Billowing Roof!

fj12ryder wrote:

ScottG wrote:
You don't have to have loose edges - just a loose center area.
As you drive, the air moving over the top of the roof is moving faster than the air under it. The faster moving air has a lower pressure than the air underneath.
The result is "lift" and exactly how an airplance flies.

We've had this discussion before, you can't have lift without air underneath the roof trying to equalize the pressure. If the roof is billowing there is a area somewhere letting air get under the roof.

Of course any way you look at it, it is bad news. Sooner or later something will pull loose in a big way.

Air is underneath - it the atmosphere and it's everywhere on earth. The difference is it's not under pressure under there until you remove the pressure from the outside.
Just like our bodies will rupture in outerspace, that air is higher pressure than the outside.

We once had a car that had a vinyl roof. It would do the same thing. Dealer tried sealing it all around but since there was no leak, it never helped. Only removing it and re-gluing the entire "field" would hold it down.

Here is a simple explanation of how lift works: (technically refered to as the Bernoulli Effect).
Lift

I just came up I-75 seen 3 class c's newer looking that had bellowing roofs and one TT that looked like it was just attached around the edges. I am going for a ride tomorrow and have my wife follow down the interstate to see if mine is that way. Hope Not don't know what I would do though never had a leak so if it must have air under it somewhere Mistry to me.

ScottG wrote:
You don't have to have loose edges - just a loose center area.
As you drive, the air moving over the top of the roof is moving faster than the air under it. The faster moving air has a lower pressure than the air underneath.
The result is "lift" and exactly how an airplance flies.

We've had this discussion before, you can't have lift without air underneath the roof trying to equalize the pressure. If the roof is billowing there is a area somewhere letting air get under the roof.

Of course any way you look at it, it is bad news. Sooner or later something will pull loose in a big way.

Today meet a large "expensive" 5er on a 2 lane road. I was surprised how the roof was flapping over the center of the nose of the 5er. Look like it was moving up and down by 3 to 5 inches.

That flapping has got to stress/tear the roof even if the edges are still attached. . . . . :M

You don't have to have loose edges - just a loose center area.
As you drive, the air moving over the top of the roof is moving faster than the air under it. The faster moving air has a lower pressure than the air underneath.
The result is "lift" and exactly how an airplance flies.

The ones I saw were just like a big ballon about 1 to 2 feet above the RV roof. No loose edges...

were the edges actually loose or was it just a "bubble" caused by vacuum on a rubber/tpo roof?
bumpy

Saw this on a very expensive looking diesel pusher near Portland. Thought maybe cheaper trailers but apparently anything.

All of us tow oblivious to what's happening on our roofs. Never had one I could see from inside the truck.

A couple years ago I saw lots of the billowing roofs but have not noticed one recently. I would like to have someone follow me down the freeway and see if mine does it. Not sure it makes a difference though, only way to fix it is to replace it and glue it down correctly.