Underbelly repair material question

Question

Im working on repairs after our tire blow out last week. I've got the water leaks and electrical taken care of. I've straightened out brackets the best I can. I'm ready to install new insulation to the damaged area and close it back up. The Darco membrane was shredded from the rear of the inner fender bracket to the rear steps. I have wood floor joist running from front to back at the frame and outer wall. I can fasten new membrane at the wood joist, overlapping the old membrane, and seal with Flex Mend or similar.  What is the best way to fasten and seal the new membrane across the hollow chamber between the wood joist? There is not enough old membrane left in those areas to overlap and nothing to fasten solidly. Will Flex mend tape adhere to the metal bracket? Would it be advisable to cover the newly installed membrane with coroplast for added protection from debris and moisture? Thanks for any guidance.

gordonthree · Answer

You could put something fancy in there. For some reason, they can't (won't) sell coroplast in Michigan. Home depot has it on their website, but as soon as I put in Michigan, it's product not available.

I made a repair using heavy duty geotextile... yup, landscaping fabric. It's pretty similar to the fiberglas stuff Elkhart used originally on my trailer, but based on nylon instead of silicon... maybe not flame retardant? who cares. a huge roll was cheap and easy to get a hold of.

Gorilla tape is still holding, after lots of miles of road spray.

mike-s · Answer

GordonThree wrote:For some reason, they can't (won't) sell coroplast in Michigan. Home depot has it on their website, but as soon as I put in Michigan, it's product not available.Just bought some at HD in MI yesterday. None of the sales pukes knew what it was or where they kept it. It was in the aisle in back, on the left of the kitchen cabinet section.

mortimer_brewst · Answer

A couple of random thoughts: Would it be possible to put cross pieces between joists to give you some structure with which you could attach the membrane? How about using foamboard instead of fiberglass insulation?
Should you go the Coroplast route, try sign shops as a source. I bought some 4 x 8 sheets for $15 each. Some shops wanted as much as $60.

sc_camper · Answer

Have been trying to post pic with Photobucket and it wouldnt work. Finally got it with Imgur.
The area right under the blue foam is the bracket at the rear of fender. Dont really have any way to properly affix a cross piece, cant access sides of joist. Plus I have electrical and plumbing running through hollow section.

Blue foam pool noodle is protection against sharp edges of bent metal. Got the metal fairly straight but still bent upwards some.

mobilefleet · Answer

coroplast or fabric material is just going to get shredded again if a tire blows, why not use a piece of galvanized sheet metal painted with black truck bedliner paint.....or just spray foam that area....my class C came factory direct with spray foam in the wheel wells

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Underbelly repair material question

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