I will agree with Alison that most quality sliders will not leak if installed properly. What brand door are you looking at? Most of the makers of the quality larger doors offer a drainage system threshold with a subsill with gutters and drains. Also you may want to look at lift and slides as they will be the most water tight when closed and locked (panels lowered right on the sill).

If your doors are in a location exposed to rain, I recommend a cover/awning. Does your home have eaves?

Sliders are frequently used in places like Florida that get a lot more rain without issue. Even here in the Midwest we get plenty of rain. I've lived in houses with sliders for many years. Not once did any of them leak.

Thanks for the info. Lift and slide are just too expensive for us. We will have two pocketing sliders, one 10' and the other 18'. Since we have vaulted ceilings, the overhangs are not going to protect them much. I was reading water could get in the tracks and they might leak since the sills will be low profile.

You might want to look at a skirt roof, appropriate to the architectural home style, to add additional weather protection. Belt and suspenders are always the best option. Buying a quality brand, and using a good installer is the first line of defense though.

"most quality sliders will not leak if installed properly"
In south Florida a tropical storm with heavy rain and sustained winds can overcome high quality sliding glass doors. Sometimes it's due to owner preference in that they don't want the recommended bottom track with a high stepover. The higher the better. If there's a step right outside the door, even better. A linear drain could help but you need to consider the scenarios it would encounter and make sure the drains wouldn't be overwhelmed. In SoCal you're probably unlikely to experience these kind of conditions but it's still a gamble. Since you'll have stone/porcelain the consequences of an intrusion are much lower than when one of my wood floor customers calls me for the same issue.

I wanted French doors, but was scared enough of leaking that I placed them under the porch roof....figure I shouldn't have to worry leaking, and can just enjoy the French doors!

Sliders can leak 'bugs' though! Pave right up to the doors and along the sides of the lanai/terrace to eliminate easy access over dirt.

The sliders will be Fleetwood. I did not think we needed the optional subsill pan. I was wondering if the proper grading will suffice. It is unlikely that we will put in a skirt roof though I have thought about it. It just kinda look strange to me. I think we can live with rare instances of water intrusion since the flooring will be porcelain/stone. I just do not want to deal with puddles of water every time it rains. It sounds like it could help if we try putting in a channel drain on the outside patio.

Fleetwood is a top brand. I would feel very comfortable with them. I have occasionally gotten water in when the rain has hit the sliders at a direct angle, but this maybe happens once every couple years. I just dry it up with a towel. Last night we had a major storm, and all eight of my sliders stayed dry.

" I did not think we needed the optional subsill pan."

If you are worried at all about water infiltration due to the exposure, use the pan. Cheap insurance.

Jeffrey, I understand your points. If we were doing that, I probably would not worry about water intrusion. As I mentioned earlier, we are doing a low profile sill. Patio will be at pretty much the same height as interior floor. Sounds like subsill pan might be best option.

Small ball, with the install- make CERTAIN that the pan/drain away is pointed in the right direction. Lol- They were planned for our house, but? My GC and I both missed that on a 16' slider- until our first rain. Yuk. No matter. GC immediately brought in a clean up crew (not a big deal, as we have polished concrete), made sure that the pans were actually placed correctly, and then replaced all boards that were affected once all was dried. And repainted the entire area. One of the few "oops" we had. Builder's Warranty is so cool!

@lc How did your sliding doors work out? I am having the exact same dilemma. Sliding doors with recessed sill and flush surface from inside to out. Almost no overhang. Door quote says "provides no protection from water intrusion" which really worries me.

@Jeffrey R. Grenz, General Contractor What issues were you referring to in western slopes of Bay Area? My project is San Jose Hills (so eastern slopes of Bay Area).

"provides no protection from water intrusion" would bother me also, especially if these sliders get wind driven rain. Would your windows face west into wind driven rain? (whichever direction it originates)

I'm aware of several in the Oakland Hills that had issues with lips not meeting wind ratings. (that means the window mfg could be absolved of warranty).

There may be other ways to meet this rating, otherwise you'll have water intrusion.

Its not a submarine

Most face into the wind so wind-driven rain is likely. I'm wondering if I should invest into lift&slide for those. Maybe also ask hardscape contractor to do linear drains right outside the doors.

@margaret17,

I decided to go with subsill pans that drain. I am not sure if your design has that as well. Also for my largest opening, while I don't have a huge overhang, I do have about 4.5' overhang.

Thank you @lc. Have you had any issues with water inflitration? I will ask my contractor for a draining sill pan.

How its done to get a warranty:

Ask engineer what the wind rating is (they used it for structural calcs already)

Give information to window supplier / manufacturer and they will show you which sills & drainage combo meet or exceed that specification

Weather facing exposed hills (ridges in El Dorado Co, Bay Area, etc) are different than suburban valley floor homes.

@margaret17,

Have not had my doors for long (Covid delays), so far no issues. I decided to get custom subsill pans which has a integrated linear drain, similar to the pic below.

My sliding doors are all on the north side of the house, so driving rain is unlikely. Not much rain this past winter, so the doors barely got wet.