Door jamb question

[aurelio alarcon]

I am going to be hanging a french door. So I sent my sister to the store for a pre-cut door jamb. She said that there were two types. One of them came pre-cut to width with the door stop moulding already applied.

The other was just pre-cut to width without the door stop moulding. This is the one that she brought me. The jamb is made out of several boards finger cut and spliced together.

This is my question: Will this spliced door jamb (the one without the door stop moulding) be strong enough to support a french door. Or is this mainly used for hollow core doors or passageways and closets where a hinged door is not used?

She can't remember if the pre-cut door jambs with the door stop moulding were spliced together as well. Or if they were made of solid wood.

Is it possible that the jambs pre-cut without the door stop moulding and finger joined are used for passageways and the ones that come with the door stop moulding are made of solid wood and primairly for hinged doors?

[Vaughn McMillan]

I've installed wooden exterior door jambs (as part of pre-hung steel doors) that were made of finger-jointed material. The finger joints should be as strong or stronger than the straight lumber. I'm no expert, but I think the strength of the jamb -- and its ability to support french doors, for example -- comes as much (or more) from the 2x framing underneath as it does the jamb itself. I'm guessing the "no door stop" option is for cases where a non-standard inset is called wanted, but I'm sure there are door experts here who'll correct me if I'm wrong.

- Vaughn

[Walt Pater]

Aurelio, You should be fine with the pre-fab jamb stock. In the future, you'll find that it's just as easy to rip 1x stock to fit, then dado or rabbet a slot for the header piece. (I personally hate FJ lumber) Just make sure that you screw, not nail, the jambs into place, placing the screws where the stop will eventually hide them. Also remember that door casings do much to aid in the stability of a properly hung door, so nail 'em to the jamb (hinge side first) close the doors (you should be able to see the hinge barrels), make sure that your reveal is good, then nail the casing to the wall.

[Chris Rosenberger]

Finger jointed jambs are ok. The main problem with fj jambs is that they do not stain well. They look fine if they are painted.
Alot of the stength of a jamb is in how it is shimmed. Shim the jamb at the hinge locations & when you install the hinges run at least one screw through the hinges & jamb & into the studs.

[aurelio alarcon]

Thanks a lot you guys for your advice. I feel safe enough now to go ahead with hanging the door. I did rip some 1X stock last time I hung a door. But it would have been difficult to explain to my sister what to get. I just thoiught that if it was pre-fabbed that it would be easier for her. I later found out that she would have understood how to get the 1X. Anyway, I will be careful where to put the shims. I will also make sure I do a good job of installing the casing. Again, Thanks you've been a great deal of help. I could not find this information anywhere else on the net.