Ask Me Help Desk - Pre-hung doors

I just bought a house, and am going to start remodelling 1 room at a time. One of my first jobs is replacing the hollow core doors with 6 panel pre-hung doors. Can anyone help me with the steps for demo & installation of pre-hung doors? I have a good basic knowledge of carpentry, but need some advice. I know I'll be asking a lot of questions before I'm done with this house, so thanks in advance for any help!

Pete

Removing old doors is straight-forward. Remove the moldings on both sides (back and front) of the door frame. I find it's easier to cut the nails or screws that hold it in place. I use a reciprocating saw with a hack saw blade. Once you get that out, the old frame slides out.

Installation is, obviously, more difficult and it's nice to have a bunch of pictures. There are lots of web sites that explain this in detail.

Let me google that for you

How to Install a Prehung Door | Step-by-Step | Doors | This Old House - Introduction

How To Install A Prehung Door

http://www.hammerzone.com/archives/d...ehung/pre.html

Prehung doors come in several widths with 30, 32 34 being the most common. Measure your opening after removing the old doors and frames. You must start by removing the trim inside and outside of each door to expose the nails holding the door frame to the home, I cut the nails with a reciprocating saw. Measure the opening and then buy a door rated 2" smaller than the actual opening. When installing the new prehung start with the hing side first . Get it plumb and square with shims and then nail to the frame with nails right at each hinge. Do you need more info?

Hi Pete

Welcome

To remove existing doors and jamb.
1. Remove door
2. Remove trim from both sides
3. Using a sawall, start at top of jamb and cut down between jamb and stud.

The jamb will now come out

To install new prehung door
1. Stand unit in opening
2. On hinge side, tack in 8d finish nail above top hinge and one below bottom hinge
3. check space at top of door, should be equal
4. Put shims in from both sides above nails
5. Use level on edge of door on lock side to level door.
6. When door is level, nail through shims with 2 finish nails.
7. Put shims midway between hinges. Put another set of shims midway between top and middle and middle and bottom for a total of 5 shims.
8. Adjust shims for even spacing between door and jamb with door in closed position. Nail shims
9. On lock side, put in 5 shims and set space at 1/8'' between door and jamb. Nail shims
10. Cut off part of shim that sticks out past jamb.
11. Install trim and passage/lock set.

U are finished

Good luck

Chuck

Didn't look at the sites above but need to mention watch for the 'Under cut" on the door in relation to any carpet that it will drag on. Also if the floor it swings on is out of level that can also mess it up.

If the hinge Jamb is plumb I like to nail the new jamb directly to it. Saves a lot of shimming. If it's a bit wide and it usually is because old jambs are a lot thicker the new, I use a 1/4 piece of luan or 3/8 ply and scab that on the hinge side.

Don't kill yourself plumbing the hinge side Jamb. I can show you 6' levels that disagree.

Set the jamb and adjust the header next for height.

Now work on the strike side. Be careful not to rack the jambs. A door works fine as long as its square to itself first and the opening next.

If you need to shim any hinges get back. There are 6 ways to shim just one hinge

Thanks for all the info. 21boat, what are you talking about with "under cut"? I don't have any carpet, they are hardwood floors. I just bought 3 doors this weekend, and I've taken off the trim on the old doors, but I'm waiting till the walls are painted before putting on the new doors. It sounds like it's not going to be to hard to do them, and I convinced my girlfriend I needed a new Sawzall to get the job done.

Thanks, Pete.

I'm going to have to disagree with Boat and say take the time to make sure that hinge side is plumb. And, that is plumb in both directions. That is to say that not only should the hinge jam be plumb in th opening, the walls must be plumb. Otherwise the door will tend to swing open or closed by it self. If the wall leans you can usually move the bottom with couple of blows with a your hammer. At this time also check the latch side wall to see if it is plumb. If not try plumbing it by moving the bottom.

Your doors will have a split jam. After you cut the bands, remove the outside casing and jam. Set that aside such that the corner joints do not get damage. From the inside the room, set the door and jam in the opening. Push it tight against the hinge side of the framing. Put a finish a nail top, bottom and center of casing each side. Pay attention to the gap between the door and the jam on the latch side. Do not drive nails home.
Remove what ever is used to tie door to frame on the latch side. From the outside of the room (assuming that the door swings into the room) shim the latch side. With door closed, take note of how the door and door stop meet. If the hinge and latch side are not in the same plane the door will strike the door stop at the top or the bottom first, as if it were warped.
If the top of the door hits the door stop first move the bottom of the frame toward the door. If the bottom of the door hits door stop first, move the top of the door frame toward the door. It may be necessary to shim behind the casing on the interior side to keep the latch side parallel to the hinge side but not usually. Usually the casing will conform to the wall. In worst case you may have to caulk between casing and wall to hide shims.

When door and door stop meet evenly, nail through door frame and shims. Just a nail top and bottom. Install outside portion of jam and casing. Nail thur casing and then through jam

If u install door frame out of plumb, u can always tell people it is new type of door. self closing LOL

Chuck

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I'm going to have to disagree with Boat and say take the time to make sure that hinge side is plumb

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I never said it not to be plumb that way. I said "Don't kill your self plumbing the hinge side Jamb.I can show you 6' levels that disagree"

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And, that is plumb in both directions. That is to say that not only should the hinge jam be plumb in th opening, the walls must be plumb. Otherwise the door will tend to swing open or closed by it self.

I disagree with hkstrud... The wall doesn't have to be plumb as you think at all. If We went with that then all the old homes in my town won't be able to get a new door. Most ALL our old walls are out of Plumb and many on New homes...

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If the wall leans you can usually move the bottom with couple of blows with a your hammer. At this time also check the latch side wall to see if it is plumb. If not try plumbing it by moving the bottom

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If that is done then make sure you take the pictures off the wall. If it's a old home with plaster better get out the Home owners insurance. Also lets not mention the banged wall in time possibly springing back to its wood memory position.. Also the plaster may crack right then or later.

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Your doors will have a split jam

We still have prehungs that aren't split jambs more so then not.

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It may be necessary to shim behind the casing on the interior side to keep the latch side parallel to the hinge side but not usually. Usually the casing will conform to the wall. In worst case you may have to caulk between casing and wall to hide shims.

Be careful shimming a split Jamb If you don't take the stapled casing off. If the shims are going in from one side then you can Twist the jamb and cause a bad installation real quick on what you thought you just had in swing and reveal. That is what causes a door to swing out on its own also.

Let me redefine some things Pythagorean theorem is more important of the frame to door then the door to the opening. Also if you finish nail a shimmed door jamb be prepared for the jamb to get wack out the jamb in being plumb and twisting the frame. The soft standard shims will compress more right when you go to set the nail. In turn the jamb may end up a tad out of plumb or to wide. God bless Passloads/air/battery nailer's. So quick in shooting the nail the compression isn't as prevalent.

Its not necessary to plumb the inside of the strike jamb. No matter what it has to be relative to the door swinging on the hinge side. The strike side has to mimic the hinge Jamb location and is turn the door hanging on it, its own footprint. Telegraphing is what's required in any door installation. Plumb or a tad out of plumb.

I Never needed to level a header or strike side of a prehung door on a wood frame or a KDF metal frame. If the door is there to swing on the set hinge jamb. The door becomes your square. Actually a Square is not needed at all if the hinge jamb is plumbed and set. The only worries is if the floor rises up when the door is opened and the bottom of the door hits the carpet or hardwood floors.

OK, one more question (for now). I just painted the first door I'm installing. The doors are split jams, but in the closet I'm not going to be able to fit the rear jam in with the trim, the closet is to narrow. Should I pull the trim off and put in the jam for stability, or is it OK to just leave off the inside jam altogether? Either way will work for me, if putting the rear jam in is better that's what I'll do. There are 2 closets that I have this situation with.

Thanks again for all the advice from everyone.

Pete.

I usually remove the trim or and rip it down and reinstall

Bottom line is if the jamb in secured enough then that's fine also.

Its aesthetics at that point

Here are some interior door installation instructions, and here is a video for removing an interior door. Good luck!

If the jambs are good why don't you just replace the doors and save yourself a lot of trouble.

Hi Patty,

Usually the problem with just replacing the door is getting the hinges and latch to line up with the old jambs. You need to buy a door slab (just the door) and mortise the hinges into the doors edge. This is done with a router or wood chisel. Prehung doors are done with jigs to make the hinges line up on the jamb and door.

If the trim and jamb are in good shape it's perfectly fine to mortise the new door slab. However, sometimes it can be more time consuming than doing new trim and a prehung. Hope that helps.