Browse Forums Building A New House Re: Brisbane - Building and Energy Efficient Home 12Aug 05, 2019 2:41 pm HI All, I created this thread a few months ago about building an energy efficient home in Brisbane, and I am posting this to bring it back to life with a few more questions on the topic of roof and external wall insulation. I have an important requirement to ensure that I have additional insulation to the roof and external walls (above the minimum standard). Roof With regard to the roof insulation, I am thinking of having: - R3.5 roof insulation batts, and - anticon blanket to the roof Q1) Does anyone have any feedback about using both anticon and batts? External Walls As mentioned in my original post above, the house orientation isn't ideal and I want to ensure that the western and eastern walls have additional insulation (above the minimum standard). The design I have chosen has both bricks and cladding for the external walls (approximately 70% bricks and 30% cladding). For brick veneer walls, no wall insulation is required to meet energy standards because brick veneer has an inherent R-value. However, external cladding walls don't have an inherent R-value and therefore R1.5 wall insulation must be added to meet the standard. In order to ensure that my walls are well insulated to give me a highly energy efficient home, I am thinking about having R1.5 batts to the brick veneer walls, but I'm not sure what R-value insulation I will need for the external cladding walls. This leads me to my next questions: Q2) Based on the fact that I have chosen to add R1.5 to the brick veneer walls in order to go beyond standard, what R-value level will I need to add to the external cladding walls in order for the overall R-value to be equivalent to the brick veneer walls? Q3) I've been advised by one of the builders that a 70mm stud frame doesn't allow for more than R1.5 wall insulation to be installed to the cladding walls, due to the lack of space available. If I want more than R1.5 to cladding walls then I will need to upgrade to 90mm wall studs, which adds a level of complexity and cost (cost unknown) to making this decision. Any advice would be appreciated. Re: Brisbane - Building and Energy Efficient Home 14Aug 05, 2019 5:40 pm Firstly I am a bit concerned about the 70mm stud walls, geez even our 90mm stud walls seem a bit flimsy to me! For brick veneer, I would strongly suggest min. 250mm total external wall thickness, to allow for 90mm studs, decent air gap to bricks....say around 50-60mm, plus the bricks obviously. No matter what insulation setup you go with, it's the air gaps adjacent that are also important to achieving the overall R-value from understanding. I'm not sure if you have 90mm studs to external and 70mm to internal walls, but at least thicken up your externals if possible. You can then go with up to R2.7, but more likely R2.5 batts in the wall. For those cladded walls, I'm not 100% sure to be honest. But whatever you do make sure your walls have some ventilation capacity. Look at the FoilBoard product possibly for these walls?....or stick with batts. What type of wall wrap are you considering? I would have thought in your climate a foil type air barrier would suit best? I would say blocking the radiant heat would be your #1 priority but I'm in a colder climate so my knowledge of the more humid/hotter areas isn't great sorry. --------------------------------------------------------------------- Check our Homeone build blog here Re: Brisbane - Building and Energy Efficient Home 15Sep 12, 2019 5:41 pm darb74 For brick veneer, I would strongly suggest min. 250mm total external wall thickness, to allow for 90mm studs, decent air gap to bricks....say around 50-60mm, plus the bricks obviously. Darb74, this advice it very specific, which is exactly what I was hoping to find on here. Thanks. I am wondering if there are any insulation guidelines published by insulation companies, or something of the equivalent which backs up your advice. One would think that if you were a tradie and worked for an insulation supplier/installer then they would need to be informed about this kind of thing, so that they know what size batts are acceptable and can be used given different wall structures, and different stud depths, different air gaps etc. Does anyone know of any such reference material? From what I have been told by my builder, the studs are 75mm in depth, and external brick veneer walls are 230mm total external wall thickness. Re: Brisbane - Building and Energy Efficient Home 16Sep 12, 2019 8:52 pm indo26slate darb74 For brick veneer, I would strongly suggest min. 250mm total external wall thickness, to allow for 90mm studs, decent air gap to bricks....say around 50-60mm, plus the bricks obviously. Darb74, this advice it very specific, which is exactly what I was hoping to find on here. Thanks. I am wondering if there are any insulation guidelines published by insulation companies, or something of the equivalent which backs up your advice. Hi, According to the NCC.... "Cavity width General: Provide minimum cavity widths in conformance with the following: - Masonry walls: 50 mm. - Masonry veneer walls: 40 mm between the masonry leaf and the loadbearing frame and 25 mm minimum between the masonry leaf and sheet bracing. Width of cavity may need to be increased if wall insulation is required to BCA 3.12.1.4." So 40mm minimum for veneer wall construction, which is likely what most builders are setting up with when using 90mm framing timber. Our builder sets overall external wall thickness @250mm, so this gives us a 50mm cavity. The bigger the cavity the better in my opinion, as this is what allows your walls to ventilate but also those air gaps are important for enhancing the overall wall insulation R-value. In other parts of the world particularly, they build with double stud walls, and with air gaps between (to remove the thermal bridging), this allows them to add massive amounts of wall insulation. Anyhow for us I would prefer 90mm framing timber for strength, with the maximum HD batt insulation (R2.5-R2.7) - and well installed - with appropriate type of wall sarking/wrap for your climate zone, combined with at least a 50mm air gap - and brick vents or plenty of weep holes. This type of information is readily available and CSR have done several tests/studies on wall cavity ventilation etc to illustrate this. But I don't think it's overly difficult for builders to setup well designed and constructed wall systems....that is if they give a crap about their products. --------------------------------------------------------------------- Check our Homeone build blog here Re: Brisbane - Building and Energy Efficient Home 17Sep 20, 2019 8:18 am Hi, I would have thought the foam/foil option would be best in terms of blocking radiant heat and on your link it has the same R value as fibreglass. Also with fibreglass you always have the risk of not being installed well and compressed etc. Also I agree with your re:roof sarking that in the warmer zones reflective foil is best....or why not get the best of both worlds and go anticon blanket....foil with fibreglass attached. --------------------------------------------------------------------- Check our Homeone build blog here Re: Brisbane - Building and Energy Efficient Home 18Oct 22, 2019 6:08 pm Hi All My first post here. Not sure if you have finally found your solution, but I'm building an R4 insulated home but not using brick veneer. As it's not just about the walls insulation its also your air leaking of the building envelop as that would be another thermal loss. Of course this is aong with correct windows frames, glazing and shading. I can upload pictures of my build to show you what we are doing. Re: Brisbane - Building and Energy Efficient Home 19Oct 22, 2019 6:23 pm Hi Momarvel, yes I am interested in any more information you have to share. Re: Brisbane - Building and Energy Efficient Home 20Oct 24, 2019 3:54 pm Hi See attached photos. All external walls are from structural 140mm timber with EPS panels with fibre cement sheets. As the external walls are constrcuted all the joints are glued and nailed into timber studs. External walls are than render finished. Insulation of R3.75 Hope that helps Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ go upvc window frames ensure insulation under colorbond. not just sarking, lighter color roof also not sure if you have seen this viewtopic.php?t=5823 last couple of pages… 4 98127 Hi, does anyone have a clue how the Brisbane Development website work in terms of how uptodate the dates on it are (developmenti.brisbane.qld.gov.au). I transfered… 0 3318 Give "Holt Surveying" they are based around Eight Mile Plains 3 1525 |