Waterproofing a new construction basement?

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Old 03-01-17, 01:03 PM
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Waterproofing a new construction basement?

Live in New York.

Looking to build a house on virgin land. Most important thing in a future dry basement is grading, for sure. But, that taken care of, next up is waterproofing the basement.

The most common residential foundation in NY consists of block walls. Internally is a french drain afforded by a 1/2" gap between the walls and a floating slab floor, underneath which is gravel, corrugated piping next to the walls, and they lead into a sump.

In the past a roll-on layer of tar was common, applied to the outside below grade, but it's not terribly robust, and can dry out, though it's what my current house has and it's done well.

Lately I've seen two main approaches used as I tour new building lots:

1) Platon dimpled membrane. This seems like it would be perfect, but the installs I've seen all involve screwing it to the wall below grade, which gives it a small hole, but then also there is a huge seam where one piece of the membane is lowered over another. Also, though it drains from the top down, it could in theory also take ground water upward against the wall.

2) Hard-core layers of "rubber" (?). I was in a house just built last year in its basement, all block wall, on a pretty flat site, and man I was impressed at its basement. There was not one lick of moisture anywhere on any wall and I don't even think it had a dehumidifier. The rubber looked to be about 1/4" thick and was sprayed on in some manner

The builder I'm going with seems to offer the platon approach with block walls OR I can pay a bit more and go with superior walls. Superior walls are pre-cast poured concrete with a high PSI and foam on the inside. I suspect they are pretty darn moisture resistant. I am somewhat hesitant on these walls because down the road with resale and this kind of wall so rare it could scare some buyers off. Also, the walls are only 8" thick and sit directly on tamped gravel, whereas block walls (like a typical poured foundation wall) sit on a separately placed concrete footing, so there is a more more area taking the weight of the house.

 
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Old 03-01-17, 03:00 PM
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I also live in NY & have sealed a lot of foundations. Of course, that was after the fact. From what I've learned, I wouldn't want anything screwed to the wall & I wouldn't want my foundation setting on gravel. The membrane is attached to the wall with adhesive & Tthe gravel goes around the footing.
 
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Old 03-01-17, 04:36 PM
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Is Rub-R-Wall available in your area. Very good product and carries warranty. This is a spray applied application. There may be other similar type products in your area.

Do not like Platon for reasons I won't get into now. There are other roll products available that are very good and typically applied on commercial projects so they are proven in durability. Bituthane is one of those but there are others such as Royston.

Be advised that there are somewhat critical conditions that any of these products must be applied under and should be carefully followed to ensure a successful outcome.

Any application needs to allow for a drainage path to the footer drain and a protection board to provide a cushion for damage as may be inflicted by the backfilling operation. Protection board can be foam or a tight fiber or mesh board product that is specifically designed to allow for drainage and protection of the waterproofing membrane.

If your soils are particularly wet you may even want to have the footings poured into a vapor/water barrier membrane to separate it from the capillary draw of water from the ground it is attached to. If no barrier below, coat the top of footer with a suitable waterproofing brush on material such as fibered asphalt prior to proceeding with block work or poured concrete walls.

I would not invest in a new home and apply only the asphalt foundation coating of yesteryear.
 
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Old 03-13-17, 07:34 AM
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Thanks, guys, for the responses!
 
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