Decking that sheds water

[Bradley Gray]

I need to build several decks attached to a house and would like it if they were water proof. Anyone else done this?

[Mel Fulks]

Yes, there is a way that’s been used for more than a hundred years , and I have posted it here several times. But it is not in any
magazines and so it is not considered valid.
But I will post it again. Build the decks with a slight slope, I have forgotten how much, but it’s easy to find on line. Use 3/4 inch
plywood. Glue canvas to plywood and paint it. Years ago boards were used.

[Malcolm McLeod]

... Anyone else done this?
I've not used any of these, but I'm researching along same lines, so to keep drips out of hot tub under a deck...

Look at "DuxxBak" decking (sort of a standing seam version of a deck, but looks a bit flimsy in pics..?).
A You Tuubie at a tool show visited a booth that offered gaskets to fit in the daddo of composite deck boards. Can't recall the YT channel or product name, but search "Dexerdry"..?? Looks close.

(I'd be worried about getting these grooves and gaps dry if using a real wood deck; figure at least a healthy pitch to shed water to edges.)

[Frank Pratt]

I have a deck 6' off the ground with ipe decking that is water proofed. Before laying down the decking, I put OSB between the joists, sloped down toward the far edge. Then I used peel and stick ice & water shield (used in roofing) to cover the OSB and the tops of the joists. That was about 15 years ago and it's been dry underneath since. The area is closed in and functions as a garden shed.

[Maurice Mcmurry]

I use steel roofing, sheet metal, or aluminum trim coil. I have a 4 foot break for 16 ga. steel and 10' 6" trim coil break that I like to find uses for. I make Pans that fit in-between the joists. I don't expect an indoor level of waterproofness but it makes a protected shed type area and there is not any wood to worry about. I am doing a repair today on a leaky under the deck shed with a plastic roof. I will take a picture. There are several ready made systems for this as well as vinyl exterior deck flooring that comes in 12 foot wide rolls.

[Bill Dufour]

If the deck is waterproof you have to allow for snow load or it will collapse. I have seen requirements of 200 pounds per square foot and higher. I do not think it snows that much in the midwest. I also believe it melts off a lot in winter there.
Bill D

[Lee Schierer]

[QUOTE=Bill Dufour;3252510]If the deck is waterproof you have to allow for snow load or it will collapse. I have seen requirements of 200 pounds per square foot and higher. I do not think it snows that much in the midwest. I also believe it melts off a lot in winter there.
Bill D[/QUOTE, but

Where the OP lives is well south of the snow belt along the great lakes. Where I live 7 miles south of Lake Erie we can get several feet from a single snow fall. Recent winters have been milder, but my deck is on the east side of my house. The prevailing winds are from the west so snow accumulates much more on the east side deck. The danger here with snow accumulation is getting a thaw with rain.
499919

[Maurice Mcmurry]

I am rained out on working on the plastic one today. It is a filthy, moldy, mess. As you think about your design plan for a way to keep the roof / ceiling and gutter clean enough for the water to run off freely, preferably without having to take anything apart. There was a thread about this not long ago with some good insights.

[Tom M King]

I'm not quite clear on the word picture. Here at the lake, there are many boathouses with decks over the boats. They cut wedges to go under the joists, and screw ribbed roofing sheets up though the ribs from underneath into the webges. The wedges put a slope on the roofing metal panels so that the water is thrown to the outside of the boathouse, but the deck above is still used as a normal deck, with many variations on types of decking boards.

[Bradley Gray]

Thanks for all the replies. This is a 120 year old house near the Ohio River. These decks are less than 2' off the ground so attaching metal from underneath isn't an option, but maybe from above. I built a 2nd floor deck 15 years ago over a 3/8"/12" pitch metal roof sitting on tapered sleepers- still doesn't leak. I was hoping for something less elaborate. The situation is I need to get water away from the house to prevent water getting under the house into the crawl space. Getting 90% diverted would make me happy.

[Tom M King]

Some of the metal form panels for pouring concrete onto (I forget what they are called) would be self supporting over that length. It you put a ledger against the foundation for them to sit on, they would shed water to the outside.

https://blog.metaldeck.com/metal-deck-for-concrete

[Tom M King]

If the ground under the deck slopes away from the house, you could just lay pond liner on it.

[Maurice Mcmurry]

If the ground under the deck slopes away from the house, you could just lay pond liner on it.

A great idea. I have had good luck with the pond liner approach. It can be run up the foundation and be attached with an aluminum strip made for terminating TPO roofing. On the last project I covered the liner with landscape rock. It solved a leaky spot that had troubled the homeowner for years. It did require some grading work but it will be maintenance free and last a long time.

[Tom M King]

Pond liner is good stuff. It's like a heavy inner tube material. I think I bought the last 90 mil on this project. This 1798 basement has been drier than any new one since we closed this up, and should be permanently.

The links on the page are no longer any good. That was 2011, but the software that website was built with is no longer supported, so I can't edit anything, and don't have the time or inclination to redo it.

http://historic-house-restoration.com/basementwaterproofing.html

[Bradley Gray]

I love the pond liner idea. Not enough pitch but maybe I could add something.

[Tom M King]

I don't know of any of these that are designed to last, but they're not much trouble to put in.

https://sandbaggy.com/products/9-inch-landscape-staples?variant=48989026948&currency=USD&utm_source=google&utm_medium=cpc&utm_campaign=google+shopping&gclid=Cj0KCQjwxYOiBhC9ARIsANiEIfblZ3zVwAo_e65vuUN3 fWRwPzA5T_7ZSh8pJFPLISwmJsioYcolenUaAiztEALw_wcB

[Bill Dufour]

Some of the metal form panels for pouring concrete onto (I forget what they are called) would be self supporting over that length. It you put a ledger against the foundation for them to sit on, they would shed water to the outside.

https://blog.metaldeck.com/metal-deck-for-concrete


Pan decking?

[Bill Dufour]

Where the OP lives is well south of the snow belt along the great lakes. Where I live 7 miles south of Lake Erie we can get several feet from a single snow fall.

Just heard today that the deep snow in the Sierras has only melted and run off 2% of the water content so far. Ski resort 75 miles from us got 61.5' so far this season. They plan to stay open until May 7 this year.
Bill D

[Maurice Mcmurry]

This is not what Bradley needs but shows a good design and the way dirt accumulates. The builder did not use flashing at the house or drip edge at the gutter. Because the slope is low I made the new drip edge 12 inches wide and made sure it overlapped the gutter.

Google Photos shared video link
https://photos.app.goo.gl/6xrEufD8fdR4cLvE9

[Thomas McCurnin]

"Deck" could be the type that Trex could be used.

The plywood/canvas method is well over 150 years old and was found on our home when I renovated it. It was an outside porch, slightly pitched, about an 1/8 to 1/4" over a foot to holes to allow the porch to drain. The canvas was tacked to the substrate, and then hot tar applied over that, which would be better than paint. Oh, and I should add that the canvas and tar wrapped up the walls about 3-4 inches.

[Mel Fulks]

Thomas , Interesting info . The tar would not be better than paint as black tar is hot …that’s why T-shirts are white. 1890 ish is when
the painted canvas caught on. But it’s certainly possible that with ever leaking boats and ships, all kinds of things were used to keep
afloat. No one’s Mom is ever going to allow anyone to walk across hot tar to get into the house without taking off their shoes ….and
“first thing tomorrow, cleaning up the mess”.