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I just ran across a specification for a new house I’m estimating, that specifies insulation baffles in the walls. I asked the Architect about it, and he said that with all the discussions, testing, and opinions on why these newer houses are rotting out, and the debate about Housewrap vs. Building Paper, he figures that this is the best way to ensure that the sheathing will be able to dry out. He figures that it works at the roof, it should work in the walls too. Another interesting point, he was very specific about spacing the sheathing, for both expansion and a very small about of venting. He then specifies Tyvek house wrap and taped joints.
My question is, doesn’t this give a better chance for any of the moisture in the walls to condense on the inside surface of the sheathing instead of passing through as a vapor? Won’t this speed up the rotting process?
I couldn’t find any discussions about this one, so I thought I’d throw it out to you guys. What do you think?
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I think you better run for cover. You know the cartoon where the character is in the dark, lights a match, and finds out he's standing in a room full of dynamite? That just might be you.
*Where are these houses that are suppose to be rotting?Where did this architect get his or her degree, by mail?Where is this air to come from and where is it supposed to go and why?Why would you waste valuable wall space with a baffle (that does nothing instead of maximizing insulation)?Gabe
*Brian, What would your architect do with walls over 8', as pertaining to fire blocking?
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Yea, I know. This guy is very green.
He has spec'd fire blocking at about 9' to double as drywall backing at the ceiling. I think I had better check with the inspector on that one, as I can't remember if they will accept it. The walls are framed to about 11' with 24" deep TJL open web trusses hanging from the top plate, for the second floor. It will be nice to have that much space to run all the mechanicals, but it's pricey.
I guess the baffles idea in the wall might be his way of protecting from a potentially bad EIFS job, however the client has changed his mind and wants fiber cement lap siding. I also told him that they make insulation boards now with channels for drainage for the EIFS system. He was unaware. I was amazed.
I think I have him understanding and convinced, that if he feels it absolutely neccessary we can hang the lap siding on a "rain screen" of 1x2s. Yes, we get some rain here in Oregon, but not that much.
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rain screen good... baffles bad...
baffles are typically made of polystyrene...they are a great vapor barrier.. soany moisture trying to get from in-to-out will be trapped at the inside surface of the baffles.. and the outside surface of the baffles is outside of the insulation zone so it is creating a PERFECT condensing surface...
he will be accelerating the rotting of this wall system..
.too bad.. reinventing the wheel from round to square seemed like such a great idea too...
*> 24" deep TJL open web trusses hanging from the top plateDang ! How big a house is this thing, anyway ? And how expensive ?If memory serves me correctly, those TJL trusses are about 5 or 6 bucks a foot. And Trusjoist is an arrogant pain in the ass to work with. They take weeks to prepare shop drawings, they won't build anything without written approval of their shop drawings, and it can take 6 weeks to actually get the joists. Keep that in mind when you bid the job...........
*I worked on a big job, a custom home designed by a green architect. Among the many details that were either a pain in the ass, stupid, or worthless, not to mention ugly, was the fact that this guy designed garage doors barn door style.But not wide enough to fit the client's vehicles. And on a garage that cost more than many people's houses.Since the guy was rich, it didn't really matter to me to fix the bad design, but now I look back and say things like, "I'd never work on a wacko house designed by a hotshot rookie again".
*Baffles in exterior walls indeed. GeneL. This "architect"is suffering from information overload.GeneL.
*Tell this guy to put his air space between siding and sheathing. 3/8" should do the job just fine.And remember, he's an archetict(experience not required), he knows, you don't.
*Don't know if you've set hanging web trusses before. Schedule is everything. Top clips for trusses are very unforgiving of wall dimensions that don't coincide with Truss Joist shop drawings, and I mean very. If plate lines are anything but paralell, the six weeks mentioned can bite you hard. Just had a pile of webs on wood and WFB, at 30, 60 and 90 degrees. Wished I knew what I was going to have for clear span distances between plates about four weeks before I did.
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I just ran across a specification for a new house I'm estimating, that specifies insulation baffles in the walls. I asked the Architect about it, and he said that with all the discussions, testing, and opinions on why these newer houses are rotting out, and the debate about Housewrap vs. Building Paper, he figures that this is the best way to ensure that the sheathing will be able to dry out. He figures that it works at the roof, it should work in the walls too. Another interesting point, he was very specific about spacing the sheathing, for both expansion and a very small about of venting. He then specifies Tyvek house wrap and taped joints.
My question is, doesn't this give a better chance for any of the moisture in the walls to condense on the inside surface of the sheathing instead of passing through as a vapor? Won't this speed up the rotting process?
I couldn't find any discussions about this one, so I thought I'd throw it out to you guys. What do you think?