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Design Build
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I was always taught only slope a deck if it is going to have an impervious surface applied to it. Otherwise, all decks (with planks) shall be level.

I am replacing water damaged and rotten rimboard on a home and the home owner has a deck attached at the back with about 2" over 12' slope (away from the house). I asked him what was up and he said he built the deck and the book he used said all decks should have some slope. I told him my understanding of decks - but it sometimes is hard to argue with a book.

I say this is bad intel from this book. Am I loco or should I stand my ground and keep on building level decks? What say the deck masters?
 

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Retired deck builder
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I've built a lot of decks, to best of my knowledge all were built level.

There is a lot of bad information in those "how to" books.
 

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I've never once sloped a deck before. There's spaces in between every board for water to go. Only time to slope a deck is on the front porch with t&g.
 

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The only decks I've seen that were built with a slope were ones on apartments that had lightweight concrete poured on second story decks. I did tear down a res. deck once that was also built on a slope, it was concrete with indoor/outdoor carpet glued to it. The framer notched his joist where they set on a beam to create the fall, not realizing his beam was all ready too low. It had about a 2" fall on a narrow 5' balcony deck, it would give most folks an uncomfortable feeling up on the 3rd story level.

A slope is for concrete only, not a deck with typical wood/composite decking. Properly flashed a level deck will not leak.
 

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If ledgered, I like to slope the joists a bit away from the house, if free standing I don't think it matters much.
 

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Curmudgeon
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I only slope a porch.
If it makes him happy,
what can it hurt? :laughing:
 

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The Deck Guy
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Custom cabinetry
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I have done both ways and still do both ways but if we slope the deck it might be 1/2" in 12' nothing you will see. Most of the time we build level... I am not sure why sometimes I feel like putting a little slope to it but when I feel like it I do it. I have learned years ago to trust my gut...
 

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I eat sawdust.
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Even if attached to the house, if it is flashed well, what are you worried about.

I'm not as experienced as most guys, but I'll chime in anyway.

I don't slope unless it's waterproof.

In general "How-to" books are full of (censored).
However, just like anything you read you should always consider who wrote the book and what sources they used when processing the information it contains.
 

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Sean
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Even if attached to the house, if it is flashed well, what are you worried about.

I'm not as experienced as most guys, but I'll chime in anyway.

I don't slope unless it's waterproof.

In general "How-to" books are full of (censored).
However, just like anything you read you should always consider who wrote the book and what sources they used when processing the information it contains.
Just my .02 - Water seeks its own level & looks for the smallest opening - why chance it coming back towards the ledger.

As an FYI, as I stated above a slight slope - not 2" in 12' - that's just ridiculous
 

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I eat sawdust.
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Just my .02 - Water seeks its own level & looks for the smallest opening - why chance it coming back towards the ledger.

As an FYI, as I stated above a slight slope - not 2" in 12' - that's just ridiculous
If you're doin' it like Mac, (minus the TT dryspace) I doubt you'd be worrying about anything. I like overkill.
I'm not saying you're wrong SLS, just that I really don't think a slope that low would make a difference unless maybe the surface was glass. I do respect anyone who goes above and beyond and actually cares enough to think of details like that, though. :notworthy

Whether I think it's necessary or not doesn't mean I'm right. Just my opinion and it's not based on field tests or research.

Anyway, g'night folks.
 

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KemoSabe
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I built homes along the coast for twenty+ years and realized after a few years that shrinkage of the framing lumber would actually cause a level deck to pitch backwards over time. Anyone who has seen vinyl siding unlock at the floor line understands the concept. We decided at that point that all decks would get at least 1/2" of pitch per 8" of deck. We were framing with GRN lumber through the 80s and most of the 90s, before a fungus problem prompted a switch to S-dry lumber.
Perrsonally, I believe that everything possible should be done to get water away from the wall assembly.:thumbsup:
 
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I eat sawdust.
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I built homes along the coast for twenty+ years and realized after a few years that shrinkage of the framing lumber would actually cause a level deck to pitch backwards over time. Anyone who has seen vinyl siding unlock at the floor line understands the concept. We decided at that point that all decks would get at least 1/2" of pitch per 8" of deck. We were framing with GRN lumber through the 80s and most of the 90s, before a fungus problem prompted a switch to S-dry lumber.
Perrsonally, I believe that everything possible should be done to get water away from the wall assembly.:thumbsup:
I'm assuming that this is only on New Construction, correct?

I basically never get any jobs on new construction stuff, but this is good to keep in mind for when it does happen.
 

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Wow interesting how something like this has good points on either side. I think when it comes to carpentry we were all taught plumb and level as the gospel truth in most everything we build so it just seems un natural to make something out of level on purpose.

I was told sloping the deck as the above examples said like a ½” in a 12’ run was to prevent ponding and help with run off. If you do it to PT knowing every few years you’re re water proofing it I guess it would come natural when using composite.

Maybe the concept or misconception (depending how you view it) started with concrete and the t & g of old where it was needed and it just carried over to spaced decking and most just never question the rationale.

I’ve done nowhere NEAR the amount of decks Ya’ll have done so my method or reasoning might be wrong.:notworthy
 
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