RV Side Wall Bulge

redboots · 01-30-2009, 01:25 PM

I recently purchased a used '08 National Surf Side with 2 slides on the same side. I noticed something very peculiar on the side that does not have any slide on it. It's a big flat panel and when it warms up in the sun it bulges out about a 1/2" to 3/4". I noticed it when I went to put the awning out. There is a large locking screw on the awning rail and when the sidewall is cool there is about 3/4" between it and the side wall. When it warms up, the sidewall touches it. On the inside there is a closet in the area of the bulge. Cool, the closet dividers are tight against the sidewall, when it bulges out there is a good 1/2" gap between the inner sidewall and dividers. All outside seams at roof, floor moulding, and rear cap are tight and show no signs of stress. Anybody else experience this with any make or model, and if so how was it corrected??

RedneckExpress · 01-30-2009, 01:41 PM

Is your Motorhome sided with Filon, or is it a solid fiberglass construct?

redboots · 01-30-2009, 01:50 PM

I really have no idea what Filon is, but it appears to be a composite panel with a fiberglass type material on the outside and paneling inside with a sandwiched insulation layer in between. It appears to be made in one continuous sheet for the whole side of the motorhome and then cut-outs for doors and windows, etc.

Pusherman · 01-30-2009, 02:40 PM

Jim,

It's possible it's a delamination of the exterior skin from the sidewall. Normally you could make a claim with the manufacturer, but with National out of business, this will not be possible.

Depending on the location of the 'bubble' where it's separating, a good RV shop can peel the skin back and re-glue the skin. If it's not close to a seam, this may be impossible.

The wall then can be repaired by a body shop, but this repair will not be cheap, but do-able.

Good luck!

redboots · 01-30-2009, 04:26 PM

Thanks Don, The skin does not appear to be delaminating. The entire wall, both outside and inside are bulging outward about the same amount. In other words, the outside skin moves out about 3/4" until it touches the awning knob, and the inside wall also moves away from the interior closet partitions. I can't believe there is that much movement with simply sunlight warming it. Can't imagine what will happen when it hits a 100 degrees here.

**RV Wizard** · 01-30-2009, 10:23 PM

I am wondering if this is a cause of leveling jack movement and the frame is twisting? How many days are you parked in the same spot and does the wall return to normal position at night and bow back out the next day? If so then it can not be the jacks settling. Have you had anyone look at the frame? This could also be a possibility. Give us as much detail as you can so we can be of more help.

DSouthw524 · 01-31-2009, 02:40 AM

Soundss like there is heat expansion involved. There may not have been any allowances made for the materials to move in the heat.

redboots · 01-31-2009, 04:29 AM

Thanks for your response Mike & DSouthw524. I don't think this has anything to do with the jacks or frame twist. Keep in mind it is an '08 model with only 5000 miles on it. It appears to be heat related to the right side panel. If it is cool and in the shade there is no movement. If you turn the RV around so that side faces the sun, it immediately starts a popping sound and within 15 minutes the panel is bulged outward. Turn it back around again and as the panel cools it contracts to original position. So far, there doesn't seem to be any effect to any of the exterior seams, but it's worrisome. You wouldn't notice it if I didn't point it out, but once you see the movement in the panel it's hard to believe. And, it's not even hot here yet. Inside, there is a closet and TV shelf pocket on that wall. When the panel moves outward you can stick your fingers in between the horizontal and vertical closet partitians and the inside wall panel, when cool they are tight against the panel indicating about the same amount of movement to both the exterior panel and the inside panel. That would suggest to me that the panel is NOT delaminating, just moving in and out as a unit. I just can't understand how such minimal heat could cause so much movement?

bldrbob · 01-31-2009, 05:33 AM

Sounds like the fiberglass side expands more than the plywood side so it bows.If the closet wall is strong enough where it touches you could try gluing.Put side in sun till it goes out and squeese some liquid nail in the space. Then turn coach around to let side cool and go back.It might just pull plywood from foam and make it worse.
BOB

redboots · 01-31-2009, 06:25 AM

This is a guess, but I think there must be some wood furring strips in the wall between the outer and inner panels. As the wall bulges and the inside gaps open in the closet, you can see some grabber screws showing that appear to be there to hold the closet partitions to the wall behind it. I can't imagine the factory would simply run the screws into the paneling and expect it to hold anything. As the panel bulges out, it pulls the screws out of it.

Max Hubrich · 01-31-2009, 10:21 AM

If it were mine-- I'd try Bob's (bldrbob) idea. No screws or clamps required-- Let the sun and the shade do the work, what have you got to lose? Sounds like a winner for around 10 bucks, or less---

Good luck,

redboots · 01-31-2009, 11:06 AM

The bulge is about half way up the panel from the floor line. It's almost like there is no stud in there. I'm worried about using adhesive to attach the inner wall to the cabinet partitions because I'm afraid it may delaminate the wall from the insulation and outer panel. Right now, both sides seem to move about the same amount. I think I'm going to remove some of the closet interior paneling and see if I can get a better idea of whats going on.

bldrbob · 02-01-2009, 12:09 PM

I think the way these walls are made there are no studs,just panels laminated to both sides of the foam core.Like a bimetal thermostat one side expand more than the other and causes it to bend.Possibly slitting the plywood horisontally would release the inside tension and allow the wall to grow without bowing.A strip of trim could cover the slit.I think if it were mine I would ignore it cause like I said before the cure might be worse than the problem.
BOB