I am remodeling my house and will be replacing my exterior door.
I have only 1/2 sub floor and am going to beef it up with 5/8 TG plywood on top of the 1/2. My question is Does the door extend down below the sub floor as mine is clearly cut out and around the sub floor and extends down below. Is this normal, or should i install the new door to sit on top of the sub floor?.
I cant see it from my basement looking up because they installed a section of blocking at a weird angle.
Any help is apprecaited.

 

Welcome to the forums!

Normally the door is installed above the subfloor but more importantly - what is your rough opening height? or do you intend to reframe the opening for the door?

 

Hi and thank you, my rough opening height from my 1/2 sub floor to rough in header is 83 inches width is 34. the door frame is 82 and feeling down through the floor looks like its another inch so 83 total.
If i put down my 5/8 sub floor on top of my 1/2, i would need a 82 , Is that a standard size door? Or what ever you recommend, as i am clueless and not ashamed to admit it

 

A standard door is 80" tall. You still need room for the door frame, I'm not sure what the rough opening size is for a prehung door.

I'm a painter, not a carpenter but I'm sure one of our carpenters will chime in later

 

Standard RO for a door is +2" in width and +2 1/2" in height to the ACTUAL door demensions (not the frame...the actual door slab).

So..assuming steel/FG prehung inswing door...

36 x 80 door would require 38 x 82 1/2" RO

32 x 80 door would require 34 x 82 1/2" RO

xx x 78 door would require xx +2 x 80 1/2"

These are minimums, some people add 1/2" extra to each..not a bad idea esp when dealing with old, out of square houses...also allows plenty of room for tile or laminate...

Most out-swing doors require only +2" in height since the sill is normally a bumper style.

 

Your old entry doors that used to have a sloped sill (which might be the weird blocking at an angle that you see from below) actually sit on top of the floor joists, not the subfloor. Sometimes the floor joists have even been notched a little bit so that the top of the door sill would be even with the finished flooring, and a threshold would cover the transition.

New doors that have an aluminum sill and adjustable threshold usually will sit on top of your subfloor. So in your case, it would best sit on top of your 5/8" that you will be adding. (in all liklihood, you'll actually need to remove the old door and repair the subfloor under the old door) Installing the new door at that height will allow room for your finish flooring (wood, carpet, tile, etc) and a rug that you will want the door to clear as it swings open. New doors are usually around 81 3/4" or 82" tall, but if you need a little extra room on top of your rough opening, just cut a little bit off the bottom of the header with a reciprocating saw. If you know that your finish floor will be thick (lets say you are also adding 1/2" cement and 1/2" of tile) you would want to plan ahead and raise your door even higher so that it clears the rug when it swings open.

Gunguy, you mentioned the wrong R.O. width for a 32" door.... but we know you meant 34.

 

Huh? I don't know what you mean? (He says with his hands behind his back and his fingers crossed as he stares up in the sky and whistles.....) lol

 

Excellent advice guys , greatly appreciate the help!
XSleeper that explains my door, and how to proceed.