FRP - Still A Viable Skin Material?

[Jwh92020]

I've been looking at some of the older posts about using FRP as the exterior skin, and there are tons of opinions on it. My walls will be 1/4" ply, 3/4 framing and 1/4" ply on the inside with 3/4" foam board between the ply. I've been contemplating using FRP on the exterior and I'm wondering if anyone is still using it? If so, float it, staple around the edges or glue to the ply, paint it (if I wanted to paint, I'd use Durabak instead of skinng the ply) or not (I actually like the shiny bumpy surface - sort of a glossy bed liner look). How has it held up for you? Thanks

 

[DezPrado]

I had a 3/4" skeletonised ply frame, 3/16" ply interior , exterior clad in FRP sheet (Filon equivalant) adhered with a flexible sealant/adhesive (cannot recall the product code [Simson 70-06 ?} but it was used in the marine industy for calking teak decks.} In the 11 years I used the teardrop, it performed well, never had an issue with it. Skeletonised frame insulated with3/14" eps. The adhesive was beaded all around the perimeter, all horizontal & vertical elements of the frame in a continuos bead. Sort of floated. but held in the middle too. Going to do the same with my new build underway.
Hope this helps

 

[Jwh92020]

I had a 3/4" skeletonised ply frame, 3/16" ply interior , exterior clad in FRP sheet (Filon equivalant) adhered with a flexible sealant/adhesive (cannot recall the product code [Simson 70-06 ?} but it was used in the marine industy for calking teak decks.} In the 11 years I used the teardrop, it performed well, never had an issue with it. Skeletonised frame insulated with3/14" eps. The adhesive was beaded all around the perimeter, all horizontal & vertical elements of the frame in a continuos bead. Sort of floated. but held in the middle too. Going to do the same with my new build underway.
Hope this helps

Thank you for the info. My thoughts on floating it with no adhesive or mechanical fasteners is that if there was an issue, I could remove the trim and replace it without tearing up the outer plywood skin.

 

[Happy Clamster]

My limited experience with frp is with bonding it to EPS foam panels. I used Henry 12116 adhesive and the recommended single 1/4 square notch per 1 inch trowel. I got good adhesion but the result has visible ripples, especially under a gloss paint job. DefiniteIy needs an additional bead of adhesive around the perimeter, with clamping along the edge, because the FRP wants to curl up slightly otherwise. I think a 1/16 v-notch might have been better.

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[Jwh92020]

Thanks for the info. I'm leaning toward floating it over a 1/4 plywood skin. That way, if I have to replace it, I won't tear the exterior wall up.

 

[DrewsBrews]

The adhesive keeps stuff like that flat when expansion rate differs from the material below.

 

[Jwh92020]

Good to know. Thank you

 

[Happy Clamster]

I used Henry 12116 adhesive and the recommended single 1/4 square notch per 1 inch trowel.

Correction: it was Henry 444 adhesive I used, with a single 1/4 v-notch per inch trowel. Also, I glued the FRP nubby-side in; nubby-side out probably would have shown ripples less.

 

[Jwh92020]

Correction: it was Henry 444 adhesive I used, with a single 1/4 v-notch per inch trowel. Also, I glued the FRP nubby-side in; nubby-side out probably would have shown ripples less.

Thanks for he update. I just talked to Parkland Plastics - (the FRP panels you get at Lowe's) and their tech said to use 3M Spray 90 to adhere it to the wood. Spray 90 is expensive, so I asked about using Fastbond 30 NF (35 years of gluing laminate & veneers to cabinets & counter tops) and he said that would be fine and would prevent the oil canning that happens often with floated panels. I also talked to KB Maxx - they make a clear UV protectant coating that will stick to the FP and prevent yellowing. ($70/gallon on Amazon or buy direct from them)

 

[DrewsBrews]

would prevent the oil canning that happens often with floated panels.

Nice to know I'm not spewing nonsense atleast. Doing my best to be helpful.

IMO find the best combination of effort and cost to get a reasonably nice result.

 

[Jwh92020]

I never thought that you were spewing nonsense. My original thought was to float it in he event I ever had to repair/replace it. The builder side of me knows that the FRP will be fine, it's the material it's fastened to that could be an issue. If the seams are all well sealed and maintained, the underlayment should stay in good shape. I've built a a ton of cargo trailer conversions and 3 frame up builds and water intrusion prevention was always my highest priority. Here is a 7x10x6' that I built using exterior grade FRP. I installed over Thermoply sheathing using a supposed exterior rated FRP adhesive. Spread it with 1/16" notched trowel. You can see in the picture that the adhesive was no match fo 100 degree OK heat. The guy who ended up with the trailer wasn't concerned abut the oil canning as he was parking it on a piece of land under the shade of trees.

 

[Happy Clamster]

Since I was applying the FRP to a free-standing wall panel, prior to installation, I originally planned to vacuum-bag it. That probably would have made for a smoother result. But with last-minute decisions about shape, the panel turned out to be too big for the bag, so I had to fall back on the standard shade-tree technique for compression: 2x4s and a pile of paving blocks.

 

[Jwh92020]

I can imagine most DIY builders wouldn't have a vacuum bag system large enough to do even the smallest camper walls. I have a ton of experience working with Fastbond 30 contact cement (30+ tears of cabinet refacing and counter top building, but laminating a 4x8 sheet solo to a verical wall will be a scary proposition. One touch in the wrong place becomes a boat load of extra work.

 

[Happy Clamster]

My big idea was to use a $20 mattress compression bag and a shop vac. Didn't get the chance to see how this worked.