Rainscreen?

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Old 03-27-13, 09:21 AM
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Rainscreen?

Are there other names for this material? What type(s) are recommended for use under stained white cedar lap siding?

There's finally a Menards near me so my first stop was a visit to the Contractors counter to ask about rainscreen. Kid didn't know what I was talking about. Neither did anyone else in the area. He couldn't figure out how to look up something on the computer that he didn't already know about. They sell wood siding but he had no clue anything was supposed to go behind it.

I need to be better prepared next time I go in asking "difficult" questions...
 
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Old 03-27-13, 09:27 AM
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I never heard of anything by that name either.....is it the same as house wrap?
 
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Old 03-27-13, 09:41 AM
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I'm in the same boat as Vic, I've never heard of it but my first thought when you said under siding was house wrap.
 
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Old 03-27-13, 10:19 AM
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Yea, I'm thinking house wrap or Tyvek.
 
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Old 03-27-13, 05:32 PM
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"Rainscreen" is not a product, its an installation technique where the siding is simply furred out away from the sheathing and housewrap to provide a drainage plane and encourage airflow behind the siding. 1/4-1/2" plywood can be used for the furring, and screen needs to be used in the open cavities at the bottom of the wall between furring/studs to keep bugs out. Cor-a-vent is a ventilation product that can be separated and used for this purpose.
 
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Old 03-27-13, 06:38 PM
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Old 03-27-13, 08:57 PM
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The stuff I'm favoring is called Waterway
Stuc-O-Flex International - Rainscreen Drainage Mats
It's a 5/16" woven mat of wiry polypro that allows air to circulate but is hard to compress (picture a scotchbrite pad on steroids). That way the siding is completely supported instead of floating between the furring strips.

My BIL used to build cedar homes for Lindal Homes and he just used a folded strip of 30# roofing felt vertically as "furring". Thin space allowed a bit of air flow but the boards couldn't flex far like they can with 1/2 or 3/4 furring. Definitely a cheap way to go but I doubt it's really the best way.

Unfortunately the young kids at Menards must think you just slap wood over Tyvek, too.
 
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Old 03-27-13, 10:31 PM
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Looks good, other than the Typar it is bonded to, IMO. In a warm climate with testing (air-drying) of OSB/housewrap, after soaking; Tyvek (58 perms) dried/stabilized in about 15 days, a low perm product like Typar dried in around 55 days (off the chart), pp. 13-15; http://repository.tamu.edu/bitstream...pdf?sequence=4
Imagine OSB/plywood trying to dry in a cold climate (after a wetting event- roof/wall leak, etc.), maybe I am being overly critical, just giving you my choice and why. Optimum perms for drying is 18-24 perms; pp.24; http://www.energy.ca.gov/2007publica...esidential.pdf

Gary
 
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Old 03-28-13, 07:51 AM
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The version bonded to Typar is their top of the line. Others are bonded to a landscaping fabric type membrane with a 247+ perm rating.
 
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Old 03-28-13, 09:44 AM
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Check out Apex Ultrex Siding System at House Siding - Apex Exterior Siding Their fiberglass siding has nailing spacers attached that provides ventilation between the siding and the weather resistant barrier. Not sure how they keep the bugs out, but that seems like a minor detail. Looks like some pretty neat stuff to me.
 
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Old 03-28-13, 09:11 PM
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The bugs won't eat fiberglass siding, unless the polymers they don't list are wood fiber... The OP has wood lap siding why would he be interested in plastic siding, even wood-grained...
In MI, will you be using a rigid foamboard on the exterior, to control condensation? Or just describe the wall make-up...for a better idea of your moisture management.

Gary
 
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Old 03-29-13, 09:09 PM
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Its a vacation cottage originally log cabin, with a frame construction addition & basement. No insulation on walls of log portion, R11 in addition. I bought the place last August and the intent is to shut it down for winter so energy efficiency is not a big concern. Right now its wrapped in Easy Gard waiting for the mill to deliver my cedar.
 
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Old 03-31-13, 02:05 PM
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I have never used the EasyGard product. Not much info to check the perm ratings on it with;


Here are some other comparisons; http://www.google.com/url?sa=t&rct=j...FLVueQ&cad=rja

It appears to be a poly product...; http://www.google.com/url?sa=t&rct=j...Yty3oA&cad=rja

Need to be careful when there is no pertinent info and have to rely on word of mouth for a major product that one should be able to find out everything about (at least perm rating); Your contractor said he would use Tvek house wrap under the vinyl siding and the house has something called Easy Gard is this the same thing

I'd research it more, doesn't sound good, IMO. If you compare the only HW in the first link that is polyethylene rather than polyolefin, it has a very low perm rating and it is even perforated. Check under yours for moisture entrapment as it may not breathe enough...

Gary
 
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Old 04-01-13, 08:08 AM
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Check under yours for moisture entrapment as it may not breathe enough...
Gary in the 3rd link (Tyvek vs EasyGard) the "answerer" claimed to have experience with both wraps and states
It tends to be so porous that if you have wind-blown rain it will be driven through the material.
Would this mean it's not a great vapor barrier but once covered with siding vapor should pass through & dry to the outside fine? I'm planning bare wood interior walls so this wrap is the only vapor barrier, except for the facing on the insulation used (only) in the addition.
 
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Old 04-01-13, 12:11 PM
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I just meant you should research that product more fully; Google

It sounds as it may trap condensation, a bad thing. Though we don't know the conditions for the results. As it is a poly and not perforated (giving a very low rating), it may trap moisture, as said, I have not used it, there is no perm rating stated (not a good sign), and I would not use it on my house for those reasons. It may take a ridiculously long time to dry behind it, who knows --without more info. All one can do is compare specs OR take others reviews (with a grain of salt)... Read them all, then decide.

Gary
 
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Old 04-01-13, 12:47 PM
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The faced insulation on the inside is fine if the WRB is permeable, Fig 4a, if your location; http://www.buildingscience.com/docum...nd-wall-design

Gary
 
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Old 04-01-13, 09:10 PM
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Unfortunately the only "facts" I've seen to help me decide whether to go to the trouble & expense to rip off all the EasyGard is one ICC compliance test for water & flame resistance.
http://www.icc-es.org/reports/pdf_fi...S/ESR-2252.pdf
I can't find where anyone has done a full evaluation and the ICC test apparently was commissioned to verify compliance in only those 2 parameters. A Pass/Fail test is really not enough to form an opinion. Could even be superior to Tyvek but nobody will ever know based on the scant info available. I'm stunned that Home Depot has been selling this for years and so little is known about it.

I keep running into articles by Dr. Lstiburek (including a similar article on Buildingscience where most of the examples were brick exterior IIRC). He seems to have the opinion that as long as the siding breathes and there's a drainage plane the actual perm rating of the wrap won't have much impact. His writing is largely why I'm planning to use a rainscreen mat under the siding.

I think it's safe to say EasyGard isn't a vapor barrier or we'd at least be finding some BAD reviews. Obviously I don't want to delay my project & incur more expense unless I absolutely have to.

It's really discouraging when every time I hire out a job I get disappointed.
 
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Old 04-04-13, 11:36 AM
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I use a lot of Dr. Joe's and his groups work in my answers. It may be at 13 perms, wet cup (#2 test) according to one answer just before one-half way through here (though I cannot find the reference paper); where do I find what the 'ASTM' numbers mean? - Remodeling Forum - GardenWeb

With your rainscreen material under the cedar, I doubt you will have any problems. IMHO, if OSB, particularly Aspen species, I would then say to add another layer of asphalt-coated builders paper over the Easygard (a low perm, drying will take months- not days), to wick any water away and out that gets by at the fastener holes from the RS/siding. With the Kraft faced batts paper as a vapor retarder, that should stop most/all the vapor diffusion from the interior, then any medium/low perm WRB would work, only needing to worry about exterior leaks. Do an EXCELLENT job of wrapping, follow their directions.

Hard to find info, and some info is just plain disgusting the way they hide it in the answers. Eg. Zip wall sheathing material perm rating.

Gary
 
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Old 04-04-13, 04:50 PM
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Speaking of Zip wall.... what's your opinion of it, Gary? The house I'm siding right now has it and I'm pretty leary of it.
 
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Old 04-05-13, 09:02 PM
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Lol, wondering if anyone caught that...

I could go on and on about OSB, but I won't. The short answer. Years ago I researched Zip System, sounds good; face-paper of +- 16 perms; http://www.zipsystem.com/uploads/tec...2010094429.pdf

Years later, someone actually tested it other than manufacturer; lo-and-behold; http://www2.dupont.com/Tyvek_Weather...rint_948_0.pdf

With that in mind, IMHO, +18 perms is best to dry OSB, especially Aspen species (molds quickly/easily)pp. 22-25; http://www.energy.ca.gov/2007publica...esidential.pdf

So, anyone putting poly on the inside and Zip on the outside is getting the dreaded "VAPOR BARRIER SANDWICH" where the wall (with an exterior water leak) cannot dry to the inside or outside. Time will tell in about 10-15 years...lol. Almost like thick foamboard outside on OSB except no interior vapor materials (other than paint) is required (generally, exceptions:http://www.buildingscience.com/docum...nd-wall-design) as it is an insulating sheathing as well; IRC FAQ: Insulating Sheathing Vapor Retarder Requirements — Building Science Information

Sorry, that WAS the short answer, lol.

Gary
 
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Old 04-05-13, 09:25 PM
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This house has Zip System wall- a wall sheathing system only... not a roof sheathing, and it doesn't have the paper face... it's more like a "painted" face. Green paint. The OSB is exposed around every single staple head that's driven 1/16" into the osb.

But you still tape every seam with their tape. The tape is the only thing I do like. Very rubbery and very sticky.
 
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Old 04-06-13, 03:00 PM
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I was talking walls on all the links.... "“The Zip System Wall Sheathing panel is an OSB wood structural panel having a laminated exterior facer. The exterior facer is a medium-density, phenolic-impregnated, polymer-modified sheet material qual…” From; ESR-1474

Here is the one I used first; almost 1/2 way down, on pp.4, 2.2, "A" #7; https://docs.google.com/viewer?a=v&q...ZoxkKEMlmyCNhg "Kraft paper"

Gary
 
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Old 04-06-13, 03:19 PM
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Well, from working with it the past few weeks, it seems the phrase "medium-density, phenolic-impregnated, polymer-modified sheet material" is just a fancy way of saying its a thin coat of some special type of paint, which the staples blow right through. I don't like it.
 
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Old 04-06-13, 04:28 PM
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Once the WRB (painted coating) is gone, water can enter. OSB is slow to dry as the BSC link showed, can you imagine how long it will take to dry with a coating, and SPF in the cavity fill, never.LOL. Bad enough using a housewrap and all the problems; http://www.buildingscience.com/docum...gement-details

Over-driven fasteners, esp. in seismic areas - strength reduction; http://www.ewpa.com/Archive/2006/aug/Paper_266.pdf

What are the staples holding up? What type of siding? What type insulation?

Gary
 
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Old 04-06-13, 04:45 PM
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Zip system says a fastener (either nail or staple) isn't a problem unless it's actually completely penetrated the sheathing. (which IMO is a load of u know what.) The sheathing was attached with a 1/2" sheathing stapler, and they are not overdriven... they are driven "normally" as all staples are, which is maybe flush to countersunk 1/16". But that's enough to see past the green paint... er, phenolic polymer substance.

Siding is fiber cement lap (nailed on, obviously), insulation is unfaced fiberglass (interior poly VB) in walls, and a combination of open cell/closed cell spray foam in some cathedral roof areas and at rim joists and under styrofoam baffles between each truss.

It's really none of my concern, as I'm just applying the siding, but it just doesn't make me feel very good if there is ever a leak anywhere.
 
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Old 04-07-13, 12:53 PM
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Yep, going to take a loooong time to dry any OSB core that gets wet (from ext. rain/water leak, int. hole in the plastic sheet, around elect. boxes); "• Avoidance of the installation of vapor barriers on both sides of assemblies
— i.e. "double vapor barriers" in order to facilitate assembly
drying in at least one direction." Look at fig.#3---- hard to say the perm rating of the polymer, but safe to say, they should use a latex paint inside or at the most-- paper-faced insulation or a Membrain-http://www.bestofbuildingscience.com/pdf/Brainy%20membrane%20HEM_23-4_p37-40.pdf but not a poly, look at the different classes/ratings perms in the list. From; pp.4, http://www.buildingscience.com/docum...nd-wall-design

Gary
 
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