Framing a door

Hi all, I am ready to frame my double doors (double walls) in many rooms of our studios. They are all solid core fire doors made out of wood. Extremely heavy! I plan to add an extra 2x4 at the bottom to compensate for a future floating floor that has been calculated and designed. I am also adding two 2x4 for a side posts to give independent extra support to the door. My question is, this: should I / do I need to add a horizontal 2x4 on the top of the door to complete the frame or can the top wall runner be the top of the frame? My common sense tells me the adding a top piece to the frame would be structurally weaker than using the runner itself and also reduce the size of the already shrinking "hobbit" door. I realize the importance of the vertical side frame posts and horizontal bottom post for structure and floating floor clearance, but the adding a top 2x4 I just can not justify. Thanks again you guys!!!

is the ceiling or other load supported on the isolation wall where doors are located? i'd suggest consulting your local building officer or construction professional since i'd be very concerned trying to support very heavy doors without all the normal construction. typically the door header supports any load on the cripple studs plus acts to brace and stiffen the overall frame and provides a nailing location for the drywall. on the base, if you were going to add an additional 2x4, why not just extend the bottom plate so you get the full support from a single piece instead of several?

gullfo wrote:

is the ceiling or other load supported on the isolation wall where doors are located?

Not at all infact, the ceiling and floor are supporting everything. The wall is built inside of a cement building. Ceiling and floors are about 3 feet of cement which already provide amazing isolation.

i think if you're framing for a heavy door, make sure it is structurally sound. you probably do not want to have a door pulling down a wall or jamming or otherwise damaging your walls because you took a short cut.

MTLA - could you please keep to one thread instead of starting a new thread for every question you have.

Sure, sorry about that John. I figured it would best to keep it separate not to confuse and be disorganized. Will do so from here on in. Cheers.