Filling holes

[stiles watson]

I ran across a Monty owner that had filled the holes in his "basement" with spray insulation. These are the holes through which the plumbing, water lines, and air ducts pass through the floor decking. On the surface, it appears to be a useful improvement to stop heating and cooling losses and to prevent vermine from having easy access to the nether world of the rig. I am interested in other's opinions of this change.

[foggyb]

Hi stiles. We had a 36' coachman 5er b4 our monty. The previous owners had done that. My opinion was that it was a mess and looked awful. Dan

[t1mrtork]

I agree. The expanding foam will stand out on the dark surface of the bottom cover. I will have to have our 5er sit out this winter and was thinking of using a black silicone so it wouldnt stand out and could be cut if you had to remove the bottom cover. Just athought.

[sreigle]

I did that both in the basement and in the bellypan. It's surprising how many openings there are.

Open both basement doors so light gets in. Go back in the coach and look under the pocket door between upstairs and downstairs. If you see light, you may want to fill that area. On ours it was along a seam between basement vertical wall and ceiling so was not real obvious. But it sure let in a lot of cold air. It can be filled from inside the basement.

Anywhere I can stop outside air from getting into the coach during this cold weather I'll do it.

If you have a 3295RK post back and we'll tell you another area you need to deal with if in cold weather -- along the back wall in the water heater compartment.

[BillyRay]

just becareful with that expanding foam as it will expand other things as well. if you think you have a gap and want to fill it with foam, the foam is likely to make your gap bigger! don't ever use it around your windows!

[t1mrtork]

BillyRay is right, when the building for my buisness was being built one of the workers had gone around the doors and filled all the gaps with evidently alot of foam because when it expanded and dried it had pushed the tin siding out from around the edges of the door and once it is dryed its about inpossible to remove without taking tin work off and removing it as it gets pretty hard.

[sreigle]

Good advice, thanks. In this case there's plenty of open room in the belly area and basement. But this is something to keep in mind.

[Montana_2694]

Just curious..... is there an alternative to expanding foam for the holes?

[stiles watson]

Talked to a service guy and he, too, advocated caution in using the expanding foam. His suggestion was to do a little at a time, i.e., do the job in stages to control the amount of the stuff used and the pressures that might be exerted by the expanding material.

[Montana_1985]

There is also a low expanding foam on the market as well. It was developed for just these types of problems that the high expanding foam creates. I've used it before, and it only expands about 50% of volume. Also, if u do get some unsightly excess, just sculpt it with an exacto knife, and paint it to match the underbody color.
I've used this stuff on my house trim where the bottoms of my wood exterior were rotting away. Rather than replace the 10+ ft. of wood trim, I "foamed" the missing area of wood, then knifed away the excess and then painted it. Can't really tell by casual inspection if it's wood or not !!!

[BillyRay]

you can use it, just be careful. use it a little at a time.

[Dave e Victoria]

I've done this on our Montana but also advise caution. On expected things can occur. The foam sets up based on the amount of moisture in the air. Some years ago< I used it in the traiing edges of the control surfaces of an airplane I was building. The idea was that it would prevent oilcanning which might result in flutter. It did that just fine. However, this work was done in New Mexico. I later moved to Minnesota and the stuff started working again. It made some swells in the rudder surface and leaked out the bottom onto the floor. No big deal but it surprised me and remeinded me that this stuff is not very well behaved.