How to fix warmer spot on wall to reduce heat transfer to inside?

[Vitriolum]

Hi, 

We are aiming to have as even building envelope as possible, therefore

hoping to have some guidance how to best address the top parts of the walls, especially above windows and doors.as a thermal camera shows there is more heat coming in. We had our brick veneer walls insulated with a blow -in insulation and batts were added to these parts on the roof side, but the thermal reading still shows in places +23C when the rest of the wall reads +17C. We have an iron roof and the roof insulation should be sufficient, the area of concern seems larger than so called thermal bridge. 

We've also used low expansion spray foam in these areas from the inside, and at the moment have foilboard there. Would something like insulated plasterboard be good to add over the drywall? or any other material that would work to keep the heat out? how about expanded polystyrene or extruded polystyrene with some type of additional dry wall behind it? 

Any advice is much appreciated.  

[MitchellMc]

Hi @Vitriolum,

I apologise for the delay in my reply.

It sounds like you’ve done quite a bit to improve insulation already.

Since the thermal readings above windows and doors are still showing higher temperatures, adding an additional layer of insulation could be beneficial. Insulated plasterboard, as you mentioned, could be a good option. It would help add another layer of thermal resistance and can be installed over the existing drywall. The added insulation would help reduce heat transfer without taking up too much space.

Alternatively, extruded polystyrene (XPS) as a rigid insulation material, combined with drywall, could offer better thermal resistance than the current setup. XPS has excellent insulating properties and is durable and resistant to moisture. You could install this material in the affected areas before finishing off with a drywall layer.

If the main issue is heat coming through the ceiling, you may want to check if the insulation in the roof space is completely covering all areas, especially above windows and doors. Adding more roof insulation or reflective foil might also help with managing heat from the iron roof.

Consider making sure there are no gaps or voids in your insulation, as even small openings can lead to heat transfer. The combination of these options, depending on your budget and what’s most accessible, should help reduce the heat coming through these spots. 

Please let me know if you have any questions.

Mitchell

[Vitriolum]

Hi Mitchell, 

thank you for your thorough response and advise. I  got some 30mm XSP boards from Bunnings to replace the foilboard and I will try and address any voids with the insulation up on the roof side, although its been hard to get to these areas, and I will see how it goes if I still add the drywall 

[EricL]

Hi @Vitriolum 

Please keep us updated with your progress, we look forward to hearing that the temperature in that section has improved due to the added insulation.

Eric

[Vitriolum]

Thank you Eric, I will do 😊

[Vitriolum]

Hi, I would like to ask your advice. These are photos from a garage that has been converted into a room, the outer wall and the upper part of the roller door has foilboard (that has been painted ). I've used silicone to seal gaps but I can see there are still some unevenness. On the roof side I applied spray foam which I could put more unless you recommend something else?  I used plaster or silicone on the corners but that may not be as heat resistant? The first two photos is showing a hotspot on top of the mirror it has foilboard and silicone. It is strange as behind the mirror is two stacked MDF boards and insulation batts behind it, I cannot think of a reason for such random leak. How to best address these spots without needing to rip off the whole board?

Your advise would be much appreciated. 

Kindly, 

Tina 

[MitchellMc]

Hi @Vitriolum,

Given that this is a converted garage, it’s important to remember that garages aren’t designed as habitable spaces. Even with insulation, some heat transfer from the outside is inevitable. The small hotspots you’re seeing, like above the mirror or around corners, are relatively minor and, in most cases, won’t noticeably affect the overall comfort of the room. In fact, a standard new build with higher R-ratings would also show small discrepancies like this if you looked closely with a thermal camera.

You’ve already done a lot to address the main areas: sealing gaps with silicone, using spray foam on the roof side, and plastering corners. These are all appropriate steps, and trying to chase down every tiny hotspot without removing boards or doing major structural work would likely give minimal benefit. The differences you’re seeing, often just a degree or two above ambient, are quite common and acceptable for this type of space.

In short, you’ve adequately addressed the insulation for the room, and the minor hotspots are normal for a converted garage. Unless the temperature differences become much more significant, the current measures are sufficient. 

Mitchell