I ran across this house recently. As you can see, to save a few bucks they do NOT shear the entire home with OSB. Hence the reason why you can see the Tyvek showing in some spots. They spend more time measuring and cutting the OSB to just place it in a tiny section instead of just placing the entire sheet on the wall, nailing it and being done with it.

It looks like they are using the Tyvek as the moisture/water barrier to protect the wood instead of the usual tar paper that I have seen.

I guess it is viewed as being more "Green" because they are using less lumber???!!!!





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I guess it is viewed as being more "Green" because they are using less lumber???!!!!

Maybe, but it seems as if it would be nearly impossible to get an air seal with construction like that.

Does the "Advanced Framing" method require full sheathing or can one do AF in this manner? Does anyone know?

I know of a house that used foam but little or no OSB or plywood. I don't recall if they used steel straps or some OSB for racking, but it has worked fine.

Just Tyvek - seems like that depends on what the siding is but some foam would be better insulation wise.

wood stud framing at 24" oc uses less lumber and is more thermally effecient too. Not as good structurally , but greener

Posted By ICFHybrid on 23 Jul 2012 01:18 PM

Maybe, but it seems as if it would be nearly impossible to get an air seal with construction like that.

These homes leak air SO BAD that I would be surprised if they can get below 12ACH @ 50PA.

Wait until you see how many times they puncture that Tyvek when they go and staple the EPS and chicken wire to the framing. They miss the studs a lot of the time and I counted over 100 significant rips in a single story home.

Posted By jonr on 23 Jul 2012 05:28 PM
I know of a house that used foam but little or no OSB or plywood. I don't recall if they used steel straps or some OSB for racking, but it has worked fine.

Just Tyvek - seems like that depends on what the siding is but some foam would be better insulation wise.

These homes rack REALLY bad in the winds. Fortunately it is usually pretty calm weather wise but all of these homes eventually develop serious wall cracks and shifted window frames due to the lack of OSB shearing and constant racking of the home in high wind events. After a significant rain event (long and heavy rain), these new homes will leak water to the interior. I talked with one construction guy and he said that 4 out of 10 new homes leak water into the walls. Out of those maybe 1 or 2 will actually notice it on the inside, the rest remains unnoticed as the studs and insulation absorb the water. He said they do not detail the homes properly and most of the damage will go unnoticed during the 2-year warranty, especially since we don't get significant rain events maybe once ever 10 years.

If this home was placed in a windy place like Denver Colorado, it would NOT pass code. They build them cheap and fast out here. In the Phoenix Arizona area they are only required to completely OSB shear commercial properties but residential look like the photos I took.

People break in through the exterior walls in Phoenix because it's easier to break through the wall than it is to break a window or door. All you have is 1/2" of stucco, chicken wire, 1" of EPS and then 1/2" of drywall and you are inside. They use skinny people to get inside as they can fit between the 2x4s which are 16" or 24" apart.

I've seen houses built that way around here sometimes.....it's just the GC wants to make as much profit by building 'just' to min code!!    

I would separate poor detailing and lack of care about rips from the basic design. Ie, anyone can make anything work poorly, but the question I have is can little or no OSB work OK when done well? Ie, tape up any rips or holes and use enough OSB in the corners and/or diagonal steel straps to meet local wind conditions.

Breaking 1/8" of glass sounds easier to me than 1/2" of stucco - but doesn't really matter, almost all homes are easy to get into.

Posted By jonr on 23 Jul 2012 07:31 PM
I would separate poor detailing and lack of care about rips from the basic design. Ie, anyone can make anything work poorly, but the question I have is can little or no OSB work OK when done well? Ie, tape up any rips or holes and use enough OSB in the corners and/or diagonal steel straps to meet local wind conditions.

Breaking 1/8" of glass sounds easier to me than 1/2" of stucco - but doesn't really matter, almost all homes are easy to get into.

The 1/2" of stucco used here has NO shear or strength value. It will dent & crumble if you bump it with a chair and a 5 year old can pierce it with a screwdriver. If you try and run a masonry anchor into it, the stucco crumbles and the anchor falls out.

These homes with their lack of OSB shearing DO NOT do well in high wind events. Codes out here are around 70MPH - Exposure A. Any high wind event causes these homes to fail and get serious damage. I've seen it personally and once winds get above 75MPH these homes will rack severely.

Talking to an engineer, they recommend completely shearing the home with OSB. This "open frame" type of construction is not as strong, even when strapped with Simpson Ties, as a completely OSB sheared home. The engineer stated that it would NOT do well in a high wind or seismic event. The engineer stated that the lack of OSB shear is simply a way for builders to save money. They approach the engineer and ask them what is the bare minimum they can build with and still pass code. Hence the reason why they are required to completely OSB shear commercial projects, as the code will not allow such lackadaisical building techniques to be used and jeopardize the safety of a large amount of people. 

To top it off, they stuff the walls with R-13 Fiberglass batts. Cheap and fast.

I'm afraid we are going to see some really cheap building as things get going again.

Another thing about this construction type. When they stop with the OSB, it leaves a lip as it goes from the OSB to the wood stud area. This lip causes an issue with the 1"or sometimes 1/2" EPS they put on before the stucco, as the EPS does not sit flush because of the unevenness of the wall. They address this problem this way. They will incorporate a thinner EPS over the OSB area and then a thicker EPS over the non-OSB area. In that transition area where the OSB stops they will press very hard against the Tyvek or tar paper to get the EPS to sit flush on the outside. Sometimes they press so hard that they rip the tar paper and some will even cut and then tape the Tyvek to get the EPS to sit flush against the OSB lip.

50% of all the leaks are found in the areas where the transition happens due to the ripped tar paper. They moved to Tyvek because it is less prone to rip and is much stronger and tear resistant than tar paper. Most likely done to limit warranty call backs.

Posted By ICFHybrid on 23 Jul 2012 08:40 PM
I'm afraid we are going to see some really cheap building as things get going again.

No doubt about that. In order for builders to build and sell a 2,500 sqft home for $150,000 ($60 sqft) and still make a decent profit, the builders will cut every corner they can. If the home falls apart 20 years from now, the warranty is long expired and the builder is long gone.

Ive yet to see something like that, just tyvek, I have seen, and it is approved to use osb or plywood at shear/bracing locations and 1/2 foamboard or fiberboard at all other areas. Theres nothing really wrong with that concept unless you really go to the minimums but calculations and a wall bracing plan is a requirement here.

I wouldnt do it, as someone said you could literally kick your way through the wall into a house, but it can work, apartment buildings do it I could see doing it on second floor levels (foamboard option, not just wrb, thats insane)

Posted By greentree on 25 Jul 2012 09:38 PM
Ive yet to see something like that, just tyvek, I have seen, and it is approved to use osb or plywood at shear/bracing locations and 1/2 foamboard or fiberboard at all other areas. Theres nothing really wrong with that concept unless you really go to the minimums but calculations and a wall bracing plan is a requirement here.

I wouldnt do it, as someone said you could literally kick your way through the wall into a house, but it can work, apartment buildings do it I could see doing it on second floor levels (foamboard option, not just wrb, thats insane)

I've seen engineers call for DOUBLE SHEAR WALLS, 1/2" or 5/8" OSB on both sides (interior and exterior) in order to gain proper strength to resist shear forces, especially in corners.

Instead of them using a glulam header above windows, I've seen them just nail a bunch of 2x4s together. Either way (glulam or 2x4) the thermal bridging would be really bad in that area but a glulam is much stronger than a bunch of 2x4s slammed together. Especially since they will dry out and move.

I've been inside these type of homes during storms, even with 30MPH winds, the homes pop and creak like crazy. We had a 50MPH gust once and I literally thought the roof or wall failed because the noise was so loud. It gave out a really loud bang and pop and it sounded like nails were pulling out of the 2x4s. Very unnerving.


The below photo shows a similar home build but using tar paper instead of Tyvek, the same issue is seen. Without the OSB shear on the outside, when they go to drive the staples that secure the 1/2" EPS and chicken wire, they miss the stud and penetrate & rip the paper. On this home, the below is a guaranteed leak. While they sometimes make an effort afterwards by caulking the rips, the caulk is not forever and will break down due to heat, causing a water leak.

Foam without a full covering of OSB can work fine (according to someone I know who has lived in one for many years). No noticeable creaking or air leaks.

As I predicted, they missed the stud in hundreds of spots and drove the nails and staples through the Tyvek into the open space between the studs. They then tried to caulk the holes they created, albeit a piss poor job of that.

These areas are all future water leaks. The water will get behind the stucco (as stucco is NOT waterproof), the water will travel down the styrofoam and will get behind the styrofoam and travel through the staple and nail holes into the wall cavity and get the batt insulation, studs and drywall wet. It's a VERY COMMON problem with these homes but they refuse to change their building practices.

As far as the OSB goes. The areas that did not have OSB, I was able to move the entire framed stud by hand and it moved the wall. Where the OSB was, I could NOT move it at all, it was pretty solid. That simple test just goes to show you that skimping on a $12 piece of OSB cuts down on the strength of the home. Not to mention the issues mentioned above with the penetrations.


 

I lived in a house we bought in San Jose, CA in 1990. It was built around 1970. The front of the house had wood siding on it and the other three sides had stucco. I was REALLY surprised when I replaced some windows (larger in one case) and found the stucco exterior was only vapor barrier (like a paper), what looked like chicken wire and stucco. I was REALLY angry at the house inspector we had hired. To make a long story shorter, being in earthquake country, we ended up stripping out most of the drywall we could get to on the inside of the exterior walls and adding in 1/2 inch plywood and then covered it back up with drywall. A lot of work, but I felt more secure and my wife could hang pictures anywhere on the walls which had the plywood backing.