Community Forums

thepilot · 11-17-2019, 05:47 PM

Is there any way to insulate a 1987 fiberglass motorhome without tearing out the walls?
thank you

skippy67 · 11-17-2019, 06:03 PM

It funny you just ask this question. I am about to add insulation in the nose of our fifth wheel Through the marker lights. In the sun, the front closet gets hot in the summer and cold in the winter, I took out the marker lights and could see the insulation blanket was in place but wasn't very thick. Home depot and lowes has a rental unit that is not very expensive to rent and they have the bales of fiberglass that gets fluffed after traveling 100 feet. They have adapters so you can fill smaller holes. I seems to me you might drill with a small hole saw on the inside of the RV at the top an inch and a half down where you could cover all the holes with a decorative trim piece. Maybe you could remove the windows to blow it underneath the window? That is just a thought. I have read the loose fill blown fiber glass doesn't settle. That's all I have.....David

thepilot · 11-17-2019, 06:27 PM

Thank you so much for your reply!! I have wondered about blown insulation...it just might work!!! Let me know how you make out if you try it!!
thanks again!!

Brob · 11-26-2019, 08:33 AM

I am renovating a 1987 class A motor home currently. I am adding an additional layer of 1/2" foam board to the entire interior of the coach. I gutted most of the coach to the studs, but there are large sections where this is unnecessary, so I'm simply laminating the board insulation on the outside of the existing Luan (on the interior of the coach) then laminating a new piece of Luan to the foam. I'm losing an inch of width, but the gain in comfort is immediately noticeable.
As Skippy mentioned, I am also adding a good bit of insulation to both the fiberglass nose and tail of the rig as they are quite poorly done from the factory.

I used the coach for a month long gig a while back, prior to completing the additional insulation. When the dew fell at night you could see the aluminum frame of the walls on the outside of the fiberglass, except where it had the additional layer of insulation.
Motor homes are notoriously under-insulated. I took the opportunity to bring mine up to participate and I am quite happy with the result.

thepilot · 11-27-2019, 05:20 AM

Sounds like a big project!! I am considering just adding the insulation to the existing walls and loosing the space inside. In a few instances, where I have had to remove wall pieces, I have only found little wisps of fiberglass insulation. On a few occasions, I have heard critters running around between the outer shell and the inside panels. I thank you so much for your advice and info about your project!! Sounds like you have a nice warm rig when you are done!!
Cheers!!

cwk · 11-29-2019, 11:34 AM

Quote:

Originally Posted by Brob

I am renovating a 1987 class A motor home currently. I am adding an additional layer of 1/2" foam board to the entire interior of the coach. I gutted most of the coach to the studs, but there are large sections where this is unnecessary, so I'm simply laminating the board insulation on the outside of the existing Luan (on the interior of the coach) then laminating a new piece of Luan to the foam. I'm losing an inch of width, but the gain in comfort is immediately noticeable.
As Skippy mentioned, I am also adding a good bit of insulation to both the fiberglass nose and tail of the rig as they are quite poorly done from the factory.

I used the coach for a month long gig a while back, prior to completing the additional insulation. When the dew fell at night you could see the aluminum frame of the walls on the outside of the fiberglass, except where it had the additional layer of insulation.
Motor homes are notoriously under-insulated. I took the opportunity to bring mine up to participate and I am quite happy with the result.

Brob: Thanks for sharing.

I have noticed a similar dew pattern on the side of our coach. We are currently remodeling the interior so this would be a great time to address the walls and insulation issues. We want to change/replace wallpaper anyway.

For the most part, the existing luan will stay. Except for some minor screw holes there does not appear to be a need for wall removal. That may change behind the kitchen cabinets once they get removed, but the majority of the walls are very sound. Adding insulation may work well. Losing the inch of width is a compromise for better insulation since some cold weather travel is in our plans.

How did you handle the added thickness of the insulation and luan around the windows? Did you remove the windows, add the boards, then reinstall the windows? Or, something else?

What type of foam board did you use? Was it faced or unfaced? Did it have a reflective side(s)?

Brob · 12-08-2019, 08:48 AM

I used unfaced foam, the pink stuff. I ordered a gallon of water based contact cement to glue it to the luan. I also used some gorilla spray adhesive as well. The gorilla spray was quicker for the installation, but you have to be careful not to get too much on any areas as it will melt the foam, perhaps it's the propellant. The contact cement works great, it's just far more time consuming. I got some ratcheting load bars that go inside the bed of a truck and used them to push plywood pieces against the foam to hold pressure as the glue set.

I removed the inner trim on the windows and cut a thin luan strip to cover the insulation edges around the windows, then reinstalled the trim. Once painted, it looked like it was supposed to be that way.

There's a night and day difference with the additional insulation. The heat and A/C run a fraction of the time as previously, and you don't "feel" the sun beating down on the rig.

cwk · 12-08-2019, 11:06 AM

thepilot: Didn't mean to hijack your thread. Hopefully I was able to add some value to the conversation.

Brob: Lots of great info in your posts.

I think I now have enough information to proceed with our coach. We are doing a major interior remodel including new cabinetry, appliances, lighting, wallpaper, flooring, etc. Now will be the perfect time for the insulation upgrade. Thank you!

thepilot · 12-09-2019, 04:03 AM

cwk...Thank you for contributing to the topic!! I was wondering about the windows myself!!
brob...very much appreciate the information you have shared about your project! Thank you for taking the time to share it with us all!!

cwk · 12-09-2019, 05:36 PM

Quote:

Originally Posted by Brob

I used unfaced foam, the pink stuff. I ordered a gallon of water based contact cement to glue it to the luan. I also used some gorilla spray adhesive as well. The gorilla spray was quicker for the installation, but you have to be careful not to get too much on any areas as it will melt the foam, perhaps it's the propellant. The contact cement works great, it's just far more time consuming. I got some ratcheting load bars that go inside the bed of a truck and used them to push plywood pieces against the foam to hold pressure as the glue set.

Brob,
The pink stuff is easy to find. The water-based contact cement, not so much. I will need to order it, but am not sure which product to use.

My online searching found a product by Dap, and a product by Wilsonart. The reviews on the Dap product were very mixed. There were not many reviews on the Wilsonart.

Which product did you use for the contact cement?

I am also thinking about laminating the new luan and the pink stuff into panels in my shop. I have a vacuum press that could keep uniform pressure on the sheets until the glue cures. Then I can use your method of the load bars in the coach to adhere the panels to the walls.

Brob · 12-10-2019, 10:55 AM

I used both the Dap Weldwood water-based contact cement and the 3M fastbond water-based contact cement.
The 3M was faster to flash off. They both seem to work well.