We are getting an old aluminum patio door removed and replaced by a new patio door. The existing wood threshold that the door is currently mounted on has rotted and the concrete base is not in the best shape.

Our door installer recommends ripping out the rotted threshold and replacing with poured concrete to rebuild the base. I have also heard conflicting recommendations to put down new pressure treated wood as the base (and spot patching the concrete base). Which is the correct base for a sliding patio door? Pressure treated wood as the base or concrete?

Thanks

 

Welcome to the forums! Your new door should come with a threshold, right? Does this adjoin a slab patio? Is it higher than the threshold? Don't understand why the concrete must be repaired. If you could post a couple of pix so we could see what you see, it may help. http://www.doityourself.com/forum/el...your-post.html

 

The patio sliding door is from Simonton and does have a threshold. I am probably not using the right terminology. The floor in the living room is concrete slab and adjoins a new paver patio that is about 2" lower than the concrete subfloor. The concrete subfloor directly under the current patio sliding door is broken up and crumbly. If you peak under the threshold (just above the patio but beneath the current threshold juts out) you can see that the patio door threshold sits atop a rotted piece of lumber (the top of this piece of lumber is at the same level as the concrete subfloor.

It is tough to describe so I will post pictures tomorrow.

Thanks for your help.

 

It sounds like they have poured a step sill in the cement slab to act as a pan flashing. If that is the case, then yes, you would tear out any wood that sits inside that lowered area and replace it with treated wood. Ideally the top of that wood would be a little lower than the cement floor inside, so that any water would not pool and come inside. That's why the step is there in the first place. This could be done by ripping a treated 2x6 that is rated for ground contact down to 1" thick.

You'd place shims and construction adhesive under this board as needed to make sure it is perfectly level before fastening it to the cement. Then you'd be ready to install the door.

I wouldn't worry about any minor cracking or spalling of the concrete that the treated board will cover up. I can't imagine that it would be anything major.

 

Treated decking also works pretty good for that. It's already1" thick. Doesn't have square edges though.

I've also seen Trex type material used.

 

The only problem with treated decking is that there is a difference between lumber that is "treated" for exterior use and lumber that is treated and rated "for ground contact". I suppose it has to do with the level of saturation and expected life of the board.

But using your idea, a piece of PVC 4/4 lumber would last forever, one would think, and never rot.

 

I posted pictures of the patio door at the following website.

Pictures by gokctx - Photobucket

As you can see the old doors sit on a rotted piece of lumber (hard to make out in the picture) which is sunk into the concrete subfloor which is not in the best condition.

The question is once the doors and rotted wood board are removed should the new door sit on pressure treated wood or should we just pour concrete where the rotted wood used to be and sit the new patio doors on concrete?

Thanks for your help.

 

No I would not fill it in with concrete. If it was my house I would anchor a pvc 4/4 filler (won't ever rot), shimmed level and perfectly straight. It's surface would be about 1/2" below the interior floor so that water would never blow under the door and wick onto your floor inside. I would sit the door on top of that, then AFTER the door is installed, if you wanted to mortar the floor in against the door threshold to give the floor a perfectly smooth surface, that would be the time to do it.

If you want a helpful hint on your photos, you can usually turn your flash to ON (instead of auto flash) so that it will flash even in light that is bright. If you do that, the flash will fill in the darker areas of the picture that are in the shadows, like the rotten wood you were trying to get a picture of.

 

No matter what you do...you will want some sort of flashing tape between the wood/concrete and the sill of the door. They make many self adhesive flashing tapes for this. Vycor I believe is one, but there are others. Basically a very sticky rubber membrane to seal and separate materials.

Newer treated lumber will eat up aluminum...concrete will as well..just slower.