Exterior doors with exposed MDF, what next?

[Phil Thien]

My benchtops are typically exterior grade slab doors (solid core). They're pretty inexpensive, stable, flat, smooth. They can sag, but I brace them in the middle so they're fine.

I was ready to replace my current top because I was reconfiguring my shop a bit, the old one was in rough shape, etc. So I went to Home Depot to get a new door.

I pulled a 30x80 off the shelf, looked at both faces ("looks good") and then put it on the lumber cart. That is when I noticed both ends of the door, the top and bottom, were MDF instead of finger-jointed lumber.

I KNOW the inside of the door is crappy particle board. But I had never seen a solid-core door before where any of the edges were anything but real wood!

These doors are exterior-rated. I can't imagine how a door with an MDF edge at the bottom could be used as an exterior door. One bit of water and it would be shot!

That was a Jeld Wen door.

So I went to Menards and found a door with a solid lumber perimeter, and bought that.

But I will also say that the Menards door has a substrate under the veneer that looks to be MDF. In the past I've mostly seen stuff that looked like it had a water-proof glue, it was kinda rough at the edge. This stuff looks just like an MDF edge.

And the veneers are getting so thin, it has got to be the eighth wonder of the world how they slice such thin veneer!

I guess people don't normally use these doors on exteriors any more? So maybe the producers think they can get away with shortcuts.

I'm kinda wondering what I'll find in ten years when I'm ready for another door, LOL.

[John Lanciani]

Probably something more like Miratec; http://www.miratectrim.com/ I've been using it outdoors in full exposure locations for almost 10 years with no moisture issues.

[Mel Fulks]

I've used the exterior MDF for years ,too. I think the first one was by Georgia Pacific between 10 and 15 years ago,it was in all the trade magazines with big ads and articles. I called our local GP and was told THEY MADE NO SUCH PRODUCT. Called the Georgia corporate office and was told the same thing .Numerous times over some months . On one such call I was transferred to a helpful lady who never heard of the stuff either ,but promised to check on it. She did (proof to me that she was their only native Georgian employee) . Due to her efforts we were finally allowed to buy a couple of units. With the single exception of that lady GP has the rudest ,most recalcitrant,and product ignorant bunch of people I have ever encountered. When the EXTERA product ,made by a rival company came out ,we switched to that. I like it.I have a deck rail for myself going on now.I need to learn to post pics. Job consists of some EXTERA imbricated pierced panels cut with CNC router ,mitred mdf posts,and wood trim and mouldings.