Bathroom extension with three cold walls

[jbolo]

I have a 1927 flat with a 1970/80s bathroom extension. I am planning on getting a new bathroom as the current one is v old. The room is SE facing and very cold. After every bath the room gets full of mould. I installed new windows but before the bathroom gets fitted I was wondering if there was a way to insulate. My budget for everything, including bath has to be under £10000 as I am borrowing the money. The walls are brick with a flat roof.

 

[robinbanks]

I was wondering if there was a way to insulate

There is; you install insulation, probably rigid board. What final wall covering are you planning?

 

[jbolo]

Large ceramic wall tiles

 

[23vc]

Surprised an extension built in the 70s/80s wouldn’t at least have a cavity wall (going by the brick bond in the pic)

 

[robinbanks]

Large ceramic wall tiles

Consider an internal stud wall, full filled with PIR between studs, vapour control membrane over, then lined with insulated tile backer board for tiling on

 

[jbolo]

How much of the room would it take up approx as the room is really small?

 

[mikeey84]

I just fitted 40mm thick insulated tile board to a northwest corner bathroom in a 1930s house that suffered from bad condensation and mould. That, along with a decent inline extractor and a larger towel rail sized used a btu calculator, has meant out new bathroom is now the warmest room in the house.

I dotted and dabbed it to brickwork, then mechanical fixings through fabs, each board sliconed on the edge to it's neighbours to prevent damp. Tiled straight on. Worked well

 

[robinbanks]

Yeah but it's only 40mm

How much of the room would it take up approx as the room is really small?

Depends on how deep you make the insulation. Unfortunately you can't have it both/all ways; as your walls exist you start with the dimensions as they are, you take off your new inner wall thickness for whatever insulation thickness you want to achieve the U value you desire and what you're left with is the tileable, usable space. If eg you decided to use 100mm PIR to achieve your U value target but that then meant the room was only 50 inches wide and you needed it to be 52, then your options are
- find a way to make do with 50
- swap the insulation for thinner stuff and spend more on heating
- swap the insulation for more expensive, performant stuff
-knock an external wall down and recreate it larger
- look at systems that put the insulation on the external face of the wall

 

[blup]

Stud wall with insulation and suitable extraction. Heat it.

 

[cdbe]

Looks small. Check the cavity - if empty get filled. We were just starting to put batts in walls in the late 80's so could be unfilled.

 

[mikeey84]

Yeah, only 40mm, but 40mm is better than 0mm, and I can still fit my bath in