Sealing underside of Flagstaff pop up camper

[CastleRockcamper]

Just purchased a new Flagstaff T21DMHW camper and underside looks like treated plywood. I would like to know I could apply over the plywood to seal and make it more waterproof.

[GalsofEscape]

if I remember correctly -the manual for my 2010 Rockwood highwall stated not to seal the underside (traded the Rockwood couple of years ago). As the Rockwood and Flagstaff are twins - bet they are made of the same materials. I would check your manual.

[cavie]

Originally Posted by CastleRockcamper

Just purchased a new Flagstaff T21DMHW camper and underside looks like treated plywood. I would like to know I could apply over the plywood to seal and make it more waterproof.

If it's treated I don't know why you would need to but if you must, try Thompson's water seal. Use a hand pump tank sprayer.

[CastleRockcamper]

I am new to camping and may not need to seal the underside. Just want to do everything I can to preserve the camper. I have had some people recommend sealing all penetrations to keep out spiders etc and this may not be necessary on new campers.
Thanks for the reply’s!

[vinmaker]

The treated wood is supposed to be fine but I share your same feelings. I have been tempted to place some tyvek underneath to deflect most of the water and road spray. I would definitely not seal it with any type of waterproofing as they warn against it. Remember, the top side is sealed tight with vinyl flooring. Sealing the bottom would not allow the wood to ever dry out if water got in. And it WILL get in.

The Tyvek is supposed to be able to breath so I figured it could protect from direct road spray and then dry out. I never did it.

Vin.

[Amartin453]

I used Raptor lining on the metal frame and the entire underbelly. The only thing I left factory was the underside of the slide out beds.

[CastleRockcamper]

The Raptor lining is waterproof so wondering if this doesn’t affect the factory warranty. Something like the Raptor lining is what I would like to do to my camper. Thanks

[jimmoore13]

A hunch....

The underside of your camper is perfectly well ventilated. That means it dries quickly if it gets wet.

It's also treated from the factory. It may make more sense to inspect it about once a year...say when you lube things. As with the underside of an outdoor deck, you'd want to watch for any any evidence of mold or fungus. If you see anything suspicious, a deck wash product (with either bleach or oxy bleach) will kill whatever it is.

But my 2014 PUP shows no signs of such deterioration. And I think that sealing the underside might do more harm than good.

Again, just a hunch.