Proper Deck Slope

Hi Paul,
I have had good luck using 1/4"/foot. This would drop the deck 2 1/2" over 10 feet. Not too much I think, but enough to get rid of all the water......Mark Hammond

I read in a deck-building book that 1/8" per foot is the correct slope.

Don't forget to place the boards so they "cup" upward in the center rather than downward. Sometimes this means putting the ugly side of the board up. If you haven't bought the lumber yet, select pieces with this in mind.

Another suggestion: use either screws or spiral nails - not smooth nails. And if you use galvanized, make sure they are "hot dipped" or they'll eventually rust.

[This message has been edited by rpxlpx (edited June 06, 2002).]

I'm assuming your deck will be some kind of planking be it 5/4, 2x4 or 6, if it is you don't really need to slope it at all.

my brother has a big deck on his roof that wasn't sloped properly and water is staying in the middle and not going off the roof. how do i fix the problem to make the water run off the deck.

What would be a proper slope for an 8' deck, with a vinyl flooring product (Weatherdeck).

Hi BV016331;
To slope your brothers deck properly you’ll have to remove the existing decking and install sleepers to obtain the required slope. For An 8’-0” deep deck you should use a minimum slope of 1%. So you would want to have a drop of about 1” to 1 1/4” from your house or inner part of your deck to the outside edge. Hope this helps!

Hi Paul, if you’re using planking or deck boards you don’t need to slope your deck, it’s just considered good practice. However once you’re deck boards dry out, similar to a fence, they will create space between the boards where your deck will naturally drain. Cheers!