I need to construct a solid core door for the knee wall attic in our new room. Rather than purchasing a custom door, have people been successful in constructing a door from particleboard or MDF? I have a doorknob borer from Harbor Freight for just such a possibility. I'm thinking about cutting a 4'x8'x3/4" into two 2'x3' pieces and sandwiching two with liquid nails, then boring the knob and latch holes.

  • What's the question, exactly? Folks have been building solid doors for centuries. The material isn't particularly important.
    – isherwood
    Commented Jun 1, 2016 at 16:10
  • The inspector would probably want to see a 10 minute fire rating on the door. Not that we'll get to test it out on anything, but if it looks solid and is painted, my guess is that it'll pass. I suppose I'm just checking if it's a valid method of making a solid door or not, or if there's another cheaper way. This is just for a 2'x3' access door for the knee wall space.
    – saigafreak
    Commented Jun 1, 2016 at 16:27

1 Answer 1


You won't get cheaper or easier than two layers of sheet lumber. Particle board is a common component in 30-minute fire doors (though they usually have a hardwood veneer).

I'd do just as you plan. Sand or route a bullnose all the way around and seal it with a couple coats of urethane, smoothing with steel wool between.

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