Author Topic: Wooden deck over concrete  (Read 13104 times)

MustardTiger

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Wooden deck over concrete
« on: February 11, 2014, 08:18:39 AM »
The wife wants a wooden deck to cover the ugly concrete patio in the backyard, so naturally I want to take this on myself after reading this blog for awhile.  Talked with my dad and he says it would be fairly easy it it was just to cover the patio, but she wants it to extend a bit further into the grass.  If I anchor brackets to the concrete, how do I extend this into the grass area and keep it level?  Not planning anything till the summer when I am off, but wanted to start getting ideas.

soccerluvof4

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Re: Wooden deck over concrete
« Reply #1 on: February 11, 2014, 08:24:52 AM »
concrete deck blocks...there available at all your big box stores like HD and Lowes. Otherwise depending on your code (which usually if not attached to house you dont have to worry) you have to figure out where your footings need to be and get some tubes and concrete. But Deck blocks work great

bacchi

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Re: Wooden deck over concrete
« Reply #2 on: February 11, 2014, 09:23:58 AM »
I wouldn't even bother anchoring to the concrete. Just put the treated post in a base bracket.

Use composite lumber. It'll pay off in time and money.

Greg

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Re: Wooden deck over concrete
« Reply #3 on: February 11, 2014, 09:54:01 AM »
Depending on the length you want to extend out into the grass area, you may be able to cantilever out that way.  A good rule of thumb is that you can cantilever out 1/4 of the distance that isn't cantilevered.  Otherwise bury some pier blocks with adjustable brackets supporting a beam out there to carry the load.

Milspecstache

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Re: Wooden deck over concrete
« Reply #4 on: February 11, 2014, 10:12:23 AM »
I second the composite lumber.  I think the latest recipe for treated lumber doesn't last as long. 

MustardTiger

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Re: Wooden deck over concrete
« Reply #5 on: February 11, 2014, 02:40:10 PM »
I wouldn't even bother anchoring to the concrete. Just put the treated post in a base bracket.

Use composite lumber. It'll pay off in time and money.

Can you go into more details about how to do this without anchoring?  Never thought of that.

dragoncar

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Re: Wooden deck over concrete
« Reply #6 on: February 11, 2014, 02:56:54 PM »
I have zero experience with decking so I'm not making a recommendation.  But I suggest looking into modular deck tiles.

5inatrailer

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Re: Wooden deck over concrete
« Reply #7 on: February 11, 2014, 06:34:55 PM »
are you elevating the deck at all? I build mine using a 2x10 on end as the stringers and then putting decking on top. Literally put the deck resting on the exposed concrete.  24x 16' out.  No anchors needed.

Weedy Acres

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Re: Wooden deck over concrete
« Reply #8 on: February 11, 2014, 09:10:10 PM »
Whoa, I have to disagree with a couple of the above posters.
1.  "Don't anchor it to the concrete"  Uh, no.  The posts need to be anchored in so the thing doesn't shift.  There are Simpson post anchors that keep the wood from coming into contact with the concrete, to avoid rotting the posts
2.  "Use deck blocks."  Not unless you live in a year-round mild climate like California of Florida.  In places where it gets cold, you need proper concrete footers. 

To extend onto the grass, you need to dig holes and pour the above-mentioned concrete footings (sonotubes work great as forms).  Depth depends on your frost line, diameter and spacing depend on your structural design.  Google a bit and you can find good info on how to engineer it properly.  Then screw post anchors into the footings, put in your posts, beams, joists and decking.

gardenweb.com has a porches & decks forum where you can get some good help on your specific project.  Decks are definitely DIY-able, and great fun in the summer.

soccerluvof4

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Re: Wooden deck over concrete
« Reply #9 on: February 12, 2014, 10:07:18 AM »
I beg to differ. I live in the artic midwest and deck blocks work fine. I agree sonotubes are the best but not seeing a picture of the yard and  pitch if any off the current concrete patio its probably hard to debate. I also agree though he should definitely secure the deck to the existing concrete. But i have used deck blocks numerous times and have had no issues. But for the most part we are on the same page! Alot depends on the soil as well.

bacchi

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Re: Wooden deck over concrete
« Reply #10 on: February 12, 2014, 10:47:10 AM »
Whoa, I have to disagree with a couple of the above posters.
1.  "Don't anchor it to the concrete"  Uh, no.  The posts need to be anchored in so the thing doesn't shift.

Eh. This is a low deck with 2x6 joists and 2x10 beams and decking (give or take), right? It's heavy. Without knowing the climate and local building code, we can't determine if anchoring and tie downs are required.

https://deckplans.com/anchoring-deck

It certainly can't hurt (unless you screw up and re-do it and put a lot of holes in your pad) but it may also be unneeded.

Exflyboy

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Re: Wooden deck over concrete
« Reply #11 on: February 12, 2014, 10:57:06 AM »
I have a bout a 1500 sqft deck that is on average 5 feet above the ground.

The deck is anchoured to the house and one end but extends 16 feet out from the house at one point.

This whole ensemble rests purely on deck blocks.. no ground anchouring at all.

How do I get away with this you ask (and yes it meets code in OR) well you need shear resistance.. this is done simply by nailing angle lumber from the post at the top of the deck block up to the underside of the deck.

This makes it extremely strong.

If you deck is near the ground the deck blocks themselves will provide the required shear resistance Thats what the slot in the top of the block does.

Frank

dragoncar

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Re: Wooden deck over concrete
« Reply #12 on: February 12, 2014, 11:49:53 AM »
You guys really know your shit.  Maybe we need a construction sub forum!

soccerluvof4

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Re: Wooden deck over concrete
« Reply #13 on: February 12, 2014, 12:27:21 PM »
Frankh.....^+1. In WI if its attatched to the house you need a permit and have to follow alot more codes. If not attatched but right up against the house its like hardscaping. The term with mine was " all good since you can pick it up with a helicopter. This was on a house i sold a few years back and the inspector raised a red flag. Anyhow totally agree on the deck block scenario.

MustardTiger

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Re: Wooden deck over concrete
« Reply #14 on: February 12, 2014, 02:18:19 PM »
Really good stuff here.  I live in dallas, but it does freeze in the winter so something to think about.  I am thinking somewhere around 16x12 and just directly off the ground.  I'm away now but will get some pictures of the current slab up soon for better advice, and hopefully can do a step by step when I begin.

soccerluvof4

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Re: Wooden deck over concrete
« Reply #15 on: February 12, 2014, 02:50:05 PM »
Really good stuff here.  I live in dallas, but it does freeze in the winter so something to think about.  I am thinking somewhere around 16x12 and just directly off the ground.  I'm away now but will get some pictures of the current slab up soon for better advice, and hopefully can do a step by step when I begin.





if you live in Dallas you don't need the 4' footings . Deck blocks are probably what most people are using down there.