Ian Stirling wrote:
etillet wrote:
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.


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?

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.

Where does the kingspan fit into the above contraption?


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.


and another couple of hundred for the timber, coredrills and all the rest of
it, per room

It can be done with rockwool, this is cheaper, though more annoying.
Also, will need deeper rockwool to get teh same result.

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