Browse Forums Owner Builder Forum 1 Mar 19, 2014 10:44 pm Hi everyone, I'm getting my structural engineering work done at present, and was wondering what the typical thickness of rendered EPS is? I have my drawings set at 240mm for brick veneer, but can EPS be less than this? What is the typical breakdown of material thicknesses? Render, EPS, batten?, stud... I know that you can get EPS in different thicknesses too. Do people have a preference for EPS over XPS, or vice versa? I was looking at Ezyclad, but the sales rep never got back to me. Any other recommendations? I'd be very interested to hear your thoughts. Thanks for your help! David Re: Polystyrene Wall Thickness and Material Recommendations 2Mar 20, 2014 8:12 am Kooltherm Masterwall ( based on Kooltherm ) Thermalwall Foamular. What you have to do is weigh up the thickness vs the R-value vs the cost per sheet and for finishing ( usually acrylic render and paint ). Some of the products like masterwall also come with the fibreglass mesh embedded on the outer layer of the sheets. Most sheets should be mounted on battens 25-30mm ( to create a still air gap )over perforated foil sarking on the timber frame with R2.0 or 2.5 batts. Sheet size is another thing to think about - some are 2400 x 600 only others are 2400 x 1200 and some can be sought at 3000 x 1200mm. Here are our proposed ground floor walls in section And here is the proposed first floor in section I've shown the battens laid horizontally but we will probably fix them vertically. We are aiming for most of the walls to be around R-5. What R-value are you aiming for ? Stewie Re: Polystyrene Wall Thickness and Material Recommendations 3Mar 20, 2014 9:55 pm Hi Stewie, Thanks for the great response. I was kind of hoping you'd reply! So, I'm not sure what R value I want for the walls. The Home Technical Manual recommends R2.8 for walls in Melbourne and Sydney (I'm in Melbourne, and I presume you're in Sydney). Will anything more than R2.8 give diminishing returns - i.e. not worth it! I've read that over-insulating may not be worth it on a number of websites (from forums to manufacturers). Is it a balance with your climate? Those cross sections are exactly what I was looking for. I see that you will have 50mm polystyrene behind your brick veneer on the ground floor. I hadn't counted on this, plus the thicker wall. Is this pretty standard??? My brick veneer walls are at 250mm at the moment, and I'm not sure if I can thicken them up. Does the 50mm polystyrene have an Reflective Foil Laminate facing into the air gap, to reduce the radiant heat? On the first floor, does your 2mm sarking have RFL, and is it facing the air gap, too? I've been looking at house wrap installed on houses, and the wrap seems to have the RFL facing away from the air gap towards the inside on many of them. Is there a reason for this? Reduce glare? I hear for roof wrap, the RFL should face down to prevent glare to the roof installers. But this makes sense, because the downward facing RFL could have an air gap below it, and minimal dust will settle on it. Did you decide on a polystyrene in the end? Kooltherm K5? I see you are using Ecobricks - recycled bricks - as well. How do you rate these? Any good? They look like they are based in Clayton, Melbourne, near where I work. I might take a look! Thanks for your advice, Stewie! Thanks David Re: Polystyrene Wall Thickness and Material Recommendations 4Mar 21, 2014 8:04 am Yes there is a law of diminishing returns but we are looking at living here in the long term so we don't mind going the extra mile. Not only should we see much lower heating and cooling costs ( and lets face it the utilities in Australia are going to be much more expensive in the future - even more so than now ) but there is the comfort factor as well. Our insulation is aimed at both summer and winter unlike say Tasmania where you would obviously insulate more for the colder months. Sydney walls I wouldn't have anything less than R3 here on the coast ( 1.5 kms from the ocean ) but out west I'd be looking at R4 at least. As a guide most of our days are around 25-28ºC in summer whereas in the western suburbs it seems to be at least 5ºC hotter. Winter we never see frosts and it is unusual for it to get below double figures maybe three or four days of 5-6ºC at most. Once again it seems to be on average at least 4-5ºC colder out west. The ground floor section is not standard BV , we are using ecobricks as you mention which have a much higher rating as well as the foam in the cavity - basically just to get the rating up. With standard BV you have a 50mm gap so you could get a 30mm foam layer in there for extra insulation and still have a 20mm air gap. We intend to do all our vertical drops for wiring in the air space not the studwork. The big problem I have with this scenario of a layer of foam in the cavity is that this has to be installed before the bricks get laid and I am not impressed by 99% of the brickies I meet. I am sure nailing their brick ties to the framework would result in tears and rips in the foam and as you probably know 5% incomplete or damaged insulation results in it being 50% less effective. One reason why I am laying my own bricks ! Another is that we are probably doing a couple of circular brick walls with a tight radius and I may have to order larger ecobricks for that section and cut them down to suit. I haven't made my mind up which foam I'm using in the cavity - maybe Foamular ? The sarking ( perforated to let the walls breathe a little while still giving us essentially a still air gap ) we use will have the reflective layer probably facing in as per normal and yes it is easier to install if you aren't being blinded at the same time. If we lived up North I'd be more concerned with heat getting in so I'd face it out. For the roof we will probably use a 50 - 70mm anticon blanket under a light coloured corrugated colorbond and R4 or 5 batts in the ceiling. It all sounds good on paper ! Plans are nearly finished and hopefully into council in another month or two. Stewie Re: Polystyrene Wall Thickness and Material Recommendations 5Mar 23, 2014 1:16 pm Hi Stewie, I'm just doing some more digging on the ATA.org.au website about the RFL. http://www.ata.org.au/forums/topic/1466 ... post-53826 Also, I plan to live in the house for decades, so I don't mind shelling out for the extra insulation too, so I might follow your lead. It seems that every few years, the R values go up, so I might as well get ahead of the curve. I'm plugging my data into FirstRate, and having trouble getting up to 6 stars as well, which surprises me, because I really did try to incorporate passive design elements. I'm a rookie at this, so I'm sure there's bits that I'm missing. Anyway, I'll learn! What are ecobricks? They don't sound like these recycled/reclaimed bricks sold here: http://www.ecobricks.com.au/ Could you tell me more about the vertical drops of the wiring through the air space, and not the stud cavity? Is this so the bulk insulation is not disturbed? Does your foam layer go over the studs? So the brickies will nail through it, and rip it, right, no matter who does it? I've never done any brickwork, so I don't follow, unfortunately. And with no experience, I'm not confident in doing the bricks myself, so I will get a brickie. It looks like a real artform, like finishing plaster. I'm too scared! If you face the reflective layer inwards, will it have the air gap? If it doesn't, do you really need the reflective part, because the radiation heat transfer will not be reduced. By the way, I really like your wall sections. I will do the same myself. Also, do you include the plasterboard in your wall thicknesses? Is that why your wall thickness is 280mm? I'll have to clarify whether I include the plasterboard in my wall thickness with the engineer. I probably won't include plasterboard, to avoid him designing my wall frame in the wrong spot - I'll definitely clarify, anyway. Any reason why you're going for R2.0 batts on the ground floor, but R2.5 batts on the first floor? Cost? I found this in the BCA for the minimum cavity width of a brick veneer wall. 3.3.4.2 (a) Brick veneer—not less than 25 mm width. THANKS! David Re: Polystyrene Wall Thickness and Material Recommendations 6Mar 23, 2014 10:46 pm I did some comparisons of EIFS (Exterior Insulation Finishing System) - basically polystyrene plus render - after a search on the internet for brands... I do like the look of Foamular, with the 2nd best product (not Total) R value for thickness, and a guarantee on the performance (90% insulation, after 20years). Bet it costs a pretty penny! I'll have to get some quotes. Are there any other EIFS brands out there, that I've missed? There doesn't seem to be consensus on whether Expanded Polystyrene (EPS) or Extruded Polystyrene (XPS) is better. Must depend on cost - XPS looks like it is more waterproof (is this necessary, since brick isn't waterproof)... Also looking at where the material is manufactured. If Victoria, then less freight and carbon for me. Is Kingspan made in the UK? Masterwall 100m, R2.7 http://wholeofhouse.bunnings.com.au/pdf ... e_Foam.pdf ALWP 100mm, R2.4 http://alwp.com.au/technical-data/ Foamular 100mm, R3.57 http://www.foamular.com.au/images/Tech_ ... Rating.pdf Kingspan 80mm, R4 http://www.kingspaninsulation.com.au/Pr ... d/R-values RMAX Orangeboard 100mm, R3.1 http://www.rmax.com.au/ob-technical.html RMAX Thermalwall 100mm, R2.7 http://www.rmax.com.au/uploads/files/11 ... ch-Bro.pdf NRG Greenboard 100mm, R2.6 http://www.nrggreenboard.com/thermal/rating Ezyclad 100mm, R2.44 http://www.ezyclad.com.au/images/CSIROV ... report.pdf Re: Polystyrene Wall Thickness and Material Recommendations 7Mar 24, 2014 9:43 am Ecobricks, ecoblocks, hebel maybe . We haven't decided yet, but something around 80-120mm thick to get the R-value up. Quote: Could you tell me more about the vertical drops of the wiring through the air space, and not the stud cavity? Is this so the bulk insulation is not disturbed? In a nutshell yes. Vertical battens gives us a dead air space and separation from the outside layer- important where moisture ingress may occur. It makes it a lot easier when it comes time to install your batts in the wall although there will no doubt be some areas where this is not possible. Quote: Does your foam layer go over the studs? So the brickies will nail through it, and rip it, right, no matter who does it? Yes. Timber frames up first , all braced , plumbed and levelled and fixed in position. Then the roof on followed by wall cladding - in this case ( ground floor ) sarking stapled to the timber studs then the foam sheets fixed through the sarking onto the studs. Next start laying bricks and use brick ties to tie the bricks to the timber framed walls. Depending on which foam product we use we may not need sarking as some poly sheets can be bought with this coating on one side of the sheets. Quote: Also, do you include the plasterboard in your wall thicknesses? Is that why your wall thickness is 280mm ? For the purpose of the sections yes although that ground floor section should read 290mm. Sorry if I've put you wrong and bear with me as all my sections and plans are still a work in progress. Whenever I draw sections I usually include the render, brick etc and plasterboard to show the client, builder and council the whole wall and all the components. The final sections that go to the engineer and certifier or council will probably also show 2-5mm of acrylic render on the outside of both floor levels. When I draw the floorplans all the measurements show brick through to the timber frame ( no wall cladding inside or out shown ) so it is easy for the builder to mark out his walls - pretty much industry standard to do this. Quote: Any reason why you're going for R2.0 batts on the ground floor, but R2.5 batts on the first floor? Cost? No, we are aiming for an R-value for both levels of around 5 so by juggling the thickness of the poly and its R-value plus the other wall components like batts etc we should be able to get pretty close to this mark. Quote: 3.3.4.2 (a) Brick veneer—not less than 25 mm width. We used to aim for 50mm - most builders go 40mm. I've looked at most of those products and downloaded all their specs too and still haven't made up my mind. I like the 20 year guarantee also. I picked this up from the Kooltherm site... "Expanded polystyrene is currently the most commonly used insulation substrate in EIF systems. “Kooltherm® is a thermoset material, whereas polystyrene is a thermoplastic. Thermoplastics soften, melt, or drip when heated, while thermoset materials harden and char, and hold their integrity. Kooltherm® also gives off very little smoke." Just another thing to consider... Stewie Re: Polystyrene Wall Thickness and Material Recommendations 8Mar 24, 2014 3:04 pm Stewie, David certainly struck the jackpot with you! Great posts. 3in1 Supadiverta. Rainwater Harvesting Best Practice using syphonic drainage. Cleaner Neater Smarter Cheaper Supa Gutter Pumper. A low cost syphonic eaves gutter overflow solution. Re: Polystyrene Wall Thickness and Material Recommendations 9Mar 24, 2014 8:16 pm Yep! I'm getting a lot of advice from both of you. THANKS! I read somewhere that you don't get any more thermal benefits beyond an air gap of 30mm. "no wall cladding inside or out shown" So, for your polystyrene cladding on the upper floor, you're not drawing that in the floor plans? Guess it will make laying out the wall frames easier. With the thinner walls on the upper floor, if you have a continuous wall, the studs for the ground floor will not be aligned to the upper floor studs, right? Do you have to deal with this in any particular way? How will you handle the interface between the 2 materials. Thanks David Re: Polystyrene Wall Thickness and Material Recommendations 10Mar 24, 2014 9:27 pm Here are my crazy overspec'd walls. First pass, until I find out how much this stuff costs! http://i65.photobucket.com/albums/h228/akapacker/WallSection_zps581f6679.jpg Re: Polystyrene Wall Thickness and Material Recommendations 11Mar 24, 2014 9:28 pm Quote: "no wall cladding inside or out shown" So, for your polystyrene cladding on the upper floor, you're not drawing that in the floor plans? Guess it will make laying out the wall frames easier. Sorry, I should have explained that better. I meant I wouldn't show the acrylic render on the external poly cladding nor would I show the plasterboard lining on the internal face. Quote: With the thinner walls on the upper floor, if you have a continuous wall, the studs for the ground floor will not be aligned to the upper floor studs, right? Do you have to deal with this in any particular way? How will you handle the interface between the 2 materials. We don't have any continuous walls from the lower to upper levels. If we did I would run the floor joists and studs for the upper level back 100mm from the face of the brickwork below [ 70mm ( poly ) + 30mm ( battens ) ]. Then I would run the battens down the studs and over the face of the floor joists and fix the poly sheets to the battens. Then it is just a case of running a horizontal expansion line of maybe 5mm max where the poly meets the brickwork and filling that with sealant. Once you render the bricks and the poly and then paint the walls all you would see would be a faint line. Voila, like this... Bear in mind I still have the battens above running horizontal. Stewie Re: Polystyrene Wall Thickness and Material Recommendations 12Mar 28, 2014 11:32 am Hi Stewie, I got an interesting response from my engineer when I drew the different thickness walls, aligned at the external face. He said they were not aligned. He needs the internal faces aligned, so the stud walls are in line and the forces being directed directly to ground. Guess this makes it easier than having the upper floor walls cantilevered over the lower floor walls. But it means I don't get any further area, by using thinner walls. What do you think? Re: Polystyrene Wall Thickness and Material Recommendations 13Mar 28, 2014 1:51 pm We've built similar versions of the above several times in the past with no drama from the engineer. The studs above transfer the weight on to the floor joists which rest on the studs below ( offset about 80mm ). It is cantilevered just slightly that's all. Line the studs up and you'll end up with a step outside - real pretty. Stewie Re: Polystyrene Wall Thickness and Material Recommendations 14Mar 28, 2014 4:01 pm I'd have to agree with Stewies take on it. Aligning the walls will mean a large flashing onto the brickwork which can look 2nd rate - the look of the façade makes or breaks a home. The joist cantilever will normally carry the upper storey load without issues. The other alternative is to batten out the upper storey walls to align the faces. This will add an air space which will increase the total wall R value if RFL is included to the face of the studs. 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. Re: Polystyrene Wall Thickness and Material Recommendations 15Mar 29, 2014 7:35 am Thanks! Yes, I can't see why that small offset of the frames will be a problem. The cantilever is very small. Perhaps the engineer is an advocate of Advanced Framing, or Optimum Value Engineering (OVE). If you line up the frames between the lower and upper storeys, you get direct load transfer, which makes the build easier, and can save you money. Easier to seal as well? http://www.nrel.gov/docs/fy01osti/26449.pdf http://www.buildingscience.com/document ... of-framing It'll be a trade-off, I guess. I have some options: 1. Line up lower (250mm) and upper (200mm) walls to the exterior face, so that I have minimal flashing, and no step between walls. The frames are not lined up. I get more floor space within the house though. 2. Line up the interior face of the walls. Simpler load bearing. Step at the exterior face. Ugly flashing to seal between upper and lower storeys. 3. Line up the interior face of the walls. Pad out the upper storey wall to 250mm with battens and larger air space (larger than 30mm air space gives no added benefit for radiative heat transfer). 4. Line up the interior face of the walls. Pad out the upper storey wall to 250mm with thicker Foam for increased R value. I think I will go with Option 1, and talk to the Engineer about why he needs the framing to line up. Re: Polystyrene Wall Thickness and Material Recommendations 16Apr 01, 2014 4:13 pm Just an update on the engineering - I had another chat to the engineer, and he will do option 1 for me. He'd never seen this before, but he checked with his seniors, and they said it was ok. Hope this doesn't substantially increase the cost of the build though! Re: Polystyrene Wall Thickness and Material Recommendations 18Nov 08, 2014 8:11 am Hi Stewie, Did you decide on your XPS foam? I was going to go with Dow Corning SMTG, but my building surveyor wanted me to check whether it was deemed to satisfy. After further questioning of the supplier, he couldn't supply me with any certification, so I am looking at alternative XPS now. Did you get the Foamular in the end? Cheers David Re: Polystyrene Wall Thickness and Material Recommendations 19Nov 08, 2014 9:17 am akapacker Hi Stewie, Did you decide on your XPS foam? I was going to go with Dow Corning SMTG, but my building surveyor wanted me to check whether it was deemed to satisfy. After further questioning of the supplier, he couldn't supply me with any certification, so I am looking at alternative XPS now. Did you get the Foamular in the end? Cheers David IMO the jury is still out on XPS or similar foam external cladding systems...most clients get hooked in by R-rating and thermal properties, but fail to understand Material & Engineering properties (strength,durabilty, stress, strain, shear etc,etc) and here is where the problem ******. If you cant get this information.. then how can you simulate and check the data. These days with software simulations it is easy to check the warranty.... and thats why manufactureres are slowly moving away from warranties and providing material information IMO HTH Designer,Engineer (Civil,Const & Envir),Builder,Concrete & Masonry Contract.Struct Repairs Re: Polystyrene Wall Thickness and Material Recommendations 20Nov 10, 2014 6:57 pm Excellent! I like hearing different views and cautionary tales, so I can make informed decisions. What are the cons with XPS regarding: Strength/Stress/Strain/Shear - I'm not intending to use it as a load bearing material, and it will be on the upper storey so will not suffer impact. Are you talking about vertical or horizontal loads? Are the shear forces from the fasteners? I thought the timber frame would take all these forces, and the XPS would fulfil the role of cladding, like weatherboards do. Weatherboards do not need to resist compressive or tensile forces/stress/strain/shear other than side impact and holding its own weight, right? Durability - definitely a concern. Hence, why I was going for XPS over EPS. XPS is a closed cell polystyrene, which is water impermeable, and resists thermal cycling. And cracking of the render over time - some houses do age quickly, particularly ones without eaves where water runs down the rendered walls. And, if not fastened correctly, then I guess you will get cracking issues. But I thought EIFS had been used for some time now, and was mainstream? I'm hoping if done well, XPS is awesome. If done cheaply and nastily, is bad, and that's what gives the building material a bad name. Really appreciate your alternate view! Is your hesitation and doubt on XPS more gutfeel, or based on technical information? Thanks David Different to what others have said but thanks for that insight. 2 5242 Not recommended! The image presented is for a sublevel area. The footings are down deep with a load bearing wall supporting the upper floor level. If you did that drain… 8 10682 Always get multiple quotes, no matter how reasonable/cheap you think it is. I remember getting a few quotes for a pool fence, roughly around the same price, thinking the… 5 9728 |