Front Door Sill Overhang Size

Old 09-02-13, 10:53 AM
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Front Door Sill Overhang Size

Im replacing a front door (36 x 80) on my house. The walls are 2 x 4 construction, so a 4 9/16 jamb. The existing door sill is 6 wide with a overhang on the front stoop. Under this overhang is a 1 x 3 board nailed to the front bottom sill of the house.

The existing sill is also totally flat, that is no sill cap under the door. When entering or leaving the house (for 35 years) we have always stepped directly on to the sill, not over it.

The replacement door will be a pre-hung Therma Tru door. The door sill size is the problem. Therma Tru doors come with either a:

1. 4 9/16 sill - too short. I would need to add a 2 extender. However, the way the sill is built, if I add an extender, then I would have to put some type of support under the front of the sill where the extender is attached. Im also concerned that with constant stepping on the sill, it might snap off.

2. 7 sill - too wide.

3. 5 sill - too short. But what if I replaced the 1 x 3 board under the sill overhang with a true or thick board. A thick board would give me a overhang, while a board would give me a overhang.

I like option 3. It eliminates the extender and its problems.


Is there a standard for what the overhang length should be?

What is the minimal overhang length that is acceptable?
Old 09-02-13, 02:17 PM
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6 wide with a overhang on the front stoop.
Yes, take off the 1" thick apron that is under the door, go with the 5 3/4" sill (could have sworn that came standard), and replace the apron trim with something not as thick. I think that you will find that if your wall thickness is really 4 9/16" that you will be able to install a 3/4" thick 1x under the door and still have a 1/4" lip, which is just about perfect.

I don't know that there is a "standard" but the sill nose extensions are an aluminum extrusion that has an outer leg that is about 1/4" back from the front edge of the sill nose. If there was a 1/2" lip, that leg would have nothing to sit on, and the sill nose would want to tip down since they are usually hollow underneath. So IMO, 1/4" is perfect. Some guys will let the apron extend out PAST the front of the sill nose a bit and caulk it, but I don't do that since I feel the caulk acts like a dam and traps water under the sill nose and door.
Old 09-06-13, 06:37 PM
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Sorry I'm late to discussion.

i agree with pour third option. When you are done, it should end up flush on front and sides. I would use PVC for durability. I would also flash and caulk under door.
Old 09-07-13, 05:34 AM
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I use 1X vinyl lumber under sill, it does not stick out past the edge and should slide right up into the track built into the threshold.
I use stainless steel or ceramic coated trim head screws to attach it.
That apron should never sit flush or beyond the threshold. Sure way to let in water.
I've had to repair dozens of door openings from this one simple builders mistake.
From that one mistake I've seen flooring, bottom plates, rim joist, and floor joist rotted out.

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