Jump to content

Drainable Sheething - Has Anyone Seen It?


hausdok
 Share

Recommended Posts

Hi all,

Wondering if any of you have run into this new drainable sheathing system yet. Basically, they've combined Advantech OSB sheathing (Advantech is a very high density and water resistant OSB) with that new green drainable wrap that came out about 3 years ago.

This stuff goes on in panels and then the joints are sealed with a special tape and no other wrap, felt, building paper or any other type of underlayment is used. The idea is to skip the underlayment step and eliminate the problems with improperly installed wrap.

OT - OF!!!

M.

Link to comment
Share on other sites

Hi,

I don't know what I think about it. I didn't spend a lot of time exploring their site for specifics. I'm a little puzzled at why the tape they use isn't trapping the water at the joints. The wrap that's bonded to the surface is designed to drain. Okay, I get that. But then you stick tape over the joint. Doesn't the water then drain behind the tape, unless there's a z-flashing between panels?

I got lazy. Instead of exploring their site and doing more research, I just posted the link here and asked the question.

OT - OF!!!

M.

Link to comment
Share on other sites

I found an entire subdivision of $500k to $700k homes with this product on them, not far from my home. I had to take a look at it. The tape looks like an Ice Shield product but it has a gooey adhesive that fills in the joints. It reminded me of a rubber backed mastic tape. I don't think that water is going to get behind the tape, but I could see water seeping in around windows, doors, etc., the typical leakage areas. I could then see how the water would then have the chance to seep into the unprotected OSB.

What I don't understand is how the brick ties are going to impact the covering on the OSB. All those nail holes have got to do something.

Link to comment
Share on other sites

Advantech is not your average OSB.

I used it as the decking for my treehouse. It's exposed to a lot of weather (it's 12' up a tree, and it's held up unbelievably well for 6 years w/no apparent problems whatsoever.

I'm not into miracle materials as the answer to underlying design & installation problems, but this stuff is amazing.

Download Attachment: icon_photo.gif treehouse sm.JPG

53.79 KB

Link to comment
Share on other sites

Hi Scott,

I think brick ties wouldn't be that much of an issue. After all, they do it now with other substrates and house wrap or felt. Since they aren't stapling felt or wrap to this substrate, you've got far fewer penetrations in the substrate than you'd have with previous systems behind brick and most of the water that's behind brick is draining down the back face of the veneer - not the sheathing.

Other types of siding applied to the substrate, like clapboards, might be another matter entirely, or, if the wrap bonded to the face of the sheathing works the way it should, might be less of an issue. That's what I'm trying to figure out.

With your typical clapboard siding, there're going to be far more nail holes than you'd have with brick, then you've got the ubiquitous staple holes and the siding is physically touching the substrate. Wind-driven water that gets blown up behind claps tends to collect along the top edge of the underlying claps, or adhesion holds it in small gaps between the backside of the clapboards and the sheathing, until it diffuses to the interior and has completely dissipated. With felt, that moisture gets absorbed, substantially increasing the perm rate of the felt, and then the moisture gradually dissipates as the felt allows the envelope to dry to the interior. With wrap, water gets behind the wrap by following the shanks of the nails and staples and then it's trapped there, because wrap allows water vapor to pass but won't allow water molecules to pass through. That's why wrap can be so problematical. Used with wood planking and plywood, wrap has less chance of causing damage, because those substrates are more permeable than OSB and allow that trapped water to diffuse more readily. OSB doesn't. OSB itself is considered a vapor barrier and will remain almost totally impermeable for anywhere from 90 to 180 days, depending on product, before it starts to degrade from moisture exposure. That's where so many contractors using wrap combined with OSB have gotten into trouble.

With this product, when the drainable material is punctured by the shank of a nail holding the siding on, doesn't the water draining through the tiny channels in that material drain directly onto the shank of every nail as it finds it's way to the bottom of the wall? It does that with wrap and felt too, but less consistently. So, do the little breaks around the nail shanks allow water into this material, or does the extra wax and the improved polymers used in the Advantech product, which have worked so well for flooring platforms and are a huge improvement over conventional OSB, prevent absorption so well that saturation around those nail shanks isn't a factor?

Obviously, these are all questions that the manufacturer should have addressed. However, the track record of manufacturer testing has shown us time and again that they're willing to rush a new idea into production and use it in thousands of homes, using the home-buying public as the test bed, before major issues are encountered with the product.

I know it's still too early to tell with this product, since it's brand spanking new. I was simply wondering whether anyone has had a chance to see it up close, and, as Stuccoman asked, am also wondering how they deal with flashing penetrations, etc..

I could have asked this over on my building science forum at JLC, but I asked it here because a few of the regulars over there tend to go off on blanket condemnations of products with dissertations that would make housewhisperer's look short by comparison, and they've worn me down to the point where I'm not willing to wrangle with them anymore. Hopefully, those answering here can be a little more analytical and open minded.

ONE TEAM - ONE FIGHT!!!

Mike

Link to comment
Share on other sites

With this product, when the drainable material is punctured by the shank of a nail holding the siding on, doesn't the water draining through the tiny channels in that material drain directly onto the shank of every nail as it finds it's way to the bottom of the wall?

Hi, Mike

I'm skeptical regarding the idea of water "draining" down out of a material that thin, porous though it may, when it is sandwiched between the sheathing and the siding.

Link to comment
Share on other sites

Okay,

Yeah, I saw all of that. It answers your question about stucco, but that wasn't the point of my original post, which was to find folks like Scott who've actually seen it and to ask them to proffer their opinions about what they saw. I've seen a lot of flashing details instructions in a lot of systems. What's prescribed and what they do in the field can be two different things and I'm wondering about what folks are seeing out there. I haven't seen it, so I don't have the luxury of looking at it up-close and comparing what's been done to how the manufacturer says it has to be done, so that's why I asked the original question.

I never asked about stucco or E.I.F.S. because I'd seen that in the instructions my first read through. Sorry I didn't respond directly to your question earlier.

ONE TEAM - ONE FIGHT!!!

Mike

Link to comment
Share on other sites

Originally posted by roadguy

Hi, Mike

I'm skeptical regarding the idea of water "draining" down out of a material that thin, porous though it may, when it is sandwiched between the sheathing and the siding.

Nah,

I'm not skeptical about that. I've stood on the south side of 100 year old homes here in the driving rain, where the only thing behind the clapboards is a thin layer of rosin paper, and I've watched water drain out from behind the claps and down the sides of foundations. I know that water gets into walls and I know that it drains out and that the concept works. I just have to wonder about this concept.

I happened to look at some of that drainable wrap one day when it was raining hard and the siding hadn't been installed. Sure, it drains, but at the same time the little openings in it were acting like a kajillion little open straw ends and a certain amount of water was being held in the material by adhesion and surface tension. When that stuff is sandwiched behind siding, won't the tendency for that material to allow water to cling to it remain, and, if so, how is that going to affect the Advantech where the nails split the face and pass through it?

We have a lot of water here (15.33 inches during November) during certain parts of the year. I've seen Advantech hold up well during the building process without swelling and deformation, but that is usually months versus the years the product will be behind the siding.

This green stuff has only been out for about 3-4 years, so it makes sense, at least to me, that they can't possibly have any actual long, long term test results of what's going to happen when you glue this stuff to the face of the OSB and leave it in a wall system for 20 years. That's what's niggling at my mind.

Then again, I guess they'll never know what the long-term results will be, unless they're willing to put a wall together and leave it out for 20 years, before putting it on the market. That sure isn't going to make any investors happy, so they make the public the test bed.

ONE TEAM - ONE FIGHT!!!

Mike

Link to comment
Share on other sites

AH, the importance of complete and concise composition of sentences cannot be over-emphasized. I meant that I was skeptical regarding the idea that all of the water would drain out. My concern centers around the idea that, at some point, the cohesion (not adhesion, BTW) inherent to water molecules would overcome the force of gravity and allow a certain percentage of the moisture to remain in the pores of the porous material. Unless there is some kind of osmosis-type action going on within the material to draw all of the moisture downward, then there will be some retainage. I believe that means that we are thinking similarly.

Regards the using public as guinea pigs, snake oil salesmen of the past only wish they could have had the lawyers some of these companies get ahold of.

Link to comment
Share on other sites

Hi,

Okay, I understand where you're going, and I agree, we are thinking similarly.

Except, that is, about the cohesion/adhesion thing. I'm going to have to, as the Myth Busters guys says, reject your reality and substitute my own. I meant to say adhesion.

Initially, I was going to say capillary action, but since these tiny openings are not continuous and are the product of a weave between different materials, I used adhesion instead. I don't see how water and wrap can cohere because they don't molecularly cohere to one another. In my mind, mortar is held together by cohesion but it adheres bricks together. Water clinging by surface tension to a surface isn't, in my mind, cohering as in part of the mass. It's simply adhering to the surface.

Maybe I've got it backward, but in my mind it's not. Anyway, you understood where I was going, so let's not get off on a long tangent about that and let's stick to the product.

ONE TEAM - ONE FIGHT!!!

Mike

Link to comment
Share on other sites

  • 1 year later...

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...