installing patio sliding door on concrete pad

I can understand the different opinions you received. Wood cannot come into contact with cement because cement will transfer moisture to wood causing rot. Vinyl would be fine on the concrete. You need to make sure there is enough pitch away from the threshold to adequately shed any liquid moisture. I would recommend wrapping the framing up the wall at least a foot with tyvek flexible flashing wrap.

Also make sure that if your slab is pretty much ground level, that you have something in place above the door to keep the constant dripping rain away and any minor snow fall away (if you get any that is).
The one major mistake made here in New England is to have a deck built right up to the sill of a doorway. If your unableto have a step down, then you must have protection.

What really works at deteriorating the seal of a door sill is constant water splash or that 2-4" snowfall that sits at the often unused patio door in the winter.

If you can't create at least a 6" step down from your door sill, I highly reccommend doing something that will keep water away.

thanks

Jaros and Crossworks,
Thanks for the feedback.

We decided to go with a Marvin Integrity sliding door. Being that the interior of the frame is wood, I then assume that I need to set the door on a sill plate vs bare concrete pad. Is that correct?

Also I read in another post about sealing the sill with NP1 caulking vs 100% silicon. Is that correct?

Thanks again.

Yes, a pt sill plate would be fine. I would also wrap the sill plate and the first foot of framing with a flexible wrap to protect it against water damage. Silicone is acceptable for sealing off the threshold. If you are in a cold climate you will need to be meticulous as water and ice that do get into the framing will cause serious damage. Buy some good silicone or sealing caulk and clean the surfaces prior to laying your beads.

pt sill plate

Jaros
what does (pt) sill plate mean? Pressure treated? Just want to make sure.

Thanks

Yes, pressure treated.