Teardrops n Tiny Travel Trailers

Hello, I'm building a teardrop on a HF trailer. I was wondering if anyone has used underlayment as the exterior, and then covering it with PMF. I know it would help keep the weight down versus using plywood. If anyone has any input I'd greatly appreciate it.
Thanks in advance,
Daniel

I use 1/4" (5.5mm) plywood underlayment to sheath the inside and outside of sandwiched walls. Is that what you're talking about?



Just Googling underlayment, I get this: https://www.google.com/webhp?sourceid=c ... derlayment I see they make all sorts of stuff that they label with the word, underlayment.

Tony

Yes, Tony, the plywood underlayment is what I have. I'm fairly sure it's the 1/4". I'm guessing it's safe to assume that it is sturdy enough if you're using it on the outside. Do you know if the PMF will work on it?
Daniel

Schantzfamily2014 wrote:Yes, Tony, the plywood underlayment is what I have. I'm fairly sure it's the 1/4". I'm guessing it's safe to assume that it is sturdy enough if you're using it on the outside. Do you know if the PMF will work on it?
Daniel

The PMF should be just fine. However, if it's the 1/4" stuff, you'll need some kind of framing. It's just too thin.



The underlayment I get is cheaper and superior to 1/4" AC ply. I've thrown a scrap in a bucket and it doesn't delaminate.

Tony

I am basically using underlaminet from Lowes in my CT interior. It stains well. Now if I was good at applying stains, the results would be better. But I have no patience for these tasks.

The stuff I used was even thinner than 1/4"! Of course it was floppy until I installed vertical battens. Hauled furniture, motorcycles and a 1300 mile camping trip. The foundation is stiff and the joints are reenforced with cleats. So sure, you can use 1/4" walls if it's made correctly.
T

My next question is: If I use the underlayment wood, with a plywood inner frame for support, should I just glue the underlayment wood to the plywood? Or should I screw it in?

I glued on the exterior battens but used small screws to hold the batten until the glue set.
T

I used 3mm hardwood ply on the exterior of mine with pmf over it and as its laminated to the foam and frame underneath its solid as a rock.
Ive got 6mm ply on the interior.

The tear in my avatar is sureply underlayment with PMF. All joints are glued with the screws removed after the glue cured.
I used 1x2 framing and filled the voids with foam.

rowerwet wrote:The tear in my avatar is sureply underlayment with PMF. All joints are glued with the screws removed after the glue cured.
I used 1x2 framing and filled the voids with foam.

Did you bondo over the screw holes before doing the PMF? Thanks for all of the information.

I filled the screw holes with PLpremium, then sanded it smooth when cured.