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Community and Q&A

Exterior door details with 4″ thick foam walls

Mike M | Posted in Green Building Techniques on

I’ve read plenty of articles on Dudley boxes and setting innie and outie windows, but doors are a whole different animal mainly due to the swing and bottom. The sides and top are basically the same details as a window to my understanding. It may be possible there is a manufacturer that makes door settings this wide that are affordable? The wood on all of the original doors is rotting because they were set 3″ off the finished grade and got wet always. The foam will be 4″ in areas and the walls are either 2×4 or 2×6 depending on the area of the house.

Some of my questions and concerns are:

-How do I build the build the box for the bottom of the door? The door currently sits directly on a slab and there is also 4″ of insulation beneath the door for the exterior of the foundation (it’s only insulated due to radiant flooring with no insulation on the inside). Should I use a steel plate and raise the door? The door sits directly on a concrete slab.

-Can I notch the king studs and header 3/4″ to allow for the same sized door or window to fit in the original rough out?

As always, any and all help is much appreciated!

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  1. User avatar GBA Editor
    Martin Holladay | | #1

    There are three things to keep in mind:

    1. How will you detail the pan flashing? Choices include: (a) making sure that your slab has a pocket to accommodate the door (see illustration below) -- probably too late for that; (b) a sheet metal pan flashing; and (c) pan flashing made of peel-and-stick.

    2. Is the height of the door threshold correct for good integration with your finish flooring? (Adjust as needed. It's usually OK to notch the header somewhat, as long as you don't remove 4 inches with a chainsaw.)

    3. Will the door be able to swing inwards without being impeded by the jambs? (This is a classic problem with "outie" doors installed in thick walls.) For a solution to this problem, see this article: Windows and Doors in Double-Stud Walls.

    See the first three illustrations below for more ideas on pan flashing. The fourth illustration below shows a solution to the problem of making sure that an inward-opening door in a thick wall doesn't hit the jambs.


  2. Charlie Sullivan | | #2

    Another possibility is to install an outswing door. Then it can be an "outie" without any concerns about space to swing. And it's a little easier to get the bottom weatherstripping to seal well.

  3. Mike M | | #3

    Thank you very much for your responses. I'm going to shy away from the outie door in the double stud wall because I would have to remove the entire original rough out. My biggest concern with this is the south side of my home has a wall of 7 windows, roughly 20' wide and 13' tall of mostly glass. I don't want to have to worry about jacking the roof up as I remove the headers to make them a few inches bigger..

    1. If I really needed to drop the bottom sill, I could saw cut a into the slab, chisel it out and smooth it back out with concrete patch. I have read articles about people making casts for the door sills out of portland, white sand, and small white aggregate. I may try this if a commercial solution isn't readily available.

    2. The notches would be 3/4" on all sides to allow the dudey boxes to sit in the original rough out of the doors and windows without having to move the header or king or jack studs. I planned on just using a circular saw, recip, or jigsaw to gut this 3/4" out, I would then glue, screw, and seal my boxes to these. There is no finished floor. When I moved in I left it exposed to see how well the heated floors worked. After realizing there was no insulation beneath the slab or in the perimeter I left it all alone because I was suing the guy I bought the home from as the home was specifically advertised as having insulated floors.

    3. I realize that outie will probably not work to well with the hinges and full door swings and will end up having to find a door sill extension in aluminum or make something. I prefer the aluminum ones, but have only found them that are 5 5/8" long and can have a 3" extension. I would need another inch or two. to clear the exterior insulation below grade.

    I will probably screw a piece of treated 1x beneath the sill on the exterior to help with the weight of people and objects on the door threshold.

  4. Whitney Johnson | | #4

    I just keepingt my front door and 2 sliding glass doors as they opposes wooden deck.s
    I'd like to know why this is or is not a reasonable option.


  5. User avatar GBA Editor
    Martin Holladay | | #5

    There is nothing wrong with innie doors, as long as you have sill pans and threshold details that can handle the rain and direct the rain away from vulnerable building materials.

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