Building Heavy Barn Doors
Can you make those barn doors stable? Here's a discussion of how to anticipate and deal with the inevitable movement of wood components. March 18, 2006
Question
I have several pairs of large barn doors to build, 5'w x 8'h x 2.5" thick. They will be clear redwood with a resawn surface showing. With redwood at over 10k/1000 my inclination is to laminate 1/4-3/8" veneer for stiles and rails onto a stable, less expensive substrate material. Does anyone have suggestions for a core material that would be appropriate? Stiles are 8" wide and horizontal and diagonal rails are 6"-10" wide. Joinery suggestions also would be appreciated.
Forum Responses
(Architectural Woodworking Forum)
From contributor A:
I just made some very large interior doors, 3" thick. I bought LVL beams, like those used for headers in homes, and built the frame work of the door with those and then skinned them with 3/4" Mahogany. The LVL's cut very easy, are easy to work with and come in many sizes.
From contributor B:
If you decide to veneer/laminate to save money on material, make sure it will still be a savings when you tally up the added labor.
From the original questioner:
Budget is part of equation as always. But primary consideration is to come up with a stable easy to build system. Using large timber to create a traditional frame and panel door this large does not seem like the best path to me.
From contributor B:
My personal experience has shown that the thicker a piece of lumber or timber is, the better the chance is that it will remain close to the shape it had when put into service.
An extreme example to illustrate this principle is this: Take a piece of solid wood 3/4" x 8" x 24" along the grain and lay it on a work bench. Now lay a piece of wood of the same species with the dimensions 1/8" x 8" x 24" along the grain beside it on the bench. Both pieces were flat when laid on the bench but the thinner one will develop a cup in a shorter period of time. It usually will take less than one hour to warp the thinner material. If you laminate/veneer these, you will either have to have complete faith that your method of veneering and your adhesive will not allow water to get to whatever core wood you choose.
If not, you will have to use something just as weatherproof as redwood for the core. I also think something like a barn door is going to be abused and treated roughly in its day to day life. It’s hard enough to keep veneered furniture in good condition for a lifetime. My suggestions for core material are old growth cedar, old growth cypress or old growth redwood.
From the original questioner:
Veneer would be a relative term in this instance. I use the term referring to gluing a finish face onto a substrate. It is possibly not the proper term. The veneer would be about 1/2" thick. Barn may also be relative in that it also seems unlikely the Kubota tractor or the BMW SUV will eat through the doors anytime soon. My thinking is that 1/2" redwood laminated onto both sides of an LVL (yielding a 2-3/4" door thickness) with West System epoxy should be quite strong and stable. Of course all opinions are welcome.
From contributor E:
If you veneer the front, then you should veneer the back. This seems to equal out everything.
From contributor B:
Laminated veneer lumber is pretty stable. When plywood is veneered, the veneer is actually a veneer thickness (1/16" or less).At 1/2" or even 1/4" thick the laminate, solid redwood will behave like solid wood and experience seasonal wood movement. If the LVL has a greatly different rate of seasonal movement from the redwood it might not be a good idea to glue the two together. In any case, I agree with contributor E that the laminating should be balanced, front and back, to keep the 8" stiles from bowing.
From contributor F:
I know it is a pain, but we have moved to staved construction with 1/4 veneers for most of our doors. The LVL approach sounds interesting, but around here they come with a protective wax coating and aren't what I would consider uniform enough in thickness for door construction. Probably good enough for a barn door though. What do you do about removing the coating?
From contributor A:
I ran mine through the planner just enough to get that wax coating off. Then I ran them through my wide belt to get uniform and a good surface to glue the 3/4" veneer to. My opinion is it makes a very solid and straight door. That LVL is not going to move.
From contributor B:
That’s just what I thought - the LVL is not going to move. The 3/4 mahogany is going to move. The only way I would do that is to fasten the solid wood skins at their centers only so they could still expand and contract from that point. If the bark side is placed to the LVL then it should cup towards it.
From contributor G:
Is this for exterior or interior use? That's the big question that will make all the difference in construction. Exterior will complicate things greatly with swings in MC, and the glues will all have to be type 1. Water shed and big movement will all have to be easily accommodated. Interior will be a more stable environment, but things will still swing with the RH. 3/4" will behave like solid wood (it is solid wood), and move at different rates than composites. I would only build with solid. There is absolutely no substitute for the real thing. If you are going to emulate a barn door, why not build a barn door? The labor and liability goes way up with all this talk of laminating and foreign (to this type of product) materials, making solid much more attractive.
What about the budget? They want big barn doors with massive timbers, but does anyone know what the cost range is? Beware - there are plenty of folks that will want to coerce the willing maker into a situation that only rewards the buyer, not both parties equally.
Using large 2-1/2" material is no problem - just follow what has worked before. Large mortise and tenon - 7/8" thick x 4-5" long x width of rails (excluding haunches) all plowed to receive 5/4 tongue and groove panels. Peg the tenons, glue with proper glue for interior or exterior, and distress as needed. If you don't have experience and equipment to do big mortise and tenon, then subcontract this out to someone who does.
From the original questioner:
This will be an exterior application, one side anyway. My thought for glue was West System Epoxy. My intent is not purely to save money. A healthy budget does exist, but I do feel it is my duty to explore some options before felling a rainforest and laying down about 15k for some nice old growth clear redwood. I have had pretty good luck with an engineered approach to door building and thought I would inquire as to what others are doing. There are some existing solid wood doors on another building on this property that were very well constructed using the techniques Dave mentioned that have not held up that well, although the loose joints and cupping tend to make them look attractively ancient. I have also noticed that most of the large manufacturers of doors and entry systems have gone almost entirely to engineered over solid construction techniques. I figured this had less to do with a stile cupping than keeping the stile of an 8, 9 or 10ft tall door flat along its excessive length.
From contributor C:
We have built a lot of barn and stall doors for trophy ranches here in Colorado. It is usually our punishment for being allowed to do nice doors for the main ranch house. Real ranchers here cannot afford custom doors and build their own with rough sawn pine 2” verticals and 1” or 2” X braces, nailed or bolted together. These doors are actually not as prone to warp as you would think and function pretty well, especially when used with RW top hung sliding hardware. We worked on one job where they built this way using recycled barn wood and it looked great.
We try to add an element of craftsmanship to the ones we build and have used several methods, such as frame and panel construction 2-½” to 3” thick using thick veneer (1/4” to 5/8”) over a solid wood stave core. I like a solid wood core for face veneers over 3.5 mm so it moves as solid wood. You might be able to get by with LVLs for stiles 6” or less in width. Our cores are pine and lately Spanish cedar for bad exposure doors. We have used mortise and tenon construction for these but for the last 1½ years we have totally gone quality dowel construction and are very happy about that.
On one job we split a ¾” gray barn wood with the resaw and planed the skins to about 5 mm thick, leaving the barn wood face. At this thickness they flatten out when vacuum pressed to a thick solid core. On this job the exposed edges were mitered to the face veneers. It was pretty labor intense. We also had good luck with showing the cut 5mm edge and working it with a wire brush sander then adding gray color back with RIT dye.
Another time we vacuum pressed 5mm barn wood onto solid core door slabs to simulate plank construction with ¾” X braces, then stile and rails were added and then bolted through with blacksmith bolts. These doors were very heavy.
My favorite construction for plank doors is Dave Sochar’s method of a ladder core with tongue and groove faces vacuumed pressed on. You can then add X braces or whatever on top. This makes for a very stable and light door. I will never use the door cores again after building this way. For rough sawn new wood we mill the tongue and groove with the moulder then take off 1/16 with the resaw.
All glue was Titebond II and now Titebond III. We are experimenting with European PVA for doors and windows but the III seems to be pretty good. All the methods I described have made for very stable and non-expanding doors, but are pretty expensive. I think in 100 years the rancher built doors will look as good.
From contributor D:
I love redwood, and for those who love redwood, there is no replacement. If the customer really wants redwood, they will pay for it, regardless of the price. Here in the west, lots of old outbuildings and fences were made completely of redwood. Most decks were made from redwood until the composite crap came out. Everyday thousands of perfectly good redwood decks and fences are torn down. Look for reclaimed redwood - you can save some money, and the lumber was from old growth trees with much tighter rings.
