Red Brick Solid Wall Insulation

Dont Be at It

Hi folks,

Following advice from BryanF and a little more research, I'm thinking of going with the follow detail for internally insulating a solid, red brick wall in a breathable manner:
- Brick wall stripped back to brick
- ~100mm battens fixed to wall
- ~100mm sheep wool insulation installed between battens
- Intello vapour barrier
- plasterboard

I'm not sure exactly how the 100mm battens will be fixed to the wall, or would it be preferable to have them free standing (in the same fashion as a partition wall) tied into the floor and ceiling joists, and leave a void between insulation and brick wall. This void could then be linked up (by removing floorboard nearest the wall) with the ventilated void under the suspended wooden floor, which would help keep the wall aired.

I also plan to insulate between the joists on the suspended ground floor. Is breathable insulation necessary across the whole floor or just along the external wall. Obviously it's a lot more expensive and we don't want to use it if it's not needed.

The rear wall is plastered externally - is breathable insulation also a necessity in situations like this? Or can (relatively) inexpensive insulated plasterboard be used without worrying about moisture buildup/mould/etc?

Any thoughts are appreciated!

I know I covered some of this in a previous, more general renovation thread. I thought this deserved its own new thread given it's quite a specific and relatively popular topic!

Calahonda52

Dont Be at It wrote: »

I'm not sure exactly how the 100mm battens will be fixed to the wall, or would it be preferable to have them free standing (in the same fashion as a partition wall) tied into the floor and ceiling joists, and leave a void between insulation and brick wall. This void could then be linked up (by removing floorboard nearest the wall) with the ventilated void under the suspended wooden floor, which would help keep the wall aired.

This idea suggests that you may not fully grasp the way the sheeps wool works.

It is the air is the insulatant so the above idea will allow air pass through the sheeps wool, which will render it useless.

Secondly the idea breaches the fire regs requirements.

https://www.nsai.ie/S-R-54-2014-Code-of-Practice.aspx for refurb options

May be useful for solid walls
http://www.josephlittlearchitects.com/articles

In passing, this is not advice, its just some random ideas that you should explore

BryanF

https://www.boards.ie/vbulletin/showthread.php?p=105818768

See above for context

I think calcium silicate would be better than battens/mineral wool/vapour barrier in this situation with the info provided

BryanF

Re the floor, just use breathable felt draped between joists, mineral wool insulation and intello vapour barrier above joists

Re the brick wall and breathability - how about you guarantee there is zero moisture going to get into the wall from either outside or inside. Once you’re ok with that, use what ever you want to insulate

Dont Be at It

BryanF wrote: »

I think calcium silicate would be better than battens/mineral wool/vapour barrier in this situation with the info provided

Interesting, thanks. I was hoping to avoid using calcium silicate due to its very high cost but will have to give some thought to it.

BryanF wrote: »

Re the floor, just use breathable felt draped between joists, mineral wool insulation and intello vapour barrier above joists

Perfect. Thanks Bryan.

BryanF wrote: »

Re the brick wall and breathability - how about you guarantee there is zero moisture going to get into the wall from either outside or inside. Once you’re ok with that, use what ever you want to insulate

Are you referring to the back wall which is externally plastered here? I'm still not sure whether itl needs breathable insulation or not.
I'd have thought waterproofing brick walls isn't that easy to do?

Calahonda52 wrote: »

This idea suggests that you may not fully grasp the way the sheeps wool works.

It is the air is the insulatant so the above idea will allow air pass through the sheeps wool, which will render it useless.

Secondly the idea breaches the fire regs requirements.

Thanks for clarifying that!

Is it recommended to dry line internal walls that join external walls at a right angle so as to ensure there's no thermal bridge? Or is this overkill?

As per usual, thanks for your comments, guys - always most helpful.

Calahonda52

Dont Be at It wrote: »

...
Is it recommended to dry line internal walls that join external walls at a right angle so as to ensure there's no thermal bridge? Or is this overkill?

.

Yes, not overkill but generally not done in Ireland.
The recommended minimum is a meter in, there is a tapered board available, IIRC
from here:
https://www.ecologicalbuildingsystems.com/Ireland

The site has a wealth of information on it anyway so worth a look.

BryanF

Dont Be at It wrote: »

Interesting, thanks. I was hoping to avoid using calcium silicate due to its very high cost but will have to give some thought to it.



Perfect. Thanks Bryan.



Are you referring to the back wall which is externally plastered here? I'm still not sure whether itl needs breathable insulation or not.
I'd have thought waterproofing brick walls isn't that easy to do?



Thanks for clarifying that!

Is it recommended to dry line internal walls that join external walls at a right angle so as to ensure there's no thermal bridge? Or is this overkill?

As per usual, thanks for your comments, guys - always most helpful.

i don’t think you can keep moisture out of a brick wall particularly an old one. And particularly if you use traditional dry lining.

Dont Be at It

Calahonda52 wrote: »

May be useful for solid walls
http://www.josephlittlearchitects.com/articles

He really advocates using external insulation if at all possible. Interesting - I hadn't realised that EWI was considered so superior. More food for thought for the rear of the house - obviously a lot more expensive compared to IWI though.
Still not sure how the external plaster finish on the brick has to be taken into account when detailing the insulation! :pac:

On a slightly different topic, what are people's opinions on insulating the ceiling between ground floor and first floor? I'd have thought it'd be quite beneficial in terms of targeted heating and isolating upstairs rooms that don't need to be heated. However, it doesn't seem to be generally recommended or detailed in guidelines?

Cheers guys

Lumen

Dont Be at It wrote: »

On a slightly different topic, what are people's opinions on insulating the ceiling between ground floor and first floor? I'd have thought it'd be quite beneficial in terms of targeted heating and isolating upstairs rooms that don't need to be heated.

I reckon you're better off focusing on continuity of plaster (and lack of leaky penetrations like unsealed downlighters) if you want to keep warm moist air from leaking through your ceilings.

Dont Be at It

Hi folks,

Has anyone any experiences of applying successfully for the SEAI grant after installing calsitherm internal insulation?
As detailed above, I plan to use calsitherm on the front of the house and externally insulate the back. Because a U-value of 0.27 W/m2K can't be achieved (which is required as per the SEAI guidelines) by the calsitherm (using a reasonable thickness anyway!), will it mean I won't be able to get the grant for the external insulation at the back?

Cheers,

long_boy

Dont Be at It wrote: »

Hi folks,

Has anyone any experiences of applying successfully for the SEAI grant after installing calsitherm internal insulation?
As detailed above, I plan to use calsitherm on the front of the house and externally insulate the back. Because a U-value of 0.27 W/m2K can't be achieved (which is required as per the SEAI guidelines) by the calsitherm (using a reasonable thickness anyway!), will it mean I won't be able to get the grant for the external insulation at the back?

Cheers,

I don't have any experience of this but have the same query. I also wonder how the Deep Retrofit program is supposed to work if they insist front walls in these houses must be insulated to 0.27 W/m2K. In my mind it doesn't make sense as the products aren't there to get the U-value....particularly if you have detailed coving, joinery etc it will just look terrible.

In my particular case I have only 10-15m2 of front facing wall (due to lots of low U-value glass) but 100m2 on the back. Surely it makes more sense to allow the grant if ~90% of the house is insulated considering the fact it's a period house etc. How else will we progress....

dathi

long_boy wrote: »

I don't have any experience of this but have the same query. I also wonder how the Deep Retrofit program is supposed to work if they insist front walls in these houses must be insulated to 0.27 W/m2K. In my mind it doesn't make sense as the products aren't there to get the U-value....particularly if you have detailed coving, joinery etc it will just look terrible.

In my particular case I have only 10-15m2 of front facing wall (due to lots of low U-value glass) but 100m2 on the back. Surely it makes more sense to allow the grant if ~90% of the house is insulated considering the fact it's a period house etc. How else will we progress....

have a look at aerogel thermaslim