Insulating behind toilet in ensuite

[GAC]

Currently midway through doing my ensuite. This photo shows the wall behind where a concealed cistern toilet will be. There will be a shelf at the top of the toilet going back horrizontally to the external brick wall - as such the top half of the brick wall will be plasterboarded and painted over, and the bottom half will be MDF to make a storage space underneath the shelf.



I thought I had a good idea about what I was going to do regarding insulating the wall but now I realise it's a rabbit hole of information... And I'm concerned about casuing damp issues. What are my options to insulate this wall, even just a little?

Those 2*4 timbers are to brace the wall hung toilet frame off - will they cause a problem with making holes in any vapour barrier?

Also, as you can see there's a hole around the soil pipe (not made by me!) on the internal brick, and a vented brick on the external brick. Would it be sensible to seal this up with expanding foam?

Any advice greatly appreciated!

FYI - the old mould marks on the wall were caused by the previous installation that had the extractor fan extracting into a void between the brick wall and a stud wall..!

 

[noseall]

Currently midway through doing my ensuite. This photo shows the wall behind where a concealed cistern toilet will be. There will be a shelf at the top of the toilet going back horrizontally to the external brick wall - as such the top half of the brick wall will be plasterboarded and painted over, and the bottom half will be MDF to make a storage space underneath the shelf.
View attachment 336563


I thought I had a good idea about what I was going to do regarding insulating the wall but now I realise it's a rabbit hole of information... And I'm concerned about casuing damp issues. What are my options to insulate this wall, even just a little?

Those 2*4 timbers are to brace the wall hung toilet frame off - will they cause a problem with making holes in any vapour barrier?

Also, as you can see there's a hole around the soil pipe (not made by me!) on the internal brick, and a vented brick on the external brick. Would it be sensible to seal this up with expanding foam?

Any advice greatly appreciated!

FYI - the old mould marks on the wall were caused by the previous installation that had the extractor fan extracting into a void between the brick wall and a stud wall..!

Fill all the gaps between the timbers solid with foil sandwich PIR. Foam any big gaps. Foil tape the B'jezuz out of all the joints. Add another layer of PIR across the timbers if you have room and foil tape again.

 

[robinbanks]

Is it a cavity wall? Is the cavity already insulated?

 

[GAC]

Fill all the gaps between the timbers solid with foil sandwich PIR. Foam any big gaps. Foil tape the B'jezuz out of all the joints. Add another layer of PIR across the timbers if you have room and foil tape again.

@noseall thanks for your response!
Just so I'm clear... should the first layer of PIR go ontop of the batterns so that there's a gap between it and the brick wall? It's not a cavity wall, just an old 100 year old brick wall. Is it then okay to fix the second layer of PIR to that first PIR? And the plasterboard subsequently directly onto that secondly layer using dry wall scews?

 

[GAC]

Is it a cavity wall? Is the cavity already insulated?

Afraid not, just a 100 year old brick wall!

 

[noseall]

@noseall thanks for your response!
Just so I'm clear... should the first layer of PIR go ontop of the batterns so that there's a gap between it and the brick wall? It's not a cavity wall, just an old 100 year old brick wall. Is it then okay to fix the second layer of PIR to that first PIR? And the plasterboard subsequently directly onto that secondly layer using dry wall scews?

No. Fit the first layer tight between the timbers.

 

[GAC]

No. Fit the first layer tight between the timbers.

Ok Great! Thanks for the help