Crazy idea for material for a door?

[laura vianello]

We are on the budget with the attic storage area. Because the doors I need to install are quite big, ordering them is not an option ($$$$). I have limited skills when it comes to "dadoing" thing. So what about building them with 1/4 MDF for the panel (full size of the door). Installing 1/4″ plywood into strips to the door panel top, bottom and sides. I will do that outside and inside of the door. That should be good enough to have a 3/4" thick door and be able to bore the holes for the hinges. Is it crazy? I need the same type of door for a slanted door to access the second area in the attic (real storage with boxes, totes, etc) and this design let me build a lot with different shape at a fraction of the cost of a normal door. Open for suggestions.
Thanks

[John Lankers]

Not crazy at all.
I don't know the dimensions you have in mind but for a 'normal' size door I don't see an issue.
Since these doors are going to go into the attic you should pay special attention to the finish you're want to apply. The temperature and humidity levels can change drastically and cause the doors to warp, this is not limited to MDF it can happen with other materials as well. I would suggest you prime and paint the doors or apply some other finish to seal the wood and MDF prior to installation. Depending on the finish you plan to apply, a shellac based primer might be a good sealer.

[Jerry Miner]

What size door are we talking about? Your idea could work fine for a "cabinet-size" door, like 16" x 24" but would be flimsy, IMHO for a "man-door" 36" x 80"

[laura vianello]

Thanks so much for your suggestions, here few clarifications. 1)The area will not be subjected to dramatic temperature changes. It was insulated with spray foam and it does not get cold there even though there is no heat at the moment. We will eventually put A/C because we are concerned about condensation and probably in the summer it will be hot. I was planning to paint the doors. 2) The shoes cabinet door will be 18x40, the other opening in the picture will need 2 doors 40x20, the central opening (which I did not take a pic for) 2 doors 25x40. The man door (slanted) will be actually 32" wide 67" high on the highest side and 47.5' on the shortest. For the big opening I was thinking to add bypass doors, so I guess I can go thicker with the MDF.

[Harry Hagan]

Oriented Strand Board sheathing would be more stable and thicker too at 7/16". About $11/sht where I live.

[laura vianello]

If you want to have an idea about what I actually building, here my post: http://www.sawmillcreek.org/showthread.php?250465-kneewall-built-ins-structural-question

[laura vianello]

Harry, I do not think it will look good when painted. Maybe for the "man door" and then covered with MDF to have a smooth finish?

[Bob Coates]

This is the part that I would worry about. "That should be good enough to have a 3/4" thick door and be able to bore the holes for the hinges." Your 1/4 material may not hold up to opening and closing with screws. I have had screws pull out of 3/4" mdf.
Bob

[Jerry Miner]

Laura, I appreciate that you want to save money, and the glued-up mdf idea might work, but I also think this would be a great time to expand your cabinet-making skills and build some "real" frame-and-panel doors.

If you're not equipped to flatten and straighten your own wood, try to find some S4S lumber that is pretty flat and cut your stiles and rails from that. With a glued-in mdf panel, a simple stub tenon-and-groove construction would work fine. Poplar is pretty cheap and works well (and holds screws better than mdf).

If you have a table saw and some clamps, you have what you need to make simple stub-tenon-and groove frame-and-panel doors.

For the man-door, you can glue two 3/4 pieces together face-to-face and use a 1/2" panel.

However you go with this, be sure to do your glue-up on a flat surface, so the doors come out flat.

[Jim Dwight]

I made a couple odd sized doors for attic access areas. I wanted them to be insulated because the wall they are in is insulated. I built a 2 inch wide frame of 3/4 softwood with the joints pocket screwed together, added two layers of 1 inch rigid foam insulation, then stapled on a layer of 5mm luan on each side. I used spackle on the staple holes and painted them. My wife is not always easy to please but she thinks they are fine. The softwood frame gave me something decent to attach the hardware to.

If pocket screws are not something you do, you could use through screws or even brads or staples to make the softwood frame. Brads could be used to fasten the luan on but staples will hold better. You do not have to put insulation in the door if you don't need it for your application. You could also orient the softwood on edge to end up with a door a little over an inch thick. These doors are plenty strong for most purposes. Hollow core doors you buy are made the same except they have cardboard spacers between the two layers in the center.

[Dan Hahr]

You can make a really solid door in the method you are talking about if you just use one sheet of 1/2 MDF. Cut the exact size door you want from the panel and then rip the rest into 5 or 6" strips. Glue these into a frame around the perimeter of the door and across the middle, or wherever you want... You can brad nail them in place but when the glue dries, it will be solid as a rock. You will need something dead flat to do this on if you want the door to be flat. Many door companies use MDF for their better solid core doors. I will be making some for my attic space soon in the same fashion.

Dan

[laura vianello]

Jerry, thanks for the confidence but I am doing this as a spare time job. I have a full time job and 2 kids and, even though I have a table saw, I am quite intimidated by it. In addition no space for a real workshop, so the table saw cannot be moved outside in the winter when I need it during my lunch breaks. I would love to be more confident and try the door built but I think I need a serious workshop with dust collection etc. I might try the router and make a grove in the solid frame and add the mdf panel. Never used a router either...boy I am getting complicated. I will do the man door as you suggested, great idea. Thanks

[laura vianello]

Jim, I do pocket holes and I have done a good amount of projects with them, tons of drawers and cabinet boxes. So I am ok with the technique, great idea. Thanks

[Jim Dwight]

Laura,

If your doors are close to the size of standard doors, hollow core doors are actually pretty cheap. They can be modified in any dimension but if you cut off more than 3/4 inch or so, you have to restore the solid wood at the edge. The simplest way to do that is to cut the plywood skin off the piece you cut off, push the cardboard filler back from the cut edge of the door and then shove the solid wood piece back in with glue on it. Brads or staples will hold it until the glue sets or you could clamp it.

If you want a frame and panel look, you could make the frame of 3/4 softwood pieces pocket screwed together and then put a piece of luan or mdf the full size of the door on the back covering the pocket screw holes. The resulting door will only be about an inch thick but it will be pretty strong. The solid wood on the edges will be a lot better for hardware attachment than plywood or mdf would be. If you wanted to get nearly the same thickness as a standard door, you could put another layer of pine pieces on the other side. Those joints could be just butt joints, or doweled or whatever you are comfortable with. The thin plywood piece and pocket screwed frame on the other side will give you adequate strength to keep the door together.

It sounds like this is more than you want to get into but I once made a whole house of interior doors using 2X structural lumber and shelving boards. I used my planner to reduce the 2X to 1 3/8 thickness to make the frame of the door. A dado in the center of the interior edge of the frame held the panels and the stub tenons in the center. On the outer edge, I reinforced the stub tenon joints with dowels and/or through screws (plugged). Panels were raised on the table saw. This was several decades ago and the work was crude by my current standards but the doors worked and we thought they looked pretty good (stained and poly'd). Hollow core doors were probably cheaper but solid wood doors considerable more expensive.

[laura vianello]

Hello Jim, if you look above I have added the dimension of the doors. I would say, probably only one is closer to a standard door but it is not rectangular because it will go where the ceiling is slanted. I never gets easy in my house! I was thinking about simple shaker door because I can cheat with panels and hardwood stiles but I would not like to have cabs with door thicker than 3/4. If I use 1x3 poplar for the strips and then add the luan or mdf to cover the screws, I would have a panel that is too recessed (usually it recesses only 1/4'). Am I right? May be I should go for 5/8 baltic birch and call the day. Would it hold the hinges (BLUM concealed)?