I need a door knob for a thick door

[jimlj]

I built a shed with a homemade door that measures close to 3" thick. I thought a typical door knob would work but there is no way. Does anyone know of a set that will work on that thick of door?

[dangitgriff]

Check your local home improvement store to see if they have the extension adapter kits.
Or, you could prank call your local plastic surgeon’s office.

[frkelly74]

When I had to do a similar thing with a 3'' thick door I ended up counter boring both sides of the door so that the lock set only had to reach about 1 3/4" to 2" and that worked well enough. So counter bore each side 1/2" or 5/8" deep at a bigger diameter than the rosette on the lock. You will probably need to make a jig to clamp onto the door so your hole saw doesn't wander. Bore and remove the wood inside the circle made by the hole saw, be sure to use a big enough hole saw so there is room for your fingers when you turn the knob.

[gwpercle]

Kwikset makes a Thick Door Extension Kit to use on standard door hardware, entry knob or lever set , that will allow the knob/lever to be used on a door 2 1/4" thick.
If your door is 3" thick , you could route out an area 3/4" deep on one side or an area 1/2" deep on both sides and mount the knob/lever in the recess . The extension kit only runs about $3.00 at home depot .
I don't know of any off the shelf door hardware for 3" thick doors...they aren't normally that thick .
Use some good hinges ...that puppy is going to want to sag in a couple years .
Gary

[cwtebay]

You can also use a standard knob set and use a piece of square barstock to replace the factory one to extend the distance between the knobs.

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[labradigger1]

Use a full mortise old time lock set with the threaded square shaft that the knob screws on to.

[country gent]

You might check Graingers or Mc Master Carr, There maybe some industrial knobs that go that thick

[jimlj]

Thanks for the ideas. I bought a Schlage lock set that apparently no extension kit is available for. I'll return it and pick up a Kwickset lock and extension and make it work.

[CastingFool]

My question is why would you need a door that thick? Security? The weakest point in a door is the jamb area where the door latches. Anyone bent on getting in, can kick the door and break the jamb, even if you have a deadbolt.

[jimlj]

My question is why would you need a door that thick? Security? The weakest point in a door is the jamb area where the door latches. Anyone bent on getting in, can kick the door and break the jamb, even if you have a deadbolt.

Not a security issue, just the way it turned out. The lock is to keep the honest people honest. Most of the time the door is unlocked, just want to keep the wind from blowing it around. The door has 7/16" OSB inside, 1 1/2" frame with 1/2" T1-11 siding on the outside, with some 1/2" trim that the lock set has to go through. I don't really want to router out the outside trim, but I think I can router a hole down to the framing inside, and with a thick door kit make a regular lock set work. I had found a couple knobs online for +/- $500 that would work, but I hate to put a $500 lock on a $2500 shed.

[jsizemore]

Surface mount lock set with a cool skeleton key.

[Petrol & Powder]

Lots of good ideas here.

The appropriate sized Forstner Bit would do the job of routing out the needed area and it would do it cleanly. However, the bit might cost more than the knob set. :shock: I would see that as a legitimate excuse to buy a tool.

I like the idea of an old lockset mortised into the edge of the door.
I also like the idea of a surface mount lock on the inside with a simple knob passing through to the other side.

The extension kit, or an improvised extension kit, is the easiest solution. The downside to that method would be the fact that the two halves will no longer interlock when assembled. If the screws clamping the inner and outer halves together are tight, it will be fine. But if the screws loosen a bit, one side will tend to twist.

I might take the opportunity to do some novel engineering and make a one of a kind latching device. My grandfather had a latch on a basement door that looked like it had been made by a blacksmith in the 1800's (it almost certainly had been) and I always remembered it was a clever design.

[jsizemore]

Most door knobs require a 2 1/8" hole saw and a 1" spade bit for the latch tube and are easily adjusted from 2 3/8" to 2 3/4" back set. The surface mount box lock doesn't require anything beyond a regular drill index to mount and a 1" sharp chisel.