But where do I find the foil backed blanket - who makes it? and how is it rated? I mean is it R4 plus foil or R4 including foil, and therefore how do I assess what R value to go for (I wouldnt put less than R4 batts in)
cathedral ceilings & insulation.
(103 posts) (32 voices)-
Frateco
MemberTry these sites:
http://www.bradfordinsulation.com.au/Products/Residential/Thermal-insulation/Anticon.aspx
This'll get you going in the right direction.
Posted Monday 7 Jun 2010 @ 6:05:03 am from IP # -
gully
MemberYou might be pushing it looking for R4 batts in a cathedral ceiling. Autex list R4 polyester batts as 210mm thick - do you have that amount of space to fit them?
The intrinsic problem with these ceilings is that:
a) There is limited physical space (read air gap) between the inside ceiling and the outside roof (eg. 100-200mm).
b) There is no (or little) possibility of creating convection in the roof cavity in comparison to a pitched/trussed roof where you can get a chimney effect going. Once it's hot it will stay hot for a long time.
c) Usually these ceilings are quite high (eg. 4.5m), so heating the room is expensive.
If I had no alternative, i'd install some kind of weatherproof ceiling vent or fan for summer. There really is no solution for winter
Posted Monday 7 Jun 2010 @ 11:33:30 pm from IP # -
acd
MemberThanks for all the info. The depth Ive got is about 230 so I think Im OK for R4 batts.
However the man I am using to install and plaster will only use poly not rockwool, so I think the blankets are out as they all seem to be rockwool.
The summer heat is worse than the winter cold:
Two thoughts
1. put poly batts R4 for winter warmth and either paint the tin roof and/or add in a vent of some sort to improve the summer problem
or 2. use one of the foil based products - aircell or concertina batts or something alone which will be more help for the summer than the winter.I know there have been lots of discussions about venting, which I havent followed closely, but some sort of thermostat controlled vent would presumably work. The room is 13mx5m and the roof is raked (one half of the cathedral) so low at one side and high at the other (I dont know exactly how high but probably about 4.5m) So total vol about 130 cubic m - to be effective how much air movement through the vent would I need? Would I need to have eave vents or could I just open a window?
Hoping for some more good advice.
Posted Tuesday 8 Jun 2010 @ 5:32:17 am from IP # -
ghostgum
MemberYour installer doesn't want itchy stuff in his eyes. Sounds fair.
You want a minimum 25mm air gap on each side of the radiant barrier.
I would try using concertina batts, leaving about 40mm between the roof and the top of the foil. You don't want the foil to touch the roof. The foil concertinas are about 40mm high. I can measure them if you need that info. That leaves you about 150mm for the poly batts. You can have the underneath of the concertina batts touching the poly batts, because they only contact at the troughs, and the foil is actually a foil/paper composite and doesn't conduct heat well.You definitely want a radiant barrier for the summer heat.
Posted Tuesday 8 Jun 2010 @ 6:17:41 am from IP # -
Frateco
MemberHave a look at this for suppliers:
http://buyinsulation.com.au/main/page_suppliers_insulco_insulation.php
If not rockwool, will he consider glasswool.
Posted Tuesday 8 Jun 2010 @ 7:59:48 am from IP # -
acd
MemberThanks ghostgum. What do you think of aircell as compared to the concertina foil? Seems that it would be easier to install and price not much different - do you think it works as well? It says it should!. It could just be laid on top of the batts (also the sizing seems much easier for the spaces Ive got) Presumably from all thats been said I should maybe have a less thick batt under it to allow an airspace above.
Frateco, I dont know if he will do glasswool, I will have to ask him, as this would be a simpler installation.
Posted Tuesday 8 Jun 2010 @ 11:25:25 am from IP # -
ghostgum
MemberI don't have experience with aircell, but I would expect it to work as well as concertina foil batts.
I would expect bulk insulation batts with aircell above to work, provided there was an air-gap to the roof.
Is dust going to settle on the top surface? This will degrade the effectiveness of the radiant barrier. A tile roof would let far more dust through than a colorbond roof.
Posted Tuesday 8 Jun 2010 @ 12:15:25 pm from IP # -
GBD
MemberJust to confirm - I think this diagram is the existing ceiling and rafter design. Is that correct acd.
http://www.icanz.org.au/handbook/R0600/
Which already has foil and batts (all be it thin) under the tin and above the existing boards.
Which with the addtion of a good level of bulk (and extra foil if desired) put between the rafters and then seal it up should help alleviate the issue, along with a vent to air the excess heat from the room.
And plant a tree in the right place to shade the roof in summer will help a lot.
Posted Tuesday 8 Jun 2010 @ 2:10:22 pm from IP # -
acd
MemberGBD the roof is tin on the outside. On the inside are exposed beams with timber pannelling between the beams (with the beams sticking down into the room, pannelling close to the tin roof). My insulation will go in this space with new plasterboard covering it all from below, so dust shouldnt be a problem. Between the tin roof and the timber there is definitely no bulk insulation. I am not sure if there is sisalation. It was build in the 80s. But in the summer it reaches high 40s inside so whatevers there is inadequate. As far as planting trees goes - of course, but its pretty high up as the ground slopes away and its 2nd storey, so tree shade will take a while..... The other half of the roof is filled in as a more traditional shape with ceiling under it (the rooms are 1/2 floor lower) and Ive put in batts between the ceiling joists. I started to try to staple aircell against the roof timbers but couldnt physically manage myself so ended up laying it flat on the batts (also ran out so didnt cover the whole area) That means the roof space still gets v hot, so although rooms below are better, not as much as I hoped. I think it would be better to get the aircell against the roof.
Posted Wednesday 9 Jun 2010 @ 1:52:33 am from IP # -
GBD
MemberMy mistake- I was referring the the original posters details re foil already existing and thought that was your place. Ooops.
Seems that your place may have no foil - best way to find out is to lift a sheet of tin and have a look. But in essence you've got all that you need from the above posts. Foil / aircell type product, poly blanket or batts, - no itch and seal it up.
Posted Wednesday 9 Jun 2010 @ 1:53:54 pm from IP # -
gully
MemberShouldn't even need to lift up the tin roof, you should see the sisalation edging where you have guttering installed. I doubt you'd have it given the age of the house.
If this is the 2nd storey it means it's gonna be far worse in summer so this should be your #1 goal.
Ghostgum has already given good advice about spacings for insulation.
An aesthetically pleasing, remote-opening skylight could be your answer in summer or
if you wanted some overkill you could whack a small roof evap-cooling system on the roof of this room, without a dropper, just a single vent
Posted Thursday 10 Jun 2010 @ 4:39:54 am from IP # -
Insulation with batts works well for me. If you are really concerned about summer heat then shade your roof ... solar panels are an option and so is shadecloth. However. I measured the temperature on my ceiling in February and it was 27 degrees when the roof tiles were at 52 degrees. The inside air temperature was 24. Outside temperature of 34. The ceiling under some panels was 25 degrees.
Hope that helps.
Posted Saturday 12 Jun 2010 @ 3:31:14 am from IP # -
matas
MemberI have a ceiling like the original poster (except with tiles instead of steel).
That is, cathedral ceiling, with 190mm deep rafters, then 20mm thick planks, then sarking, then tile battens, then clay tiles on top.
My house also gets very hot and cold.
I put in two whirlybird fans, at high points, and this does help a lot, in summer.
I thought about trying to shade the tiles, as much as possible.
And I even grew pumpkin vines over some of the roof. last summer.
It was amazing how quickly they spread, and I even got about 10 large jap pumpkins up there.
Of course I removed the vines at the end of summer.
I have also just got 8 square metres of solar PV panels installed.
So that would assist in the shading.
I have also thought for ages, about how to insulate inside.
And have heard about the option of covering the rafters completely, with plasterboard and batts behind.
But all that extra weight of plaster, and hiding the feature rafters, and expense (I am a big cheapskate) didn't appeal to me.
But more importantly, you could never check between the rafters, for insects, termites, or vermin.
This is my idea - 100mm thick polystyrene panels (standard basic cheap type), held up with timber beading strips, so about 50mm of rafter is still visible.
I don't think the polystyrene would warp.
I just have to work out how to cover the bottom side of the polystyrene, so it looks something like smooth plaster.
I thought maybe just water based paint or wallpaper.
I would love to hear what anyone thinks of this idea, and whether it may not work, for some reason.John
Posted Thursday 17 Jun 2010 @ 9:57:51 am from IP # -
Frateco
MemberJohn,
Simple solution - glue & screw (use washers) your polystyrene to the 20mm planking, cut thin sheeting eg 3mm MDF, masonite (as light as possible) and glue and screw to the polystyrene and boards behind.
This should give you a flat finish.
Posted Monday 28 Jun 2010 @ 1:51:04 am from IP # -
matas
MemberThanks Frateco, thats an excellent idea.
I will look into getting some thin sheeting like that.
I'm guessing you think that 100mm polystyrene sheets just painted or wallpapered, would not look very good.
Or maybe that they would sag ?
The span between the rafters is 660mm.
I was sort of wondering whether a small air gap between the polystyrene and ceiling planks, might be a good idea.
And even have aluminium foil stuck to the top of the polystyrene, for reflective heat insulation, and coping with any condensation.
The EPS panels are fire resistant too.John
Posted Saturday 3 Jul 2010 @ 4:50:31 am from IP # -
termite
MemberThis seems like a similar situation to mine. Please help!
Raked ceiling, 1975 Pettit + Sevitt-style house
Tile roof (yuk dark brown, concrete)
Sisal
Gyprock ceiling lining
2 square diffused plastic skylights
Room height at side: 2100mm, at peak: about 3600mm
No cavity (just the roof joists - sorry I can't measure them, it's currently rented).
Downlights everywhere (I inherited them with the house)
No beams under the gyprockDue to the low ceiling height at the side (the windows are only about 100mm short of the ceiling), it won't be feasible to add a layer of insulation under the ceiling and hang a new ceiling.
Due to the downlights (I suppose I could replace them but it would still be a hassle), I suspect any insulation inserted under the sisalation would need to be like Swiss cheese.
Oh and there are 2 clerestory windows at the peak of the roof.Anyone familiar with this? I want winter warmth as well as summer cool (selfish, aren't I?).
Is there anything that would give me even an additional R1.5 safely, without needing to rip up the tiles and pay $20k-plus?
Posted Friday 9 Jul 2010 @ 5:13:06 am from IP # -
termite
MemberAddendum: has anyone used a "Sun Lizard" fan/ducting system successfully with a non-cavity ceiling?
They're a solar-powered fan that uses ducting to send cool air from under the house into living areas in summer, and hot air from the ceiling cavity (or at least the peak of a ceiling) into living areas in winter.Posted Friday 9 Jul 2010 @ 6:23:01 am from IP # -
gully
MemberI looked at these briefly. Conclusion was you're far better off installing evap cooling / ducted heating than this system. It might give save you money in the shoulder periods (autumn/spring) but not doing to give comfort in the depths of winter or the burning heat of summer.
Think it would be a good solution to a very small house / studio / granny flat.
I must say I agree with the idea in princple of opening floor vents and ceiling vents in summer, rather than closing the house up and running air-con.
Posted Friday 9 Jul 2010 @ 6:34:45 am from IP # -
Frateco
MemberMatas, 100mm polystyrene panels won't sag initially but over time with heat, I'm thinking they could sag. The finish will be absolutely dreadful! unless you heavy coat it with a textured paint.
You won't have much gap so I can't see how effective it would be unless you are able to vent the air out. Reflective foil would be beneficial.
Posted Friday 9 Jul 2010 @ 7:54:41 am from IP # -
Frateco
MemberGeez termite, you're not giving much to work with ???
What direction are your clerestorey windows and are they openable?
Best I can think of is to use large air extraction vents to extract any heat out of the room. This is without going to extent of ripping things out. Is a shaded skylight in the roof unreasonable? Hot days, open and use it for venting, winter get the sun in???
Last idea - using your tank water, set up a trickle hose and water our roof through summer to cool it through the day.
Winter warmth is going to be a bit trickier.
Posted Friday 9 Jul 2010 @ 8:03:33 am from IP # -
termite
MemberThanks, Frateco.
The gable roof line runs due north-south. Both clerestory windows face east. Both are fixed, but one has two overlapping panes with a small (<1cm) gap between (for the bathroom, which is central, though I intend moving this room in a major renovation some time beyond the next two years). So I suppose that may be my opportunity to completely re-shape the roofline (that is so drastic - I can see the $$,$$$ cost accumulate in my mind).
To the west of the house, a rocky outcrop completely shades it from the afternoon sun. I've just had a bank of louvres installed high up on the south wall, which should help exhaust hot air in summer. It is 1km from the ocean, and I replaced a lot of fixed windows on the eastern side with casements several years ago, which definitely helps catch cool easterly breezes in summer (and catches morning sun in winter very well). So I suppose the main need is for warmth in winter - so foil will not be the greatest benefit... at least the 'comfort plus' glass in those new windows is making a real difference.
There are a couple of ceiling fans, though I don't think they are very useful moving hot air downwards if it's quickly escaping through the roof again.
I think I'll need some sort of masonry floor that can heat up in the morning to re-radiate it at night. Not too keen on that - it'll be cold first thing in the morning and unkind to dropped china.Posted Saturday 10 Jul 2010 @ 2:03:19 pm from IP # -
does the high roof have an eave extending out beyond the clerestory windows ? It should have one ,they are relatively easy to retrofit .
Those particular type of skylights leak heat. what colour are the walls of the house ?
As with all potential retrofits there are dozens of possible strategies but the first thing to work out is the budget and the time frame . Then you can prioritise your changes . Where is the house ?Posted Saturday 10 Jul 2010 @ 10:16:30 pm from IP # -
termite
MemberNo eave over the clerestories (though the east/west of house side eaves are about 900mm, thank goodness). If what you say is correct, replacing the fixed clerestory (in the living area) with 'comfort plus' glass will make quite a difference - and be quite economical - great! All the other living area windows are now comfort plus or double glazed.
External (brick) house walls are Dulux 'Hog Bristle' (very pale stone), recently repainted with heat reflector additive mixed in (+0.3R).
House is on Sydney Northern Beaches, about 1km from ocean. 2 storey at front, 1 at back, level with backyard. Rear faces north. Front/east is downhill, sandstone outcrop to west (partially excavated around house footprint), clear access to northern sun. East side is overshadowed by 3 mature eucalypts (dropped branches regularly puncture roof tiles). The living area upstairs runs along the east side.
No work planned for the next year. I'm moving back mid-late 2011, after which I intend extending an upstairs room on the south-west corner to capture views (Warringah Council willing) and reconfigure the entry to make downstairs a s/c flat, so something can be done then. I'm not in a great hurry. Budget for all the planned works will be well into six figures (excluding any roof work), but I don't know yet how much by. $50k has been spent in the past year already, painting and making several important repairs. So I'm a bit weak from paying big bills lately.Posted Saturday 10 Jul 2010 @ 11:21:30 pm from IP # -
matas
MemberOne small thing, you said you have some exhaust ceiling fans.
I find these great in summer, but they must be blocked in winter, or any heat pours through them.
There is also thin polystyrene insulation, you can cut and slip under the tiles, from above, between the tile battens.
http://www.foilboard.com.au/docs/Foilboard%20Tech%20Brochure%208pg.pdfI am in a similar situation to you, in coastal Sydney.
Really the climate is very mild.
I spend nothing on active heating and cooling, except for a tiny amount on a few air fans in summer.
I think just putting some insulation on your body in winter - ie a couple of layers of clothes, is very underrated.
Advantages -
virtually free,
the house can always be well ventilated and not stuffy,
you can walk outside any time, with no preparation.Posted Sunday 11 Jul 2010 @ 3:03:24 am from IP # -
termite
MemberNot exhaust ceiling fans. Just overhead.
Agree about minimising artificial cooling in summer - I hate having to close everything up. Am living in SEQ at the moment and never would have thought I would appreciate having bars on the windows so much - I don't think I have closed all the windows since I moved here. Makes it so much cooler when I get home from work. Fans work well - an overhead one on low gets me through hot humid nightsHowever I do feel the cold. It seeps in and stays - I find myself having long hot showers, which is not a saving at all. I find warm clothing all the time doesn't help with that.
Thanks for the lead about foilboard - I'll look it up.
Posted Sunday 11 Jul 2010 @ 6:27:14 am from IP #
