Warping Doors

[lindstrand]

I am just about ready to build my door and I am concerned about warping. I was thinking making it with 2x2 spruce and 1/8" plywood like I made my walls. I have a fairly large door 28x30 so I think overtime it will warp and cause sealing issues. I am trying to think of the best and cheapest way to make a door. Couple thoughts I have is run tensioned cables corner to corner but this interferes with my window. Fiberglass over the plywood pricey and I don't know how much resistance to bending that would add. Use aluminum instead of wood for studs and thats pricey and I can't weld aluminum. Laminate plywood together for a solid door but that would be heavy.

Anyway enough thinking out loud any comments or experiances (good or bad) would help

[caseydog]

That is the number one reason I have aluminum doors.


CD

[dh]

If you laminate the plywood together and cut your frame out of it, this would cut down on the weight.

[Steve_Cox]

Doors - oak framing with two layers of 1/4" oak veneer plywood. No screws, nails or staples. Epoxied together on a flat table clamped and weighted with a sandbag all at one time. No warping, no problems. the plywood was cut oversize and trimmed with a router after the epoxy cured. I liked the exposed framing look, I could have put the oak framing in between the layers of plywood, same results.

[timlsalem]

That's a mighty fine looking door Steve.

[Larry C]

I am just about ready to build my door and I am concerned about warping. I was thinking making it with 2x2 spruce and 1/8" plywood like I made my walls. I have a fairly large door 28x30 so I think overtime it will warp and cause sealing issues. I am trying to think of the best and cheapest way to make a door. Couple thoughts I have is run tensioned cables corner to corner but this interferes with my window. Fiberglass over the plywood pricey and I don't know how much resistance to bending that would add. Use aluminum instead of wood for studs and thats pricey and I can't weld aluminum. Laminate plywood together for a solid door but that would be heavy.

Anyway enough thinking out loud any comments or experiances (good or bad) would help

I have the same concern as you. It seems the same issues plague most builders. There are several, but the door warpage is a major one.
Here's my thought:
I Built my wall periameter with 1/8" laminations and it is really stiff and strong.

So, I ripped some 1 X 2 lumber into 1/4 x 3/4" strips and glued it back together with Titebond 3.

This was an experiment to see the difference between solid wood and the same wood cut into strips and glued back together.

I layed the 1X2x3' solid wood piece over the edge of a bench and pushed each end to see how much it would bend. I was fairly easy to bend.

I did the same thing with the laminated lumber. It was much more difficult to deflect this board.

I don't know if the laminations will help prevent warping, but they clearly stiffen the board. Maybe I could add some thin strip of hard wood, fiberglass or carbon fiber in the laminations to further stiffen these inner doors frames.

This method needs more thought.......Engineers please chime in.

Larry C

[Juneaudave]

I'm not to sure that I've heard any tales of woe related to warping of composite doors (other than those being glued up with a warp built in). Seems to me...a door with 2x2 framing and 1/8 ply sheeting shouldn't be susceptable to warping if the wood is dry and the door sealed....

[Larry C]

I'm not to sure that I've heard any tales of woe related to warping of composite doors (other than those being glued up with a warp built in). Seems to me...a door with 2x2 framing and 1/8 ply sheeting shouldn't be susceptable to warping if the wood is dry and the door sealed....

Dave,
With your level of craftsmanship, I am sure your tear has not experienced any door warpage.

However, I am conserned about anything that may be a possible problem. Also, I'm sure my build won't have the quality construction or stoutness of yours.

I have recently checked out several Teardrop trailers, mostly home built and during my inspections, I asked the question about door warpage. Some builders said they had at least some issues with warpage even if it was minimul. In my half empty (glass) world, that means "the sky is falling", "the sky is falling" (Type A and Anal)

A 2x2 framed door with 1/8" skins would be less prone to warpage than my proposed thickness of 3/4" with 1/8" skins. I probably have more to be conserned about.

I would like to hear from others with 1" total thickness doors about warpage. Maybe I am just being too anal about a non-issue.

Larry

[timlsalem]

I agree with everyone else that said "if the door is made out of dry treated wood and is sealed right there won't be any warping" If you can't get by your fear of your door warping I suggest you make it out of aluminum. Even if you choose to build from wood, and it does warp, what's the big deal of building another door?

[Larry C]

I agree with everyone else that said "if the door is made out of dry treated wood and is sealed right there won't be any warping" If you can't get by your fear of your door warping I suggest you make it out of aluminum. Even if you choose to build from wood, and it does warp, what's the big deal of building another door?

"what's the big deal of building another door?" I wish it was that simple. However, I am building with strip construction similar to Juneaudave's. (No where near the quailty of his workmanship).

I will only get one chance at my doors because the doors will be cut out of the finished wood strip sides. It would be impossible to duplicate. That's why I am a little concerned. I have fairly thin doors and I can't just build another one if it warps.

I am just looking for a fool proof construction method. From the thousands of post I have sifted through, I have seen this issue brought up several times.

I am trying to learn from others mistakes. It seems one of the biggest issues is water intrusion, resulting in rot. The largest openings for water intrusion in a Teardrop are galley hatches and doors. Just thinking ahead...

Larry C.

[timlsalem]

I just looked into your album and can't see any pictures of what your doors will be made from. Could you post some of the sides your planning to cut the doors from?

[Larry C]

I just looked into your album and can't see any pictures of what your doors will be made from. Could you post some of the sides your planning to cut the doors from?

I can't post pics of my actual sides yet because I am not that far.
All I have is the outside perimeter laminations done.

The construction will be 1/8" x 3/4" Cedar strips in an artistic pattern directly over 3/4" internal framing with foam insulation between. Fiberglass/epoxy over the strips. The finished wood will show. The inner wall skin will be 1/8" Russian Birch. Total sandwich wall is 1" thick.
Doors will be cut directly from the walls. Because the strips will be a finished pattern, they could not be duplicated. I can't mess up the doors while them cutting out or any other reason such as warping.

If I can make my 3/4" internal door framing so it won't twist or warp, that's all I need to accomplish. I have had enough experience with large panels not staying flat, including house doors, to want to make sure I do it right the first time.

Look at Juneaudave's stripped side walls to see the wood strip method I'm using. However, I am not stripping over plywood as Dave did. My outer wall will be 1/8" thick.

Here's a pic of the wood strip method I will be using for my outer wall/door skins:


Larry...

[Corwin C]

I'm contemplating the same issues for my build for the same reasons. My proposed solution (I haven't actually built it yet) is to maintain the torsion box structure by adding a layer of 1/8" ply under the strips. It will either make the wall thicker or reduce the insulation, however, like Larry C stated, once the strips are done, there's no going back, so maintaining a rigid structure during the building process is paramount.

My current wall lamination design (subject to change) will have:

prefinished wood flooring for the interior (5/16" thick)
1/8" marine ply
hardwood framing & insulation (haven't decided upon thickness)
1/8" marine ply
decorative exterior strips (5/16" thick)
6oz fiberglass/epoxy

Proposed construction process will be to lay up laminations (except for exterior strips and fiberglass) and vacuum bag to a flat floor. At this point the torsion box should be secure and the door can be cut out. Temporarily re-attach the door from the inside, then the stripping can be applied to the exterior. Cut and trim strips to match framing and apply fiberglass, wrapping edges of door and door opening during the process.

I believe that this would work, but if someone has suggestions/experiences, I would also love to hear them.

[Larry C]

I'm contemplating the same issues for my build for the same reasons. My proposed solution (I haven't actually built it yet) is to maintain the torsion box structure by adding a layer of 1/8" ply under the strips. It will either make the wall thicker or reduce the insulation, however, like Larry C stated, once the strips are done, there's no going back, so maintaining a rigid structure during the building process is paramount.

My current wall lamination design (subject to change) will have:

prefinished wood flooring for the interior (5/16" thick)
1/8" marine ply
hardwood framing & insulation (haven't decided upon thickness)
1/8" marine ply
decorative exterior strips (5/16" thick)
6oz fiberglass/epoxy

Proposed construction process will be to lay up laminations (except for exterior strips and fiberglass) and vacuum bag to a flat floor. At this point the torsion box should be secure and the door can be cut out. Temporarily re-attach the door from the inside, then the stripping can be applied to the exterior. Cut and trim strips to match framing and apply fiberglass, wrapping edges of door and door opening during the process.

I believe that this would work, but if someone has suggestions/experiences, I would also love to hear them.

Hi Corwin,
I am glad you understand the concerns about this issue. I don't see you having as much to be concerned about as I may have. I think your walls will be super heavy duty.

But...why all the wood? 5/16" skins both sides over 1/8" ply over hardwood framing/insulation and 6oz glass to boot! Your walls will be bombproof and probably 1-3/4" thick.

I made my 5X8 floor (see my album) using 1" framing on 1' centers, 1/8 ply skins, covered with 4 oz. glass/epoxy. This 1-1/4" thick panel is stiff and strong.

I don't understand your reasons to build such heavy duty walls. Is hardwood framing really doing anything in a torsion box? Wouldn't the 1/8" marine ply be enough without the extra 5/16" layers? or maybe a much thinner outer skin than your planned 5/16" both sides?

Please don't get my wrong, I'm not saying your method isn't good, I just like to understand the reasons why others do things the way they do. That's why I am here, to learn from others. I may be the one that's wrong.

Larry

[kennyrayandersen]

Things warp for a couple of reasons. Either because they have residual stresses or because the part takes on a different shape after it is assembled due to incomplete drying. Either way the effect is similar.

In composites, we stress symmetry to avoid the residual stresses that occur when the parts are built at one temperature and then cool to another. Something similar to that occurs when different materials are glued up together and then as they dry they try and change shape (which creates internal stresses). So, the way to avoid or at least minimize warping is to avoid both asymmetry and using wood that is either not dry or is prone to warping.

Even plywood can warp, but it is usually because it gets leans up against a wall, or gets wet or something. You’ll notice that plywood comes in odd numbers of plies to keep the symmetry and is generally stable (or at least it was back in the day). Unfortunately, solid plywood would probably be heavy as pointed out and just using it as the core with skins on the outside may make installing the latch (if it is internal to the door) difficult. So, there are reasons to want to use a wood frame that is skinned in thin plywood.

I think the warping could be minimized by using straight-grained kiln-dried lumber when building the door. The more figured or angled grain a piece of wood has the more it will tend to warp. Even if it is kiln dried it can absorb moisture later and then warp anyway. These days it’s not that easy to find straight-grained lumber, but the door isn’t too big, and if you are willing to puck through a pile, you may be able to find enough to do the door.

Skinning the frame with thin plywood by bonding it all together would also help stabilized the door. And, whatever you put on one side, put on the other (as has already been suggested). If you do all of that, I think the warping should be minimal (you may never get rid of 100%, you just want to get rid of enough to where the door will function (seal) properly).

The only way to REALLY get rid of it is to not use such organic materials (i.e. using composites (foam and fiberglass) or metal etc.). If you use something as natural as a tree, you get what goes along with it.