Plywood Door Construction

[John Baum]

I plan to create some doors using grooved 5/8” thick plywood paneling that was used as the exterior of our 1955 post-and-beam house and was also featured on one interior wall of the living room. The doors will close an opening in the interior wall. The largest will be ~32” x 24”, and hung on scavenged heavy-weight chrome continuous 1-5/8” piano hinge. I also have a stock of dry, aged birch in varying lengths that is 1-1/8” thick and 5-3/4” wide. I propose to plane it to 7/8” thickness and then rip it into 1-3/4” wide boards to provide material for interior framing for the doors.

The attached image shows a detail of what I propose. The upper image shows the plywood dadoed on the back face by 1/8” (roughly one ply) to accommodate a 7/8” X 1-3/4” birch edge. I plan to do this on a router table. The dado is needed to move the hinge screw from the interface between the birch and the plywood and give it good purchase. Am I correct in concluding that the 1/8” of birch between the frame and the plywood is sufficient to allow good support for the hinge screws? I plan to use System Three epoxy in the joint. The door will be backed with 0.18” thick birch faced lauan paneling dadoed into the birch. I see this as a stressed skin torsion box; is my perception misplaced? Do I need diagonal braces for a door like this? I am interested in comments on my plan to remove just one ply from the back of the 5/8” plywood. I can remove more and make the birch thicker to compensate. I am concerned about approaching the grooves, which vary by about 1/16” in depth, from the back too severely. Removing most of the first two plies leaves this part of the panel vulnerable to breakage during the routing and glue-up.

What else do others see that I have missed?

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Thanks,

John

[Sam Murdoch]

If I understand your plan correctly I would change the width of your birch frame stock. If you can skip the luan backing (is that for a more finished look on the back side?) I propose going to 2-1/4" to 2-3/4" wide and calling it good. I would prefer too that the hinge screws are set further back into the thickness of the frame (but that's not a deal breaker). Rather than making the rabbet into the ply deeper just set the hinge deeper so that the knuckle of the hinges sits flush to the ply face in that edge bevel. If you can do that you will need to thicken the frame. Everything else seems more than fine. With the frame glued to the back that will be the real structure of the door. As with all such projects - making certain that your frame stock is FLAT as well as straight is the key to success. In this case flat might require adding some shape to "pull" the plywood into submission. Not sure that T111 stock will be flat off the saw and the frame could be built to compensate for its shape. Kind of a pain. The piano hinge will help immensely to keep one edge straight. Good top and bottom catches will help on the other edge.

[John Baum]

Sam, thank you for responding to my post in a supportive way.

I should have included the photo below. It helps to show what I am working on. The opening for this ‘sewing closet’ is ~48”x 84”. To keep the hinge load reasonable, the doors will open both to left and to right. We elected to place the hinge knuckles proud of the panel because this will allow the doors to swing fully open against the existing panel face. The shelves are installed with this approach in mind. The opening is across the entry foyer from our galley kitchen; it is a high traffic area.

The upper two shelves are to be used to store china and glassware. The lower two shelves are to serve as a liquor cabinet. The desk in the middle allows whoever is sewing to open a full length bifold door and sit in the bedroom hall facing out with a view through the rest of the house. Large sewing projects can spill out into the foyer side.

We decided to have the upper door cover about half of the facia on the upper shelf system. The soffit behind it contains lights for the sewing counter. The middle set of doors will cover about half of the face trim on the sewing counter. You can see the hinges on the left side if you look carefully. For the bottom door to open fully, it cannot extend below the top of the baseboard. I have yet to experiment with scraps to see how that looks. The bottom shelf may need to be made into a shallow trough for esthetic reasons.

We have yet to decide on catches to keep the doors closed. I can tolerate the esthetics of good magnetic catches for the top and bottom doors, but the middle set present a problem yet to be solved. Perhaps will need to resort to a catch that is released from the ‘inside.’ That is clearly the simplest solution. I am open to solutions that others might have to suggest.

I included the panels on the back because I already have them. They were ‘left over’ from a recent remodel when they failed to perform the way that the stiffer, genuine ¼” lauan plywood panels used on the remaining interior walls by the original developer, Joseph Eichler. I included them both for esthetic reasons and because I thought they might create more of a stressed skin box-beam if the door was a sandwich of plywood faces on both sides on birch dimension lumber for the framing.

Am I correct in concluding that simple butt joints at the corners of the framing are perfectly adequate? Should I concern myself with installing any diagonal bracing?

The original ‘T-111’ is remarkable stuff. Back in 1955 Eichler found a mill that would make 16”, 32”, and 48” wide panels for him, in lengths up to 144”. There are no boat patches, even on the internal plies as far as I can tell. There are occasional internal voids of less than 1/16” caused by internal plies not being laid up tightly one against the next. The external ply was redwood.

The hinges were scavenged from an executive office remodel at work. They originally supported 8’ 8” x 36” x 1-3/4” solid core doors, so they are way stronger than this project needs. Some of the ‘walnut’ trim came from the same source. The birch was originally door casings, so it is by and large nice straight grained material. The doors are now storage shelves in my garage/shop. Even the bifold doors seen in the background were once sliding closet doors twice their present width. It has been fun using repurposed materials for most of this project. It has been challenging fitting counters and shelves into a space that is not quite cabinet maker square.

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Thanks,

John

[Sam Murdoch]

Sam, thank you for responding to my post in a supportive way.

Your welcome - that's is of course one of the reasons we are all here.:)

We decided to have the upper door cover about half of the facia on the upper shelf system. The soffit behind it contains lights for the sewing counter. The middle set of doors will cover about half of the face trim on the sewing counter. You can see the hinges on the left side if you look carefully. For the bottom door to open fully, it cannot extend below the top of the baseboard. I have yet to experiment with scraps to see how that looks. The bottom shelf may need to be made into a shallow trough for esthetic reasons.

Consider running the baseboard all across the front, perhaps attached to another shelf. Let the door swing free above the base board. As it is paint grade you can connect the 2 new baseboard ends a little crudely, i.e. without perfect joints to the pieces attached to the wall. Since the sewing is done from the other side of the table you will not be interfering with access.

We have yet to decide on catches to keep the doors closed. I can tolerate the esthetics of good magnetic catches for the top and bottom doors, but the middle set present a problem yet to be solved. Perhaps will need to resort to a catch that is released from the ‘inside.’ That is clearly the simplest solution. I am open to solutions that others might have to suggest.

Again, since the sewing is being done from the other side, consider adding a little riser or stop block to the desk top and under the band above to catch your middle doors, though it might be completely practical to only access the middle doors from the sewing side using an inside release catch - no knobs needed. Another thought I had regarding catches is to add a band to the underside and top side of the respective panels above and below the center doors on which the center doors would land. The down side to that plan is that you would always need to open at least 2 sets of doors, so I prefer the first option. I really have come to like the cupped sets of rare earth magnet sets that Lee Valley sells. The smallest are plenty rugged enough. http://www.leevalley.com/en/wood/page.aspx?p=60007&cat=1,42363,42348&ap=1

I included the panels on the back because I already have them. They were ‘left over’ from a recent remodel when they failed to perform the way that the stiffer, genuine ¼” lauan plywood panels used on the remaining interior walls by the original developer, Joseph Eichler. I included them both for esthetic reasons and because I thought they might create more of a stressed skin box-beam if the door was a sandwich of plywood faces on both sides on birch dimension lumber for the framing.

I don't think the panels will add much except for a smooth finish but see no reason NOT to use them.

Am I correct in concluding that simple butt joints at the corners of the framing are perfectly adequate? Should I concern myself with installing any diagonal bracing?

I would make a glued joint so that the frame is a unit independent of the panel. Butt joints are OK, but at the least reinforce with pocket screws on the ply face side or dominos or biscuits or some other loose tenon, or better yet, construct 1/2 laps. As for diagonal braces - I'm thinking - no need - especially for doors this size and in particular if you widen your stock as I suggested in my first post. The wider butt joint will resist racking well enough if properly put together.

The original ‘T-111’ is remarkable stuff. Back in 1955 Eichler found a mill that would make 16”, 32”, and 48” wide panels for him, in lengths up to 144”. There are no boat patches, even on the internal plies as far as I can tell. There are occasional internal voids of less than 1/16” caused by internal plies not being laid up tightly one against the next. The external ply was redwood.

I haven't used T-111 since the 80s but I was impressed with it then, and one building that I sided in those days still looks great after 20+ years of Maine weather.

The hinges were scavenged from an executive office remodel at work. They originally supported 8’ 8” x 36” x 1-3/4” solid core doors, so they are way stronger than this project needs. Some of the ‘walnut’ trim came from the same source. The birch was originally door casings, so it is by and large nice straight grained material. The doors are now storage shelves in my garage/shop. Even the bifold doors seen in the background were once sliding closet doors twice their present width. It has been fun using repurposed materials for most of this project. It has been challenging fitting counters and shelves into a space that is not quite cabinet maker square.

Nothing wrong with oversized hinges and recycling dependable old stock. It's all coming together nicely.

Thanks,

John

Don't mention it :)