How to seal exterior concrete-metal gap

[Ray]

The gap, no more that 1/4 inch, is between a concrete sidewalk and vertical metal walls surrounding steel metal doors that cover stairs to the basement. The concern is water getting in the gap, then freezing in the cold New Jersey winters, expanding and damaging the concrete.

I couldn't find any caulk in Home Depot that specified both concrete and metal. That may be just because the situation isn't that common, and one of the caulks may very will do the job without having to be replaced every couple of years.

Thanks,

Ray

[Edwin Pawlowski]

Use silicone sealant

[tbasc]

As Pawloski, says, silicone. Clean both surfaces well. If the crack is deep, push closed cell backer rod in far enough to equal the width of the crack. TB

[Robatoy]

I'm agreeing with the silicone suggestions.

Do keep in mind, however, that not all silicone is created equal.

In tests, the strength can vary by a factor of more than TWO! (I wish I still had the links..I believe I started somewhere on Gluguru.com's site. Either way, it's one helluva site for adhesive information. They even have an adhesive that will stick to Karl Rove *G*)

I am not affiliated with Gluguru, btw.

Stick to GE. They make most of it in many grades for just about all brand names. 'Silicon II' they keep to themselves, so it seems....it's by far the best of them all. (Aquarium builders insist on that one, I'm told.)

[Ray]

Thank to both of you for the suggestions. Strength isn't as important as adhesiveness and the ability to shed water.

Ray

[Robatoy]

errmmmm.... you don't see a connection?

[Rick]

I'd be careful with silicone. Unless it specifies that it is OK for concrete, it will not adhere. The strong vinegar smell is acetic acid and will attack concrete - no bond.

Urethane caulking would be a better choice. Clean the substates and consider a backer rod.

Regards, Rick

[DanG]

Amen, it is refreshing to hear another professional who knows that silicone doesn't stick to much of anything. The only one I would consider using is Dow Corning 795. The urethanes are a much better caulk alternative most of the time. Butyl rubber is very difficult to tool and control, but is still the best for certain applications.

(top posted for your convenience) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Keep the whole world singing . . . . DanG (remove the sevens) [e-mail]

[Robert Allison]

I have to third the motion about using silicones. I have yet to find anything that they adhere to for very long except maybe glass. Urethanes or butyl are the way to go. As an example, I do alot of leak repairs and when the owners/maintenance people use silicone to try to repair a leak, the explanation is always the same; We had a leak there and sent the guy up to fix it and it stopped for about 6 months. Now it is back.

I can go up on the roof or side of the building, find the strings of silicone laying on the roof (or swinging in the breeze), pull it out and do a real repair. It does make finding the leak a bit easier.