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Veneer Exterior door11/19
how would you make an exterior door that is 2-1/4" thick, 4' wide x 7' high, white oak rift cut veneer (horizontal grain) on both faces. I thought of using a Med X (exterior MDF core), laminate it to get the thickness and wrap it in hardwood, then veneer the faces. Any suggestions?
Exterior rated glues, fully acclimated parts, torsion box to reduce weight, full thickness real veneers (no paperback), pressed all at the same time, or both sides at once, minimum, wide enough stiles to take hinge screws and latch, proper finish and weatherstrips. Wheaties for moving the thing.
The Medex may not make any difference - if water gets that far into the door, it is gone anyway.
Thanks David, What would you use for the skin material on the torsion box?
1/2" MDF for the faces of the torsion box, and I like 1/16" or thereabouts for faces on this type of door. It gives plenty of room for sanding and refinishing down the road.
David, much as I respect your experience, I disagree on using straight mdf as a substrate for an exterior door. Extira is inexpensive insurance against water penetration around hardware or possible future checks in the veneer face. Of course, hardware penetrations and field cuts should be sealed, but the maker may not have control of that process. Mdf is too susceptible to swelling if any moisture does get in for me to feel comfortable with it.
Kevin is right, it costs little for the added peace of mind. I just don't think it makes much difference in the real world.
Some years ago, upon receiving a sample of the first 'waterproof' MDF, I put it and a piece of the regular stuff - both cut to the same size - in a bucket of water, then forgot about it.
Went back over a month later, and they were both about the same swollen size, but the regular MDF was more spongy than the exterior grade. This convinced me that the exterior grade is only water resistant, not waterproof. I believe their literature makes the same claim.
I think once water gets into the interior of a door - to the MDF - the game is over and it is only a matter of time. The only time I use MDF in a door is if it will not ever get wet. If it gets wet, then I use MDO 2 sided board - a true waterproof product.
These overhead doors have panels of MDO corestock, with shop veneers applied on top of them. they get wet about anytime it rains, and they look fine after 2 years. I have made many panels the same way - MDO - and they all last better than any other core.
It's true that medex is moisture resistant mdf, and I would not recommend it for use in an exterior door that would get wet. I was referring to Extira, still pressed sawdust, but pressed with a real waterproof bond and exterior rated. My mate tells me he gave it the bucket test and it didn't gain any weight or swell. I haven't done the test myself, but I do have a door in my shop 3 years old, unfinished, epoxy bonded, 1/16" cypress skins over Extira and foam board. It regularly gets wet, but it stays flat and stable. It grows about 3/32" over 38" in the summer. I'll get a better read over time, but I feel confident it's a good product.
MDO is good too. Maybe harder to get flat sheets. For a premium job, good marine plywood could be justified.