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Flashing a new patio door?

Debra_Ann | Posted in General Questions on

We’re building a new home, and will be having a 6′ wide vinyl patio door installed.  It does not include nailing flanges or any brick mold casing. We have 6″ walls, and I’ve been told the jamb of this patio door is 5.5″ deep – which seems an odd size.  Too wide for a 4″ wall, and too narrow for a 6″ wall (doesn’t include sheathing or drywall depth).  We’ll be installing vinyl siding on the exterior of the house.

My biggest concern is properly flashing this door, without a nailing flange or any casing.  I plan to use a Jamsill sill pan under the door, and flashing the rough opening down over the sill pan.  But I’m not sure how to best flash the sides and top of the actual door jamb without an integral flange or casing to work with.  I think the door is designed to be installed flush with the exterior sheathing, but I’m not really sure.  

I asked the manufacturer for installation instructions, but that only showed how to put the door together – and nothing about flashing or weatherproofing the installation, or even the depth to set the door inside the rough opening.

Any suggestions on how I can best flash this door? (or additional questions I should be asking?)  Thanks.

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  1. Expert Member

    Hi Debra,

    No chance of switching to another brand of door with flanges? It would eliminate a number of the concerns.

    As far as the width. Vinyl patio-doors are typically installed like vinyl windows in that the interior gets a wood casing and interior trim. Alternately you can use drywall returns. In either case the depth of the frame doesn't matter.

  2. Debra_Ann | | #2

    No, no chance of changing at this point. So, would the jamb of this door normally be installed flush with the exterior siding, or projecting outside the wall to a certain amount?

    Jamsill folks don't carry 5.5" sill pans, but they do carry 4 9/16" and 5 1/4" ones.

    1. Expert Member
      Akos | | #3

      You flash it out the same way as a flangless window.

      Take a look at detail Fig. 5.2.11 and Fig. 5.2.20. There are other details there depending on how you want to trim out the door.

    2. Expert Member
      MALCOLM TAYLOR | | #4

      As Akos says: You should flash it as you do flange-less windows. Keeping the vinyl frame back about 3/4" from the trim surround would allow you to caulk between the two. The trim below the sill should be sloped.

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