Good Sam Club Open Roads Forum: Adhesive for insulation foam board
Open Roads Forum Already a member? Login here.   If not, Register Today!  |  Help

Newest  |  Active  |  Popular  |  RVing FAQ Forum Rules  |  Forum Posting Help and Support  |  Contact  

Search:   Advanced Search

Search only in Do It Yourself Modifications a...

Open Roads Forum  >  Do It Yourself Modifications and Upgrades (DIY)

 > Adhesive for insulation foam board

Reply to Topic  |  Subscribe  |  Print Topic  |  Post New Topic  | 
Page of 2  
Next
Flyin Finn

Battle Ground, WA, USA

Senior Member

Joined: 12/31/2003

View Profile



Good Sam RV Club Member

Offline
Posted: 11/21/22 06:08pm Link  |  Quote  |  Print  |  Notify Moderator

I am redoing a couple sections of the roof on my Fifth wheel.

I removed the membrane of the whole roof. Then I removed the 1/4"plywood and the 2.5" insulation foam from the sections I am replacing, leaving the ceiling panel intact (the way the roof is constructed on this Rockwood Signature Ultralight is that the ceiling panel, insulation and plywood are sandwich-glued together).

I plan on gluing a 1.5" thick insulation panel to the ceiling panel, with through cutouts for the duct channels and the speakers, and then gluing a 1" whole insulation panel on top of the 2.5" panel (matching original thickness dimensions).
Then I would glue the plywood on top of the insulation panels.

My issue is that I can't quite figure out what glue to use.

I plan on using either the R-tech or the Owens Corning panels.
The R-tech panel instructions says to use non-solvent urethane adhesive, which comes in caulking gun tubes. My understanding is that the panels have foil on one side, but not the other side, and I am wondering if each side requires different type of adhesive? Also, instructions tell to apply the adhesive in beads, some distance apart.

But I would prefer to bond the surfaces at 100% coverage. Does any of you know if there is a suitable adhesive, for example in 1 gallon buckets, that I can use to roll (or spray) on for full coverage? Or any other suggestions for gluing the panels together?
I haven't been to the HD store yet (Home Depot, Lowes). I guess I can ask there, if there are knowledgeable staff on site. Thanks for any help.

[image]


97 Silverado 2500HD Ext Cab 2WD 7.4L towing a 08 Rockwood 8281SS Fifth wheel


agesilaus

North Florida

Senior Member

Joined: 05/06/2008

View Profile



Good Sam RV Club Member

Offline
Posted: 11/21/22 06:46pm Link  |  Quote  |  Print  |  Notify Moderator

Liquid Nails works, get it at a hardware store.


Arctic Fox 25Y Travel Trailer
2018 RAM 2500 6.7L 4WD shortbed
Straightline dual cam hitch
400W Solar with Victron controller
Superbumper


EricKim

Boston

New Member

Joined: 11/21/2022

View Profile


Offline
Posted: 11/21/22 07:53pm Link  |  Quote  |  Print  |  Notify Moderator

How long does the whole process take? I want to try it too

Flyin Finn

Battle Ground, WA, USA

Senior Member

Joined: 12/31/2003

View Profile



Good Sam RV Club Member

Offline
Posted: 11/21/22 08:42pm Link  |  Quote  |  Print  |  Notify Moderator

EricKim wrote:

How long does the whole process take? I want to try it too


Didn't take too long to remove roof accessories and the membrane (destructing the membrane in the pricess). I only took out 2 sections of the plywood, little trickier.
The time consuming part was removing the styrofoam, separating it from the ceiling panel without damaging the panel.
I have only worked on it on my weekends, a few hours per day, for a few weeks.
Count on it taking longer than you plan. My guess is this could be 3-4 days if you work long days.
Need 2-3 people to install new membrane, if you are going that route.
And after all that, cleaning out the old lists and reinstalling them will take time.

So the whole process? I will probably spend more than 40 hours. That's my guess. I'm not in a hurry either, though.

JBarca

Radnor, Ohio, USA

Senior Member

Joined: 12/16/2004

View Profile





Offline
Posted: 11/21/22 09:40pm Link  |  Quote  |  Print  |  Notify Moderator

While I have done the foam board roofing, when I have been in a bonding unknown situation what is the right product, I call the manufactures of the adhesives and ask for tech service. It is a hit or miss on who you get, and you may need to do a few companies, but here are a few to try.

Tell them the 3 substrates you want to bond to. Bare virgin wood and wood with old glue on ceiling board are two very different surfaces. Make sure you tell them, as one is porous and the other sealed shut from the old glue and the foam board is in the middle. It may be that you need two different adhesives pending the new plywood or the old ceiling board.

Loctite Corp, they are into a lot of adhesives
https://www.loctiteproducts.com/en.html

3M adhesives. 3M is into a lot of adhesives across many different industries.
https://www.3m.com/3M/en_US/p/c/adhesives/

Sika adhesives
https://usa.sika.com/

They are just a few of the bigger ones. Also make sure you let them know the application of the joint. This is more then just being able to bond foam board to wood. The roof flexes as the whole camper rolls down the road. The adhesive needs to not shear off in the event of a twisting action of the camper. As the roof load increases if you are in a winter/snow situation, the roof will compress and go below freezing. They make adhesives to deal with a lot of conditions, but the tech on the phone needs to know the application and may have very little knowledge of what stresses an RV can create. So you have to help ask good questions to hopefully get back good answers.

I do agree with you on wanting to try to get more close to total coverage on the adhesive. The bond ideally is working on 100% of the surface area to make it the most strong. Beads of glue works OK if you are just holding a panel to a wall. In this case, the foam board is structural in the ceiling/roof.

Also ask about compression to make the bond. Since the roof is still on the camper, it is going to be harder to create a 100% clamp like at the RV factory to clamp the sheets while the glue cures. The clamp you can create or not, need may change what adhesive is used.

Let us know how to make out.

Hope this helps

John


John & Cindy

2005 Ford F350 Super Duty, 4x4; 6.8L V10 with 4.10
CC, SB, Lariat & FX4 package
21,000 GCWR, 11,000 GVWR
Ford Tow Command
1,700# Reese HP hitch & HP Dual Cam
2 1/2" Towbeast Receiver

2004 Sunline Solaris T310SR
(I wish we were camping!)


Cummins12V98

on the road

Senior Member

Joined: 06/03/2012

View Profile


Offline
Posted: 11/22/22 07:57am Link  |  Quote  |  Print  |  Notify Moderator

35 years in Commercial Construction, I can tell you Liquid Nails is childs play compared to LocTite PL3. With it you won't want to tear your own work apart!!!


2015 RAM LongHorn 3500 Dually CrewCab 4X4 CUMMINS/AISIN RearAir 385HP/865TQ 4:10's
37,800# GCVWR "Towing Beast"

"HeavyWeight" B&W RVK3600

2016 MobileSuites 39TKSB3 highly "Elited" In the stable

2007.5 Mobile Suites 36 SB3 29,000# Combined SOLD

JBarca

Radnor, Ohio, USA

Senior Member

Joined: 12/16/2004

View Profile





Offline
Posted: 11/22/22 09:49am Link  |  Quote  |  Print  |  Notify Moderator

Flyin Finn wrote:

I am redoing a couple sections of the roof on my Fifth wheel.

I removed the membrane of the whole roof. Then I removed the 1/4"plywood and the 2.5" insulation foam from the sections I am replacing, leaving the ceiling panel intact (the way the roof is constructed on this Rockwood Signature Ultralight is that the ceiling panel, insulation and plywood are sandwich-glued together).

I plan on gluing a 1.5" thick insulation panel to the ceiling panel, with through cutouts for the duct channels and the speakers, and then gluing a 1" whole insulation panel on top of the 2.5" panel (matching original thickness dimensions).
Then I would glue the plywood on top of the insulation panels.

My issue is that I can't quite figure out what glue to use.

Thanks for any help.

[image]


Hi Flyin Flinn,

I keep looking at the way your roof is made. While I know the RV industry has gone to glued sandwich flooring (and pending brand, issues with that) I did not realize they went to the roof with it.

The roof appears to be a flat roof? Yes/No?

By your sig, it seems your camper is a 2008 model. And I'm assuming the reason you are doing the roof repair is due to a leak? or was there another reason?

I'm not trying to talk you out of what you are doing, but I will throw this out as, friendly ideas to think through and convince yourself you can actually make a good repair that will last.

Up above in blue highlight, there may be a word or 2 missing, but what I gather you are doing is bonding a 1" thick and 1 1/2" thick foam panel to create 2 1/2". Then glue the ceiling and then the roof top plywood to blend into the part of the original roof.

I did not pick up on that before, but now realize it. You now have 3 glue joints that have to have a perfect bond, foam board to old ceiling glued luan, foam board to foam board, and then foam board to new plywood. Just thinking about that makes me nervous. There are no rafters in this setup. Those 3 bonds create the entire structural load carrying design. All 3 bonds have to be right to hold the load.

At the factory they may use a vacuum chamber or pinch rollers to create the 100% compression of the panels while the adhesive is curing, and it seems it has lasted since 2008. Once past the right adhesive to use, how do you plan on getting clamping done? The 2 foam sheets and the plywood you can do this off the roof, down on the ground and create some form of weighted clamp all over. And that "might" be enough, OR add an 1/8" bare luan sheet for the ceiling side and bond that down on the ground also. Then put the whole new sandwich up on the roof and bond to the old ceiling board is not really structural any more, it is just to hold the ceiling board to the roof system. Adding the new 1/8" luan sheet eliminates the need to create a 100% structural bond to the old ceiling.

The 4 x 8 bottom layer and the 1/4" top plywood layer create rigidity in the sandwich. By having a known good bond of both top and bottom layer, you have a fighting chance your repair might last as long as the original.

What foam board are you thinking of using?

Is it the closed cell Owens pink foamboard? This stuff? They offer 2 types, have to sort out which on the roof works better.
https://www.owenscorning.com/en-us/insulation/products/foamular-250

If that is it, they do make 2 1/2" foam board. While you may have to hunt to find it, it gets rid of one of the bonds in the sandwich.
See here https://dcpd6wotaa0mb.cloudfront.net/mdm........50-XPS-Insulation-Product-Data-Sheet.pdf

They also talk about adhesives and what not to use as it can affect the foam board, Have a look if you have not seen this.

Here is another thought, if you feel you cannot create the right structural bond, suggest making a test sample and trying to break it compared to the original, have you thought of creating a rafter setup with wood decking on top and no foam board? This might require the whole roof to be changed, but you gain an arched roof. I cannot see what the top wall plate looks like, (the rafters rest on, attach to this) but if going the rafter route, I have lots of pics of older campers I have restored, all apart that used the older wood rafter setup. From the pics, you can see how they used to build RV roofing to help sort out how this might work for you. Glad to share if you want to consider this route.

Hope this helps, just trying to help you think through the whole concept.

John

LMHS

NM

Full Member

Joined: 06/27/2022

View Profile



Posted: 11/22/22 10:02am Link  |  Quote  |  Print  |  Notify Moderator

Use Loctite PL 300. It's specifically for rigid foam insulation. Basic Liquid Nails will "eat" rigid foam board. Yes, it will stick it up there but the solvents will melt the backside if you put too much in one place. Which kinda defeats the purpose of the insulation.

https://www.homedepot.com/p/LOCTITE-PL-300-10-fl-oz-Foamboard-Adhesive-1421941/202020476

PastorCharlie

NC

Senior Member

Joined: 03/28/2004

View Profile





Offline
Posted: 11/22/22 02:53pm Link  |  Quote  |  Print  |  Notify Moderator

Use a temporary sheet of plywood inside ubder the ceiling supported by temporary bracing down to floor. This will give support as you finish work on roof. Once roof is replaced use weights on top pressing it down to ceiling inside. This will be like clamping the ceiling and roof together. Best to have all material ready and assembled before any glue begins to cure.

Loctite PL3 should work for all your needs. Read the instructions on the tube. Using a chaulk gun and an old brush will insure a 100% coverage of glue to all the surfaces.

Flyin Finn

Battle Ground, WA, USA

Senior Member

Joined: 12/31/2003

View Profile



Good Sam RV Club Member

Offline
Posted: 11/22/22 11:13pm Link  |  Quote  |  Print  |  Notify Moderator

Thanks for all the replies! I'm in the middle of a busy work week and won't have much time to go through all the comments and the suggestions at the moment. Hopefully this weekend i will find time to go through all the suggestions.
In short: yes it is a sandwich roof, not structurally strong even out of the factory.
I will experiment with foam board samplings and various adhesives and applications before putting it all together.
I won't replace the whole roof, except the membrane. Only the first 4x8 section in the front, and 2x8 section in the rear. Most of the roof is good and best to leave as it is.
Again, thanks for all the responses, i will have more time with a more detailed response after Thanksgiving.
The roof is flat. I believe level in the center, and slopes down toward front and rear.
There are no curved sections in any directions on the roof.

Reply to Topic  |  Subscribe  |  Print Topic  |  Post New Topic  | 
Page of 2  
Next

Open Roads Forum  >  Do It Yourself Modifications and Upgrades (DIY)

 > Adhesive for insulation foam board
Search:   Advanced Search

Search only in Do It Yourself Modifications a...


New posts No new posts
Closed, new posts Closed, no new posts
Moved, new posts Moved, no new posts

Adjust text size:




© 2023 CWI, Inc. © 2023 Good Sam Enterprises, LLC. All Rights Reserved.