can I waterproof plasterboard by glueing roofing felt to it?

[cjard]

1200x800x12 @ topps tiles - £14.49.. approx. £15/sqm

"TT, ripoff merchant for weekend warriors" I hear you say.. I agree. Check some more places.. ebay, 5 of the same board 88.75 - it's worse! 10 sheet deal, same £15 sqm again.

OK so there are some guys in Liverpool offering full pallets of 67 sqm for 300 notes - 4.50/sqm but it's collection only and you have to take your own forklift or handball them into your own van. Could palletforce it for £100 I suppose and it's 6/sqm but we're talking about an exception rather than a rule..

The £30 sqm was some marmox board I happened across

insulationexpress.com, i see they have it for a tenner a metre - that's still 5 times the price of the plasterboard though, and £480 saved across all the places that need tiles could be a bath suite y'see.. Or a couch..

There are limits on what I want to spend, chiefly because I don't want to be mortgaged up forever.. If it's possible to get good performance out of a cheaper material by throwing a bit of prep time at it, it's the preferred route.

"An engineer can do for five bob what any fool can do for a pound" - my old man (ok, so he takes it to the extreme. I'm not so bad as to make my own nails like he does..

 

[freddiemercurystwin]

You could use felt nails to fix the felt to the boards?

 

[^woody^]

Ha ha. I like it.

Have we answered the question yet? Because I'm wondering about the glue for bitumen, and whether it will need torch-on felt instead?

You can get 8x4 sheets of MgO cement board for under £30 instead of Hardie backer, or cement bonded chipboard for about £20 a sheet.

Once we have a consensus, I'll post the link to the Just Giving page for our Cjards Palace campaign.

 

[noseall]

Once we have a consensus, I'll post the link to the Just Giving page for our Cjards Palace campaign.

Just spat me coffee all over the keyboard. You are a one Wooodspoke! I'd only just cleaned it off having read the opening post.
Awesome thread, great comedy.

 

[cjard]

Ha ha. I like it.

Have we answered the question yet? Because I'm wondering about the glue for bitumen

I wasn't aware Tyvek Supro was bituminous..

You can get 8x4 sheets of MgO cement board for under £30 instead of Hardie backer

Now that looks like an impressive product

Once we have a consensus, I'll post the link to the Just Giving page for our Cjards Palace campaign.

Star man, thanks for setting that up for me

 

[cjard]

Just spat me coffee all over the keyboard. You are a one Wooodspoke! I'd only just cleaned it off having read the opening post.
Awesome thread, great comedy.

Don't expect woody to get you a replacement; there isn't enough space in his hallway to hold it until he can get it to you

 

[Chud]

Is it a wetroom you're building cjard - do you really need to cement board the entire room?

 

[Chud]

Rather than using Tyvek you'd be better off using something like Schluter Kerdi anyway.

 

[cjard]

Is it a wetroom you're building cjard - do you really need to cement board the entire room?

I'm thinking not, hence the query as to whether I can use something "proper" for the zone that's gonna get routinely rained on by the shower, but for other areas of various rooms that will be subject to high humidity/occasional splashing something a little less intense. The query regarding Tyvek is essentially I have a load of it spare, don't like waste but it's small pieces not so usable for applications like felting a roof.. Plus, the waterproof tape from the wet room shower tray kit (something like kerdi) seems to be something like Tyvek, which is what set me thinking..

 

[theprinceofdarkness]

To get back to your imagined problem. I reckon that at least 50 % of modern houses have basins or sinks mounted on gypsum plastered walls over plasterboard. So if you are going to wet the walls about the same as a domestic sink or basin then I don't think any exotic backing is required.
To get back to your original suggestion, tile cement does not adhere very well to smooth shiny surfaces. For Synthaprufe, a bituminous paint for tanking, to get the render to stick to it, means hurling sand at the surface which is a very mucky and hit or miss process. So you want a cheap liquid that is waterproof, is not dried out too quickly by the suction of the plasterboard and provides a rough surface for your tile cement to adhere to. The best i can think of is a slightly diluted EVA with some sand added to it. Use it at your own risk !
Frank

 

[stardanny]

Use cement backer board for wet area such as above bath and shower area up to shower door then use plasterboard for the rest of walls. It will be fine.

Felt onto plasterboard sound a bad idea, I can see tiles falling off. Roof felt is for roofing not for back for tiles.

Pay more or bodge it, you choose.

Daniel.

 

[TonyW2]

I still cannot see a reason given why it would not work.
If the felt is bonded to the plaster board-- not just hanging from nails-- exactly what would cause a problem?

 

[theprinceofdarkness]

And how would you bond it to the plaster board. You would have to prime the plasterboard with a primer, while the plasterboard goes slurp and dries the primer out. After two or three coats its now black. So you put on your felt cement, but the felt slides of it. So now you have to nail it on to keep it in place, while the cement goes off. Now you tile, some fool turns on the heating and the felt goes droopy and expands, the tiles sound hollow, but seem to be hanging on. Some months later some one slams the door and the tiles fall off in a sheet. Err not something I would risk.
Frank

 

[TonyW2]

I was thinking contact adhesive to attach the felt to the plaster board.
But I also thought the OP was referring to shed roofing felt, not Tyvek, so that tiles could be attached to its rough surface with tile adhesive.
No intention of doing this but it did seem a good economical use of some surplus material

 

[cjard]

As noted, when this all began I was discussing the roll of corner waterproofing tape that came with my shower tanking kit. To look at it it seems to be broadly similar to Tyvek Supro; it's like a strip of some kind of plastic "fabric" - by this I mean it's fluffy, with little squares in that look like a pointy hot roller has rolled over it and caused the fluffy part to stick to a plastic feeling substrate. It thus reminded me pretty much of what I misleadingly referred to as roofing felt - breathable roofing membrane would have been a more apt description. Sorry about that..

So, I have a set of marmox style backer boards for the wet area anyway, but there is a large expanse of tiled areas around the house: kitchen splashbacks, WC, ensuite etc etc..
And I have a stack of roofing membrane too small to be usable on a roof (no application for it) and I was wondering if it could be repurposed. Given its similarity to the waterproofing membrane in the shower tanking system, that was one thought. I'm also wondering about using it in place of schluter ditra as an underlay for for tiled floors that are going onto eggerdeck water resistant chipboard decking. This stuff, when correctly glued can apparently be exposed to elements for up to 42 days (not to be specific or anything) so it's reasonably water resistant on its own, but I can't help but think that it'd be a good idea to lay a membrane over it/glued to it before floor tiles are applied

any thoughts on this? I'd naturally be looking for an adhesive that would bind the membrane well to the floor, and lap the membrane edges to provide a continuity to the waterproof layer. I was thinking it would also decouple the tiles somewhat so that slight movement wouldn't cause as much distress to the flexible grout/adhesive