Working with 9/16" plywood doors - Suggestions?

[kmagill]

I bought a partly built teardrop a few days ago. It is a 4x8 cabin on a custom trailer. Floor, walls and spars were already in place. I've skinned the inside roof and added the hatch. The walls are 9/16" plywood. If I had built from the ground up I would have allowed room to insulate and skin the walls to result in a (roughly) 2" wall. Because the the cabin is now just under 47" wide, I don't want to insulate/skin and lose further interior space. I'm trying to figure out the doors - I want to put windows in the 9/16 plywood doors. Will I find windows to fit that thickness? I guess if I found 1" thick windows I could add 1/4" trim inside and out to make them fit. I'm also planning on using Tee hinges (rather than piano hinges) on the doors fastened with machine screws and T-nuts. Any comments or suggestions regarding my skinny plywood doors?
Thanks
Kyle

[RandyG]

My walls are 1/2" and I plan on making my doors the same, but I have 1/4" inner skins. I was going to just cut 3/8" plexiglass to fit in and add trim and a frame. I havent thought about every detail yet, Im planning as I go. Have you decided on a door latch yet? Thats another problem I am having on the thin doors.

[kmagill]

I have a pair of T-handle latches that came with the trailer. I'm hoping for a more elaborate window set up - ideally a slider with screen. I'm going to buy some hinges, hang the doors and just see what works out. I'll post some pics. Good luck with your project!

[KCStudly]

I've not heard of 9/16 ply. Could it be sanded 5/8 ply (19/32 thk)?

What are your thoughts on the stability of that thickness and its ability to remain flat (and thus its ability to look good and seal properly) without some sort of frame work?

Maybe encase them in them in epoxy and glass weave to hold them stable and add some rigidity?

On the windows, if using a commercial unit, you could build out a frame around the window RO giving you something to attach the trim rings to. I'll have to look at my trim rings again; I think they are a 'Z' section and might be able to reverse them so that they can clamp a wall that is thinner than the window is thick, dunno for sure. Even if the factory ones don't work that way, you could make your own that do. the window and trim would still stick in from the wall some, butt it would be above the surface of the mattress anyway, so shouldn't encroach much while you sleep.

I babble.

[halfdome, Danny]

I've seen a couple teardrops with doors under 3/4" and they never seal up good enough to keep out wind driven rain.
Plywood will bend in at the door handle and splay the remaining wood out to compromise a good seal.
Danny

[Roo Dog]

Kyle,
Our doors are a lamination of ply, aluminum and steel sheet on the outside with caravan wind out windows.
The ply is the plug in the hole. It is the section that was cut out for the door hole.
The ally and steel lamination's overlap the hole.
The whole TD is steel clad over the ply.
RD

[KCStudly]

I've seen a couple teardrops with doors under 3/4" and they never seal up good enough to keep out wind driven rain.
Plywood will bend in at the door handle and splay the remaining wood out to compromise a good seal.
Danny

Danny said the same thing that I did, but without tip-toeing around it.

I would consider adding a 1x2 frame on edge around the door and jamb. It will come into the cabin 1-1/2 inch, but only around the perimeter of the door; you don't have to insulate and panel the inner skin if you don't want to loose the space all over.

If you are planning an inner seal, you will need to add a flange inboard of that, but if you can get it to seal between T-molding on the door and the outer surface of the wall you might get away w/o (some people do both for a double seal, like Aggie79 Tom and his Silver Beatle).

Another crazy idea, or if you are considering making it a woody, you could route a channel down the center face of 1x2 and cap the edge of the door and jamb. Some of the frame would stick in, and some would stick out. Might have to trim around the hinge some. Taking this idea a little further, you could rabbet the frame and have the offset all to the outside.

Taking that thought one step further still, what's to stop you form building the wall out thicker, adding 1x2 wall framing to the outside of the existing skin, fitting insulation outside, then capping that all with another (perhaps thinner) outer skin? Wouldn't steal any from the inside and would give you thicker walls with insulation.

Which leads to another idea; laminate another layer of ply on the outside making your walls thicker (not my first choice, but may work for you). If you go this way I would seriously consider planning on laying the cabin on its sides while doing this, so that you can weigh down the new skin evenly and get a good bond, otherwise you would need to use a lot of screws putting a lot of holes in (maybe not an issue if you plan on skinning w/ alum.).

Don't mind me. I babble sometimes.

[kmagill]

Many thanks for all the input. The ply probably is, in fact, 5/8". It measured as a little wider than that so thought maybe 9/16. Anyway, I roughed in the door with 2 Tee hinges and a latch and I can see immediately that I need to beef up the structure. I'll frame the door from the inside. I am planning on covering the roof with aluminum. I'm undecided on the walls. The were already finished with a waterproof seal when I got the trailer and I like the pairing of wood finish and aluminum. I may clad the door in aluminum for added structure and as an accent. Inching forward....
Thanks again.
Kyle

[KCStudly]

Here's something else to consider, on my doors, which are pretty large by TD std.'s, I have the door latch as near to the middle as the window will allow (without crowding it or putting the window awkwardly high), and I will fit the hinges as near to the top and bottom corner radii as is practical.

This creates a triangle between the hinges and latch with nearly equal parts of the door above and below the latch. Because the span between "support points" across the corners of the open side of the door are as short as practical, there will be less flex in the door panel when pulled tight against the seal. i.e. Imagine a line between the top hinge and the latch, and another between the bottom hinge and latch; the farther the edges of the door are away from these lines, the more they can flex.

With your test fit, you have the top hinge well down from the top of the door, and your latch very near the bottom. I bet that your worst fit is currently near the top of the door opposite the hinges.

BTW, welcome to the forum. I like to tell newbies, "You will probably get more help here than you can stand".

[kmagill]

Thanks KC. Point taken on the strength of the triangle. My latch certainly is a bit low. It was an arbitrary position based on my imaginary window. The angle of the photo skews the apparent position of the hinges a little. They are both 5" off their respective corners. The door is 31" along that edge. The ply door isn't perfectly flat (it came, pre-cut, along with the rest of the trailer) and even if it was was, I can't imagine it would stay flat for long. If I was willing to part with the money I'd buy a pair of factory made aluminum doors but I can't do it. In the meantime I'm starting to wonder about a wood frame hollow door skinned with lauan and clad with aluminum on the outside. Too many possibilities.

[KCStudly]

Too many possibilities.

Yup.

That's the hardest part, deciding what you want and how you're going to get there. It is a journey.

Good luck. I will be following along.

[working on it]

I've seen a couple teardrops with doors under 3/4" and they never seal up good enough to keep out wind driven rain.
Plywood will bend in at the door handle and splay the remaining wood out to compromise a good seal.
Danny

I have 3/4" ply doors (actually 23/32" sanded). One is perfectly flat (was stored flat), but the other was neglected and leaned against a wall for months in humid conditions (warped a bit). After sealing, and painting them, I laid them flat for another coupla months, and they're both pretty good now. This is critical because I'm using a compression seal with no offset. The automotive doorseal was cut down by 1/3, and then stapled and glued to a 1/4" thick inner flange. I used three very hefty hinges to keep the door/frame perfectly aligned. I wanted to use a compression-type twist lock as a door handle, but couldn't find one large enough, so I used 2 slide bolts, one high and one low, to keep uniform pressure on the seal all around. I haven't tested it with wind driven rain, yet, but it is very well sealed (almost an airlock!). Granted, it has a rough-hewn appearance, but is what I wanted it to be: very secure, and tight.

detail of seal

(head)%20of%20bedding.jpg (16.06 KiB) Viewed 1168 times

slide-bolt

033923005340lg.jpg (18.59 KiB) Viewed 1168 times

[Sputterputz]

^^. Ummm is there a way for you to lock yourself in or is this a spouse/kiddie timeout area ?

[working on it]

^^. Ummm is there a way for you to lock yourself in or is this a spouse/kiddie timeout area ?

No and yes. No, because you can padlock it shut when away from the trailer, and padlock it open when inside (an inner latching bar is used from inside) a 3/4" diameter oak dowel is dropped/slid into the aluminum receivers to seal it. Oak used this way has good resistance to shear, and just enough "give" to be able to fit into the receivers (if not ideally aligned). The dowel can be cut from the inside, also, as a fail-safe in case my wife can't pull/lift it out (inside cabin tool kit w/mini-saw). Here is a table to show why I used a dowel in this door "lock".

Oak properties.pdf

(56.75 KiB) Downloaded 35 times

Yes, I built it for the wife to play in ("timeout" of my way).

[halfdome, Danny]

I have 3/4" ply doors (actually 23/32" sanded). One is perfectly flat (was stored flat), but the other was neglected and leaned against a wall for months in humid conditions (warped a bit).

Each side of the door needs to be equally sealed as much as possible to prevent warping.
Years ago while working in an Oceanside,California Cabinet shop, we made all the cabinet doors for a hospital out of 3/4" particle board with Vinyl on the back and plam (plastic Laminate) on the face. They all had to be replaced because they bowed out towards the front of the cabinet about 1/2".
We replaced them with 3/4" particle board with plam on both sides and they didn't warp.
Just something to keep in mind when applying your finishes & or aluminum.
Danny