Sealing snap tie holes in poured concrete foundation walls
The contractor pouring the concrete foundation walls on my new home is using flat snap ties, steel plates roughly 3/32″ thick and 1-1/2″ wide, to retain the interior and exterior wall forms at the proper spacing while the concrete is being poured. The snap ties have indentations along each edge which allow them to be broken off after the forms are removed with the “snapped” end of the plate being slightly below the surface of the concrete.
What should be done to seal the ends of these snap ties at the surface of the wall so that they don’t rust and won’t provide a point for moisture ingress?
The exterior surface of the walls has a brickwork pattern. The intent of this is to avoid a costly exterior covering or finish. I am planning to just apply concrete sealer and/or stain to the above grade portions of the walls. So I want any material applied at the ends of the snap ties to behave similarly to the concrete with respect to stains and sealers. Perhaps just brick mortar? Perhaps sanded grout?
Any help would be appreciated.
Jim
BTW… The contractor says he typically does nothing to seal the snap tie ends and has never had a problem or call back. Am I worrying too much?
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Replies
Jim, snap tie holes should be sealed with something, but what product is best depends on what you're sealing the foundation with. Typical asphalt emulsion damp-proofing does not really span gaps; I have used hydraulic cement to patch the holes before applying damp-proofing. Damp-proofing is the minimum protection required by the IRC. Heavier-duty sealers such as elastomeric membranes may not require that snap ties are sealed first.
Jim,
Builders here have been using flat-ties for decades on almost all their house foundations. I've never seen them sealed or patched, and I'm not sure it's even possible to effectively do so. The below grade portions of the wall are protected by whatever damp-proofing you use, and I've never heard of any problems with those that are above grade. If you wanted to hide them for aesthetic reasons I'd try sanded grout.
Just to be clear it is best to apply Michael sealer on the exterior.
Generally the ties break about ½ an inch below the surface leaving a small hole you could fill but the pattern of holes will likely be unmistakable in a flat wall.
Is the brick pattern built into the forms or are you applying it later?
With you brick pattern they have likely worked out the best camouflage
Walta
Thanks for the replies guys.
Sorry about using the term "snap-tie" in my original question. I didn't realize that is a trade name for a specific product. These are flat-ties.
There really is not a "hole" left behind; they break off only about 1/8" below the surface. The end of the tie is visible in a little slot in the surface. The brick pattern is part of the forms and the slots align with the fake mortar joints. They aren't very noticeable but they certainly will be if they start to rust. I think they could be filled if needed, though the fill material would probably be conspicuous.
The walls below grade will be covered by asphaltic damp proofing and drain board. Going to be back filled with crushed stone all the way up to within a foot below grade. Plus the house is located near the top of a hill so I'm expecting excellent drainage around the house.
Seems to me that these slots should be filled but the contractor said exactly what Michael said - been doing this forever and never had a problem. If anything is done I'll probably need to do it myself and I don't want to make a mess of my brand new walls. I'm a bit surprised there isn't a standard product to fix this issue since the flat ties have been around for years. Guess that is evidence that this isn't much of a problem.
Thanks again.
Jim
Jim,
I'd wait a bit before deciding. Here is a picture I just took of my board-formed foundation with flat-ties. It's 25 years old.
Thanks Malcolm. That is exactly what I needed to see! I will let them go.
BTW... that 25-year-old wall looks awfully clean. Have you protected it with some type of masonry sealer?
No, that's under the cover of my front porch roof with a slab below, so not much to get it dirty. That corner does see quite a bit of wind-blown rain in the winter though.
This is probably a perfect application for mortar caulk. Mortar caulk is like plasticized mortar but in a caulk tube, and is used to latch small holes in concrete, grout, and other similar things. I’m not sure of its waterproofing abilities, but it will work great aesthetically.
Bill