out from the cemented floor for which I have cut holes in the boards.

It is for a bathroom but it is on the 3rd floor and it is not damp.  Also the boards are polystyrene with a plaster board already glued to it.

I would love to understand the above let alone be able to do it, however I dont think that will happen on this job.  Do you think I could just stick them to the wall with the glue, with them just sitting on the floor.  Then putting tiles to stop any water getting to them?  The original wall is just a rough cement at present. 

thanks

osie

[BIG MAC]

Sorry didn't realise you were up in the attic yes I would still supplement with long drywall screws and if tiling theres litlle point in taping and jointing. I would however give the boards a liberal coating of PVA once in situ.

[Le Plombier]

Osie

You talking about thermal board?

Your description of the board is more like doublage, polystyrene backed plaster board, in which case you mix the colle liberally dab it on the wall and stick and level the doublage on to the dabs of colle

Le Plombier

[osie]

hi Plombier

It is a XTHE Ultra 32 Phonik  ... at least that is what it says on the facture.

I think I understand  that I need to put it on in 10cm 'boudins'... 30cm's apart.  does this mean I put 4 sausages along the width of it.

I am also wondering if I need to put the adhesive all round the outside otherwise there will be a gap..

Is there a reason for the gaps.. there seems to be... is it for extra insolation or does it make the glue stronger...

thanks

osie

[Le Plombier]

Osie

I don't know that name

Doublage is normally 10mm plasterboard with either 50 or 100mm polystyrene insulation glued on the back

If this is what you have then you fix it by dot and dab the same as plasterboard

Use the correct plaster and put dabs of plaster colle on the wall 300mm apart in all directions

Stick the doublage to it and then use a level and big sraight edge to batter it level and square

When you fit the second sheet make sure you use the long straight edge across the two sheets to ensure they are aligned as well as level

The gaps between the joints are filled with the proper plaster for joints and taped

The tape is important as it stops the joint for cracking

You need to dab the colle on the wall to allow space for it to spread when you apply pressure otherwise you will find it difficult to adjust the board

Le Plombier

[osie]

Hi Plombier

Okay... so things are looking good...

I actually put the dabs on the doublage and then mounted the doublage on the wall... I did have a few dots/dabs fall off with this method which is probably why in hindsight it may have been better to put it on the wall first.  I will leave it for a bit and then tape the sections together.  There is virtually no space between the sections so I wont need much joint plaster.

I actaully had to rest a bath against the doublage to add some pressure.

What I find a bit odd (which is what I meant by gaps) is between the dabs, there is quite alot of space even though the dabs have been squashed.  This is especially noticeable along the top of the doublage where there was no adhesive to get squashed.  Would it be a good idea to put a layer of the adhesive in there.  I will be covering the top with tiles or plaster soon so maybe it is not necessary.

Thanks

osie

[BIG MAC]

Probably little need if you have got enough material behind.

[Le Plombier]

Osie

Looks to me you are doing ok

Plaster dabs best on the wall, gaps no problem

Le Plombier

[osie]

Yep.. things are looking good...

As a step 2... I had a chat with the woman in Chauson's and she said I would need a special paint (5kg for 77euros of paint) on the plaster as it will be in contact with a bath.

Do you think this is necessary as it is quite expensive?

I am still not sure if I am going to paint the doublage or tile it... is there a preferable option due to it being in a bath room and will have contact with water?

Also, I am going to put tiles on the floor and would like to ask if there is something I should know about joining the floor tiles to the doublage?

Thanks again

osie

[Le Plombier]

Osie

I use a special waterproofing paint and edge sealing band, the one I use is made by Weber Broutin, very expensive but effective

I only use it on floors and where the bathroom is on the first floor and there is an opportunity for water to pass through the floor

Nothing to do with leaks, more to protect from messy people using the bathroom and soaking the floor

I think not necessary in your case unless you are messy in the bathroom

I do normally use Placomarine in bathrooms, the green board which is much more resistant to water and damp

Provided you take care with the tiling and particularly the grouting you should not have a problem

The most important area is where the bath has contact with the wall

I always batten the wall so the edge of the bath, end and side, will rest on it when the bath is in place when positioned

I coat the batten with silicone then place the bath in position

Once the bath is in position I then seal the joint with the wall with silicone

All this with clear silicone

When I tile I use a thin wooden batten 2 or 3mm on the edge of the bath to maintain the gap and prevent any cement or grout gettting down to the edge of the bath

Once all is finished I fill the clean gap on the top edge of the bath with white silicone

If you do it this way you will not have a problem and the silicone seal will last for many years and not peel away and go black with mildew

Le Plombier

 

[Rookery]

If you're going to fix tiles, on no account use pva on the plaster/plasterboard. Its completely the wrong thing to use.

[BIG MAC]

[quote user="Rookery"]If you're going to fix tiles, on no account use pva on the plaster/plasterboard. Its completely the wrong thing to use.[/quote]

If tiling to plasterboard then a weak solution of PVA is exactly the thing to use to give a good cure....nothing to do with waterproofing it slows the drying time for the adhesive and allows it to set up properly without drying out too quickly.

(Ex bathroom fitter)

[Rookery]

[quote user="BIG MAC"]

[quote user="Rookery"]If you're going to fix tiles, on no account use pva on the plaster/plasterboard. Its completely the wrong thing to use.[/quote]

If tiling to plasterboard then a weak solution of PVA is exactly the thing to use to give a good cure....nothing to do with waterproofing it slows the drying time for the adhesive and allows it to set up properly without drying out too quickly.

(Ex bathroom fitter)

[/quote]

I must disagree and so will the vast majority of tile adhesive manufacturers as well as The Tile Association and probably BS5385. PVA sits on the surface, in the same way as wallpaper adhesive. When it gets wet, which it will with adhesive, it becomes 'live' again and could cause de-bonding of the tile, especially with heavy ones. If using a cement based tile adhesive on gypsum plaster or gypsum based boards, you should prime with an acrylic tilers primer. This serves 2 functions. Firstly, it stops the adverse chemical reaction you get between gypsum and cement (Ettringite) and secondly it stabilises the surface, preventing the plaster sucking out the moisture too quickly. If you are using a dispersion adhesive, generally speaking, they do not need priming first, unless the surface is overly dusty or porous. Whilst on the subject of tiling onto gypsum plaster, you should never tile onto a bonding coat, only a finish coat.

(Professional tiler in the UK, not advertising and not looking for work, only offering professional advice )

[BIG MAC]

[quote user="Rookery"][quote user="BIG MAC"]

[quote user="Rookery"]If you're going to fix tiles, on no account use pva on the plaster/plasterboard. Its completely the wrong thing to use.[/quote]

If tiling to plasterboard then a weak solution of PVA is exactly the thing to use to give a good cure....nothing to do with waterproofing it slows the drying time for the adhesive and allows it to set up properly without drying out too quickly.

(Ex bathroom fitter)

[/quote]

I must disagree and so will the vast majority of tile adhesive manufacturers as well as The Tile Association and probably BS5385. PVA sits on the surface, in the same way as wallpaper adhesive. When it gets wet, which it will with adhesive, it becomes 'live' again and could cause de-bonding of the tile, especially with heavy ones. If using a cement based tile adhesive on gypsum plaster or gypsum based boards, you should prime with an acrylic tilers primer. This serves 2 functions. Firstly, it stops the adverse chemical reaction you get between gypsum and cement (Ettringite) and secondly it stabilises the surface, preventing the plaster sucking out the moisture too quickly. If you are using a dispersion adhesive, generally speaking, they do not need priming first, unless the surface is overly dusty or porous. Whilst on the subject of tiling onto gypsum plaster, you should never tile onto a bonding coat, only a finish coat.

(Professional tiler in the UK, not advertising and not looking for work, only offering professional advice )

[/quote]

 

You must disagree ...Hmmm ok then...disagree with the majority of those in your chosen profession if you will. a Pva solution will be absorbed into the facing paper (That's why it goes dark...see) and will help to create a low suction (Not impervious layer) It will not become 'live' again and as an intrinsic part of the board will not present delamination issues either. The PVA is not there as any kind of waterproofing agent (Popular misconception) what is does do is allow as per my previous posting for a uniform cure and maximum dwell. The rest of your treatise would seem to centre around using an acrylic primer to perform exactly the same function as PVA solution. You pays your money...you makes your choice. Incidentally I have gone back to bathrooms which I installed previously some 10 or so years before and literally had to remove the boards rather than take the tiling off the face of them. BAL Aqua was great in it's day.

As someone who hires and occassionaly fires tilers in the UK I may just have an idea what I am on about although at any one time we probably only have about 150 tiling jobs proceeding on a national basis.