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Old 06-01-2018, 07:48 AM   #1
DownEastGC
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GoBoard, moisture sandwich

Hi All,

I've been lurking here for years. Couldn't resist posting this. I've used the JM goboard manual as a reference more times than I can count, I never noticed this before...
Is it just me or are they implicitly suggesting you use kraft insulation behind their goboard
Don't get me wrong - I love GoBoard. It's been my favorite backer for years now. Maybe I'll send them an email lol
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Old 06-03-2018, 01:01 PM   #2
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Some homes use the paper backed insulation as part of the vapor protection for the home. Is there any manufacturer that warns against installing their waterproofing material over this type of insulation?
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Old 06-03-2018, 03:22 PM   #3
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Chris, in your part of the world I expect your building code actually requires a vapor barrier on the inside of exterior stud walls and I doubt the Kraft-backed insulation would satisfy that.

That said, the ICC-ES Report (ESR-3767) specifically requires that a vapor barrier be used behind the GoBoard in shower applications or:

Quote:
Originally Posted by ESR-3767
4.2.7
Showers:

When the GoBoard® backer boards are utilized in wall and ceiling applications in showers, a manufacturer approved vapor barrier shall be installed directly over the wall studs and ceiling framing behind the GoBoard® backer board per the manufacturer’s instructions or a manufacturer approved vapor barrier or waterproof membrane shall be installed over the external surface of GoBoard® backer board per the manufacturer’s instructions.
I can't see that makes it of any greater value in use as a shower backer board than a CBU except for weight, perhaps. Not knowing the relative pricing, I can't speak to that as an advantage at all.

And for a waterproof joint application (separate from shower application?) it requires:
Quote:
Originally Posted by ESR-3767
4.2.2.4
Waterproof Joint:

For a waterproof joint installation, use the mortar and tape method in Section 4.2.2.2 to seal the joints, then apply two coats of a liquid
waterproofing membrane to the joints and fastener locations ensuring the liquid waterproofing membrane extends a minimum of 1-inch beyond the mortar.
That means you gotta mud and tape the seams and wait for that to cure before applying the required waterproofing membrane.

'Fraid I'm just not seeing any big advantage to the product. What is it you find so attractive about it?

Are you installing it per the manufacturer's instructions?
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Old 06-04-2018, 06:17 AM   #4
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Johns-Manville makes and sells insulation.

Actually, having a barrier directly behind the waterproof board doesn't bother me much. I can't for the life of me see why it would be required, though.

GoBoard is a good product. I met the GoBoard team at Coverings. They and the company are relatively new to the tile business. Some of the specs might change as they get going.
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Old 06-04-2018, 10:37 AM   #5
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Well I stand corrected! - I have always been under the impression that no vapor/moisture barrier should be behind my showers, exterior or interior wall. I usually just put a few cuts in the paper if it's kraft faced.

Hope I didn't mislead anyone
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Old 06-04-2018, 10:42 AM   #6
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Quote:
Chris, in your part of the world I expect your building code actually requires a vapor barrier on the inside of exterior stud walls and I doubt the Kraft-backed insulation would satisfy that.
Yep! I've been trained that kraft insulation is an acceptable vapor barrier on the interior of homes. However, any new construction we do we put a vapor/moisture barrier on the exterior now, Tyvek, Henry Blueskin, what-have-you, as well as the kraft faced on the inside.
I can't speak to what the code book actually says regarding kraft faced insulation as a solo barrier. Usually when it does come up (remodels) it's a "best effort" type situation, so we'll put it in during a remodel.
I've also seen some insulation crews around here do unfaced and cover it with 3mil clear plastic on the inside of the studs. We have a lot of old barns that get refinished into living space. Often they just have the clapboards nailed right to the rough cut framing. So the insulation stays on the "wet" side. Not my preference, but beats pulling all the siding off, I suppose.

Quote:
GoBoard is a good product. I met the GoBoard team at Coverings. They and the company are relatively new to the tile business. Some of the specs might change as they get going.
Definitely. It's my favorite yet (although I haven't used Wedi yet).
I recently moved to Maine from Vermont. There's no local vendor that carriers GoBoard here (that I can find) so I've actually been having it shipped in to my house and just keep stock
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Old 06-04-2018, 10:48 AM   #7
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Quote:
That means you gotta mud and tape the seams and wait for that to cure before applying the required waterproofing membrane.

'Fraid I'm just not seeing any big advantage to the product. What is it you find so attractive about it?

Are you installing it per the manufacturer's instructions?
Well apparently I'm not! Now I'll have to do a little research. I went to a sales pitch/hands on training at my tile store - not going to name names here, don't want to make any implications.
I was told that the GoBoard is waterproof and only needs waterproofing at the seams and fastener locations. So what I've been doing is alkalai resistant mesh tape at seams & corners, 2 coats hydroban at seams/corners/fastener heads, wait 24hrs for full cure, then tile right over.
I was under the impression that vapor barrier was only "required" for steam showers when using GoBoard.

Where'd you get that reference manual, Cx?

edit: NVM i see your link: http://www.jm.com/content/dam/jm/glo...s/ESR-3767.pdf
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Old 06-04-2018, 11:14 AM   #8
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Sorry for the multiple posts - Now I'm worried I've been doing my showers incorrectly! I'm feeling conflicted; the verbal instruction I got on GoBoard and the manuals seem to me misaligned with the ICC-ES report.

I'm actually about to put some GoBoard & tile on here this week, got any advice? Should I call my regional JM rep and see what they have to say?
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Old 06-04-2018, 12:57 PM   #9
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I'm also curious on how this gets hashed out. I normally install 6 mil poly behind my mud, and also thought a kraft paper on the insulation was doubling up.
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Old 06-10-2018, 12:51 PM   #10
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That's strange because the installation instructions make no mention of a vapor barrier unless the application is a steam shower.

I've attached some screenshots of their website (1&2) and the installation instructions (#3).

The installation instructions don't list "wet areas" as an application- instead referring to "walls". However, the implication is clearly that the board is waterproof by adding the sealant.

What do you guys think the reason is for the incongruency?

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Old 06-10-2018, 03:15 PM   #11
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Quote:
Originally Posted by Jim
The installation instructions don't list "wet areas" as an application- instead referring to "walls". However, the implication is clearly that the board is waterproof by adding the sealant.

What do you guys think the reason is for the incongruency?
Possibly to dupe the unsuspecting into using it in showers without actually ever having told them to do so, therefore relieving them of any potential liability?

Or perhaps all the inconsistencies are just the result of honest mistakes on the part of the advertising department? Or miscommunication between the advertising department and the technical department? And just coincidence that all the discrepancies seem to lean in the same direction?

I dunno. I find it a bit worrisome, though.
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Old 06-10-2018, 05:02 PM   #12
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So I looked a little bit closer at this and here's a couple of screenshots from their own GoBoard brand sealant which has only been out for about a year, or so http://www.jm.com/content/dam/jm/glo...NTAlisting.pdf:

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Additionally, before they had their own sealant they had a recommended sealant and waterproofing list for how they recommend their board be waterproofed.

So JM is clearly making the claim that their board is waterproof by simply applying a sealant to the seams and fasteners.

The NTA report, which is newer, mentions using GoBoard brand sealant.

Quote:
Originally Posted by bold is mine
6.4 Water Resistive Construction.
6.4.1
The following construction shall be used for GoBoard® when used in interior wet areas such as showers and baths. GoBoard® may serve as the waterproof barrier when installed in the following manner;
6.4.1.1
1/4-in and thicker GoBoard® panels shall be layed out with an 1/8-in. gap provided at all joints.
The gap is filled with Johns Manville GoBoard® Sealant, a silyl-modified polyether hybrid sealant meeting ASTM C920, Type S, Grade NS, Class 25 or better.
The sealant is to be spread over a 1-in. area adjacent to the seam on each piece of GoBoard®.
The same sealant is used to cover a 1-in. diameter area over all fastener heads.
6.4.1.2¼-in and thicker GoB
The ICC report is to be updated this month and I'm wondering if they will incorporate GoBoard sealant in their updated report, or not.

Anyway, I'm not worried about it anymore but everyone needs to do their own research and come to their own conclusions.
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Old 06-11-2018, 06:12 PM   #13
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GoBoard Installation

If I can find a distributor I'll give this a try. No taping necessary.

https://www.youtube.com/watch?v=B-AOAAkUqlk
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Old 06-12-2018, 09:12 PM   #14
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Goboard

I use the Goboard pretty much on a daily basis and have been to JM for a tour, and helped them with a mockup for a Robertson test...it is my wallboard of choice if you can find it in your area it is a pleasure to install compared to cement board..My experience comes from the engineering staff at JM and they recommended polyurethane sealant between the joints with a 1/8 inch gap between sheets...I use a 3 inch putty knife and spread the sealant to cover a inch on each side of the joint and seal all screw penitrations ..keep in mind the skin of the goboard is absorbent and not waterproof the foam core is the waterproofing...this is closed cell foam no moisture or vapor gets thru the core. This is why seams and penitrations are critical and a additional vapor barrier over the studs is a belt and suspenders installation to insure not a molecule of h2o gets to the studs.
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Old 06-13-2018, 03:30 PM   #15
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GoBoard ICC-ES Report

The ICC-ES report section 4.2.7 fails to mention the vapor barrier is for steam showers only.
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