Browse Forums Heating, Cooling & Insulation 1 Dec 16, 2009 1:10 am Hi, I'm not sure how often this happens, but I found out recently that I have a fairly big (1m. high) pile of leftover insulation in one section of my roof area. Would these be adding to the heat problem I have in the upstairs rooms of our 2-story townhouse? Would it be collecting heat in the daytime and then giving it off later in the evening? Thanks. Re: Effect of excess batts on room temperature 2Dec 16, 2009 1:39 am I can't think of a situation where more insulation would be a bad thing. Insulation does not retain heat to be released later. Thermal mass would retain heat to be released later (eg. internal brick walls). Rather than have a 1 metre high pile of insulation, why not spread it out and get a benefit from the excess insulation? The problem with two storey houses is that the upper storey is generally hotter. The best strategy here is to open the windows once the outside temperature gets lower than the inside temperature. You'll need flyscreens in order to do this. Demolition August 2009, Construction Started September 2009, Completed December 2010 Re: Effect of excess batts on room temperature 3Dec 16, 2009 3:07 am I solved a "really hot upper floor" issue in my own home by installing a thermally-controlled electrically-powered attic fan -- maybe 18" across. It blows out the hot air in a matter of hours. The result this past summer (in Canada) was that my air conditioning was called-upon a whole lot less!! I'm talking about a difference of several degrees from what I'd previously been used to. Since you're in a town-house, you'd need to work with the co-op or rule-makers, but it's possible they'll let you do it if you pay for it yourself. I, too, have never seen a case where 'too much' insulation is a problem, unless a huge pile of it is physically impeding airflow and allowing hot-spots of air to not circulate around the attic freely. Seems like good advice to spread it around a little bit. cheers James d. Re: Effect of excess batts on room temperature 5Dec 16, 2009 10:27 pm Thanks for the replies. I found out about the pile of insulation because I am planning to install sarking/ reflective insulation in my roof area, under the rafters. I will look at spreading out the batts after I've installed the sarking. =) Re: Effect of excess batts on room temperature 6Dec 17, 2009 8:25 am hi there.. sorry. I've no contacts for that sort of thing over in your neck of the woods.. I'm in Canada. BUT.. I should caution you about reflective-backed batts for use in the rafters.. from what I've read, doing this could potentially super-heat the shingles and plywood above, and cause premature curling/baking/shrinking and subsequent failure of your roof shingles and maybe your decking material. Heat needs to be able to travel up THROUGH the rafters, and get expelled out of the peak of the roof - also, "intakes" are required at the bottoms in the soffits. Your best bet if heat is the issue, based on my research.. 1) PLENTY of intake air at the bottoms of the roofline 2) PLenty of ways for air to escape out the very top.. #1 being a ridge-vent running the entire length of the roof #2 being some kind of fan unit. 3)good insulation all over the attic. Oh.. I HAVE read about people who had had success with shiny metallic shards/bits of stuff sprayed all over the floor of the attic... this keeps the heat "in" the attic space.. BUT.. you'll still need lots of ways to get fresh air into it, and hot air out! If you are at all handy, it is not a difficult task to install one of those fans yourself, by the way. good luck James. Re: Effect of excess batts on room temperature 7Dec 17, 2009 9:05 am betaone BUT.. I should caution you about reflective-backed batts for use in the rafters.. from what I've read, doing this could potentially super-heat the shingles and plywood above, and cause premature curling/baking/shrinking and subsequent failure of your roof shingles and maybe your decking material. Hello James You might be surprised to learn that we don't use plywood or timber shingles for roof sheeting in Australia (at least not in the part of Aus that I come from). Mainly corrugated steel sheeting or cement tiles. So while these might get a bit hotter with the use of a radiant barrier underneath the roofing it has no consequence. It is better for the heat to be on the outside than to be let into the roof cavity (or attic) and then try to expel it through ventilation. Usually roof space ventilation alone is not enough in hotter climates of Aus. Roof sheeting can get up to 90 degrees C (or more) in the hotter climates of Australia. Without sarking or a radiant barrier this heat would then re-radiate down onto the bulk insulation heating it up and leading to higher conduction through the ceiling to the living space. Radiant Barriers / Sarking greatly decrease this. So much so that roof ventilation is not usually required - especially if the roof colour is light. Regarding the "shiny metallic shards/bits" I think you are referring to a product called radiant barrier chips. I don't think they are available in Australia - which is unfortunate because they probably would have a use here. Regarding the additional batts - the only down side that I can see is that if the living space under the affected roof is not air conditioned and the heat builds up in the area the batts can act to keep the heat in the house of a summer evening when it is cooling outside. However this is easily overcome so long as you can open the windows or in other ways vent the hot air from the living space. I would definitely use them. Re: Effect of excess batts on room temperature 8Dec 17, 2009 9:38 am krangsquared Thanks for the replies. I found out about the pile of insulation because I am planning to install sarking/ reflective insulation in my roof area, under the rafters. I will look at spreading out the batts after I've installed the sarking. =) What sarking/RFl are you planning to install ? You can buy concertina foil batts that are designed to be retro-fitted under the rafters - is that something that you have looked at ? They look easier to install than cutting the sarking sheets to work around the roof timber. Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ They appear to be about $100 for 20sqm coverage. Has anyone else had any experience with these ? Re: Effect of excess batts on room temperature 9Dec 17, 2009 9:44 am Oh that looks interesting JilaMint? Too late for us now, but I am interested in what anyone can tell us about them. www.themaxbuild.blogspot.com forum.homeone.com.au/viewtopic.php?f=31&t=20717&start=300 www.leahspaperpassion.blogspot.com Re: Effect of excess batts on room temperature 10Dec 17, 2009 10:02 am JilaMint You can buy concertina foil batts that are designed to be retro-fitted under the rafters - is that something that you have looked at ? They look easier to install than cutting the sarking sheets to work around the roof timber. Has anyone had any experience with these ? No but I wish I had his roof space. Usually they are cramped and tight and definitely can't use a ladder in there. And it is interesting to see that he is fitting the concertina foil as a second radiant barrier under the sarking (probably because the photo is from a site that sells foil). You can also get narrow rolls of radiant barrier - typically used for insulation subfloor - that might work in the same fashion. The concertina profile does not increase its effectiveness. Try the local large hardware store. However larger span sheeting would work in this roof space - especially in the bottom section. It depends on what the roof structure is as to what is quickest to install. (Sometimes the best way is to remove the sheeting!) Re: Effect of excess batts on room temperature 11Dec 17, 2009 10:07 am themax Oh that looks interesting JilaMint? Too late for us now, but I am interested in what anyone can tell us about them. Yeah - I only came across these the other day. They do look very interesting. Why do you say "too late for us now" ? The whole idea of these is that you install them after construction (after handover). They look much easier to install than taking a rolled up sheet of RFL sarking and trying to cut it to fit while up in a cramped roof space (you would need some serious origami skills for that). @ $100 for 20sqm coverage (or $5per sqm), I think that is comparable in price to decent RFL sarking. Eccles I wish I had his roof space. Usually they are cramped and tight and definitely can't use a ladder in there. And it is interesting to see that he is fitting the concertina foil as a second radiant barrier under the sarking (probably because the photo is from a site that sells foil). You can also get narrow rolls of radiant barrier - typically used for insulation subfloor - that might work in the same fashion. The concertina profile does not increase its effectiveness. Try the local large hardware store. However larger span sheeting would work in this roof space - especially in the bottom section. It depends on what the roof structure is as to what is quickest to install. Good points. The picture is from the site that sells them (and other foil products). I agree, I don't think the concertina profile will increase effectiveness - just the expanding/contracting nature makes it easier to manipulate between the rafters. Also, there is an unusual amount of roof space and clearance in the photo (I imagine to enhance the appeal of "look how easy these are to install"). Re: Effect of excess batts on room temperature 12Dec 17, 2009 10:15 am We already have sarking and insulation installed in the roof. www.themaxbuild.blogspot.com forum.homeone.com.au/viewtopic.php?f=31&t=20717&start=300 www.leahspaperpassion.blogspot.com Re: Effect of excess batts on room temperature 13Dec 17, 2009 10:22 am krangsquared Thanks for the replies. I found out about the pile of insulation because I am planning to install sarking/ reflective insulation in my roof area, under the rafters. I will look at spreading out the batts after I've installed the sarking. =) If you have an overheating problem often it is not just one cause or one cure. If your roof is letting in say 40% of the heat and you cut this to say 20% it still means a lot of heat can be getting in from other areas and the overheating only partially addressed. So also look at things like unshaded Northern and Western (and Eastern) windows that allow sun light directly in. Look for air leakage around window frames, doors and elsewhere. This applies to the whole house as (as you have discovered) heat entering anywhere in the house will tend to go to the top storey. Re: Effect of excess batts on room temperature 14Dec 17, 2009 10:56 am Eccles The concertina profile does not increase its effectiveness. I should have said "The concertina profile does not increase its effectiveness in this usage". If the concertina foil is laid directly on top of insulation batts in the ceiling (another way of using them) the concertina shape is highly important as it provides an air space between it and the batt. All radiant barriers need an air space to work. Re: Effect of excess batts on room temperature 15Dec 17, 2009 6:03 pm krangsquared - The only real way that I can see the pile of insulation could be adding to you heat problem is by the extra efficienies in that area of your ceiling and I assume that it is more over one room - is the overnight/cooler day time looses would be less - so you have a lower rate of heat loss from the room - which equals - it feels hotter with any heat that gets in there. Re: Effect of excess batts on room temperature 16Dec 18, 2009 12:30 am Eccles: Wow. I was not at all aware of construction techniques used in your part of the world. Your posting was indeed a very enlightening one for me! Thank you! With only my North American perspective, it seems the attic is the least of the original poster's worries, since _I'm_ the one full of hot air! HEHE! Cheers! James. Re: Effect of excess batts on room temperature 17Dec 22, 2009 12:14 am James, No worries. I've done a fair amount of research into the issue of using sarking, so that matter's pretty much already settled for me. I was really just wondering about the excess batts that I had and if it was making things worse. JillaMint, From the previous posts in this forum, the general idea I got was to just get the cheapest possible sarking, as long as it doesn't tear easily. =) And there isn't much difference between .03/.05/.07 emissivity, so whatever is available should be fine. I was planning to get Sisalation from my local Bunnings but they didn't have any, so I just got Tradewrap wall wrap foil insulation, which is also from the same manufacturer (Fletcher Insulation). My roof space is really cramped so it's going to be a bit of a struggle to install the sarking. All the installation diagrams and photos I've seen are always showing these spacious roof cavities, while I have: Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ The pile on the right is the insulation I was talking about. Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Makes me wonder if the concertina batts will be any easier to install! Re: Effect of excess batts on room temperature 18Dec 22, 2009 9:52 pm Quote: Makes me wonder if the concertina batts will be any easier to install! Certainly will be - and is only in the order of 0.3 less effective than the tough option. PM me your email. I have a build excavation calculator you can use based on your plans to double check what your builder is telling you. Cheers Simeon 1 10206 Found the answer. The recommended distance is .... 1 5956 |