Craig5_12 said

Jamie (K6NUB) said

The only latex foam I could find would not stay in that large of a gap, so I ended up just doing a big gap filler. After cutting and shaping it I covered it with a DAP paintable elastomeric sealant (Dynaflex 230?). My test run seemed so come out well and I think the sealant will make it more durable and sealed from water, will also make the paint look better than just on foam. Here are a couple pics before paint, will be painting it tomorrow.

  

Does that foam absorb water?  I may follow your lead now that I've removed the liner from my wheel wells. Seems like a pretty easy solution although I've got some massive holes to fill.

  

My theory is that the foam will deteriorate from water and debris, my bet is that it will not absorb it much but it will wear away over time. My test painting on the raw foam did not look very good, it completely stood out. I use the DAP Dynaflex on the exterior of my house a lot and really like how it flexes and protects from the elements (I mainly use it like an exterior caulk). So again it is just a theory, the coating of it on top of the foam will help protect it and provide a better looking painted surface, the samples I painted looked pretty good. Paint goes on tomorrow and then we will know more. Time will tell how it wears, but I suspect it will be pretty good.

Side note, I did not do inner fenders on the rear and saw a lot of gaps that I was worried about water getting in so I sealed them with the foam and then sprayed them raw just so the white did not stick out in the black fender well, so that will tell us how the foam on it's own holds up. Now that the fender project is done, I wish I would have just bought the rear inners (assuming they they covered the holes), I wasted too much time trying to make the area look good, then seal it, then try to make it look good again... was not worth the time