Notching Slab For Patio Door -- How?

[Robert Allison]

If shimming is necessary, then the slab is not completely level. Most of the time the slab is close enough that the sealant STILL seals the underside of the threshold to the slab. I use a urethane sealant that is pretty stiff, and the beads of sealant stand about 3/8" tall off the slab. I have not had more than a few instances of the slab being out of level by more than 1/4" or so in the six feet of the door opening. When I do run into this, then I usually discover it when I check the door opening for plumb and level.

If you have this problem, then you must address it before installing the door. I have had to make 6' long shims to seal down to the floor, then install the door on the shims and seal the door to the shims.

Usually you don't have this problem and the sealant will seal the track to the slab even if you have to shim a spot or two. I always seal the track to the slab on the outside anyway, just to be sure. If I have to shim the door by more than a

1/4", then after the door is installed, I push some backerrod under the door and fill the space with the same sealant to prevent water intrusion.

[Robert Allison]

I do that all the time. Removing the door is fairly easy. Just reverse the installation process. One thing that you may run into is that often, expanding foam insulation will have been used on the sides and top of the door. This glues the door into place and you have to cut the foam to release the door. It is easy to cut with a sawzall blade and, in addition, will help you to find any screws or nails that you missed.

When the sides and top are loose, you may find that the sill is glued to the concrete and if you just try to pull it up, it will bend and become junk. Be careful at this point to cut or pry gently under the sill until it comes loose. This is where the sawzall will come in handy again. If you can get a long blade under the sill, you can cut the adhesive loose and the door will rotate out of the opening (make sure you have someone holding the door).

Clean all the old foam, caulk, or adhesive off of the floor and the door, then reinstall correctly.

I have done four of these exact jobs in a day with just a helper.

[Rick]

There was an article quite a while back in either Fine Homebuilding or Journal of Light Construction on reinstalling a doorwall on a slab. If I can find it I'll let you know...

[jim evans]

I don't think this is likely in my house. It's 25 years old.

Thanks again, very much, for all your help.

jim ___ Posted & Mailed

[Duane Bozarth]

The FHB article was cover story in issue No 169 (March '05)--it was the picture on the cover that is the reason I recalled it.

The author there says in a paragraph subtitled "A level sill is critical"--

"For a subsill that's more than 1/2 in. out of level, cut two continuous wedges (one placed toward the inside and the other placed toward the outside) running the length of the opening. If the subsill is less than

1/2 in. out of level, use opposing wedge-shaped shims, bedded in polyurethane caulk, every 10 to 12 in. to provide continuous support for the sill."

[jim evans]

A couple of weeks ago when I posted my original message, the consensus was that the installers had failed to seal the bottom of my sliding doors and it was not necessary to notch the floor. That removing the door and liberally caulking under them to seal between the sill and the concrete would solve the problem. I have now found a cutaway view of my doors --

As you can see there are channels on the bottom of the sill plate (threshold?). This design doesn't look like it was intended to use a bead of caulk under it to seal it to the slab.

jim

[Robert Allison]

Oh yes it is! Like I said before, you should place a bead of stiff adhesive sealant (not caulk) under this threshold. You can make sure that you hit the area you want the sealant to seal by measuring and snapping a line. Your sealant should stand up at least 3/8 to 1/2" and will seal against the bottom of the metal. You can also put a bead of sealant on the widest rib on the bottom of the door just before you stand it up into the opening. Then, to be sure, put more sealant on the outer lip of the threshold and seal it to the concrete floor after the door is installed.