Garage to house wall. Very cold in house rooms

[demontec]

Hi all,

We have lived in this house for coming on 4 years and have never understood why the extension to the house is always a lot colder than the rest of the house. The extension consists of a garage that backs onto a office room and partly above the office and garage is the master bed room (ground floor bigger than 1st floor).

I have been doing some cabling today (RJ45) and needed to pass a cable through the garage into the office. I removed some breeze blocks that were at the base of the connecting wall. They were not physically held in place and just wedged in there. I was surprised to find the setup as per the attached picture (sorry, hand drawn by an accountant so hopefully makes sense).

I can fully understand why both the office and the bedroom get so cold as there is nothing stopping the cold air going up the cavity between the garage and the office and then subsequently into the floor boards of the upstairs bedroom.

Is this usual to have such a setup? I guess the problem is because the garage floor is a good foot lower than the house floor and so although there is installation in the wall, there is nothing stopping the cold air going under the insulation and into the gap. The wall does almost seem like it is floating.

Now how would you address this? I am thinking about using just loft attic insulation and wedging like a foot or so up the cavity all along the wall. I would let this hangdown to the garage floor and then refit the breeze blocks and seal around them. Do you think that would make it better? Is there another better solution for this? I was tempted to just blast a couple of cans of expanding foam up there but concluded this probably would be very wise.

Any help would be appreciated.

 

[rssteve]

If the blocks are just wedged in what is holding the wall above them up? Does the cold room have 3 outside walls and part of the roof to outside, this may explain why it is colder than the main part of the house.

 

[Doggit]

It's more than likely that whilst there are a few loose blocks, there are even more that the wall is sitting on, but for some reason, the mortar has shrunk slightly above the loose ones. If you take out a loose block, can you see the insulation behind it, and if so, how thick is it. What is the orientation of the house, as north facing walls are always colder. Is there any insulation under the bedroom floor, as this could also be part of the problem. Rather than stuffing extra insulation behind the blocks, you might be better off lifting the floorboards, and adding 170mm of loft unsulation under there.

 

[^woody^]

Any relative coldness of the house is not due to any gap in the wall but lack of adequate insulation in the cavity and floor above. Just blocking that gap wont do much to solve the problem

 

[John D v2.0]

From you diagram I can't see the insulation.
In terms of construction, there are various voids in houses some of which are heated and others unheated. The insulation should be continuous between them, and generally blocking out draught. A bit like zipping up your coat on a windy day. depending how good the builder was, the insulation may be missing in places allowing draughts through. A good test is to wait for a windy day and go round with a smoke stick or a candle.
Remedial work can be tricky if you don't know the exact construction, because some gaps are for ventilation of unheated voids.