1/8 ply & Aluminum question

[Snide61]

Sorry if this has been discussed before but I was wondering what the point is of applying a layer of 1/8 ply on the outside of a TD when you are going to cover it with Aluminum anyway? It seems to me that you could could up the thickness of the aluminum from .030 (I think that's the number I've seen) to like 0.050 and still have the benability and additional rigidity that the ply provides. I'm also assuming that you could use the adhesive to seal the seams between the aluminum and framing.

Thanks,
Scott

[madjack]

Scott, commercial trailers are built that way...a frame work stuffed with rigid insulation, a ply panel on the inside and AL on the outside...this is usually vacuum bagged to form a SIP...on your TD build, where so much of the strength comes from the "torsion box" effect, I would still use a ply underlayment on the sides...however, for the roof, I apply the AL skin directly over the spars(9" centers" with no underlayment...I use .040 AL for this...the edges/seams are sealed with either an RV molding or AL angle...a sealant is placed under this trim...a product such as SikaFlex 201/252 or 3M5200 works extremely well in this application OR just use RV putty tape...lots cheaper and lasts/works just about as well...........
madjack

[Snide61]

Ok thanks Mad . . . that at least confirms my suspicions that it is possible even it is not preferred. Good info in planning either way. Thought of this because if I do chose to skin in AL I may try to make it look like a vintage plane (even paint it OD green w/ nose art) with the fasteners showing on the outside of the skin much like the rivets on WWII planes would have.

[boardhead]

You will really appreciate having the aluminum installed directly on 1/8" ply the first time you try to sleep when it is raining! While the roof on my tear is fully insulated, I did not put ply on top of the insulation layer, just glued the aluminum sheet to the stringers. The insulation does little to deaden the raindrop noise. Had I installed 1/8" ply to the top of the stringers and the aluminum on top of that, I would sleep sounder when it rains.

[planovet]

Yes. like MJ said it's possible and doable. Preference is up to each person. I put down an 1/8 underlayment before I put my aluminum roof down. Just my preference. Do whatever you want, it's your tear.

[madjack]

You will really appreciate having the aluminum installed directly on 1/8" ply the first time you try to sleep when it is raining! While the roof on my tear is fully insulated, I did not put ply on top of the insulation layer, just glued the aluminum sheet to the stringers. The insulation does little to deaden the raindrop noise. Had I installed 1/8" ply to the top of the stringers and the aluminum on top of that, I would sleep sounder when it rains.

AMAZING...after 2 years, I still haven't put insulation or a ceiling in because the wife and I both LOVE the sound of the rain on the aluminum...to each his own...............
madjack

[kennyrayandersen]

You will really appreciate having the aluminum installed directly on 1/8" ply the first time you try to sleep when it is raining! While the roof on my tear is fully insulated, I did not put ply on top of the insulation layer, just glued the aluminum sheet to the stringers. The insulation does little to deaden the raindrop noise. Had I installed 1/8" ply to the top of the stringers and the aluminum on top of that, I would sleep sounder when it rains.

AMAZING...after 2 years, I still haven't put insulation or a ceiling in because the wife and I both LOVE the sound of the rain on the aluminum...to each his own...............
madjack

That is funny -- everybody is so different. I wake up at the drop of a pin (my ancestors evidently were responsible for waking up the tribe should there be an intruder!). Here in TX we not only get horrific rain but some pretty load thunder as well (which suddenly makes me wonder about a lightening strike!).