I am a newbie and I've never done anything like this in my life, so any help on this is greatly appreciated. We currently have a number of doors in our house that are 78" that we want replaced. I have read that Prehung doors are the best way to go. Wasn't sure if I should buy solid or hollow either. Please add anything to this, but the gameplan I was going to follow is:

1). Take the existing molding off and see where the beams are that the existing door is attached to. Measure that opening. Also measure the size of the wall, so I make sure I buy the correct size (h x w x d) jamb.
2). Remove the existing door jamb.
3). If the new door jamb is too big, cut the bottom of both the door and new jamb to fit. I read to take a compass and hold that point against the bottom of the door. THen draw a line. Would I need to buy some kinid of circular table saw for this? I only have an electric chop saw.
4). Put the door in the opening, and shim so there are equal openings around each side. Starting with the hinge side, paritally nailing that in through the jamb and shim. Make sure the rest is plumb and then continue nailing in the top and other side.
5). Pray the door closes.
6) Attach molding
7) DO this 5 more times for the other doors.
8) Have a beer.

Am i planning this out right? ANything to add or tips that I don't know about?

 

Your "game plan" sounds basically good. But start with one door and take the casing off. If you have room at the top to install an 80" door, then take the top casing off of the rest and make sure that they are all the same. Otherwise, order PH doors that are 78" tall. That is a "standard" size, but nobody stocks them. cutting an 80" door to 78" tall is a pain if they are hollow core doors. You are taking too much off of the bottom, and will need to save the bottom of the door frame and reinsert it into the door. That will mean cleaning enough of the webbing out to make room for the bottom of the frame.

If these are all interior doors, solid or hollow is your call. Price them both ways and then decide.

 

Yeah, I agree with Lefty. Try to determine what is above the head of your windows, and whether or not you can heighten your rough openings to accept a standard 80" door.

Like Lefty said, if you cut a hollow core door that much, you will have to glue and reinsert a solid filler into the bottom of the door. (Not bad if there are 1 or 2 doors, but a real pain when you have a lot of doors to do.)

Also, when you cut a veneered door, you run the risk of the saw coming up thru the door and blowing out the veneer. Some people will tape the door to prevent this- I prefer to score the upper side with a sharp knife, and then bevel the bottom of the door with a sander when I'm done.

Taking a couple inches off the jambs is kind of a pain too. In all, I think it would be worth the trouble to heighten the R.O's. Your tall friends will appreciate the added headroom.

Buy a 78" level if you don't have one. They are invaluable when it comes to setting doors. Some prehung door jambs are really wimpy, so getting them plumb and straight is a lot easier with a long level. I'm happy to see that you have learned enough about doors to know that you start shimming and nailing on the hinge side! One thing I like to do is nail my hinge side shims onto the opening before I even set the door in the hole. I'll plumb the shims, nail them to the hinge side, then slap the door in, check to see if the head is level, then nail off the hinge side. I dunno if it's faster or not, but it works for me.

Oh, I almost forgot. Your 8th step could be repeated a few more times here and there.

 

Guys, I appreciate all of the help here. I was already to do as you guys suggested, however there is now one more obstacle to overcome. I measured the width (or depth, I guess) of the existing door jambs and they are 5 1/4 inches. The standard pre hung doors in the store are 4 1/4 inches. So, I'm now thinking the final option here is to order doors to spec. Rationale is that I can just order the 78 inches with the 5 1/4 jamb. COmes to about $50 extra bucks a door, 6 doors = $300. Not too bad.

Other than that, would you have any suggestions on how I could manage it by buying the standard 4 1/4 jambs. Seems to be too much of a hassle to try and rectify AND cut the door shorter, but I'm open to any thoughts.

ONce again, I appreciate the help in advance.

 

Rather than buy doors that are 5 1/4, I would cut my own extention jamb and nail it to the 4 1/4" frame. I can't see spending an extra $50 a door when that is something easy you could do yourself. To do it, you would need to either: buy some side jambs and rip them down to 1", or just cut an extention jamb out of some similar material (S4S oak or poplar 1x4s). The extention jamb gets nailed to the side which the door swings away from (not the hinge side) If the head of your door is 33 1/2, make the head of the extention jamb 33 3/4. That way you will be able to have a 1/16 to 1/8" "reveal" where the extention jamb meets the 4 1/4" jamb. (standard jambs are 4 9/16, by the way) If you don't own a tablesaw or a nailgun, then maybe $50 a door would be a bargain.

 

Now for the latest update. I took the molding down and the rough opening is actually 82". So, I can now buy 80" doors, which I am pretty happy about. Now I still have the issue with the 4 1/4 door jambs. XSleeper was explaining to me that I could basically make extenstion jambs to fir the 5 1/4 existing opening. Could XSleeper or anyone else expand on this. I'm thinking this is the way to go.

Appreciate all the help once again.

 

Jambs in PH doors for 2X4 walls are 4-9/16" -- 3-1/2 for the 2X4, 1/2" allowed for the exterior siding, and 9/16" allowed for the interior finished wall (sheetrock). This allows the jambs to be flush with the finished wall on both sides of the door.

If you need to fur the jambs to 5-1/4", simply add a 3/4" piece of pine trim (3/4" X 3/4", or 3/4" X 1") to the exterior (away from the hinges) side of the door jamb. A brad nailer or pnuematic staple gun (narrow crown) works well for that. Otherwise, attach these pieces (both sides and the header of the jamb) with small finish nails (i.e. 4d)

However, the 5-1/4" measurement you are using for wall thickness sounds weird!! (Not saying it isn't right -- it's just a really unusual wall thickness.) Double or triple check it one more time, once you have the existing jambs out of the rough opening and make sure that's what it really is. If the 5-14" is a true number, I'm guessing that you are dealing with old, full dimension 2X4's (actually a full 2" by 4"), and probably plaster walls.

 

Lefty,

They are plaster walls in a pretty old house. I haven't taken the existing jamb out yet to measure the wall, but the actual jamb itself is 5 1/4. A friend of mine told me to buy extension jambs, but I have 2 concerns there. One, we are not painting the molding, but rather staining it and you would see a seam between the extension and the regular jamb. Two, he told me they were about $20 each, which isn't much, but a custom sized door is only $50 more. So is it worth the extra time and looks for only a $30 difference? Probably not.

Thanks for the help.

 

Your jamb delemia is'nt a real big issue, comes down to do you own a table saw? If you dont or a buddy does'nt have one to borrow, order the doors complete and your headache free and money ahead. Otherwsie you nedd to figure $300 for a table saw and then on top of that the lumber you need to buy to build out the jambs, so you are money ahead by just ordering the doors per your specs. For many of us that do this day in and day out, we normally dont think twice about doing some of the tweaks ourselves smply becasuse we have the knowledge and most improtantly the TOOLS to get'er done correctly.

I think your freind may be referring to jamb extensions for exterior doors. That price is more in line with typical exterior door jamb extesnsion and if your staingin your doors would not work since they are clear pine that's primed. When building out interior door jambs, you need to get the wood that your door jambs are made out of. Pine door/jambs you would use clear pine to build out the jambs. Oak door/jambs you'd use oak lumber to build out the jambs, pre-painted 6 panel door you can use popular or birch, this way you dont see the "jamb extension" you had to install.

But given your posts, I'd recommend ordering the doors with what you need, that way you just focus on installation and saving money in the long run....unless you've been looking for an excuse to buy a tabel saw...now's the time

 

I have similar problem. My existing framing is 1x3 not the more common 2x4. The jamb is 3 1/2 inches not 4 9/16. Does anyone know whether I can order prehungs for this situation.

 

geoffo,

Welcome, but let's make sure we are on the same page here.

"My existing framing is 1X3's" -- you must have a mobile home, or you walls were built with 2X3's. The 4-9/16" jambs I was referring to account for the framing (3-1/2") and another 1/2" for the interior and exterior wall coverings -- sheetrock inside and siding on the outside. What you need to measure is the wall thickness including both of those -- NOT just the width of the stud. If your walls were built with 1X3's or 2X3's, then you'll have to order prehung doors with 3-9/16's jambs, or have access to a table saw to make the standard 4-9/16" jambs work for you.

 

You're right, the framing is 2x3. The problem is, I cannot find anyone that distributes prehungs for this size framing. Any ideas?

 

Go to a lumberyard (NOT a 'big box store' like HD or Lowes!!) and order them. It's either that, or find a friend who has a table saw. or invest in own so that you can make your own jambs.

 

The pre-hungs I get from my door and trim supplier (and those I've seen at HD and Lowe's) don't have square edges on the jambs. There is a little "hump" to indicate the appropriate reveal. So I rip off about a half inch of jamb, put in a "filler" piece (glued and nailed), then put the original piece back on.