Browse Forums Heating, Cooling & Insulation 1 Aug 27, 2012 8:00 am Hi all, I never put any thought to the insulation in the roof. It does it's job. But at the moment we are renovating the bathroom/bedroom and there is big, open, easy access ot the roof space. If there was ever a time to replace insulation - it's now. The house was built in 1981 so the bats are 30 years old. Do they lose their insulative properties over time? Should I consider doing this job? ... and if so, do you replace the current insulation, or add to the top of it? Cheers, HC Re: Time to replace roof insulation? 2Aug 28, 2012 1:32 pm From the response, I get the feeling I asked a silly question..... obviously something everybody should "just know" Cheers, HC Re: Time to replace roof insulation? 3Aug 28, 2012 5:46 pm The only thing that matters is its ability to retain air, because the air is what insulates, not the material. If it has lost depth, then it will be less effective. Perhaps you could look at adding another layer. Ed "ECOECO" At 'EcoEco', we design windows, we design the best windows, we do it for you, so that when you’re happy we are happy. Tel. 1800 326 326 Re: Time to replace roof insulation? 4Aug 29, 2012 11:07 pm High "R" values weren't such an issue 30 years ago but there is a price point versus efficiency. If your house doesn't maintain relatively stable temperatures and your heating bills are higher than expected new/improved ceiling insulation should help. To work correctly a good house thermal envelope requires a holistic approach. There's no point in having R 6.0 ceiling insulation if there are large gaps under the external doors or there's no wall insulation, etc. If you're planning on installing yourself may sure you take all the safety precautions regarding not covering down-lights, electrical wires, working in enclosed spaces, etc. Re: Time to replace roof insulation? 5Aug 30, 2012 5:49 am I would certainly be putting an extra layer of new batts on top of the existing insulation. Brian The Harder You Try - the Luckier You Get ! Web site http://www.anewhouse.com.au Informative, Amusing, and Opinionated Blog - Over 600 posts on all aspects of building a new house. Re: Time to replace roof insulation? 6Aug 30, 2012 6:10 am If the current bats are about 6 inches thick they might be ok, but after 30 years they are probably flat and filled with dirt! As mentioned earlier the air trapped in the bats is what insulates, so a compressed bat is nearly pointless! If your comfortable working in the ceiling space and want to add some bats it couldn't hurt! 2 Re: Time to replace roof insulation? 7Aug 30, 2012 7:39 am theyetti ... ....There's no point in having R 6.0 ceiling insulation if there are large gaps under the external doors or there's no wall insulation, etc. ... I agree with everything but I would like to clarify this. If you heat your home, then every added piece of insulation reduces heating costs. If you insulate your walls and not your ceiling or vice versa, then you will lower your energy costs. Drafts are the number 1 thief of energy, followed by single glazed windows and doors, and in a well sealed and well insulated home, single glazed windows are the number 1 thief. Every batt helps. Ed "ECOECO" At 'EcoEco', we design windows, we design the best windows, we do it for you, so that when you’re happy we are happy. Tel. 1800 326 326 Re: Time to replace roof insulation? 8Aug 30, 2012 7:59 am Thanks for the replys. I guess i need some sort of measure to see if the current insulation is doing it's job. Is my current insulation dirty? Yes, filthy. I know 'cause I removed the cieling plaster and insulation from two rooms. Does my current insulation look flat? No. It sits about as high at the bearers, but what would I know. .. and I'm guessing it's nothing you can really measure easily. Perhaps a photo would help.... HC Re: Time to replace roof insulation? 9Aug 30, 2012 4:53 pm If its sitting up to the rafters it will be working fine but if its been there for thirty years it will be much less than what is now considered adequate. The Harder You Try - the Luckier You Get ! Web site http://www.anewhouse.com.au Informative, Amusing, and Opinionated Blog - Over 600 posts on all aspects of building a new house. Re: Time to replace roof insulation? 10Aug 30, 2012 6:30 pm bashworth it will be much less than what is now considered adequate. Oh, referring to it's original R rating? Anyone want to have a go at guessing what the minimum standard of R ratings was in 1981? That'd be what's in my roof..... HC Re: Time to replace roof insulation? 11Aug 31, 2012 7:45 am heat_crime bashworth it will be much less than what is now considered adequate. Oh, referring to it's original R rating? Anyone want to have a go at guessing what the minimum standard of R ratings was in 1981? That'd be what's in my roof..... HC To help with your decision: - The difference in dollar terms for heating and cooling a home in Melbourne with 100m2 of ceiling, using R4 versus R2 batts, heating or cooling 33% of the time would be under $150 per annum ($0.20/kWh, assumed ±10° C outdoor v. indoor). Using the same base, R4 to R6 would save under $50 p.a. Just factor in your ceiling size and electricity or gas cost. That is of course at today's prices . Ed "ECOECO" At 'EcoEco', we design windows, we design the best windows, we do it for you, so that when you’re happy we are happy. Tel. 1800 326 326 Re: Time to replace roof insulation? 13Aug 31, 2012 8:17 am ed @ ecoclassic To help with your decision: - The difference in dollar terms for heating and cooling a home in Melbourne with 100m2 of ceiling, using R4 versus R2 batts, heating or cooling 33% of the time would be under $150 per annum ($0.20/kWh, assumed ±10° C outdoor v. indoor). Using the same base, R4 to R6 would save under $50 p.a. Just factor in your ceiling size and electricity or gas cost. That is of course at today's prices . Ed Awesome info. Thanks. HC Re: Time to replace roof insulation? 14Aug 31, 2012 2:14 pm Next question. Is there any reason why you don't add the new insulation over the top of the original? Is this what all the installation companies do? HC Re: Time to replace roof insulation? 15Aug 31, 2012 4:43 pm I think if you lay batts deeper than the bearers you will be wasting some, as the air won't be trapped along the edges. Otherwise no problem. Ed "ECOECO" At 'EcoEco', we design windows, we design the best windows, we do it for you, so that when you’re happy we are happy. Tel. 1800 326 326 Re: Time to replace roof insulation? 16Sep 25, 2012 8:38 pm Hi HC You can just lay new batts over the top of old ones if you want to. The pic of the flat batt appears to not be in good form to say the least. I have R4.1 ceiling batts. The usual is R3.5's. The cost outlay to go to R5.0 or the highest R6.0 R rating is not worth the small amount of benefit. I would want them out rather than topped up but that is hard work. Hope that all made sense. Re: Time to replace roof insulation? 17Sep 27, 2012 7:46 am Vess I would want them out rather than topped up but that is hard work. Yup. That's exactly where I'm at right now. It's all function, not fashion. If I can add R3.5 bats on what's left of these poor old tired things, and not have the thermal properties compromsed somehow, then that's what's going to happen. Yes it would be a large crap job to remove the old, as well as dospose of it. Someone quoted me $1400 just to remove the old stuff, so I assume that nobody ever has their old insulation removed and all the new insulation is just layed over the top. I have seen articles saying you should lay the new bats perpendicular to the joists (as opposed to in between like the existing) so as to not squash the existing bats and degrade their performance - but I don't think the performance of mine can be degraded any further! I got a quote (1st only) - to supply only was $1000, to supply and install was $1400. $400 labour to install a house full of bats? I'm guessing the supply ony cost here is inflated. I'm not afraid of installing these myself, espacially since the ceiling plaster is off on some rooms right now, but for $400 extra I'd probably let the tradies come in (and screw up all the lighting and surround sound wiring in the roof!) So questions: Best place to buy cheap insulation? And is there any reason I can't put Rockwool bats on top of fibre glass? (only 'cause rock wool will be nicer to deal with) Any comment on laying the new bats perpendicular to the joists? Any hep appreciated. Cheers, HC Re: Time to replace roof insulation? 18Oct 02, 2012 9:10 pm Hi HC Rockwool is heavy and I'd say you'd need to string it in so it doesn't pop the plasterboard off. I can recommend an insulation installer if you were in Sydney. He did my place and so many people commented on how neat and well done the job was. I haven't heard of installing as you described. We have always been told to install over the top of existing batts and between the timbers not across them. You should look up the ICANZ website for the installer user guide. Interesting stuff. ok thanks - yes was wondering if that should have been listed as Option Three! 2 7755 Your house roof does not show rusting other than some surface rust on the flashings. In my opinion you dont need to replace or paint the roof other than treat surface rust… 1 10228 |