8' x 10' Deck Platform on ground

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Old 08-15-16, 05:37 AM
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8' x 10' Deck Platform on ground

Iíve finished my deck and want to have some stairs going down to a platform next to the door on my garage. Iím planning on using 2x8s for joists on this platform and regular decking on top. I was thinking of having 4 footings (1 on each corner), and then having this platform on it. But then I was thinking do I really need that? Can I just use cinder blocks or even just grade my ground correctly and have it sit on the ground? Thanks.
 
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Old 08-15-16, 06:32 AM
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At a minimum, the stair stringers need to be anchored. It's usually easiest to level the grade and pour a concrete landing, like a small sidewalk.... but some prefer to pour a column for each stringer, using a sonotube concrete form.
 
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Old 08-15-16, 06:46 AM
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Why would the stringers sitting on the platform not be enough?
 
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Old 08-15-16, 07:22 AM
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Wood decks on grade or low to the ground tend to have a shorter lifespan. Most 2x lumber is NOT treated for ground contact. And even sitting on blocks the small space underneath a low deck does not allow for enough air movement. The wood stays wet and prematurely rots. For a low application a patio (concrete) is a better way to go.
 
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Old 08-15-16, 07:44 AM
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You asked if the platform was necessary. Its not. But attaching the stair stringers to something that is solid- that wont sink or shift- is.
 
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Old 08-15-16, 08:30 AM
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I'm with Dane, you should probably be thinking about a patio and not the low-level deck.
 
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Old 08-15-16, 11:22 AM
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Patio would require a lot of soil to be brought in to bring it up the right height. Even ground-contact-rated pressure-treated is no good on the ground?
 
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Old 08-15-16, 12:36 PM
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Lumber treated to a higher level is readily available in coastal areas but it's a special order if you are inland. As you'd expect wood treated to a higher level is more expensive. There are probably a dozen levels of treatment and I'm sure those designed for saltwater contact would hold up pretty well in an inland deck. I've found that using regular 2x treated lumber in a low to the ground deck results in something lasting about half as long as I expect.

How long will a low deck last? There are a lot of variables like wood quality, level of treatment, how high off the ground, airflow, weather in your area... So, it's impossible to say how long a deck will last. I did a deck for target shooting on grade with 2x pressure treated. Signs of trouble appeared at 6 years and after 10 years it's a total loss. The same year I built that low deck I did a small porch 6' up and it's still going strong and all the wood is in good condition. So, good airflow to allow the wood to dry is important.


Use Category Brief Description

UC1 Interior Dry
UC2 Interior Damp
UC3A Exterior Above Ground, Coated with Rapid Water Runoff
UC3B Exterior Above Ground, Uncoated or Poor Water Runoff
UC4A Ground Contact, General Use
UC4B Ground Contact, Heavy Duty
UC4C Ground Contact, Extreme Duty
UC5A Marine Use, Northern Waters (Salt or Brackish Water)
UC5B Marine Use, Central Waters (Salt or Brackish Water)
UC5C Marine Use, Southern Waters (Salt or Brackish Water)
UCFA Interior Above Ground Fire Protection
UCFB Exterior Above Ground Fire Protection
 
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Old 08-15-16, 01:31 PM
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I see. Thanks.

I'll still explore the patio option and see what it ends up costing.
 
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Old 08-16-16, 06:41 AM
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If I went with footings / posts, what's the minimum height off the ground to where you'd say "yeah there should be no rot problem"?
 
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Old 08-16-16, 10:40 AM
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It all depends on the grade of lumber. Like I said, I'd pour a strip of sidewalk thats level... (maybe 1" above grade) and have the stairs land on that if you dont want an entire patio right now. A cement column should be 1 - 2" above grade... more if you plan to build up to it later with a future patio.
 
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