I've an entryway with a 9 inch jamb.
I'm planning on buying a slab door and building a custom jamb.
Few questions :
What kind of wood is the best for exterior door jambs ?
How do I extend the threshold ? The one that comes with the door is made of aluminum.
whenever i build a custom exterior jamb, i use ipe. its stronger and harder than anything else you will find for exterior work, takes paint well, clears beautifully, and is a great wood in general. the biggest problem you will run into with exterior jambs is moisture related warpage. ipe wont warp.
to be honest, i learned long ago the best way to do what you are doing is just build the entire jamb from scratch. that way you get all the stops, seal mounts and extensions as an integral piece of wood. you can make your own threshold from oak or ipe and its never going to fail. if you do want an aluminum one, try here:
you will have to mill a sub-threshold out of wood and joint the aluminum one into it to get it work as you wish
if you try to cobble something out of an off the shelf unit, you will have caulking and glue that will eventually let in water, or you have to set the door so far towards the outside, that you get hinge swing issues with your inner nailer extensions.
you can definitely buy an exterior door, and all the seals. then build your own jamb and put it all together. you will be much happier for much longer.
I'm in agreement with ipe, but thought it was worth noting that the price for premanufactured ipe thresholds is currently 5 times that of oak. Oak is also good quality and often used for outside door jabs. Oak has a long history of surviving punishment. Although, if you build your own threshold you could save a lot that expense. Other notable woods are maple and cherry, which some people find prettier, but you need to make sure it is well sealed or else you'll probably get some unsightly water stains.
Extending or building the threshold depends somewhat on what (style) you buy. Premanufactured thresholds are pretty self explanitory and some come with harware (screws). If you are looking for custom build ideas, I think you could try studying the designs that already exist.
Grocery list: knee pads, sawzall, hammer and prybar (to remove old stuff?), borate for termites, subsill and toe kick, flashing (over the subsill and top edge of the toekick), adhesive, skill saw, jigsaw, and/or coping saw (for shaping and/or cutting the horn), medium grit sand paper, screws and drill, foam filler, caulk or silicone caulk blend, paint or varnish.
