shed door, torsion box style

[cody michael]

I am building a shed and I need to build the doors, I am planning to make a 2x4 frame and screw/glue 1/2 plywood to it, I have enough 2x4's to go around the outer edge then have 4-5 crossbeams going horizontally. I have never built a torsion box before...

my questions are the plywood I have is 4x4, is that okay to have a seam in the middle of the door? I was planning about 1/2inch half lap joint gluing them together and then gluing/screwing them to 2x4. if it would be beneficial I could stagger the seam, have the outer seam in the middle, inner plywood centered over seam and seam about top and bottom. about 2 ft in would this be good or cause more harm and work?

the door will be about 4ft wide 6-7ft tall. should I use the full 2x4 or rip them to 2x2 or something else? I will also be making a 2ft wide door, copying the bigger doors construction.

should I have more pieces of wood going vertical? or will the 2 outer pieces be okay?

I also read you can use styrofoam inside the plywood, I have some 1 inch maybe a little over blue styrofoam, ct I use that inside the 2x4 frame? I could plane the 2x4's down to thickness of foam. I think I should have at least 1 2x4 in the center to screw the plywood seam to... would the foam be better then wood for the rest?

I have a box of house door hinges will 3-4 house door hinges work to hang these?

the picture is my rough idea for 2x4 frame, with the 2x4's evenly spaced... will this work, is there a better way?

the shed project went way over budget so I am trying to use stuff I have on hand, but if I need to buy something I can.315576

[Kent A Bathurst]

Cody - from my little bit of relevant experience, a couple points I can offer:

1. lap joint on 4x4 ply is fine as you have described. Just be sure it is waterproof when you are done.
2. hinges are one of those "you get what you pay for" things in life. Stainless or brass, ball bearing construction, swaged not folded.........nobody ever saved money buying $10 hinges, they only wasted $10 per hinge, in the long run
3. Those are big, and heavy, suckers. You might consider a corner-to-corner tension bolt on threaded rod......that would, IMO, obviate the need for all but one of the interior 2x4 members [you gotta have one behind the seam]


EDIT: Ooops - forgot one biggie..........I would use pressure treated for the sill plate, and extend those full-length, so the jambs/stiles sit on top. Shed doors + water = rotten door sill plates.

[John Schweikert]

Appears overkill. 3 cross beams would be fine. The key is good 2x4s. Joint or hand plane them if needed to get them very straight. Cut exact 90 degree ends. The larger Kreg screws work great for this. Done it multiple times with no issues.

No need to make the 2x4s to 1 inch to match the foam. Any trapped air in the door between outer plys will also be insulating.

It's just a shed door. Don't over think it or over build it.

[Eduard Nemirovsky]

Coddy, are you reading mine mind? You are scared me man. Only my wife can do this.:eek: I just open SMC to post exactly the same question.
Thank you for doing this.
Ed.

[cody michael]

Coddy, are you reading mine mind? You are scared me man. Only my wife can do this.:eek: I just open SMC to post exactly the same question.
Thank you for doing this.
Ed.

Lol, 2 for 1!


Will 2x4s all around work the best? Or should iI make them 2x2? I want to make sure the door Doesn't warp...

[cody michael]

how long of kreg screws do I need? can I just use normal construction/deck screws? I have a kreg jig but I don't think I have any big screws.

[Jebediah Eckert]

They aren't insulated but this is how I have built shed doors. This set is about 5 years old and are still straight and shut as they should. The door is framed inside with 2x3's (2x2 would be fine but I didn't feel like ripping these) with a 2x4 across the center. I used a 2x4 to give me more leeway to attach the latch hardware. In the past I have made them way stronger but found the extra material and weight wasn't worth it. The doors in the picture are 3' wide each for a total opening of 6'. They are 6 1/2' tall. I built the frame on the flat plywood floor then attached the T-111, if the frame ends up twisted so will the door.

315585

315586

Sorry for the sideways picture. No matter how I orient them on my phone they always seem to post wrong.

[Ethan Melad]

I built a pair of carriage doors, each 4'x8', and used engineered 2x4s rather than KD. I'd recommend doing that, since all of them were perfectly straight and flat - KD 2x would definitely not be. Get the stranded type, I think its made by Weyerhaeuser, not the laminated LVL type.

The door was built with the 2xs flat, not on edge like a stud wall. I believe I just made a frame and aded one (maybe 2?) horizontal member. Joints were screwed and glued. the 1 1/2" deep cavities i filled with rigid insulation, and sheathed with either 1/2" or 3/4" CDX (don't remember), then I added additional stock around the perimeter to conceal the layers of construction. i also added a 1'x3' polygal light in the top portion. I can get a picture if it would be helpful.

Also, neither this nor your original design are really torsion boxes at all, closer to a ladder core door.

[Bob Michaels]

A 4' x 7' door is a monster. Might want to consider double 2' doors. The orange borg has heavy duty ball bearing hinges that are relatively inexpensive that I used when building double 4' x 7' doors for a period style garage at one of my properties. I used 4 hinges on each door and they haven't budged in 2 years.

[Terry Therneau]

I built carriage house doors for my shop this way, using LVL 2x4s because they are so straight. 1/4 inch ply on the inside, 1/2 on the outside, 1.5 inch rigid foam in the middle. I have seen 1 U-tube video where the builder used a can of window/door foam before laying the ply down so that the insulation was part of the strength, but that is probably overkill. After glueup and drying I added 3/4" cedar boards to the ouside; they cover the seams and make it look like a frame and panel door. I agree with the comment about good hinges.
Fine Woodworking had an article on this a few years ago; google "Dress up a garage door with insultated carriage doors".

[Larry Frank]

I have built quite a few shed doors and the weather gives them a beating.

With my l last shed, I gave e up buildings and installed a roll up door. Was one of the best things I have done.

[cody michael]

I have built quite a few shed doors and the weather gives them a beating.

With my l last shed, I gave e up buildings and installed a roll up door. Was one of the best things I have done.

I would love to have one, but my budget is closer to 20$ then the couple hundred+ the roll up would cost.


I am making 2 doors, 1 4ft, 1 2ft, the shed is for my motorcycle, I need the wider door to be able to get in and out without worrying. I built my last shed (before I moved) that way and it worked great, but I just used a 4x8 sheet of plywood and it warped, that is why I am trying to over building this one, to prevent warping.

I am going to start this tomorrow can someone let me know if I need to use kreg screws or if the deck screws I have will be fine?

[Bob Michaels]

I would love to have one, but my budget is closer to 20$ then the couple hundred+ the roll up would cost.


I am making 2 doors, 1 4ft, 1 2ft, the shed is for my motorcycle, I need the wider door to be able to get in and out without worrying. I built my last shed (before I moved) that way and it worked great, but I just used a 4x8 sheet of plywood and it warped, that is why I am trying to over building this one, to prevent warping.

I am going to start this tomorrow can someone let me know if I need to use kreg screws or if the deck screws I have will be fine?

Cody, Not sure what you are using the Kreag screws for. Are you going to assemble the frame with pocket hole joinery to keep the shape while gluing and screwing the ply on to the 2x4 frame ?

[cody michael]

YYes I was planning on using pocket holes to screw the 2x4 together

[Jebediah Eckert]

Why not just face screw them with the deck screws you have?

If you get too crazy with this thing you can no longer call it a "Shed". :D

[cody michael]

Why not just face screw them with the deck screws you have?

If you get too crazy with this thing you can no longer call it a "Shed". :D

It's not really a shed, it's my motorcycles new house/ over flow for my tools the wife says are cluttering up the garage.

I want to use the kreg jig because I'm laying the 2x4's flat, so to face screw I would have to go through the 3.5 inches of 2x4 and into the other 2x4, also not having screw holes on the outside will make painting/weather proofing easier.

I made the frame, I am going to go work on putting the skin on shortly, I used 2x4 for the sides, and spaces 5 2x4's through the middle, top and bottom, center where the plywood seam is, and in the center of the sheets of plywood, I don't want any warp...

[Jim Andrew]

Think I would put some plywood on the inside of the door as well as the outside.

[ian maybury]

A few thoughts Cody, coming in late.

If the door is exposed to heavy weather (especially driven rain, or run off from the building) then it's possibly best not to sheet both sides of it. Not unless you are certain that all of the joints will be 100% long term sealed. (I had a double skinned gate leak despite the joints all being sealed with silicone - luckily it's in iroko and hence highly rot resistant. Scary what it can get in through) It's not an absolute certainty it would get in (probably would be if it was a gate out in the weather, or if it was T&G board sheeted), but water can sometimes run down inside a double skinned structure and find itself with nowhere to go - and cause rotting especially along the lower edge. It only takes a very little if it's trapped inside the structure.

If you go to a single skin then it may rely more on the frame for support (but ply is good in this regard, so it may not be an issue), this is the traditional structure over here (the diagonals stop sagging): http://wiki.diyfaq.org.uk/index.php?title=Making_a_framed_ledge_and_brace_do or Lighter versions don't need the fancy joinery (tenons etc) provided the diagonals are placed so they run down to the hinge side and are tightly fitted.

It may not be necessary, and it might not be visually to taste - but if going double skinned as a second best (presuming sealing is not certain) it can pay to drill a horizontal line of say 1 in dia drainage/ventilation holes through the skin flush with the top edge of the lower batten. Also to make provision that the water can migrate down inside the door (and not e.g. pool over a higher batten) to this level. It's hard to keep timber dry, but with good ventilation it's slow to rot.

The ply obviously needs to be fully waterproof too (better if it was marine ply as the WBP varieties are not always trustworthy in this regard), and the edges well sealed.

It's very hard to beat a single skin door constructed as in the link from a rot resistant solid wood like iroko for longevity….

[Pat Barry]

For the design you are considering here I would use construction adhesive to laminate the 2x4's to the plywood. I don't feel those pocket screws are going to do much for you as structural / strength except make it easy to assemble the frame. For the plywood, make a rabbet in each piece to create an overlap joint and be sure to use the construction adhesive in this joint as well. Plywood is going to need some good primer and paint to weatherize it. It is likely to delaminate over time on the bottom edge due to water absorbtion and not drying completely and quickly after moisture exposure. I built some similar using Smartside brand sheet materials 10+ years ago and they are holding up great. I don't think plywood would have.

[Jim Dwight]

Your plan will work if you can find a way to hang it without it sagging. I would try to lighten it, however. 1/4 on both sides would make a stronger door than 1/2 plywood on one side. Rabbeting the 2X so you have solid wood at the edges will help avoid the sheet goods delaminating. Pocket screws are fine for joinery but use glue too. Construction adhesive if your joints are not so great. Titebond 3 would be fine is the joints are. Prime edges and both faces.

[Dan Rude]

Cody, check out the current family handyman. About this time every year the same editor builds a different shed. This year he did sliding doors. Try to go with a frame and panel. I did mine with ply topped with carsiding. They are big and heavy, too big and heavy. I plan on replacing them this year, and converting the old one's into new shelving. Dan

[Halgeir Wold]

2x4's seems massive heavy duty for a torsion box type door, unless you want to make it extra heavy. adding the plywood sides, that door will end up quite thich,too. Hinges wil also have to be heavy duty. Doors like this used to be common over here for many years, but normal thickness used to be appx 2", interior doors slightly thinner, appx 40mm. For structural strength, i'd use much slimmer internals, and fix and glue it together as a regular torsion box.... just my 2 c's......