Hydraulic cement question

[Guest Lester Weevils]

Been at least a week since asking a dumb question, so here goes--

This summer an excellent "smarter than the average plumber" did some work, including replacing the prehistoric galvanized water run from street to house. Noticed he sealed some of the basement holes with black goop which he identified as hydraulic cement. He spoke real highly of the merits of hydraulic cement. Being as he did such excellent work am inclined to credit his opinions.

So anyway this old house was built in the 1940's. The original owner built it by the sweat of his own brow and generally did an excellent job. The unusual nature of some of the original materials made me wonder if the fellow worked for combustion or some other heavy industry. Maybe he brought some materials home from work. Ala johnny cash's cadillac song, "One Piece at a time". Maybe some of the materials were common in residential construction back then, but some of them look "industrial strength".

The basement is a slab, level with the sloped lot in back and about 5 foot underground at the front. Maybe the basement wall material was purpose-made for foundations at the time, or maybe it was second-purposed, but the basement foundation up to the first floor is big square terra cotta pipe. Real thick hard but brittle terracotta pipe. As long as you don't shatter it with a sledge hammer, that stuff will last forever. It is laid with mortar between the rows like you would lay concrete block.

Only mentioning that detail because regardless whether they actually special-made square terracotta during WWII shortages for the purpose of basement foundations, it maybe wasn't a half-bad innovative original dea. The old basement walls generally don't leak, which may have something to do with having been constructed out of completely waterproof material.

Anyway, about twice a year when we get ginormous toad-strangler rains, about a five foot section of the "underground" front wall will leak a little bit, and we get a thin stream of water going across the basement and out the basement back door. The water doesn't leak thru the foundation walls. It all leaks thru between the lowest row of pipe and the concrete slab.

So if I glom a bunch of hydraulic cement on the wall-floor interface on that five-foot section maybe it would completely stop the rare occasional leaks. But was thinking that a little more care in application might make it a better patch.

Was thinking if I get about a 1X1 or 2X2 beam of something waterproof, and bolt it down onto the slab, standing off about 1" away from the wall. Then fill that 1" X 1" trough with hyraulic cement. That sounds like something that might last a few years without moving or springing a leak. The erosion and pressure of a gradual intermittent trickle of water might eventually push out an un-backed bead of hydraulic cement, but possibly less likely to "gradually erode" a big seam of hydraulic cement "backed" by a beam bolted to the concrete slab?

So if there seems something wrong with that plan am eager to hear about it. But if the plan seems reasonable, any suggestions what material to use for the 1X1 or 2X2 beam bolted to the slab? Pressure-treated wood would probably last longer than I'll live, but something more impervious to water might be better. Aluminum might get some kind of electrolytic corrosion going against the concrete, and obviously iron or steel would eventually rust.

Something I've begun to admire more and more, is materials like PVC or HDPE plastic. tt is generally waterproof and takes a long time to break down except for solar damage (which wouldn't apply in the basement). It doesn't corrode and miccrobes or critters don't appreciate the way it tastes.

So where would I find square tubular beams of PVC (or square solid beams of HDPE) without having to special-order something? They probably make square stock for some real common purpose that I could find in a local store, but dunno what to ask for.

[peejman]

Hydraulic cement is cement that's specifically formulated to expand when it dries and fully cure even when the area stays wet. Standard cement typically shrinks a little as it cures.

That said, you fix basement/foundation leaks from the outside, not inside. Yes, that typically means digging a really big hole. If you seal the inside, you may stop the leak at that point but the water is already through the wall. Where's it gonna go next?

Got pics of the basement walls? The terracotta pipe thing sounds really interesting.

Edited October 26, 2012 by peejman

[Hershmeister]

Your best solution will be to create proper drainage outside the house to redirect the water. French drain is one solution. Basically a trench with perforated black pipe and gravel. Move the water away.

[Guest Lester Weevils]

Thanks for the good ideas peejman and Hershmeister

Will try to upload a sample picture of the terra cotta foundation wall next day or so. Some years ago we painted the inside white, so there's not much to see. It was originally dark brown of course. The "unimproved" parts of the basement were near-impossible to brightly light til changing dark brown walls into white walls.

The outside has stucco on the foundation (basement) walls and vinyl siding on the rest of the house (which we added 10 or 15 years ago, got tired of painting wood siding). Dunno what the guy did to get stucco to stick to that slick terracotta pipe. Hazarding a guess, I'd guess using fasteners into the mortar between-rows of the terracotta pipe, to hold on the stucco wire mesh.

Yeah probably the best cure is to improve drainage on the outside. Will look into that. Was just thinking that the leak is so slow and intermittent, and has been about the same amplitude for 30 years, that just sealing the gap between the slab and first row of terracotta pipe might do the trick.

The basement generally isn't humid or damp, except the once or twice yearly small trickle. The unimproved part of the concrete slab floor was painted with oil-base polyurethane porch paint and the moisture level hasn't made the paint let go. Part of the basement is an add-on apartment that was put in by the original owner back in the 1950's, and that section never gets wet. Then another part is a laundry room and walk-in closet I put in a few years ago, and that section never gets a wet floor either. The back section has woodworking tools and workbenches. Maybe sometime will move that stuff somewhere else and finish the back part of the basement into a couple of more rooms, but its convenient having those tools there until I ever finish remodeling the house if I live long enough. Been remodeling forever, a little at a time.

So anyway I keep spilling paint, glue and chemicals on the porch paint and staining it up, which is easily cured by another coat of paint every once in awhile, but if there was never any moisture back there then maybe sometime put down some of those polyethylene click tiles they make for garages. If those plastic tiles are as resistant to paint as yer typical PE plastic-- Ever tried to paint or glue a HDPE milk jug or gas tank? Its near impossible. Not completely impossible, but awful close. Maybe paint and glue I'd spill wouldn't stick.

Edited October 28, 2012 by Lester Weevils