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Help on prehung doors

glennh | Posted in Construction Techniques on May 20, 2007 07:05am

I need some help on hanging prehung doors. What I’m interested in is if there is a
standard for the gap beneath the door to the subfloor. I’m guessing that part of
that might be related to what surface finishing will eventually be on the subfloor.
In my case it will either be some type of engineered wood flooring (subfloor is
concrete slab) or carpet with pad.

What I’m trying to avoid is ending up trimming the door post the installation of
the flooring.

But also: I have 3 pocket doors to install as well and would prefer to not have to
do that on these either.

Bottom line: I’d prefer to sand and finish all woodwork before the floor goes in.
Is this a bad idea??????

Thanks for any help you can provide.

Glenn

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Replies

  1. User avater
    Huck | May 20, 2007 07:16am | #1

    Not sure if there is a "standard" gap.  How much of a gap would you like?  Are there air supply registers inside the rooms, with a central return outside the room?  If so, you have to take into account allowing for air flow from in the room to out, probably want to leave 3/4" or so, check with your HVAC contractor.  If air flow beneath the door is not an issue, then the gap may be tighter. 

    "I needed a drink, I needed a lot of life insurance, I needed a vacation, I needed a home in the country. What I had was a coat, a hat and a gun."

    Raymond Chandler's Philip Marlowe

  2. Piffin | May 20, 2007 07:19am | #2

    Well, finishing the baseboard first would not be a good idea.

    But no problem on the doors if you want to do it that way.

    I usually leave the door bottom 3/4" above finished floor. If you don't know what the finished floor material will be, you have a problem.

    I would like to leave it closer to 3/8", in my area it is very common with all the older homes to have a threshold at each door anyway and if I install the door too close, somebody inevitable gets a rug and places it where the door won't open until I get a chance to go back and cut it off again.

    LOL, on a house we remodeled two years ago, I had left a door with 1-1/4" above finished floor. It was too much IMO, but it was an original door andthey wanted it.

    Then last winter they had an interior designer go in and do some decorating. She placed a rug that must have been nearly two inches deep right in the way of the door so it would not open and close! Can't win for losing!

     

     

    Welcome to the
    Taunton University of
    Knowledge FHB Campus at Breaktime.
     where ...
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  3. User avater
    brucet99 | May 20, 2007 07:32am | #3

    "I'd prefer to sand and finish all woodwork before the floor goes in.
    Is this a bad idea??????"

    Yes. You're going to do baseboard before your wood floors go down? Pre-paint if you want, then all you need to do is touch up afterward.

    Case the doors before your wood floors are in? Sure, but expect to have to trim the bottoms to allow the floor to slip under. Much less labor to case after the floors are in.

    "What I'm interested in is if there is a standard for the gap beneath the door to the subfloor."

    How much daylight will you accept under the doors? Your pre-hung door probably comes with 3/4" of jamb beyond the door bottom. Carpet and pad come in different thicknesses, so there is no "standard" that works for all situations.

    "What I'm trying to avoid is ending up trimming the door post the installation of
    the flooring.

    "What I'm trying to avoid is ending up trimming the door post the installation of the flooring."

    What's the big deal? put a rip fence on your circ saw and trim as needed. If you try installing pre-hung doors to clear the various flooring materials, you'll end up with head jambs at different heights. better to install all the same height and trim the door bottoms as needed.

    I suggest clicking on the "bookstore" tab at the top of this page and looking for Gary Katz' book, "Installing and Hanging Doors" or look for it at HD or Lowes

    Good luck.

    1. Piffin | May 20, 2007 12:57pm | #4

      "Your pre-hung door probably comes with 3/4" of jamb beyond the door bottom."Wow! I get more like 2" and trim it to my needs 

       

      Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!

      1. jesse | May 20, 2007 06:23pm | #5

        I installed a prehung from Home Cheapo on Thursday, and one leg was 3/4" and the other was 1 1/4"!!!

        1. Piffin | May 20, 2007 08:16pm | #8

          Congratulations! that is just the ticket when the floor is 1/2" out of level! 

           

          Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!

    2. User avater
      JDRHI | May 20, 2007 08:20pm | #9

      Wow.

      One post that raises four issues I disagree with.

      First....sanding and painting before flooring is installed? Unless its getting carpet, no way. Heck....I wouldn't even be installing baseboard prior to just about any other type of finished floor.

      (b).... 3/4" jamb extension? I don't often buy prehungs...but it has been my experience that there's about 1 1/2" "excess" of jamb legs. Often, sitting legs atop subfloor leaves plenty of room for flooring installation.

      III....Cutting doors is usually a last resort for me. First...if by chance his prehungs are hollow core, its inviting disaster to plan on cutting them. Secondly.....the flooring he installs today, may require trimming of the doors. But what about in the future should he change out the flooring?

      And finally....Gary Katzs' book on door hanging? Ugh. I hope his article from FHB regarding hanging doors without shims aint in there!

      Other than that.....I agree 100%.  ; )

      I would recomend the OP first decide on his finished floors before installing doors. At the very least narrowing his choices down so that he has an idea of what the finished floor heights will be.

      J. D. ReynoldsHome Improvements

       

       

  4. slykarma | May 20, 2007 07:44pm | #6

    It's not hard to trim the door jambs and casing before floor installation so that flooring fits snugly under the jamb. A piece of scrap flooring or tile and a Japanese hand saw will do the job easily. Install the doors and case them, then trim the jambs when you know exactly what the finished floor will be.

    Lignum est bonum.
  5. User avater
    Huck | May 20, 2007 08:00pm | #7

    I would do like the old plaster interiors - put a wood baseboard the thickness of the wall covering, with the drywall on top.  Painted, all you see is a hairline between the base and the drywall, but you have a stronger base to resist bumps from furniture and such.

    I have installed composite wood-look Pergo-type flooring over a thin pad - it looked great, and the stuff is strong, but it was so slick that the office chairs on wheels they used would squirt around like a watermelon seed between your fingers.

    (Always better to reply in the same thread - it gets confusing when a new thread is started in answer to a previous thread.) 

     
    From:  glennh   9:50 am 
    To:  ALL  (1 of 1) 
      90072.1 

    Thanks for your replies. This list is great. I don't post very often but get alot of good
    answers whenever I do. Just what an inexperienced person like myself needs.

    Consensus seems to be to wait til the flooring is in before I trim doors and finish them.
    My home is southwest style and I'm not casing at all. Just using kerfed jambs with
    bullnose drywall corners into the kerf. No baseboards (ok: I know I'll need something
    around the wood but it will be minimal).

    I probably will try to cut the pocket doors ahead of flooring. The bullnose corner sits
    abit high and intrudes slightly on the opening size making it more difficult to remove
    the door after its installed.

    Any ideas as to what might be a good wood flooring to lay over a concrete slab and
    whether or not to use a pad? I've looked at Kahrs but that seems pretty expensive.

    Thanks...........Glenn

     
      View Image Options  View ImageReply  
       

    "I needed a drink, I needed a lot of life insurance, I needed a vacation, I needed a home in the country. What I had was a coat, a hat and a gun."

    Raymond Chandler's Philip Marlowe

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