Bubinga Exterior Door Question

[Alan Turner]

I am being consulted about a set of exterior doors, to be built in Bubinga. I have seen photos of the existing doors and side light panels, and have been given measurements of 2'-8" wide by 6'6" wide, with the side light panels narrower, perhaps 24".

Does anyone have any experience with using Bubinga in this application? Any thoughts? I anticipate they would be of frame and panel/light construction. I know they will be heavy.

My concern is not with strength,but rather with wood stability. The exposure is East, and there is a smallish roof/cover over this area.

Any help on this would be appreciated.

[Mark Singer]

Alan,

Stiles and rails should be laminated with 3 plys of hardwood....it will warp if you use solid stock

[Alan Turner]

Yes, I wondered about that. I also thought about cutting some pretty heavy veneer and using that over something, not sure what.

[Jamie Buxton]

Yes, I wondered about that. I also thought about cutting some pretty heavy veneer and using that over something, not sure what.


There's a custom door-building shop down the street from me. They mostly build magnificent big doors out of expensive stuff like honduras mahogany. Their standard "lumber" is actually a composite. The exterior cladding is the finish wood, about a quarter of an inch thick. The core is a lamination which looks like plywood, except that the laminate grains all run the same direction. They buy the stuff in 4'x8' sheets, rip, and laminate to whatever they need. However, exactly the same stuff is sold as man-made construction lumber. When sold as construction lumber, it is called LVL (laminated veneer lumber). (The manufacturers sell it as framing lumber which is straight to start with, and will stay straight in the home.) When the door shop completes a "plank", it has all the grain running lengthwise, so there are no expansion issues trying to destroy the plank. They treat the composite plank just like solid lumber; for instance, they do big mortise-and-tenon joints with it, and the tenon is all the core material. The guys who run the shop say that the composite construction is less likely to warp than solid lumber. They also observe that it saves on precious woods -- like their favorite mahogany.

[Earl Kelly]

Alan, what I would do, is make up a sample with the construction of your choice. Finish it with an appropriate exterior finish and throw it outside and let the rain and sun hit it for a week or two. This will tell you more than anything else will.

[Jamie Buxton]

One more thing about that core...

If I were starting out to make a core from a panel 1" thick, and I were making a core which is for instance 2"x6", I'd do the obvious thing and laminate two layers of the panel to get the 2" thickness. However, these guys turn the core the other direction. They'd make that 2x6 from six layers of the 1" stock. They say this makes the plank less likely to warp. I have to admit I can't see why this would be true, but I also can't see why it wouldn't.

[Steve Evans]

Alan

I work a little bit with a Hungarian fellow who builds beautiful doors out of mahogany. He's currently building one for a customer of mine. Like others have said, his solid stock is all laminated out of 3 layers of lumber. He uses all mahogany. His panels are of 3-part construction, two outer panels with a layer of closed cell foam insulation between them. He says it creates less stress in the panel.

Steve

[Alan Turner]

Interesting idea, Jamie. Any chance you might know, or learn, the product name of the core material that shop is using? I might try to see if I can source it in my area.

[Jamie Buxton]

Interesting idea, Jamie. Any chance you might know, or learn, the product name of the core material that shop is using? I might try to see if I can source it in my area.

IIRC, they said they got the LVL-in-sheet-form as a special order because they use so much of it. However, you can order LVL's in standard framing-lumber dimensions at any lumber yard in the country. Same stuff.

[Alan Turner]

Jamie and Mark,

I sort of knew intuitively that going with 8.4 solid Bubinga would present a real risk of warpage. The three section approach would work wsell, I am sure, but those glue ups would be difficult to get right, in my experience, as getting clamps everywhere, sans a mechanical veneer press, would be a PITA. Plus, going with epoxy would be a PITA in terms of clean-up etc. I use it only when necessary.

My potential client's designer has drawn the door that I am to bid, and I have not yet seen this design, or sketch. All I have seen so far are pix of the existing doors/lights area of the house. I have not used LVL before, but have understood that it is rather routinely made up per order. So, I could just spec the dimensions of the core, perhpas a bit oversized, cut the 1/4" veneer, and this would make the build a bunch easier. I am thinking I would glue solid edging to the LVL to achieve proper width of the rails and stiles, bag the 1/4" veneer with Unibond 800, and have the door parts done, and stable, in a fairly straightforward manner. They would work just like solit wood.

I have a 36" drum sander, which I might press into service on this guy as hand planing Bubinga has been difficult for me in the past. While my Bubinga is "free" in the sense that I already own it, I am wondering the cost of the LVL. I am assuming from the photos shown that the doors are a rather standard 1.75" thick. This method would also lighten the load on the jambs as LVL has to weigh less than 8/4 Bubinga, which would simplify hinge selection. I don't know what they have in mind in terms of hardware yet, but I would be inclined to install it in the shop.

Thanks so much for the ideas.

[Jamie Buxton]

Alan --
Really big heavy doors are often not hung with hinges, but rather mounted with door pivots. Rixon is one of the big names (www.rixon.com, and drill down to Pivots). Pivots transfer the weight of the door directly to the floor, rather than to the wall. This prevents distorting the wall, and preventing pulling out the hinge screws. You'll often see pivots on exterior doors in commercial buildings, particularly doors which are mostly glass.

[Mike Vermeil]

Alan,

Have you considered using Jarah? I know your customer wants bubinga, but jarah is an excellent choice for exterior doors, and is somewhat similar in appearance. No need for laminating with LVL, etc, as I believe Jarah is more than stable enough to handle the job on it's own. All oiled up, it's a pretty nice looking wood.

Mike