# Door Jamb size - what door do I use?



## jvaruzzo (Aug 18, 2007)

Hey, thanks upfront for any help, first time post.

I purchased a 30x80 prehung door with a rough opening of 32x82 1/4.

I didn't really measure the door opening first, I just roughly measured 30x80.

The actual dimensions of my door opening are:
31 7/16" x 80 1/2".

All the prehung doors I see have rough opening bigger than 80 1/2". Is it normal to shave down a door that much to get it to fit height-wise? 

For the width, I imagine a 28" door would be more suitable.

Not sure that it matters, but this is an interior solid wood prehung I'm trying to install to seperate two rooms. The opening was already framed out when I bought the house, but had a folding door installed. I suspected that originally a real door was there, but now I'm thinking perhaps I was wrong.

Anyhelp appreciated.

Thanks, 
Justin


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## Ron6519 (Mar 28, 2007)

Whatever door you get will need to be shortened to fit the opening height. This is the easy dimension to deal with. Get a 28" door and cut it down. There is a learning curve concerning hanging a door ,even a door that fits into the opening.
Ron


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## jvaruzzo (Aug 18, 2007)

Thanks, that is what I figured. I'm new to this whole homeowner thing 

Do I just cut it down with a circular saw? 

Thanks,
Justin


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## Ron6519 (Mar 28, 2007)

If it's a hollow core door you want to cut it differently then a solid wood door. A solid wood door won't splinter like a hollowcore luan door will. Use a sharp 40 or 60 carbide tooth tipped blade and cut it with the least visible side up. If it were a closet door the inside of the closet face would be face up on the saw horses. With the luan doors I score the face with a utility knife so you can avoid blow out on the face veneer.
Clamp a straight edge to the door and run the saw along it if you don't use a saw that often.
Ron


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## jiggyjack (Mar 30, 2007)

The problem you are ruining into is that a Bi-fold door and a regular door do not have the same rough opening.

That being said Ron gave a very nice breakdown of how to cut it. The only thing I would add is that if it is a hollow core door make sure that if you cut out more than 50% of the bottom edge 2 x 2 you should carefully remove whats left and make a new piece then reinstall and glue it.

Also a drawback to cutting door is that your handle will not be at the standard height. A little quirk most people will not notice, but that kind of thing drives me nuts.

GOOD LUCK


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## ron schenker (Jan 15, 2006)

> Also a drawback to cutting door is that your handle will not be at the standard height. A little quirk most people will not notice, but that kind of thing drives me nuts.


I recently had to hang a door that a homeowner framed under a bulkhead, and I had to cut it down 5". I took 2 1/2" from the top and 2 1/2" from the bottom, replaced the support blocks, hung the door, and the handle was still at the right height. Isn't science wonderful:laughing:


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## jiggyjack (Mar 30, 2007)

ron schenker said:


> I recently had to hang a door that a homeowner framed under a bulkhead, and I had to cut it down 5". I took 2 1/2" from the top and 2 1/2" from the bottom, replaced the support blocks, hung the door, and the handle was still at the right height. Isn't science wonderful:laughing:


 
The problem with cutting the top is you have to remortise your hinges or cut and route the jamb.


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## ron schenker (Jan 15, 2006)

jiggyjack said:


> The problem with cutting the top is you have to remortise your hinges or cut and route the jamb.


No hinge remortising at all, but the upper door stop corners were a bit of a pain.


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## jvaruzzo (Aug 18, 2007)

Thanks for all the great info.

It's a solid wood door I'm putting in.

I essentially need to take 2 inches of the bottom, and it's a door that wont' be used. It's to seperate the apartment from the rest of the house. It is locked from the inside and would only be opened in a fire-emergency, so placement of the knob is not important.

I have to return to 30" door I bought that is too big back to Home Depot and grab a 28" door. I'll let you all know how it turns out.


Thanks,

Justin


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## Ron6519 (Mar 28, 2007)

Measure the jamb width before you go. Standard width is 4 9/16". You might have to add extenters to flush it with the two walls.
Ron


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## papashaq (Mar 8, 2007)

Check your codes for it being a fire door. In WI...my city, we have rental inspections and something like that would need to be fixed if you don't have 80" of clearance through the door. More than likely you won't have to worry about it, but my city is a stickler for something like that, if there is nothing worng they will find something!! Sounds like you have enough room just make sure you snug it to the header.


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## jvaruzzo (Aug 18, 2007)

I'm learning as I go along.

I did get the door cut down and it's ready to go in.

The 28" door is a little too narrow, it left almost an inch on either side, I was trying to shim that gap and everytime I'd toucha nything, all the shims would fall out.

Someone suggested just framing out the opening a little smaller, to make a snugger fit, instead ot framing out w/ shims, that seemed to make a lot of sense.

I'm not exactly sure what is and what is not code. From what I understand where I am, as long as there are no problems and your not opening any building permits there really are no "spot" inspections. Basically, someone would have to complain they think something is unsafe.

The door is not entirely nescessary, worse case scenario if someday it turns out it it's not to code, I can just sheetrock it up. The problem is my side ofthis house only has one exit on the lower level. They don't require exits, they require "egresses". My building inspector when I bought the house brought it up, but wasn't positive as to how large a window would need to be to be considered and egress.

Thanks for the info, I'll still let everyone know if I can get this thing hung!

-Justin


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## boman47k (Aug 25, 2006)

> it left almost an inch on either side


As in on both sides? Add another jack stud to inside of rough opening, then shim as necessary. Assuming there is an inch on each side.


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## sflamedic (Oct 21, 2006)

I just helped my dad with an exterior door and the rough opening was too big so we added a thin fence board to one side and it made a tighter fit and easier to shim. Good luck


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## Ron6519 (Mar 28, 2007)

If you want the door centered in the opening, put a 1x4 or 1x5 on either side. Then the shims will stay put. You want the shims behind each hinge and the locksets. Space out the rest evenly on the sides. Add one on top in the middle.
Ron


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