Before "re-doing" our bathroom I was considering dry-lining the two external walls with plasterboard, or even insulation-backed plasterboard. Currently the walls get very cold at this time of year and this of course is a great condensation producer.
I'm hoping dry-lining will help against this.
However, how far away from the physical brick wall would this put the tiles? How do I then go about securely fixing things to the wall, through the dry-lining?
Secondly, can I do anything similar for the ceiling? The ceiling itself is also suffering from condensation soaking into it, cracking/peeling the paint and the outer lining paper on the plasterboard, especially near the external walls and all the area around the extractor fan.
I'm doing the not unrelated task of insulating my whole house.
If I was doing this, and making no comment about any regulations which may apply.
I would first get enough sheets of 50mm kingspan to cover the entire bathroom walls + ceiling area. They are around 20 quid a sheet.
Then drill the brick with 38mm holes (diamond core drills are cheap and fun) to some 50mm or so.
Into this, cement 5" or so lengths of 1"*1" timber.
This is every 400mm or so. Over this goes a framework of 19*38mm (or so) lattice, fixed to floor and ceiling, and all of the fixings.
Thence the (foiled) plasterboard. (I foiled my own, as it was cheaper)
There is a small cavity 1-2cm behind the kingspan, and this should be ventilated to the outside, to prevent damp.
The fan _must_ dump its air outside the wall, not into the cavity.
Also, the cavity shoudl be sealed from the rest of the house, as otherwise it'll cause condensation behind it from the warm moist air behind it.
You lose maybe 50mm + 19mm + 15mm +12mm = 100mm of space on each wall. If I had shares in No More Nails, or some other company, I'd lose the lattice, and glue the plasterboard to the kingspan. The kingspan is secured to the wall with dot and dab. This gives more like 75mm, but is more difficult to fix anything to securely.
Do note that around a dozen nails through the kingspan halves its effectiveness.
This will make the bathroom pretty toasty warm.
I'd guess for a 8feet cube bathroom, with 2 external walls, you'd be looking at a couple of hundred extra or so, for the insulation.
It can be done with rockwool, this is cheaper, though more annoying. Also, will need deeper rockwool to get teh same result.
Can you explain what's going on here? Are you coredrilling 38mm diameter holes out, knocking inch timbers in and using these for affixing studding to the wall?
Where does the kingspan fit into the above contraption?
and another couple of hundred for the timber, coredrills and all the rest of it, per room
3X2 scant, drilled, screwed with 100mm screws, rockwool, plasterboard and skim...new houses are only built with rockwool/fibreglass insulation and they come up to building regs
Personally I'd be unhappy about cementing bits of timber into a solid wall which is going to be very cold given the new insulation: too much risk of damp and decay for my liking.
Pretty much, though concreting in the inch timbers. Works well IME.
In my case, it's a pretty good fixing into friable sandstone, it was this or replace the hammered in wooden pegs, or use other relatively expensive fixing method - the coredrill has cost me 14p/hole so far, and dropping.
Offer up to the pegs, tap firmly, cut holes with a knife, push on, attach battens, job done.
It's based on what's been holding the plasterboard up without issue for
20 yearsish in my house. (not installed by me.
Hokay, rough BOM.
For a bathroom, 2 2.4m*2.4m walls, one 2.4m*2.4m ceiling. With 400mm spaced timber, that's around 7 per wall, or 33m in both directions. Call it a hundred meters, or 30 quid, 50 quid including some for the top and bottom. Coredrill is 15 quid, and will easily do the 40 or so holes. A bucket of concrete is a poundish, screws another,
Sure - taking 50mm of extra room up with rockwool is going to be quite noticable in some bathrooms though.
100mm screws going all the way through hurt your overall insulation quite a lot.
Just done something similar, but no way could I lose that much space. I glued 25mm celotex/kingspan to the wall, put 12mm cement board inside that and screwed the whole thing into the wall with 100mm frame fixings at intervals. Cement board will be tiled. Some cold bridging for the fixings obviously, but the plastic around the screw should help. No cavity between wall and insulation (gasp !) - no space for one. Since the celotex provides vapour barrier, the outside wall is not rendered, and the celotax is hard against the wall, I'm not too worried about the condensation thing. I mean you don't have a cavity between wet plaster and the wall - it's stuck to it ! I would be bothered if using rockwool however. Obviously an extractor fan to remove water vapour is required in a bathroom. Simon.
Well, Simon has hit the nail on the head with his suggestion of an extractor fan. Most old houses have problems with modern bathing/showering changes. The amount of steam far exceeds that from even 20 years ago. An extractor will usually help and also prevent the horrible black mould appearing.
That said if you want to increase the warmth of the room then by all means dryline the room. I would use 50mm battons nailed or screwed to the wall at 400 or 600 centres with kingspan/celotex insulation in between (I would put 100mm in new property, but 50mm will see a huge improvement). Then be sure to use foil backed plasterboard. I like to use plastic frame fixers with the floating piston inside to fix battons to the wall.
Calum Sabey (NewArk Traditional Kitchens 01556 690544)
Fortunately, in my bathrooms case, there is an under-windowsill void, which I can open up in my case, for extra storage, which will mean the bathroom has more storage, and more usable space in afterwards.
I'm also considering simply setting the temperature in there 5C higher than the rest of the house to help with eliminating any trace of damp, and have nice warm bathroom furniture.
Often if you're doing this sort of stuff, there are ways to better arrange the space.
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