Hi during the summer months our living areas with raked ceilings are extremely uncomfortable. We have raked ceilings and are considering using insulation between the rafters/beams. Then plastering over the top so the beams are no longer visable.
Can anyone advise if this is a reasonable solution and any advice for achieving the best result.
Alternately would installing whirlybird be another solution.
We have an older style A.C unit but this cannot compete against the heat radiating thru the roof.
Thanks in advance.
P.S not sure if you can attached a photo to give better explanation.
Raked Ceiling Insulation(6 posts) (5 voices)
Hi during the summer months our living areas with raked ceilings are extremely uncomfortable. We have raked ceilings and are considering using insulation between the rafters/beams. Then plastering over the top so the beams are no longer visable.Posted Tuesday 4 Apr 2017 @ 12:55:07 am from IP #
Its a common problem I see Kyla. I presume you are saying that you have exposed beams under the current ceiling ? These are often 200mm wide and so give a great space to install bulk insulation (R4 batts or better). Just fix gyprock sheets under the beams and slide the batts in on top - if you want to make it reject heat even more get a batt with a reflective foil on one side and position the foil to the top but make sure there's an air gap between the foil the current ceiling. Putting the last sheet in can be tricky unless you can also get to it from the roof side.
Whirlybirds will do absolutely no good.Posted Tuesday 4 Apr 2017 @ 5:51:38 am from IP #
Thanks BennyPosted Tuesday 4 Apr 2017 @ 6:55:09 am from IP #
I did something rather like this with my back porch. It's an area about 5m x 6m square under an iron roof supported by 200 x 35mm rafters. It is on the western side of the house and open to the north.
It used to get very hot under there on a warm afternoon; you could feel the heat radiating off the underside of the iron. It had silver foil sarking immediately under the iron, more to prevent condensation drips than for insulation. The sarking was starting to decay and needed replacing.
You can't just push insulation up in between the rafters as you need something to stop it falling down again. What I did was make a number of batterns to go between the rafters. To start with I used 50 x 25, but that was really a bit too light for the job. So I switched to 70 x 35 merch. Merch is non-structural grade pine. It's very cheap (cheaper than 50 x 25!) and perfectly OK to use where there is no significant load on it. Here, the batterns don't have to support much more than their own weight over a 1200mm span, so merch is fine. (You can also use it for noggins, but obviously not for things like studs and joists where you use something graded for structural aplications.)
For the insulation, I needed (a) reflective foil, and (b) something to stop the foil re-radiating heat when it gets hot. (Yes, foil reflects radiant heat, but it still gets hot, so you need something under it.) The ideal product was building blanket. A 15m roll 1200mm wide costs about $80 or $90 for the R-1.3. Normally, it's used fibreglass-side-up to prevent condensation, laid in contact with the iron. In this case though, I used it foil-side-up and pushed the batterns up from below so as to support it close to but not generally in contact with the iron.
Finally, I cut plywood sheets to size and screwed them into the batterns. In total, I used half the depth of the beams. (I didn't want to cover the beams in entirely; I like having exposed beams. Now I have a four inch sealed space with air gaps and insulation, but still have four inches of exposed beam, which looks much nicer to ny eye.)
Is it effective? My word yes! It's made a huge difference, and I spend many hours out there under the roof even on hot days. It has to get over about 37 or so before I feel the need to retreat inside.
The moral of the story here is that even a little bit of insulation (a mere R-1.3 in this case) can make a massive difference.
Another thing you could use would be Foilboard (that's a trade name, there are similar prodcts under other names). It is essentially a thin layer of polystyrene foam coated with silver foil pn both sides. It has the advantage of being very light and reasonably stiff, so it can be self-supporting over longer distances than most insulation products. It's also very thin and has two replective layers rather than just one. It's reasonably cost-effective, though not as good in that regard as building blanket, or foil plus batts.
Whatever you use, you are going to have to hold it up with something such as plywood, masonite, or plasterboard. You will also have to support the supporting material unless you use (for example) a heavy grade of structural plywood which is self-supporting over quite large distances - but is also expensive and very heavy, which means difficulty installing it, and some consideration of the strength of the structure you are attaching it to.
Of these, plasterboard is the weakest and needs most support, but cheap and light. Personally, I dislike it, but that's a matter of taste. Plywood is cheap and strong for its thickness. Masonite is one of the great neglected building materials. Unlike pretty much any other manufactured wood-like board, it is manufactured without nasty chemicals. Most manufactured wood-base products rely on large amounts of formaldehyde glue, which is pretty scary stuff. (Plywood, chipboard, craftwood, and so on.) Masonite is simply shredded wood formed under heat and pressure. Nothing else. It's a wonderful material. Cheap too, and very easy to work. The only reason I didn't use it for my porch was that it doesn't like too much moisture, so you can only really use it indoors.
I think the first thing you need to decide is whether you want to enclose the entire space between the rafters (as it seems you do) or only part of it (as I did). Bear it in mind that the easiest way to do the job will be to attach batterns across the bottom of the beams, and then attach sheeting (plasterboard or similar) to those batterns. Depending on the spacing between the beams, you'll probably give up something like 25mm for the batterms, plus another 12mm or so for plasterboard. Will that make your ceiling too low?
Alternatively, you can inset the batterns such that they are flush with the beams, or (as I did) inset them further again. Either of these will give you a higher ceiling and a more spacious look, but at the cost of a good deal more work.
Or you could use a commercial sold-for-purpose fixing system. I'm not aware of any, but I bet that there are half a dozen different ones, that they are probably pretty good, and that they cost about three times as much as simply using timber.
(Sorry to reply at such length. I'm just jotting down random thoughts really, but perhaps some of them may be of some use to you.)Posted Thursday 6 Apr 2017 @ 10:38:46 am from IP #
I retrofitted bulk insulation to my raked roof (the beams were already plasered over). It was a pain in the ass job and I understand why the professionals said that it can't be done.
I found that it made a massive difference in the comfort of my home and it was worth while.
My house is half raked half standard cavity ceiling. I find that cableing of any kind on the raked side is near impossible. I would give some thought on how to run cables before sealing up the beams with gyprock.
I hope you have ceiling fans. I installed them and they made my RC/AC a lot more effective. You would have a much lrger ratio of air volume to floor space than a house with a standard cavity ceiling. Without ceiling fans in winter the hot air from the AC would float above your head while you are down with the cold air. I run my ceiling fans on summer mode even in winter as I don't seam to get cool drafts from it and they seam to mix the air better in summer mode.Posted Saturday 15 Apr 2017 @ 8:18:23 pm from IP #
Kyla, another option, although very involved, is to remove your roof, add deep battens (or counter-battens), insulate on the exterior side of your ceiling lining and then replace the roof. You would then use a very high performing insulation product like phenolic foam between the new battens. This has all kinds of fun consequences, like lifting your gutters, making your downpipes too short and requiring new fascias, but in some cases, I think it can be the best solution.Posted Sunday 16 Apr 2017 @ 11:32:11 am from IP #
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