soft roof on alpine 3450RL

[matstam13]

went up on the roof of our new alpine last night and noticed it to be kind of spongy when you walked on it until you got to one of the cross bars is this normal? we just switch from a motor home to the 5th wheel and the roof of the motor home was solid with no give, so i'm a little curious as to why or what the difference is

[sandy43]

I have a new Alpine and have walked all over the roof and hadn't noticed anything different from previous 5th's. I do wear sneakers, which are kinda spongy. Hopefully other Alpine owners will drop by and give you their opinion.

[SteveC7010]

Originally Posted by matstam13

went up on the roof of our new alpine last night and noticed it to be kind of spongy when you walked on it until you got to one of the cross bars is this normal? we just switch from a motor home to the 5th wheel and the roof of the motor home was solid with no give, so i'm a little curious as to why or what the difference is

Is your roof "spongy" all over or just in a few spots? If it is just a few places, it may be a sign of leakage and damage to the underlayment.

However, if it is uniformly spongy across the whole length and width of the roof, read on:

Some rigs are built with 1/2" or thicker plywood under the membrane and are considered to be "walk on" roofs. However, others are built with materials that are thinner and are not recommended for walking on without extra support like a piece of 1/2" plywood large enough to span two or more roof joist intervals. On some product lines, the walk on roof is an option, but is standard with others. The thinner roofs are fine for snow load because it is uniform across the whole roof.

My '99 Sunline had the thinner roof. The Dicor membrane was bonded to a sheet of material not unlike an industrial grade of shirtboard about 3/16" thick. This was then laid down over 1/4" luan which was fastened to the roof joists. It worked fine as a roof, but not as a place to walk.

If you want to verify how your roof is constructed, drop the the inside plastic frame of one of the roof vents. You will be able to see the roof construction with a little poking about.

[therink]

I believe most late model Keystone have 3/8" roof decking. I know that is what I have and it gives a bit when walking between the trusses. I wouldn't consider it spongy though. When on my roof, I just make a point to spread out my weight and walk gingerly. As long as you don't hear any cracking of the decking, I wouldn't worry about it. If you have isolated soft spots due to water damage, that is a whole other thing.
Steve

[matstam13]

its not isololated it was everywhere i walked. there is no cracking sound which is good, its just diffrent then what i am used to and made me a bit paranoid. i will look up into the vent and check it out. i dont want to spend much time up there but its nice when your trying to wash it. thanks for the info

[steamfitter78]

i have a 3450 rl also. After one trip on it, i am afraid to go back. It could be my trim 235 lb. frame but my roof is soft all over. i will wash it off a ladder.