Browse Forums Heating, Cooling & Insulation 1 Jan 16, 2009 2:01 pm We are building a new house and we are wondering about the pros and cons of steel frame houses. We want the house to be energy efficient and we are concerned about problems with thermal bridging heat loss via steel frames. (We live in southern victoria and the main concern is heat loss here) I've heard that insulation can be placed between the frame and cladding to prevent bridging loss there, but what about the connections between the wall framing and the roof trusses? In steel frame houses, wouldn't the cold roof trusses convey that cold directly into the attached steel wall framing - and hence into the house (or worse - cause condensation in the walls)? Is there a way to prevent this? Are there other pros/cons of steel framing with respect to energy efficiency? Re: thermal bridging in steel frame houses 2Jan 16, 2009 8:37 pm Interesting thoughts. We have a steel frame home - no idea what the effect is on the energy rating you should ask Peter from Ausdesign.
I can say we have no condensation problems. BTW it's heat that moves through materials, not cold. Ed Re: thermal bridging in steel frame houses 4Jan 16, 2009 10:27 pm hiker Thanks for the correction on the hot/cold issue! What do you think of your steel frame house in general - were there any particular reasons you chose that over wood frame? generally speaking, termites prefer to eat wood over steel. Re: thermal bridging in steel frame houses 6Jan 16, 2009 11:21 pm If you had insulation and sisalation in your external walls, I don't see how it would be any different to timber... but I'm no expert on this subject.. Re: thermal bridging in steel frame houses 7Jan 17, 2009 7:57 am hiker Thanks for the correction on the hot/cold issue! What do you think of your steel frame house in general - were there any particular reasons you chose that over wood frame? No reason - we liked the design at the time. Wall fixings need to be cavity type. Retrofitting electricals etc is more difficult. Steel frames are more expensive by around $2,000 per house. They are safer in bush fire areas I believe. The termites need bigger teeth... Ed Oh - I think your insulation concern is s legitimate one and you should ask Peter... the outer edge of the frame will be exposed and the inner edge will be against the plaster - is the 10mm plaster enough??? In our roof space on a hot day I cannot touch the trusses as they are too hot. Re: thermal bridging in steel frame houses 8Jan 17, 2009 8:08 am EcoClassic Retrofitting electricals etc is more difficult. Steel frames are more expensive by around $2,000 per house. And a little bit more... Now it's more like $20,000.... Steel frame takes a lot longer to fit out, electrical and plumbers hate it! Electrical Engineer... Don't hold that against me... And keen owner builder... Mainly the building part!! Re: thermal bridging in steel frame houses 9Jan 17, 2009 11:30 am chuth77 EcoClassic Retrofitting electricals etc is more difficult. Steel frames are more expensive by around $2,000 per house. And a little bit more... Now it's more like $20,000.... Steel frame takes a lot longer to fit out, electrical and plumbers hate it! I would have thought they prefer it.. all the noggins are pre-drilled! Re: thermal bridging in steel frame houses 10Jan 17, 2009 12:04 pm wakeboardandy chuth77 EcoClassic Retrofitting electricals etc is more difficult. Steel frames are more expensive by around $2,000 per house. And a little bit more... Now it's more like $20,000.... Steel frame takes a lot longer to fit out, electrical and plumbers hate it! I would have thought they prefer it.. all the noggins are pre-drilled! I belive you are right - our trades seemed to be happy enough... Ed Re: thermal bridging in steel frame houses 11Jan 17, 2009 3:07 pm wakeboardandy I would have thought they prefer it.. all the noggins are pre-drilled! Depends on the frame manufacturer... But all holes must be grommeted.... And this takes longer than putting a speedbore through timber... For electricians, you can'y simply throw the cable between rooms, it must be "carried" so it doesn't drag across a steel edge... A typical house, will take many hours more... Electrical Engineer... Don't hold that against me... And keen owner builder... Mainly the building part!! Re: thermal bridging in steel frame houses 12Jan 17, 2009 4:23 pm hiker we are concerned about problems with thermal bridging heat loss via steel frames. A very good question and I have never seen anything that can definitely answer your questions. However, the Passivhaus construction systems in Germany are really big on this issue of thermal bridging. Calculating the magnitude of the effect is a bit complex. The amount of heat transfer is proportionate to the surface area exposed and the distance it has to travel through the material. There are all sorts of considerations such as what other kinds of materials are interposed to provide thermal breaks in the system. I guess you could get some idea by directing a thermal camera on the walls inside a steel framed house and see how many 'cold spots' sit behind the internal cladding. This may give you some semi-quantitative information compared to say facing the camera towards the window, ceiling or floor. Termites might not eat your frame but other things in the house make tasty meals for them and they can be just as much of a nuisance. The conventional wisdom now is that the best termite barrier around the perimeter of the house are not chemicals or mechanical devices but a vigilant pair of eyes. Re: thermal bridging in steel frame houses 13Jan 17, 2009 4:38 pm chuth77 wakeboardandy I would have thought they prefer it.. all the noggins are pre-drilled! Depends on the frame manufacturer... But all holes must be grommeted.... And this takes longer than putting a speedbore through timber... For electricians, you can'y simply throw the cable between rooms, it must be "carried" so it doesn't drag across a steel edge... A typical house, will take many hours more... The grommets are just plastic plugs which are easily slipped in - I will ask an expert on steel homes if there is a cost difference on services - but I think Wakeboardandy is right... Ed Re: thermal bridging in steel frame houses 15Jan 17, 2009 9:07 pm My contract states this:
Sisalation to external walls of house. Ceiling and Wall thermal performance insulation to comply with 6 Star Energy requirements. so is that this thermal stuff you speak about? Re: thermal bridging in steel frame houses 16Jan 17, 2009 10:59 pm wakeboardandy My contract states this: Sisalation to external walls of house. Ceiling and Wall thermal performance insulation to comply with 6 Star Energy requirements. so is that this thermal stuff you speak about? I would want to know exactly what kind of insulation material is being used, how thick, what R value and where it is being located. The ultimate question is whether or not it will achieve the same outcome as a timber frame with standard insulation. The BCA star rating is a mere series of tick boxes of which insulation is one of them. I wouldn't trust that it can properly discriminate the level of insulation required for a steel frame over a timber one. Re: thermal bridging in steel frame houses 17Jan 17, 2009 11:41 pm dymonite69 I would want to know exactly what kind of insulation material is being used, how thick, what R value and where it is being located. The ultimate question is whether or not it will achieve the same outcome as a timber frame with standard insulation. The BCA star rating is a mere series of tick boxes of which insulation is one of them. I wouldn't trust that it can properly discriminate the level of insulation required for a steel frame over a timber one. But it is using FirstRate, not a deemed to comply system, of ticks - and I for one don't know how FirstRate treats steel frames. So over to Peter... Ed Re: thermal bridging in steel frame houses 18Jan 18, 2009 12:32 am dymonite69 wakeboardandy My contract states this: [i]Sisalation The ultimate question is whether or not it will achieve the same outcome as a timber frame with standard insulation. .......I wouldn't trust that it can properly discriminate the level of insulation required for a steel frame over a timber one. I would say that for a steel frame house to achieve the insulation level of a timber frame house every piece of steel forming a thermal bridge, ie all outside wall studs, noggings, top plates, bottom plates, and all the ceiling joists would need extra insulation over them equal to the insulative value of 90mm of pine timber. That is assuming a plantation pine frame, 90mmm studwork and ceiling joists, and assuming steel has near to zero insulating value, (which it has). This would be easy to achieve in the ceiling (except where joists are joined to trusses) but harder to achieve in exterior walls where space may be limited and brick ties intrude just where the insulation needs to be fitted. Give me wood, more environmentally friendly, less embodied energy and unless you are living in the tropics the termite fear hyped up by steel frame builders is an unwarranted one. Johnnojack Re: thermal bridging in steel frame houses 19Jan 18, 2009 12:38 am Johnnojack I would say that for a steel frame house to achieve the insulation level of a timber frame house every piece of steel forming a thermal bridge would need extra insulation over them equal to the insulative value of 90mm of pine timber. I think this would be a fair approximation. Re: thermal bridging in steel frame houses 20Jan 18, 2009 4:45 pm dymonite69 I guess you could get some idea by directing a thermal camera on the walls inside a steel framed house and see how many 'cold spots' sit behind the internal cladding. This is a privately funded study by a steel company: http://www.dofasco.ca/bins/doc.asp?rdc_id=2520 Hi I am wanting some opinions about the build of a steel shed I am going to get one about 4.5 x 2.5 m steel shed and the height will be about 2.3-2.4m high The one I am… 0 10508 Hi, I have a steel frame house which was built 2 years ago. When you are down stairs you can hear clunking noises when someone is walking around. We were told if you… 0 3024 Hi, We have a single story MacDonald Jones house, on a waffle pod slab with steel frame. Are we able to build a second story extension? Other info is we are 900mm from… 0 5819 |