FAQ · Heat, comfort & your home
My western wall gets scorching in the afternoon — can it be insulated?
Yes. A western wall in Queensland receives direct afternoon sun from about 2pm to sunset, and an uninsulated brick or weatherboard wall conducts that heat straight into the room. Wall insulation is a separate job to the ceiling but is often the piece that finally fixes the afternoon problem.
Here’s how to confirm the heat is actually coming from the wall, what method we use to insulate each wall type, and why Peter’s recommendation is almost always to do the ceiling insulation first. The wall insulation service is the follow-up that makes the whole-house result complete. The Australian Government Your Home guide on insulation is also worth a read for the broader picture on where heat enters and leaves a home.
Before you book the wall job
Make sure the heat is actually coming from the wall.
This is a simple test you can do yourself around 3 to 4 pm on a hot afternoon. Stand on a chair or a ladder inside the house and put your hand flat on the plaster of the western wall, at about chest height. Then put your hand on the plaster at the same height on an internal wall — a partition wall that has another room (not outdoors) on the other side.
If the western wall plaster is noticeably warmer than the internal wall plaster, the heat is coming through. Then check the ceiling: stand on the ladder and put your hand flat on the ceiling in a few spots. If the ceiling feels cooler than the western wall, the wall is your target. If the ceiling is the same temperature or hotter, the ceiling is still the bigger problem — and fixing it first will deliver more comfort per dollar than the wall will.
“The hand test never lies. If you’re standing in a hot room at 4 pm and you can feel the heat radiating off the wall plaster, that wall needs insulating. But I always check the ceiling at the same time, because if it’s as hot as the wall, doing both is what solves the problem — doing just the wall won’t fix the afternoon heat that that room is experiencing.”
The method depends on the wall type
Brick veneer and weatherboard are handled differently.
In both cases we’re pumping blown-in insulation into the wall cavity through small access holes — the same principle as a ceiling job but adapted for the tighter geometry of a wall. The wall cavity target is typically 50–75mm for a brick-veneer home, and the full stud-bay depth for weatherboard or fibre-cement cladding.
Brick veneer
The cavity sits between the brick skin and the timber frame of the internal wall. We access it from the roof space: lift every third tile along the top of the wall, insert a long thin pipe into the cavity, and pump it full of blown-in insulation. The internal wall lining is not touched. It’s a low-disruption process on a standard brick-and-tile home.
Weatherboard & fibre-cement
Here we drill holes on the inside of the wall at the top of each stud bay — typically 40–50mm diameter, one hole per stud space, across the full width of the wall. A 5-metre wall will have around 10 to 12 holes. We pump each stud bay full, then patch the holes. A cosmetic skim and paint is your responsibility but any competent plasterer can do it in an hour.
Peter’s recommendation on order of works
Do the ceiling first. Then the western wall. Then the other walls if budget allows.
The ceiling carries the largest heat load in a typical Queensland home. The Australian Government’s Your Home guide puts ceiling heat gain at around 25–35% of the total for a typical home. Your western wall in the afternoon is real, but it’s affecting one room for one part of the day. An uninsulated ceiling is heating the whole house all day long.
If you insulate the western wall and skip the ceiling, you’ll get some afternoon relief in the rooms on that side, but the house will still overheat from above. The ceiling job almost always delivers the biggest comfort result per dollar spent.
Once the ceiling is done, the western wall is often the specific fix that makes the afternoon liveable. Combined with a good ceiling insulation job, a properly insulated western wall means the house stops loading heat from above and from the most aggressive sun angle of the day. If you’re also thinking about whether to hold off until after air-conditioning, read our FAQ on whether to insulate before air-conditioning.
One side note: if you insulated the house and skipped the garage, the garage heating up is a known consequence. There’s a separate FAQ on why the garage is hotter since insulating the house that explains exactly what happens and what to do about it.
Ceiling insulation — biggest heat load, best return on investment.
Western wall insulation — fixes the afternoon problem once the ceiling is sorted.
Other external walls — adds to the envelope if budget allows.
What a western wall and uninsulated roof are actually up against.
These clips show the real temperatures Queensland homes face in summer, what bad roof work looks like, and how cellulose fibre performs in those conditions. The egg video is a favourite — if anything explains why a western wall needs insulation, watching a roof fry an egg in summer does it.
Read the transcript
We've just insulated your house — what did you think of the job? I think it's fantastic, I can notice the difference already, which is amazing. So we've got some eggs here, which is not the normal thing, but Ruth has indulged me to cook some eggs on a roof, and I'll hand over to my off-sider to film. So this is the Comfort Zone cooking show now. I'm not a very good cook because I'm a single bloke, but the roof is so hot up there, we'll just see how long it takes to cook an egg. Too hot to touch. Just keep that in there with a bit of bread — there you go, starting to go right on the bottom. I don't know whether this is the best way to cook an egg, but we'll see. If this works, we might just bring eggs along with us — normally some onion, some eggs and some bacon, and we'll have a fry-up on people's roofs. The roof is actually too hot for me to put my hand on. But the eggs were cold when they came out of the box. What's happened is it's actually taken the heat out of where it was sitting — if I had a fry pan up here it would have heated up in the sun, and because the fry pan's thicker on the bottom it would have held the heat. The iron's only a millimetre thick, so I didn't think about that. So I don't think it's working very well. Oh well — it was worth a shot.
Read the transcript
So you can see here I'm on a tile roof, and all of this roof has been painted previously. But you can see the paint's actually been put on over the top of mould, and because they didn't pressure-clean the roof before they started, it's actually not stuck to the roof. So this is what one of those cheap paint jobs will do: they won't clean it properly, and then your paint will just come off. It'll look good for about a week — well, probably three months or so — and then it'll all look terrible. And now, to get all that paint off, it's going to be a lot more work to fix it.
The clips play right here on the page, or open the playlist to watch them all on YouTube and subscribe.
Some of these were filmed a while back. Our methods, safety standards and products have moved on since. For how we work today, see the rest of this page.
Some of these were filmed a while back. Our methods, safety standards and products have moved on since then.
More on insulating a hot western wall
How do I know if the heat is actually coming from the western wall rather than the ceiling?+
Stand on a ladder around 3–4 pm on a hot afternoon and put your hand flat on the plaster of the western wall — about chest height. Then put your hand on the plaster at the same height on an internal wall (one with no sun on the other side). If the western wall plaster is noticeably hotter than the internal wall, the heat is coming through that wall. Then check the ceiling. If the ceiling is cooler than the external wall plaster, the wall is the culprit. If the ceiling feels the same or hotter, ceiling insulation should come first — it shifts a much bigger amount of heat than a single wall does.
What product do you use to insulate an external western wall?+
For brick-veneer homes, the cavity between the brick and the timber frame is the target — that gap is typically 50–75mm. We pump it full using a long thin pipe inserted through small holes, usually accessed from the roof space by lifting a tile above the top plate, without touching the internal lining at all. For weatherboard or fibre-cement clad homes, we drill holes on the inside of the wall at the top of each stud bay (about 40–50mm diameter, one per stud space) and pump blown-in insulation in from the inside. The holes can be patched by any competent plasterer.
Why do you recommend doing the ceiling before the western wall?+
The ceiling carries the largest heat load in a typical Queensland home — the Australian Government’s Your Home guide puts ceilings at around 25–35% of total heat gain or loss. A western wall is only one face of the building, and only in the afternoon. If you do the walls first and skip the ceiling, you’ll get some afternoon relief but the house will still overheat from above all day. Ceiling first, then the western wall, then other walls if budget allows — that order gives you the most comfort per dollar spent.
Will insulating the wall make my air conditioner redundant?+
Not redundant, but meaningfully smaller in terms of how hard it has to work. A well-insulated wall slows the rate at which heat enters the room, which means the room takes longer to heat up and the air conditioner can hold the temperature with less effort — shorter run cycles, lower energy bills. For the full picture on how insulation and air conditioning interact, have a look at our FAQ on whether to insulate before or after air-conditioning.
Is the drilling process very destructive?+
For brick-veneer homes, the process is almost entirely non-destructive — we work from the roof space and the internal wall lining stays untouched. For weatherboard or internal-wall cavities, we do drill 40–50mm holes at the top of each stud bay across the wall. A 5-metre wall might have 10 to 12 holes. We patch the holes after pumping, but a proper cosmetic patch — skim-coat and paint — is your call and is at your cost. The result is a wall that performs permanently from that point on. Most customers consider it a straightforward trade-off.
Does the wall insulation come with the same life-of-house guarantee as the ceiling?+
Yes. Our blown-in cellulose in wall cavities carries the same life-of-house guarantee as our ceiling work — it won’t settle, it won’t be eaten by rodents, and it won’t need topping up. The fibreglass (Jetstream Carbon Plus) option we use in brick-veneer cavities where there is any moisture concern also carries a product guarantee. Either way, you do the job once and it’s done for the life of the building.
Comfort Zone Franchise
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Or call Peter on 0414 586 315 — happy to talk through whether the ceiling, the wall, or both makes sense for your home.