I’ve got a bunch of irregular sized doors in my renovated attic and instead of slicing and dicing hollow core slabs to fit, I want to build some doors from scratch. One is going to be a bifold for a 6×6 closet door opening and the rest are short knee wall openings. How do I build them so they’re straight, don’t warp, and hold up on the hinges? MDF frame sandwiched between hardboard sheets?
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Don't build them just cut the prefabricated doors to size. You can use spray foam on the top and bottom to keep the blank rigid. And if you need to cut off the jamb edge just glue in a new piece of lumber for the hinge or strike.
I have done this exact thing for kneewalls, under-stair closet doors and low clearance basements. I have even cut down louvered doors so that there is ventillation.
It's not worth building from scratch
Why not build solid core doors? Much easier and stable.
Steve: Cutting down prefab slabs was the original plan and I may yet do that for some if not all. But I have knee wall doors that are 22x37, 25x35, and 29x35 or something like that ( width x height ) and the closet door is 40x60. If I had to cut up slabs, that'd be 2 prefab sides on all the doors and I'd have a lot of waste. Seemed easier to just put some planks around the perimeter between 2 sheets of hardboard. Would you cut down bifolds? Regular slabs would be too thick.
Mike: how would you build a solid core door that would be easier than gluing+pin-nailing some poplar or MDF planks between 2 sheets of hardboard? Not being a smartass, genuinely asking.
Since you suggested MDF frames which would mean that the edges of the door would be MDF, I'd use two pieces of light weight MDF (now there's an oxymoron) laminated together, for a paint grade door. If you want real wood on the edges that's a different story. If you want a standard thickness you could use 3/4 and 5/8 to make an 1 3/8 inch door.
Yes I have cut down bi folds before. It's not a problem .
And it's not 2 prefab sides- if you leave the top or bottom open and squirt in expanding foam you only have the strike or hinge side to deal with. In the past I have reused the original wood stile from the offcut. Just peel the outer plys off of it then give it a good belt sanding and slide it with glue back into the door blank add some spring clamps to keep it in place and you are done
By looking at a door manufacturer's dimensional specifications, you can determine how you might get a nice looking door panel for under-sized/non-standard doors. I had a project where I cut down 6-panel doors, and only used the top 4-panels for undersized doors. Depending on the door style, you might even be able to get more that one panel from a door slab. Take a look at Jeld-Wen's webpage and see if you find a solution for your project that is both functional and aesthetically pleasing: https://www.jeld-wen.ca/images/pdf/sizing/Moulded_Door_Specifications_11_2015_Revised.pdf
Hello. Have you considered nail guns for better performance? You might need it if you ask me. I'll be planning new minimal designs for my home this summer. I would say choose your vehicles carefully. Good luck now! :)