Raked, cathedral & exposed-beam roofs · SE QLD & N-NSW
The raked and exposed-beam roofs other companies won’t touch.
We pump cellulose into raked, cathedral and exposed-beam roofs that batt companies say can’t be done. The exposed-beam gap is often just 40mm. We made our own flat-pipe tool to reach it without lifting your whole roof.
I’ve insulated thousands of raked and exposed-beam sections over the years. We’re one of very few teams in the area that can actually do these roofs, because we’ve got the rig and the training, not just a ute and a stepladder.
A 40mm gap, pumped full
flat pipe, no whole roof lifted
What is a raked or exposed-beam ceiling?
A sloping ceiling that follows the roof line, and gets brutally hot.
A raked (or cathedral) ceiling is a sloping ceiling that follows the pitch of the roof instead of sitting flat, so there’s no roof-space crawl room above it. An exposed-beam ceiling goes further again: the roof sheets sit straight on the beams, leaving a gap that’s often only 40mm. Both can be insulated with pumped-in cellulose. You just need the right gear.
These sections are exactly the spots that turn a kitchen or a living room into an oven, because there’s nothing but a thin sheet of plaster between you and a roof cavity that climbs past 60°C on a summer afternoon. The ceiling is the largest single surface in the building envelope and the most cost-effective place to insulate. The Australian Government’s guide reckons roof and ceiling insulation can cut heating and cooling costs by up to 45% (yourhome.gov.au). You only get that result if every part of the ceiling is covered, raked sections included.
That’s why we’d never leave a raked or exposed-beam section uninsulated. Miss it and the heat just pours in through that one stretch. In most cases you’d be wasting your money insulating the main ceiling if those hot sections are skipped. If you want the full technical case for why we pump cellulose rather than fight batts into a tight roof, read why I only recommend cellulose.
Downlights sitting in a raked tile roof. We pump cellulose right around them, into the corners a batt could never reach.
Know the difference
Raked vs exposed-beam, and how we insulate each.
They look similar from the lounge room, but the gap above the plaster is very different, and that changes how we get the cellulose in.
Raked / cathedral ceiling
Normally about a 150mm gap
A raked ceiling follows the roof pitch but still leaves a cavity of around 150mm between the plaster and the roof sheets. A normal tile raked roof is fine to insulate with pumped-in cellulose fibre, and an iron raked roof is pumped the same way. The cellulose runs up the slope and fills the cavity as one continuous blanket, no joins, no gaps, into the corners a batt could never reach.
Because cellulose pumps well past the end of the hose, we don’t have to lift the whole roof. We open up enough to feed the hose in and let the product do the travelling. One installer on the roof instead of a crew dragging batts around is safer, too.
Exposed-beam ceiling
Normally only a 40mm gap
On an exposed-beam roof the sheets sit straight on the beams, so the only space to work with is the 40mm pattern the iron or tile sits on. Where the roof is iron, we pump cellulose into that gap with our flat pipe. Where it’s a tile roof with exposed-beam sections, we insulate those with pumped-in Jetmax instead.
In that confined space the flat pipe actually compresses the cellulose, increasing its density, so it performs better than it normally would at just 40mm thick. It’s a fiddly, skilled job, which is exactly why batt companies wave it away. After thousands of these sections, for us it’s routine.
The 40mm gap & the tool we built for it
A proprietary flat pipe that slides into 40mm.
The hard part of an exposed-beam roof is the gap. It’s normally only the width of the 40mm pattern that the iron or tile sits on. Comfort Zone made our own proprietary tool for getting into that gap: a flat pipe we slide straight in, so we can lift a lot less of your roof and pump cellulose about 3–5 metres up the roof from each entry point.
That 40mm matters more than it sounds. I’ve held a blowtorch flame straight onto a handful of cellulose and it chars and glows but won’t take light. The borate treatment is shown to slow fire spread, so you can imagine the difference even a thin layer makes to a roof. And because the flat pipe compresses the cellulose as it packs the cavity, you get a higher density than the same 40mm would normally give, which means it performs better, not worse, in the tight spot.
The reason this is full-contact and gap-free matters: an R-rating only counts if there are no gaps, and even small gaps greatly reduce the result. Sustainability Victoria’s government housing manual has a nomogram (Figure 5.18) showing effective R-value collapsing as just a few percent of the ceiling is left bare, and it documents that even a 5% gap can drop an R3.5 batt’s effective R-value to R2.1, about 40% (Sustainability Victoria, p.63). Pumping the gap full leaves nothing for the heat to slip through.
“Sorry, that can’t be insulated”
When a company tells you it can't be done, you're talking to a sales rep, not an installer.
It's the most common thing I hear from people with a raked or exposed-beam roof. Here's what's really going on.
Most companies can’t install cellulose at all, because it needs about $60,000 of specialised equipment and training to do it properly. So when another company just sends someone out with batts in a ute (which, since insulation stopped being a licensed trade in 2006, needs no trade qualification), it’s easier to tell you the job can’t be done because there’s “not enough space” than to admit they don’t have the rig or the trained staff for it.
That equipment barrier is actually a good thing for you: it keeps the fly-by-night operators out, because you can’t rent your way into a cellulose rig the way you can rent a trailer and a stepladder. The roofs other companies decline are the ones we do every week.
“I’ve insulated thousands of raked sections and exposed-beam roofs with very good results. We’d never leave a raked or exposed-beam section uninsulated. It ruins the rest of the job, and you’d be wasting your money insulating the main house if those hot sections are missed.”
So before you accept “it can’t be done,” ask whether the person telling you that has ever actually pumped a raked roof, or whether they just sell batts. We’re one of very few teams in South East Queensland and northern NSW set up to do these roofs, and they’re some of the most satisfying jobs we do. See the other roofs batt companies say can’t be insulated.
Solar panels on a raked roof
Pumped under the panels. We never touch the solar.
A raked or exposed-beam roof with solar on it makes people assume the section can’t be done, but it’s often fine. If we can lift a sheet of iron or some tiles beside the area the panels are bolted to, we can pump cellulose in from either end of the panels with the flat pipe, reaching 3–5 metres up the roof without removing them or the roof.
We do not touch your solar panels, ever. In the rare case we genuinely can’t get access to a section, it’s simply discounted off the quote and you’re told on the day, so if you ever did remove the panels for some reason, we could come back and finish that area. The bonus is the roof under solar panels is in the shade, so it’s usually a bit cooler than the rest of the roof anyway.
Honest answers
Raked & exposed-beam: the questions I get asked most.
I've got a raked ceiling and other companies said it can't be insulated. Can it be done?+
Yes. Raked roofs (which normally have about a 150mm gap) and exposed-beam roofs (normally only a 40mm gap) should definitely be insulated, and they can be, by a well-trained team using pumped-in cellulose where the roof is iron. If your roof is tile but has exposed-beam sections, we can insulate those with pumped-in Jetmax. A normal tile raked roof is fine to insulate with pumped-in cellulose fibre. I've insulated thousands of raked sections and exposed-beam roofs over the years with very good results. We'd never leave a raked or exposed-beam section uninsulated, because missing it ruins the rest of the job. You'd be wasting your money insulating the main house if those hot sections are skipped.
Why do some companies say raked or exposed-beam roofs can't be insulated?+
Most companies can't install cellulose because it needs about $60,000 of specialised equipment and training. So when a company just sends someone out with batts in a ute, which currently needs no trade qualification, it's easier to tell you it can't be done because there's “not enough space” than to admit they don't have the rig or the trained staff for it. Usually you're talking to a sales rep, not an installer. We've got the equipment and the people, so for us these roofs are just part of the job.
How do you get insulation into a 40mm exposed-beam gap?+
Comfort Zone made our own proprietary tool for getting into the gap in an exposed-beam roof, which is normally only the width of the 40mm pattern the iron or tile sits on. That lets us lift a lot less of your roof, slide a flat pipe into the gap, and pump cellulose about 3–5 metres up the roof from there. In that confined space the flat pipe actually compresses the cellulose, increasing its density, so it performs better than it normally would at just 40mm thick.
Can you insulate the raked section under my solar panels?+
Often, yes, and we never touch the solar panels themselves. If we can lift a sheet of iron or some tiles beside the area the panels are bolted to, we can pump cellulose in from either end of the panels. The 40mm flat-pipe method means we can reach 3–5 metres up the roof without removing the panels or the roof. In the rare case we genuinely can't get access to a section, it's discounted off the quote and you're told on the day, and the bonus is that the area under solar panels is in the shade anyway, so it's usually a bit cooler than the rest of the roof.
Does the weather matter for a raked-roof install?+
It does a bit more than a normal ceiling. For a raked or exposed-beam roof we lift roof sheets, so we want a fine day (a cloudy day is actually better than a scorcher) and not much wind, because we don't want sheets blowing around up there. We screw each sheet down as we lift it and take all kinds of precautions, but a still day makes it safer and tidier. Heat we just work around: on a 40-plus day we start earlier and take more breaks, and we still get it done.
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Got a raked, cathedral or exposed-beam roof?
Don’t take “it can’t be done” for an answer. Send me your address and I’ll give you an honest, fixed-price quote within 48 hours for most houses, no deposit, no day-of surprises. Servicing Brisbane, SE QLD & northern NSW.
Peter Johnson
Owner / installer · Comfort Zone Insulation Team® · Since 1986
In the trade and want to do the roofs others won’t? We make cellulose in Tiaro and run exclusive territories, franchise with the family.