Browse Forums General Discussion 1 Feb 20, 2016 1:50 pm We are building a two storey home and still at initial stages. I don't see any cavity wall insulation in my quotes (ground floor - double brick). I particularly wanted it, whether we need it or not for energy efficiency... am I being silly? Is it essential? I want a house that will keep cool! Any advice from experts on whether it's essential (in Perth), cost etc.? cavity wall insulation 3Feb 20, 2016 7:56 pm We are building a single story home and the exterior walls are double brick. You don't put any insulation in it. That's how it is meant to be. The cavity between the walls is there for air flow and that is what helps keep the house cool. Let's put it this way. Sunlight and hot air will hit the outside face of the brickwork. That heat has to work its way through the brick. Then it comes up against a cavity with airflow. Then it will try to work its way through another layer of brick. It's a lot of effort to try to get to warm you up. The cavity is the key and to block it off defeats its purpose. My partner's parents have a solid brick home too and any time we go there on a hot day we walk in and say "Ahh, it's so cool in here!" and the response is always the same. "We don't even have the air conditioner on!". If it's possible keep the cavity as clear of mortar as you can, don't cover the weep holes on the bottom course, and get insulation in all the timber walls and ceiling upstairs. Owner Builders in boot-shaped Yorke Peninsula : viewtopic.php?f=38&t=80264& Re: cavity wall insulation 4Feb 20, 2016 10:16 pm Quote: We are building a single story home and the exterior walls are double brick. You don't put any insulation in it. That's how it is meant to be. Biggest load of crap and misinformation I've heard on these forums for a while. Double brick is only so-so at insulation and way behind what you can do compared to a well insulated brick veneer home. I should know . I live in a DB house and while it is OK at up to say 30º after that it is a heat box. The bricks absorb all the heat and when the sun goes down and the outside air goes down in temperature, the brick walls will radiate that stored heat back out for hours. Read some of the info here... viewtopic.php?f=3&t=75129&p=1285297#p1285297 and here... viewtopic.php?f=31&t=74832&p=1277819#p1277819 Boosting the R-values of walls of a BV house is a lot easier than upgrading the walls of a DB house. Stewie cavity wall insulation 5Feb 20, 2016 10:41 pm How old is your house? How wide is the cavity or is there any? Ventilation of the roof? Whirly birds. Eaves. There's nothing wrong with what I said that blocking off the wall cavity defeats its purpose. It is common sense. It is for airflow. There are other things affecting insulation. It is our first hand experience as well with a double brick home. And it is not a heatbox. Will let you know when our house is lived in. I went quickly to one of the threads that you posted and it's your opinions mostly there so not surprised. Owner Builders in boot-shaped Yorke Peninsula : viewtopic.php?f=38&t=80264& Re: cavity wall insulation 6Feb 21, 2016 6:37 am Quote: How old is your house? How wide is the cavity or is there any? Built in 1947, standard 270mm wide cavity brick construction ( 110mm brick - 50mm cavity - 110mm brick ). The other things you mention - 450mm eaves, R 2.0 batts in the ceiling space etc help however the thermal effect of the bricks heating up during the day and radiating that heat back out is mostly why it is a hot house. As I quote in one of those links above... Quote: A BV wall without sarking or insulation is a paltry R 0.4. A double brick wall is R 0.5. However add sarking and R 2.0 batts to the BV wall and you are looking at R 2.5 - much better. You can add cavity insulation to the double brick wall of course but you can also add that to the BV wall as well. Quote: I went quickly to one of the threads that you posted and it's your opinions mostly there so not surprised. Hmm, opinion only - I doubt it. twylamc, if you go to any comparative study on R-values of various building materials and methods you would quickly realise that double brick without any other form of insulation added to it which is probably about 95% of DB homes built in the past and still being built that way you would quickly come around. I have also been in the building industry for nearly forty years with a background as a carpenter then builder. For the last fifteen years I have been drawing plans fulltime - renos, additions, new houses and in my clients best interests I always try and incorporate as much insulation in the build as possible as well as all the other design criteria - passive heating/cooling, correct orientation etc. I also base all my comments on facts not opinions. Stewie Re: cavity wall insulation 7Feb 21, 2016 10:41 am Firstly, you don't put R2 batts in the ceilings, they go to the walls. Council regulation is 4.5. Look,you seem to know everything. I do not claim to be an expert going around every thread and have my "facts" because I read it from a study or from the Internet. But I feel strongly about this because of personal experience and wealth of knowledge from tradies around me (50 years or so each years of experience too). Add on top new technology and it is great. Walking into my partner's parents home and it is cool is my fact, not big words out of a study by someone else. This is what we are doing and it works which I am sharing to anyone that is doing a double brick home. Brick is an insulation in itself. But obviously, like every other thing it has its maximum capacity. It needs help. The cavity wall is for movement of air. That's what it's supposed to do. That's its role. Hot air rises (fact). Then there is the weep holes in the bottom where air goes in and help push air upward. You have good roof insulation to help with these hot air and good roof ventilation (ie whirly birds) to extract the air outside of your home. Then it is not up to just the bricks to absorb all these heat. This is a continuous process. Any other house with just wall insulation is gonna be a hot house, BV included. Also, these insulation on the roof will gradually degrade overtime and will need changing but the cavity wall will still be doing what its supposed to be doing. Let air moves. I really do not think these things require an "expert" to understand that this makes sense. There are a lot of variables why double brick home is not done a lot nowadays. In our case, we have free bricks and free bricklayer. For other states like Perth, it is because bricks are cheap. But it can be a dear and lengthy process. So a more viable and quicker option is BV. We are the same. We picked what's working in the partner's parents's home and do things differently in others. We are doing double brick exterior but we opted to do internal timber walls because firstly, we didn't have enough bricks and we're happy to save time by just doing internal wall frames. Secondly, we have waffle pod foundation and a heavy home is not what it needs. We prefer the render look compared to the brick face look. Things like that. I am not saying that brick is the be all and end all of insulating your home. Nothing is. There is not one magic insulation out there to solve heating/cooling issues. There will still be time that you will have to turn on the aircon to make you comfortable but not for a long period of time. All I am saying if it is done right, brick works great and makes for a wonderful home both in winter and summer. When our house is ready, you are very much welcome to check it out and I will show you fact. Owner Builders in boot-shaped Yorke Peninsula : viewtopic.php?f=38&t=80264& Re: cavity wall insulation 8Feb 21, 2016 1:43 pm This quote is from www.yourhome.gov.au Insulation Clay and concrete brickwork have low thermal resistance and therefore relatively poor insulation values. Combined with internal and external air films and a cavity, they achieve moderate thermal resistance. The thermal resistance of brick and blockwork walls, including veneer or cavity construction, can be greatly enhanced by adding foil or bulk insulation. Wall insulation should be accompanied by appropriate detailing to avoid thermal transfers by bridging through window and door frames, by radiation through window openings or by convection through leakage (see Insulation). Re: cavity wall insulation 9Feb 21, 2016 4:21 pm Dear oh dear! your "facts " are so wrong I can't bring myself to comment further. I wish you well with your build however we for one won't be building DB but an improved BV that will net us an R-value of around 4.5 min ( that's 10 x what your DB walls will be ). Good luck with your hot house. Stewie Re: cavity wall insulation 10Feb 21, 2016 4:37 pm Thank you tezzab, perfect quote to resolve this tussle. I'm with Stewie on this one. I'm not a fan of high thermal mass exterior materials (thermal mass on the north facing interior is a much better idea for most climates), & particularly don't like uninsulated double brick. Twylamc, which way is your house orientated? My sister's uninsulated double brick home on Sydney's coast faces south (on a south facing slope), & receives minimal sunshine. The ground floor stays nice & cool in summer (the top story can get hot by the evenings). But come winter & the place becomes an igloo, with the thermal mass absorbing much of the heat from the large gas fireplace, a proportion of which is re-radiated externally. Brick is a relatively poor insulator, the addition of a wall cavity helps a bit, but double brick still performs much more poorly than many other wall systems with much higher insulation values. Re: cavity wall insulation 11Feb 21, 2016 5:07 pm Ddaroch, I came here to answer the question about putting insulation into the cavity for double brick. I said no because it will not work. I still stand by it. I don't discount the fact that there may be better materials out there nor saying that using bricks is the best option. Owner Builders in boot-shaped Yorke Peninsula : viewtopic.php?f=38&t=80264& Re: cavity wall insulation 12Feb 21, 2016 5:36 pm Well here is a direct quote from 'Think Brick Australia' whose job it is to promote brick construction. While insulation in external walls is essential, the R-value is a static parameter which alone does not predict the energy used in maintaining internal temperature in real life dynamic temperature environments. If you want to read the full research paper it is at http://thinkbrick.blob.core.windows.net ... ciency.pdf 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: cavity wall insulation 13Feb 21, 2016 10:29 pm I would seriously rethink the double brick argument as its a personel biast based on circumstances that very well has everything going its way to perform ok. Your going against a guys opinion who is basing it on hundreds of build experiences and can talk from a very broad and practical experience, its an uneducated apprentice telling his boss , he knows best, do yourself a favour and research it much more before you make an expensive stubborn mistake. Re: cavity wall insulation 14Feb 21, 2016 11:20 pm I'd say yes you do!!!! Especially in WA....Double brick aren't even really the great insulator people think they are! They have quite low r-ratings.For those who say there will be no airflow they're not correct. They use ties to ensure there is still a gap to enable airflow. Ask your builder about the products they use or visit some sites with builds going up and you'll see what they use. We have it on every wall in our double brick and it makes a big difference but it's also important to focus on the ceiling insulation and maybe something like anticon over your roof frame and under your roof tiles or tin, given that heat rises. Re: cavity wall insulation 15Feb 21, 2016 11:40 pm We built a large (350m2) single storey last year in WA and paid approx $4000 I think for rockwool insulation. I have since seen their van around a few new builds in my area. In our case it wasn't initially planned but when our final plans went through the 6 star energy assessment it was added in then. Everyone comments our house is lovely and cool and I do think it is a cooler house than our previous double brick house. One thing that baffles us is that our mobile phone reception inside the house is terrible, yet it is fine outside. We lived in the old house before it was demolished which was also double brick, and phone reception was fine. Only two variables I can think of is that the older house sat about 50cm higher on the land, or this insulation. (Edit - actually now that I think of it mobile phone reception is poor in front of glass windows too so it is unlikely the insulation causing the issue!). Re: cavity wall insulation 17Feb 22, 2016 9:55 am lazandjohn, I'll post up my reply here as general info and quote from your PM if you don't mind... Quote: We are having reverse brick veneer on the second storey with R2.5 wall batts in the stud walls. Then there's R 4.1 ceiling batts. The reason I asked the question initially is because the architect suggested cavity wall insulation on the ground floor but I noticed that the builder had put in the contract "cavity wall insulation as per energy efficiency report". I am not expecting we will need the cavity wall insulation for the energy efficiency rating, but I'm keen to make the house as cool as possible so we dont need to use the air conditioning in summer (we're in Perth). So, do you think R2.5 batts for the second storey sounds right? And what should I expect to see the builder include in the contract for insulation downstairs (double brick construction)? Thank you in advance...there's just so many things to get right I am grateful for this forum to get some unbiased advice! I'm not a great fan of RBV however for a few that I have seen they do seem to perform pretty well. A standard BV wall performs as good provided the insulation is installed for both. I like the improved BV wall better as from what I have read the bricks on the inside of a RBV have a high thermal mass and tend to absorb a lot of the heat during Winter before it starts actually heating the room. Seeing as you are in Perth I'd imagine the Summer temps are more of a problem. R2.5 batts will have to be the HD - high density so more expensive than standard R2.0 batts to enable them to fit in a 90mm timber stud wall but if it makes your house more comfortable then the added cost is worth it in my opinion. R4.1 for your ceilings are good too. Sydney it is recommended R4.0 or higher. I'd imagine Perth would be similar Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ I'm unsure about your state or council requirements re your EE rating however the better you can insulate your walls the better. Insulation to the cavity is the way to go. A standard cavity brick wall is 110mm brick - 50mm cavity - 110mm brick, however depending on what sort of insulation you are having in there you may have to increase this total wall width to still keep a minimal separation of around 30mm. There are now quite a few manufacturers of cavity wall insulation - Foamular etc. It depends on what sort of an R rating you are trying to achieve for your wall which will dictate how thick and also how expensive it will be not to mention how much of a cavity you want left in there. Here is what we are proposing to do for our build. Not double brick obviously but improved BV Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ A standard BV wall is as you probably know 250mm however with ours only being 30mm wider we achieve nearly R2.0 better thermal performance for the wall. I'm still tossing up whether to go for R 2.5 HD batts in the wall and cutting the foam thickness back to 30mm just as a cost exercise for much the same R rating. I'll be interested to see what your architect recommends to you and what kind of cavity insulation the builder quotes you on ( and its R rating ). I can do another section of a DB wall for you if you like similar to my drawing above showing what you could achieve. Here is a standard brick cavity wall Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ And here is an improved brick cavity wall Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ This last one is as a general guide only. Thickness, R rating, expense etc all come into play. Edit: I have to add to that I'm not a real fan of pump-in insulation either, whether for brick cavities or ceilings. I've seen too many in the past where the guys doing it haven't gone the extra yard to ensure it gets to every nook and cranny. 5% gaps in your insulation makes it 50% less effective but I guess the same can apply to the other types as well. Stewie Re: cavity wall insulation 18Feb 22, 2016 1:59 pm Unbelievable this thread. Just because someone has balls to put their opinions out that are different to theirs, they resort to these kinds of comments. Stewie, You claim to have all the experience/titles in the world that no one is asking about, and yet all you can say is Goodluck to my hot house like a kid. And to the person that worships you here, go follow him whatever he says. Good on you both. Owner Builders in boot-shaped Yorke Peninsula : viewtopic.php?f=38&t=80264& Re: cavity wall insulation 19Feb 22, 2016 2:17 pm Not at all twylamc. If you have a close look at this thread and mostly my posts, you will see all the R-values ( R values give a materials thermal value so by adding them together you can see how well it will perform ) stated for various materials. Not an opinion - fact. All these facts are readily available to download and have a look at so you can compare different building methods - DB vs BV vs RBV and how to improve them as illustrated by my drawings above. I also saw in your OB topic viewtopic.php?f=38&t=80264& that under your dark coloured metal roof you also don't have sarking as a minimum and what most people would install - given your location - a 50mm Anticon roofing blanket at least to help keep your roof space temperatures down. Hence my hot house comment. It is going to be scorching up there and even with R 4.5 ceiling insulation the heat will eventually find its way inside your house. Heres a couple of links for you if want to educate yourself regarding thermal insulation... http://www.google.com.au/url?q=http://i ... n_e0CdHCRA http://www.google.com.au/url?q=http://w ... 6skHMbGGDA Stewie Re: cavity wall insulation 20Feb 22, 2016 3:26 pm The need to include insulation in an external double brick cavity wall is essential, possibly to a larger extent in 'cool climate zones'. To my mind an extruded poly sheet type insulation to the face of the inner skin still leaving a cavity which is primarily to allow water penetration through the external skin to escape either to the subfloor area or via weep holes on a slab type construction. I will not design a home with this type of construction without cavity insulation. Peter Clarkson - AusDesign Australia www.ausdesign.com.au This information is intended to provide general information only. It does not purport to be a comprehensive advice. Hey guys, what’s everyone opinion on James Hardie linea direct fix to frame? Would this be the most common method and anybody ever had any problems down the track? 0 5151 Firstly, if your house is still under builder's warranty (10 years in Victoria) you should have no need to crawl into roof space but let the builder handle it, unless you… 3 5639 Hi all, Just wondering if anyone had suggestions on installing/replacing wall insulation on an external wall which doesn't have wrap, our miners cottage being constructed… 0 4942 |