The bottom rail of my patio slider (20 years old) is being eaten away by something in the cement base. Holes appear along the track and don't know what is causing this to happen. The house has a cement floor.

Likely corrosion...

Likely corrosion....

That is true... but what could be coming up from the area beneath the rail. This is happening to our neighbors doors as well. Who (type of worker) would we get to fix the problem?

Concrete conducts moisture... it is also corrosive in nature to metals... particularly aluminum if its in direct contact.

Even Wood if not pressure treated will quickly rot in contact with concrete.

What would prevent it (or at least slow it way down) is a moisture proof membrane of some type between the sills and the concrete

Concrete conducts moisture...it is also corrosive in nature to metals...particularly aluminum if its in direct contact.

Even Wood if not pressure treated will quickly rot in contact with concrete.

What would prevent it (or at least slow it way down) is a moisture proof membrane of some type between the sills and the concrete

Thank you, that helps with the issue. We need to have new doors installed and want to be assured this will not happen again.

Thank you, that helps with the issue. We need to have new doors installed and want to be assured this will not happen again.

Concrete often contains salts, besides being highly alkiline, consider it conducts water so think of it like putting something in saltwater (not as extreme but that's so you understand some of the chemistry behind it). Wet concrete can actually burn you skin sometimes... it does decrease after its cured and dry and aged long enough...