Innie patio door extension sill and flashing detail
Hi. I’m adding 4” of foam to my house during my re-siding project in Minnesota. I’m trying to figure out the flashing and extension sill details around the patio door. I’ve made a sketch but I don’t really know how to properly flash the extension sill for drainage.
As you can see, I’m thinking about using sandwiched PT 2x10s as the main load-bearing base of the extension sill, which is lag screwed into the house rim. Then I cap that off with some cement board and tile to bring the whole sill out to meet the thickness of the walls. Is the whole thing as simple as making sure that the til is underneath the lip of the sill pan? (Note that the gaps in between materials in the drawing is so that all of the lines don’t blend together.)
My drainage plane is behind the foam, using #30 felt as the WRB.
I’d appreciate any advice.