Replies

1. 
   Malcolm_Taylor | Apr 27, 2021 09:54pm | #1

   Andy,

   One other alternative, which does come with an energy penalty, is to reduce the depth of the walls at the door, and perhaps six inches each side. This removes the problems of sealing the difficult intersection between the sill-extension and whatever you are using to extend the jambs, and providing support for the deep sill.

1. 
   artisanfarms | Apr 27, 2021 10:23pm | #2

   That is an idea worth considering for the front door as the door is on a porch and I can see some ways to integrate the transition into the facade. I'm not sure about the back though.

1. 
   Malcolm_Taylor | Apr 27, 2021 11:11pm | #3

   Would it work if you kept the same amount of thinner wall at the head too?

1. 
   artisanfarms | Apr 30, 2021 07:44pm | #7

   Yes.

2. Expert Member
   Michael Maines | Apr 28, 2021 09:32am | #4

   Andy, I wrote about some of my approaches here: https://www.greenbuildingadvisor.com/article/how-to-install-doors-in-thick-walls. The most straightforward is to simply order doors with thick jambs and sill extensions. Not all door shops/distributors will do them, but some will. If you are stuck working with 6 9/16" jambs, Pemko makes sill extensions. Depending on your details you might have to get creative, but it sounds like some minor metalworking is within your skill set.

   Here is a sill extender: https://www.assaabloydooraccessories.us/en/products/thresholds-ramps/residential-thresholds-pre-hung/millwork-sills/ext2/

   Here are ramps, which works better in some cases: https://www.assaabloydooraccessories.us/en/products/thresholds-ramps/modular-ramps/

1. 
   Jon_Lawrence | Apr 28, 2021 11:49am | #6

   Michael,

   Thanks for the link. I have a slider in the rear of my house that really needs a metal sill extension and it looks like this will work well.

3. 
   Jon_Lawrence | Apr 28, 2021 11:48am | #5

   Andy,

   I ran into the same issue and my door supplier did not have a solution. After doing a lot of research and some help from Malcolm, I came up with something that seems to have worked well. The door jambs were pretty deep, but we still set the face of the door jamb 1 ½” proud of the Zip sheathing. We added 2x4 furring around the door to give us additional nailers to secure the door. I have 3” of Roxul on the exterior, but I was only able to cover the nailers with an 1 1/2" layer of the Roxul which was a trade-off I was willing to make. The sill is ½” proud of the jamb so 2” proud of the Zip. The concrete footings for the front steps stopped at the top of the foundation wall. This allowed me to cover the Zip in the rimboard area with a layer of butyl tape and 2” of foam board on top. I notched a 1”x1” portion of the foam board where it meets the sill to allow me to recess the cumaru sill extension. I used cumaru for the sill because of its durability and I used it in the portico ceiling above the door so it pairs well (as you can see by the picture I need to oil it). Supposedly it is FSC certified. Underneath the cumaru is a 5/4 piece of pressure treated decking that is covered by ¾” of Azek. We then poured the landing and finished it with paver stones. This way none of the masonry touches the sheathing.

   I also have a French patio door on the front exposure (opens inward) that I had the same problem. We used aluminum flashing to make the sill extension and it works fine – but only because it will not see any foot traffic. Typical aluminum flashing will get beat up pretty quickly if used as a sill. I think if you go the metal route you will need to get something more durable like what Michael posted.