I need to build a new door frame for the front door. Should I use treated wood or will that rust the hinges out?

 

You can do what you want but I certainly never would. There isn't much that warps and twists more than treated wood as it dries out. Plus it doesn't hold paint well until it's dried out. And then yeah... treated doesn't play nice with the aluminum door sills and your hinges and all fasteners (including trim nails) wouldn't likely all be acq approved.

If its a shed that's one thing. For your house, probably not.

 

Homes have been built for hundreds of years without using treated wood for rough framing. Frame the RO using traditional framing and it will out live you.

 

Ok that's kind of what I thought. Thank you

 

Menards has pvc trim that is 1x8 solid. I was thinking about getting that to build a door frame out of.
but I had another question, the wall that the door is on is 8 inches thick and the pre made doors have a trim that goes around the outside and are only 6 inches thick. So I would have a 2 inch gap to trim in and the door would recessed that 2 inches which I think would look odd.

 

Most professionals would order a prehung door that is the right thickness for the wall so that the sill and jambs are thicker.

You could also get a prehung door that is made for a 6 9/16" wall (fairly common size) and then get an extension kit, which has an aluminum sill nose extender and jamb extensions. You take off the brickmould and then cut those extensions to the right width on a table saw, and add them to the exterior side of the jamb. The interior side is installed flush to the interior wall. Then the brickmould goes back on.

One caution about the PVC trim is that it bends like a noodle, so its not very good for hanging heavy doors on, since it will want to sag. I would never build my own door jamb when prehung doors are available.

 

Well our door is an odd size that I can't find pre made doors that fit.

 

"Odd size" isn't too descriptive if you want ideas. How big is the door slab?

 

34x76

 

If you have the ability to do a little demo by removing interior and exterior trim, I'd suggest you try to determine the rough opening size and see what it might take to get a bigger standard size door to fit. Typically this is a good opportunity to resize the opening if you can do it without too much trouble. If its a masonry opening, or a brick house, that's a different matter.

Most places can special order 34" doors, but the 76" is a problem and it limits the styles that are available. Anytime I have needed a door shorter than 78, I usually ask for a flush fiberglass slab door. Then spruce it up with some applied mouldings if the customer wants a paneled look. They can put pretty much any kind of glazing in, if you want glass.

And if you do need a custom size, your major lumber yards in most cities will have a door department that can make you a door to fit your exact needs, and they are not that much more than the standard doors. I get them on occasion. What they cost more in materials you make up for in labor when they fit right in.

 

I found a place that sells the right size door but think the brickmould is part of the frame. I think I'm going to end up just building a new frame myself and then try and souce just a screen door to put in.