Thermal break advice needed

[gratefull1]

Hi,
The picture is of the back wall in my garage, the white painted brick on the left is a single leaf exposed to the outside, the block way is a cavity with the loo on the otherwise.
The cavity is full of rubble and snot and is about 15 to 20mm at it's widest so is too small to insulate (I've drilled holes and looked with a borescope and measured with calipers).
The downstairs loo is very cold, I think what is happening is that the single leaf wall soaking up the cold and passing it down to the outer blockwork of the cavity that in turn is passing the cold through the rubble and snots to the inner leaf to the loo.
If you touch the blockwork and then touch the brickwork you can feel the difference in temperature.
Whats the best way to sort this issue without taking the blockwork down and rebuilding with a proper cavity ?
I don't want to insulate inside the loo as it's already small and insulating the blockwork I don't think would help, it may actually make it worse as the garage gets quite warm with the sun on the door.
Would trying to create a thermal break between the blockwork and bricks be worth while ?

Thanks in advance

 

[^woody^]

If you touch the blockwork and then touch the brickwork you can feel the difference in temperature.
Whats the best way to sort this issue

What issue? That's normal.

 

[stuart45]

Hi,

The downstairs loo is very cold, I think what is happening is that the single leaf wall soaking up the cold and passing it down to the outer blockwork of the cavity that in turn is passing the cold through the rubble and snots to the inner leaf to the loo.
Thanks in advance

Cold is not an energy force, unlike heat which can travel along a solid object. Cold air can get into a room, but cold itself will not travel up or down a wall.

 

[gratefull1]

Hi Woody,
You're right, the single skin brickwork that's exposed to the outside is (and will be) colder than the blocks.
The problem is that the loo is much colder than any other room, it's not a direction issue as it's south facing, the floor is the same as the rest of the house and the ceiling insulation is the same as the utility. All of the walls are cavity insulated with the exception of the one in the photo so my reasoning is that its this lack of insulation that make the loo colder.
As I can't insulate the cavity my thinking was to isolate the warm side (blocks) from the cold side (bricks).

 

[gratefull1]

Cold is not an energy force, unlike heat which can travel along a solid object. Cold air can get into a room, but cold itself will not travel up or down a wall.

Hi Stuart,
maybe a better way of me putting it is that heat from the room is going into the wall and without insulation it's going straight to the brickwork. The single skin brickwork is acting a bit like a heat sink being out in the open.

 

[stuart45]

Hi Stuart,
maybe a better way of me putting it is that heat from the room is going into the wall and without insulation it's going straight to the brickwork. The single skin brickwork is acting a bit like a heat sink being out in the open.

Yes, that's probably what's happening.

 

[gratefull1]

I'm thinking that a vertical section (say 60mm) of the blockwork next to the brickwork could be cut out, i could then try and clean as much of the cavity out and stuff a bit of rock wool in and then use something like Marmox thermoblock to fill the 60mm gap. Any thoughts ?

 

[^woody^]

Insulation does not make a room magically warm, it just reduces the rate of heat loss until both sides of the wall are the same temperature. And the thermal break you mention is not going to do a thing as explained by Stuart.

Is the toilet heated, because that's the simplest thing to do if you want a warm toilet?

Unless you are prepared to line the inner face, anything you do to the wall of an unheated room is going to have little effect on the internal air temperature, as almost all of the latent heat from the room air is going into the wall to heat up the wall before any insulation on the other side of the wall does a thing.

 

[gratefull1]

Insulation does not make a room magically warm, it just reduces the rate of heat loss until both sides of the wall are the same temperature. And the thermal break you mention is not going to do a thing as explained by Stuart.

Is the toilet heated, because that's the simplest thing to do if you want a warm toilet?

Unless you are prepared to line the inner face, anything you do to the wall of an unheated room is going to have little effect on the internal air temperature, as almost all of the latent heat from the room air is going into the wall to heat up the wall before any insulation on the other side of the wall does a thing.

The loo has a new radiator of the correct btu value but the room looses heat quickly and rather like having a window ajar I can brute force the room to be warm by having the rad on for longer/higher but I'd rather close the window as it were.

As you mentioned the single leaf wall is (and will be) colder than the cavity so I think breaking this bridge should help ?

The loo has a 74cm gap between the basin (on the cavity wall) and the opposite wall so I don't have much width to play with if I did insulate the inside wall, in addition the stop cock is in the corner so it may look a bit odd with the wall notched around it, I guess I could box it half in half out of the wall but it would look naff.

 

[^woody^]

The loo has a new radiator of the correct btu value but the room looses heat quickly

Then it can't be sized correctly. Was the correct value for the wall used when the thing was calculated?

There are millions of homes with solid walls, and they can all be kept in a reasonable estate of comfort with appropriate heating. Your issue is whether to try and insulate, or to bash the wall about to create an air cavity in a toilet-sized wall (a couple of m2?), in the hope that it creates a difference that is worth the effort. I would doubt it, but the two options are there to alter the wall, and the third option is to alter the heating.

 

[gratefull1]

Then it can't be sized correctly. Was the correct value for the wall used when the thing was calculated?

There are millions of homes with solid walls, and they can all be kept in a reasonable estate of comfort with appropriate heating. Your issue is whether to try and insulate, or to bash the wall about to create an air cavity in a toilet-sized wall (a couple of m2?), in the hope that it creates a difference that is worth the effort. I would doubt it, but the two options are there to alter the wall, and the third option is to alter the heating.

From memory the rad is oversized on the btu rating using the wall as an uninsulated cavity, that said one if the walls is insulated so I think the btu rating is enough.
Not surprisingly I'd rather try and reduce the need for heating by insulation rather than just turning the rad up.
If I went down the route of rebuilding the wall I'd be doing it myself and once it had a nice spec of insulation in I think it would be noticeably warmer, however as you say, is it worth the time effort and cost in blocks, sand,cement etc to do it....it would be a long payback time! Like you say, I doubt it's worth it in my lifetime.
It's not going to make a big difference but then again it's not a big job so I think it's worth putting a break between the hot and cold walls, once this is done I may also put some insulation on the outside of the block work. It may not be the best way but it's not worth rebuilding the wall and I can't think of any other options. Thanks for your help.