Browse Forums Building A New House 1 Apr 26, 2019 10:07 pm Hi All, I am planning on building a new home in Brisbane. I haven't chosen a builder yet but I am having in-depth conversations and have short listed to a couple of builders, and their designs. Due to my overall budget I am heavily leaning towards choosing a low/middle tier project builder. Note: Hiring an architect and building with a custom builder is out of the question due to the overall expense. Before getting into the questions at hand, here are some details about the land and the new house to be built: Land size is 10m x 40m (405sqm) Land is flat The new house will be 2 stories at approx 320sqm in size. Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ One of my main considerations in choosing a design is with regard to energy efficiency. I am particularly concerned about minimising energy usage to cool the house during the warmer months (which is most of the year in Brisbane). Before choosing a design I want to think about and evaluate how well it will perform in terms of energy efficiency, with an objective to incorporate "passive solar" principles into the design. Note: I have done some research and found some information and studies done in relation to "passive solar" design. I have attached a list of references at the bottom of this post. The orientation of the land isn't ideal (it's not northerly facing), but it's not the worst orientation either. Due to the long and narrow shape of the land, obviously there is no ability to alter the position of the house on the land, due to the tight constraints of the land itself. I have attached a diagram showing the house and land orientation (in relation to North). I realise that in choosing a project builder, and choosing one of their standard design, I am somewhat limited in terms of being about to make major design changes, but I figure I can still make choices within the design by choosing things like: 1) roof material (colourbond versus concrete tiles) and level of ceiling insulation 2) external wall material (brick veneer versus other options) and level of wall insulation 3) window types (double glazed / single glazed / other) and window positioning 4) window size and positioning With regard to point 1, this is a fairly straight forward decision. I will go with a colourbond roof combined with maximum ceiling insulation. I may even have whirlie birds installed into the roof to help extract hot air in the summer from the roof space. No further questions here. Regarding point 4, I have done some sunlight and shadow modelling using computer software, and analysed based on principles of "good passive solar design". On the upper floor I will try position the windows high on the eastern and western side of the house to gain maximum shade from the roof eve. On the ground floor, I will will consider having window hoods for the windows on the eastern and western side of the house, for maximum shade performance. I still have some things to work through but I have no further questions here. Point 3 is fairly straight forward. All research and findings that I have read (see list of online resources at the bottom of this post) tend to conclude that double glazing windows perform much better than standard single glazing windows. There are other types of windows which also perform better than standard single glazed. The complicated part is working out if I am willing to spend more (and how much more) on upgrading the window types. I still have some things to work through but I have no further questions here. Making a choice with regard to points 2 is where I am having trouble - choosing an external wall material. Out of my short-listed builders, most of the designs comprise of a vast area of brick veneer covering most of the external walls, with some small cladding areas i.e. the upper floor above the alfresco area, etc. Based on the orientation of the house which I am stuck with, which has high exposure on the long eastern and western walls, is brick veneer the best choice? These are the options for external wall material that have been offered by project builders as part of a standard design, or can be offered as a modification to a standard design: - Brick Veneer - Cladding (fibres cement sheeting) with R2.5 Wall Insulation - Autoclaved Aerated Concrete Below I will list the pros and cons that I am aware of for each material type: Brick Veneer - Pros: - low cost, low maintenance, doesn't require painting, has been used for many many decades in SEQ. - has an inherent R-value which meets energy efficiency requirements according to the Australian Building Standards - is strong enough to be used as a masonry anchor point (i.e. for fixing mounts, brackets, hanging objects, gates, fencing etc to). Brick Veneer - Cons: - has high thermal mass, which means direct sunlight (radiation) will heat up the bricks during the day, and will retain the heat at night, which causes the internal temperature to remain high. Cladding with R2.5 Wall Insulation - Pros - has an R-value (due to the insulation) which meets energy efficiency requirements according to the Australian Building Standards - has low thermal mass, which means despite being exposed to direct sunlight (radiation) it will not retain the heat at night. - has been used for many many decades in SEQ (referring to fibres cement sheeting used for external walls). Cladding with R2.5 Wall Insulation - Cons - costs more than brick veneer (according to one of the short-listed builders), higher maintenance than brick veneer, needs painting and re-painting. - not strong enough to be used as a fixing anchor point. i.e. is not strong enough for fixing mounts, brackets, hanging objects, gates, fencing etc to). Although, as a workaround, perhaps the internal timber frame could be used as a fixing point (by drilling through the cladding and into the frame). I am not sure if this is "the done thing"? Autoclaved Aerated Concrete - Pros - according to reports, this material is inherently high performing in terms of R-value and U-value (which is theory will translate to a very good energy efficiency house). Autoclaved Aerated Concrete - Cons - according to reports, this material is very high performing in terms of R-value and U-value (which is theory will translate to a very good energy efficiency house). - not strong enough to be used as a fixing anchor point. i.e. is not strong enough for fixing mounts, brackets, hanging objects, gates, fencing etc to). Note: I've heard both good and bad reports about Autoclaved Aerated Concrete although finding opinions and advice from actual home-users and people who own a house with Autoclaved Aerated Concrete appears to be limited. Most of the advice has come directly from sales people, or directly in publications from the manufactures of Autoclaved Aerated Concrete products. In conclusion and to my key questions: So in summary, I am trying to justify and be comfortable in choosing brick veneer, but I am concerned about the heat retention issue of bricks. Q1) Based on the orientation of the house which I am stuck with, which has high exposure on the long eastern and western walls, is brick veneer the best choice? Q2) Is there any way to reduce the unwanted resultant effects of heat retention in a brick veneer house? Bearing in mind that I am stuck with high sunlight exposure on the long eastern and western walls of the house. There is not enough room on my land to created a source of shading (i.e. planting tall trees is not an option). Q3) What about brick veneer with added R2.5 wall insulation? Would this increase the overall R-value and U-value? Would the increased R-value/U-value provide a barrier between the retained heat in the bricks and the internal living space inside the home at night time? Apart from the questions above, if anyone has any comprehensive advice to help me achieve the objective of building an energy efficient home, please enlighten me. Here are a list of resources which I found with regard to energy efficient home design: Design guide for 6-star energy equivalence housing http://www.hpw.qld.gov.au/SiteCollectio ... deline.pdf icanz INSULATION HANDBOOK version 3 http://icanz.org.au/wp-content/uploads/ ... r-2016.pdf HPW - Designing for Queensland’s climate http://www.hpw.qld.gov.au/SiteCollectio ... limate.pdf HPM - Smart and Sustainable Homes - Design Objectives - http://www.hpw.qld.gov.au/SiteCollectio ... ives08.pdf HPW - Smart Housing - Towards Sustainable Housing http://www.hpw.qld.gov.au/SiteCollectio ... ooklet.pdf HPW - Jacobs and Associates - The Performance of Various Glass Types - http://www.hpw.qld.gov.au/SiteCollectio ... dy2008.pdf WERS - Provides a list of windows rated for their energy performance - Certified Product List Search - QLD Residential https://awawers.net/ressearch/search/qld Building Materials and Inherent Insulation Characteristics (it's fairly VIC-focused) http://web.archive.org/web/201304262129 ... _types.pdf Re: Brisbane - Building and Energy Efficient Home 2Apr 27, 2019 1:02 am Good discussion. Bricks have high thermal mass, but this thermal mass is insulated with air gap and insulation to the inside but remains uninsulated to the outside, so during the night the heat will be flowing to the outside, not to the inside. Also, keep in mind that real thermal performance/R values of brick veneer houses will be 25+% lower than calculated R values due to the thermal bridging effect of the timber frame and inconsistencies related to the installation of the insulation. On the other side, Reverse Brick Veneer design is more suitable for energy efficient homes, but in this case you would still need to consider some cladding to the outside (and in this case Hebel AAC panels might work really well, but overall system will become expensive and comparable to double brick in costs). It is always better to keep thermal mass insulated from the outside and opposite your northern windows or facing your heaters, etc. Keep in mind, that high thermal mass works well in the locations with high diurnal (day/night) temperature differences, but may be a burden if your temperature difference is not enough, e.g. in hot tropical climates high internal thermal mass is rather a liability as the house walls won't be able to cool themselves properly during the nights after the hot days, so heatwaves will be awful. Look into that carefully. When it gets to AAC - it is a fantastic material, but are you talking about AAC blocks or Hebel panels, as they behave differently and have different pros and cons. AAC (both blocks and panels) need to be rendered too, but, on the other side, is much less labor intensive then bricks and if you are using AAC blocks you don't need a frame. If you are going with the blocks, it has reasonably high thermal mass too, but walls need to be wide enough to reach proper R values (e.g. around 30 cm to reach R value of 3.0). On the other side, its high thermal mass adds to the flyweight effect, so you really do not need very high R values, e.g. similar to double brick scenario where R value of 1.4 provides better comfort than highly insulated brick veneer. AAC houses are very popular in colder parts of Europe and States, however, they may not be the best choice for hot tropical conditions. When AAC is used as a panel - it still serves its purpose when it gets to insulation and acoustics, but additional insulation and the frame will be needed. As you are in Brisbane, I wouldn't be worried about heavy insulation, it rather just needs to be done right. If you are going with BV, consider rendering your bricks on the western side in light colours (e.g. white), install double glazed Low E windows with good shading systems. Just my 2 cents. Re: Brisbane - Building and Energy Efficient Home 3Apr 27, 2019 10:35 am Alexp79, you mentioned the issue about thermal bridging. In response to that, I have the following question: Q4) Is there any way to reduce the unwanted resultant effects from thermal bridging in a brick veneer and timber frame house? I found the following article: TECHNICAL NOTES on Brick Construction - Brick Veneer/Wood Stud Walls https://www.gobrick.com/docs/default-source/read-research-documents/technicalnotes/28-brick-veneer-wood-stud-walls.pdf?sfvrsn=0 Bearing in mind, I believe this company is based on the US, so references to standards will not be Australian based standards, but the science should still apply. In terms of thermal bridging, they speak in terms of "heat loss" rather than "heat gain", which I am more concerned about due to the hot Brisbane climate. But again, I believe the same science still applies i.e. a solution to reduce the effects of a thermal bridge for heat loss should also apply to reduce heat gain. This article states: Batt insulation between studs is sufficient to meet energy requirements for above-grade walls in some climate zones; however, better performance results from the use of continuous insulation on the exterior of the sheathing adjacent to the air space, which reduces thermal bridging through the studs. It also states: Where continuous insulation is placed between the veneer and backing, maintain 1 in. (25 mm) between the back of the brick and the face of the insulation. What are your thoughts? Can anyone contribute to more to this? Does anyone you have any more references to good quality technical information which is based in Australia? Update: I also found this resource Boral - Energy Efficiency in Building Regulations and the Use of Concrete in Housing https://www.boral.com.au/sites/default/files/media/field_document/Energy%20Efficiency.pdf Which states: Conduction Heat is transferred through opaque relatively airtight barriers by conduction. The thermal resistance of a material, R, measures the attenuation of steady-state conduction. Thermal bridging occurs when heat bypasses insulating materials and passes through conductive materials such as metal window and door frames, structural steelwork or other such items. And also states: Radiation Heat is transferred by radiation through transparent or translucent media (such as glass) exposed to direct sunlight. Large windows exposed to direct sunlight are an advantage during the daytime in winter, but a disadvantage in summer or during the night in winter. The conduction of heat through walls may be reduced by incorporating materials with a high thermal resistance, such as insulation. However, much of this benefit could be lost if thermal bridging, radiation and convection are not controlled. There is little point in installing insulation in walls if the heat simply transfers elsewhere by thermal bridging through windows and door frames, by radiation through windows or by convection through leakage. Re: Brisbane - Building and Energy Efficient Home 4Apr 27, 2019 12:30 pm I am just telling you that calculated R values are far from the reality due to thermal bridging. Continuous insulation (e.g. EPS ) is a way to prevent this thermal bridging effect, but in that case, yes, at least 25 mm air gap will be needed between insulation and the brick layer to prevent any moisture issues and to allow walls to dry out naturally, but when using this type of insulation you better do not use traditional insulation in studs, as Brisbane still has winter nights and the is risk of condensation/moisture ending up in your studs still exists. I wouldn't be much concerned with thermal bridging effect in your case, though, yes, it will reduce ultimate calculated R value, but on the other side, you really don't need that much over there. Windows and doors will be always your narrow point, so ideally you would have to minimise glazing on your Western and Eastern sides, if you still have windows there - just use double glazed Low E ones, also shade your Northern windows from summer (but not winter!) sun by putting in right sized eaves or plant deciduous plants there. Don't worry much about walls, you will be just fine with insulated brick veneer over there. But if you are still really very concerned, take a look into what ICF (insulated concrete forms) systems can offer you - they do provide continuous insulation without thermal bridging and some systems such as Nexcem Durisol can also provide some thermal mass and highly breathable/moisture regulating walls with overall costs just slightly higher than brick veneer construction. You can also attach heavy items to such walls too. Re: Brisbane - Building and Energy Efficient Home 5Apr 27, 2019 3:24 pm Azimuth is important but there's a madness to it all.....I'm currently using a Master Bedroom with massive glass sliding doors facing EXACTLY due East and with a minimal eave....and, right now - this time of year in SA - it's gorgeous in the mornings! Re: Brisbane - Building and Energy Efficient Home 6Apr 27, 2019 3:59 pm This conversation is way to complicated for me. We went brick with wall and ceiling insulation (R1.8 under colorbond and I cant recall the wall rating). We went a custom design with a project builder as we wanted to optimise our views. The Eastern sun is not a concern for us, we were simply concerned about western facing - my preference would be to avoid western facing windows at all if possible. You have a small block, try not to over complicate things. Re: Brisbane - Building and Energy Efficient Home 9Apr 28, 2019 6:19 pm alexp79 Nope, I am rather an amateur, but I did a lot of reading on building science and also talked to a lot of experts in this area. I am owner building 9-9.5 stars ICF house. Alexp79, that's awesome! I'd like to know more about this. Have you done much in terms of computer modelling for energy efficiency? I am referring to software such as FirstRate, or others? Re: Brisbane - Building and Energy Efficient Home 10Apr 28, 2019 7:32 pm I’ve only had a quick read but my thoughts if you are thinking brick veneer, would be to firstly ensure the total external wall depth (assuming 90mm studs?) is at least 250mm, this should then give you a decent air space between Bricks and outside face of wall. For the wall constructions personally I would go “foilboard” (15mm maybe?) on the outside of studs, then say and R2.5 wall batt to fill the stud bays? Foilboard is designed to a avoid the need for bulk insulation so you would have to do more research on the difference between having an air gap or batts in those stud bays. The foilboard in your climate should work well as a vapour barrier stopping humid air moving inside the house, plus is has a reflective R value rating with the foil and the EPS core. It will also assist with the thermal bridging on the timber studs. Also ensure your roof is properly ventilated in addition to appropriate sarking and levels of ceiling insulation. We were going with ceiling batts until I had some more conversations with our insulation contractor. Last few days we have gone and installed R4.0 ceiling batts on the perimeter (top plate and then in around 500mm) with another perpendicular layer of R2.0 Earthwool roll. Once we are ready for handover the insulation guy will then come in a blow in close to R5.0 cellulose material to get into all the small gaps that are an unfortunate reality of houses (service pipes, wires, heater platforms etc). Good luck with your research and design, it’s good fun but also seems to go on forever too! --------------------------------------------------------------------- Check our Homeone build blog here Re: Brisbane - Building and Energy Efficient Home 11Apr 29, 2019 12:08 pm indo26slate alexp79 Nope, I am rather an amateur, but I did a lot of reading on building science and also talked to a lot of experts in this area. I am owner building 9-9.5 stars ICF house. Alexp79, that's awesome! I'd like to know more about this. Have you done much in terms of computer modelling for energy efficiency? I am referring to software such as FirstRate, or others? I am using HTFlux for my simulations, but also work directly with my BASIX guy. Re: Brisbane - Building and Energy Efficient Home 12Aug 05, 2019 1:41 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 4:40 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 4:41 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 7:52 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 7:18 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 5:08 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 5:23 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 2:54 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 110230 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 4621 Give "Holt Surveying" they are based around Eight Mile Plains 3 8724 |