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what about sips for roofing, compared to conventional roofing. are there more problems or less?
any suggestion’s appreciated
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Get a hold of the Journal of Light Construction. good article this month about widespread SIP roof failures in Juneau ,Alaska. Multiple suppliers,multiple installers.
*It's interesting that this problem has been reported, and is occuring in Alaska...specifically that part of Alaska, but there haven't been widespread reports of it occuring elsewhere. I'd be real curious to see what they conclude. I've been hearing about this incident for a while, and did read that "some" of them were not installed up to specifications, but that still doesn't obviate the fact that something is wrong with this application in this climate. However, as far as I know, and said earlier, there haven't been these types of problems in other locations. So as far as "more problems or less"....hard to tell...there aren't nearly as many SIP roofs as there are other systems, all of which have also, at one time or another or under certain conditions--particularly in applications, have had problems as well.
*I read about the Sip's roof problems in Alaska several weeks ago at http://www.sipweb.com The articles claimed this problem resulted from several factors coming together in a bad way. The climate in Juneau, which is extremely wet, a lack of technical support and/or training by the sips manufacturers, very poor construction practices by those assembling the structures, and in some cases the homeowners disabling the mechanical systems intended to control indoor moisture.The Juneau/sips rot subject seems to be popping up in a lot of building forums and publications and could easily become a major black eye for the sips industry. It would be interesting to know whether this is a sips only problem or if this is a widespread problem in different types of buildings in Juneau.
*Do you have the JLC issue and page? I have not been able to find it. Thanks.
*When using SIPs for roofs, you need a structural ridge beam. That's the extent of what I know about them.
*I used to have an engineering manual for R-control panels, but it unfortunately disappeared at some point. It detailed just about every possible joint situation you were likely to run into. I recall that their maximum spanning capability was 8', so for most roofs you needed more than just a structural ridge beam. They could, however, incorporate structural rafter beams into the SIP's, generally at a joint between panels. It sounds like poor panel assembly techniques are responsible for the problems in Juneau - I remember very detailed fastener and adhesive sealant schedules for every joint.did
*One major problem with SIPs as far as roofing ,in general is the inabilty of of the 7/16" OSB to hold fasteners for any length of time. On the few occassions where SIPs have been spec'ed, we have glued and screwed batten strips for nailing. If I have any choice in the matter, I would avoid using them.Also, I think the "energy efficiency" of SIPs is a sham. Especially if you factor in the energy used in production over the lifetime of the product. There are other ways of achieving a good, well insulated roof that actually work.walk gooddavid
*speak up david, do tell of these roof systems that are are easy to install and will solve all the venting problems, and remove all the structure that they can.i could do with all suggestion'sbecause i'm in ireland, i do not have access to the same supplies you lot do. so that is why i am thinking of SIPs
*Chris----JLC January 2002,pg19
*eddie, One roof system I like using where applicable is parallel chord truss for framing. I design them so the bottom chord sits on a hanger/ledger on the inside of the wall and the top chord sits on the top plate. This will give you a cathedral ceiling that is the same pitch inside and out. With 16" thickness of the truss, and blown in cellulose I can achieve an effective R-55 for my roof. Sheetrock on the inside and however your ceiling will be finished . I like standing seam metal roofing for my roof, so I use an inexpensive board (1x4 or 1x6) for my skip sheathing. Depending on fascia / soffit detail, I furr out / down accordingly. With the metal roof and skip-sheathing I have my roof venting.If I were to use a composition shingle and need solid sheathing for my roof, I would spec 18" trusses and run a rafter vent on the inside of the rafters for 2" of air flow, much the same as you would for stick framing or trusses in general. 5/8 CDX for sheathing and traditional soffit or fascia venting as desired with ridge vent.One thought; I do not like tyvek etc, in general and especially as a housewrap. Poor use of more petrochemicals. Poor performance as well in my opinion. However I do like the tear resistance of tyvek for roofs, being able to stretch it over my rafters prior to skip sheathing. It is much more durable than felt or rosin paper for tearing, sheds water well from condensation, and breathes reasonably well under roof conditions.walk gooddavid
*"in general is the inabilty of of the 7/16" OSB to hold fasteners for any length of time."--evidence?"Also, I think the "energy efficiency" of SIPs is a sham"...is this in comparison to how most houses are built, or to yours? Sham? Hmmm...too bad most evidence doesn't point to the increased insulation value, reduced air infiltration, and overall, whole structure effeciency as being a "sham". Why, just out of curiosity, is it a sham?
*david, appreciate the post.but the reason i thought of SIP's in the first place, is because i can't source the venting products, needed for shingle roof, here in ireland.thanks anyway.will look into the parallel trusse option though
*Jason, I do not work much with OSB. By choice. However I do have some experience working with it on projects where it was speced, both as sheathing and as a SIP's product. My experience is that it does not hold fasteners unless you also hit a stud, rafter etc. Many other carpenters/builders I know and work with share these observations.As far as the energy efficiecy of SIPS, the majority of the insulation used in their construction is rated about R-4 per inch. About the same as cells. I suppose it is possible to achieve a tight fit and seal at the joints, but I have not seen it. Also by the time one runs plumbing and wire chases, etc. you are creating the potential for heat loss. Also there is serious debate about the long term R-value effectiveness or to put another way, R-value reduction over time. Another example is what is happening in Alaska with SIPS and the mold/dry-rot problems beginning to surface. But the context I mainly speak of is the energy usage throughout the entire process from manufacturing through install and end of life. Most SIPS require sufficient energy in manufacture, maybe enough to off-set any theoretical energy savings at the house. This unfortunately is true with many of our so-called energy saving building techniques and materials.I call it a sham, because I believe industry is deliberatly misleading in their claims. Agriboard was one SIPs that was caught misleading theirr R-value. Another product is ICFs. Several manufacturers have reduced their supposed R-values.walk gooddavid
*About 4 or 5 years ago there was an article in FHB, I think is was called "Cold Roofs". It is designed for cold weather climates, and appeared relatively easy to install, yes there was a little more work and material, but it really buttoned up the roof and provided good ventilation. If I were building in a cold climate I think that would be my choice.Basically it involves putting a thin skin over the rafters (I think 3/8), followed by felt, followed by vertical (this is where the air flow comes in) furring strips and finally plywood sheathing. The real detail in the article is how they vented the eaves and ridge.I would like hear what you think.
*Thanks for replying David. I am not, for a change, trying to start an argument with you...but, I find them to be just the opposite of a sham, but of course that's from my own viewpoint. In relation to most of the building practices I see in stud-wall construction, I think that SIPs are a vastly superior method for improving the overall, whole-house effeciency. And again, considering how most homes are framed and erected these days, the "life-cycle" idea of looking at materials and effeciencies is very good, and again I think they do a better job, particularly when you look at the amount of recycled material in them and the overall energy savings for those structures. They might not be as effecient as some of your homes, but than again, they are a darn sight better than most I see or read about. Thanks again.
*Jason, The difficulty ,as you hint at, is talking generally without specifics. There are several different SIPs products out there, using everything from expanded polystyreen to polyisocyanate to a new company using dense-pack cells. Some are using recycled materials; however it seems most are not.Building techniques and quality vary so much across the country and even locally again it is hard to find real common ground to speak generally. My use of SIPs, and I pride myself on being a quality -conscience and thorough builder, has led me to not use them. I think there are better ways to frame and insulate, achieving comparable results at comparable costs. All my environmental concerns are icing on the cake if I can keep true to them. It is hard to do, and I find myself considering those concerns more cake these days and keeping the added costs minimal, more the icing. walk gooddavid
*Here's a big article on SIP problems in Juneau. It's posted on an SIP site, but what the heck:http://www.sipweb.com/monitor/monitor_feature.aspThanks for the post, Dave...I guess I really need to fly out there and see your building methods to get a better idea...got any good fishing?
Sips for roofing.
Eddie,
Moisture would create a huge problem with conventional SIPS with the OSB skins, I will be truthful I now work a manufacturer of Steel Skins SIPS panels and while moisture is not a strutural issue as our panels or gavlvanized and primed and painted as well. With the tight shell construction common to all SIPS and even more with ours, health issue arise from lack of air exchanges through the walls causing the " Sick House Syndrome" as a policy we will not send out a home package without inclusion of a programmable EVR we use Renewaire as ours but others are on the market as well.
As for as load bearing capacity most SIPS manufacturers provide span charts stay within the perimaters and most often you will be safe unless some condition as we are discussing arises, just check for things like snow load and wind loading with a P.E. prior to sizing your panels for installation.
Before rejoining this company after 15 years, I felt strong enough about the product I completed 8 houses after Katrina including a Net 0 and Near net 0.
Eddie B.