Results 1 to 11 of 11

Thread: Will this interior door design work?

  1. #1
    Join Date
    Oct 2006
    Location
    Minneapolis, MN
    Posts
    3,923

    Will this interior door design work?

    I need to build a custom door for a bathroom in an RV. The door will be about 71" tall by 25" wide. What I would like to do is to take a 1/4" sheet of sanded plywood as the main body of the door and then place 1x4 Pine all the way around the edges on both sides plus a diagonal piece across on both sides. I would use pocket screws to join the 1x4s together at the corners.

    Will this be strong enough to not sag? I am trying to reduce the weight as much as possible while still being no more than 1.75" thick to accept a standard door knob.

  2. #2
    It's not so much the door would sag I think the problem you will have is with the hinges tearing out. You would be better off to use solid wood like 2x6's and make tongue and groove joints and insert the 1/4" plywood into the grooves for the panels. The joints would still need to be doweled but it would make a real door that would last for you.

  3. #3
    Join Date
    Mar 2003
    Location
    San Francisco, CA
    Posts
    8,753
    The common interior door thickness is 1 3/8". 1 3/4" is generally an exterior door.

    If you want light-but-stiff, a torsion box is the way to go. That's how common interior slab doors are built. There's thin skins on both faces, and a spacer grid which connects the skins together. For your door, you could use 1/4" plywood, or even 1/8". The spacers would be your 1x pine ripped to whatever width you need to make the door thickness 1 3/8" -- like 7/8" to go with the usual quarter inch plywood which is more like 3/16" thick. Run the pine around the perimeter of the door. Run a few pieces across the door too. Add some where you expect the handle hardware will be, and where the hinges will be. Glue it all up on a flat surface. (If you glue it up warped, it will stay warped.) Done.

  4. #4
    Join Date
    Oct 2006
    Location
    Minneapolis, MN
    Posts
    3,923
    I think I am going to have to rethink this whole project. I am going to end up with a 100 pound door by the time I start using 2x6s and the like. 2x6 studs seem to weigh more than Pine plus I'll win the lotto before finding enough straight ones. I could buy 2x6 Select Pine that might be lighter and is generally straight, but each 2x6 would cost me $30 or more.

    I am concerned that a 1/4" panel might not strong enough without stiffening. Going to 3/8" or 1/2" plywood adds weight.

    A traditional RV interior door is a crappy hollow core door designed to both save weight and cost as little as possible. I am almost certain the way I use my RV I would end up destroying a hollow core door in a few years. This is actually a bus converted to an RV that currently has a sliding vinyl door like used in closets in cheap houses. A really heavy door would probably break from going down the road and use, but a really light door could break from use. I am trying to come up with something in between,

  5. #5
    Join Date
    Oct 2006
    Location
    Minneapolis, MN
    Posts
    3,923
    Quote Originally Posted by Jamie Buxton View Post
    The common interior door thickness is 1 3/8". 1 3/4" is generally an exterior door.
    Door knobs will generally fit up to 1 3/4" so that is why I was thinking 1 3/4". I don't need a door that thick.

  6. #6
    If you use plywood for the main panel it won't sag, so there is no need for the diagonal pieces. Your pocket hole frame will give you stiffness so the door is flat and meat to attach the hinges. I would use a hardwood such as poplar or maple instead of pine for better screw holding. I would cut a groove in one edge of the fame boards and fit the panel into the grooves and glue it in place. Your only worry then would be whether the panel would bow over time. You would only need to beef up the thickness in the area of the latch if you choose a conventional lock set. There are screen door latches that work with thinner doors, that should work fine in an RV.
    Last edited by Lee Schierer; 09-26-2019 at 10:10 AM.
    Lee Schierer
    USNA- '71
    Captain USN(Ret)

    My advice, comments and suggestions are free, but it costs money to run the site. If you found something of value here please give a little something back by becoming a contributor! Please Contribute

  7. #7
    Brian,

    2x6's for an RV?

    I think your initial plan will work fine. I would glue the 1x4's to the plywood. Re: hardwood, not necessary. The door is light & pine will hold hinge screws just fine (think about what standard door frames are made of: softwoods - poplar, spruce, fir, etc.)

    The only issue I can see is warping which will be more of an issue with a pocket door. But this can be minimized if you start out with very flat plywood and when you glue on the pine, keep it clamped to a flat surface while glue is drying.

  8. #8
    Join Date
    Jan 2016
    Location
    Longmont, CO
    Posts
    505
    why not just get a hollow core door and cut it to whatever size you need? easy to modify, strong torsion box construction and light weight. just cut the side or height, and fill the void with a stick glued in.

  9. #9
    Join Date
    Oct 2006
    Location
    Minneapolis, MN
    Posts
    3,923
    My concern with a hollow core door is by the time I finished modifying it to fit I might as well have just built my own door. I need a door that is something like 25" x 70".

  10. #10
    Join Date
    Jan 2016
    Location
    Longmont, CO
    Posts
    505
    i think you could modify a hollow core door in about 30 min, depending on how many clamps you have for the filler. It's also going to be hard to build something different that has all the same attributes of a hollow core door in ones own shop. cheap, light weight, strong, easy to hang.

  11. #11
    Join Date
    Oct 2006
    Location
    Minneapolis, MN
    Posts
    3,923
    I ended up ordering a custom size hollow core door from Home Depot a week ago. I went to Home Depot thinking I would order a 26 by 80 door and cut it down. I discovered during the order process that Home Depot can order custom sized doors so I paid the extra to have the door made the right height instead of needing to cut almost 10 off the door.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •