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Building a ground level deck

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Forum topic by MrRon posted 05-30-2017 08:23 PM 1231 views 0 times favorited 15 replies Add to Favorites Watch
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MrRon

4491 posts in 3077 days


05-30-2017 08:23 PM

I’m planning on building a ground level deck, 16’ x 16’. I’ve looked at many articles on line, but none seem to satisfy my situation. I am located in South Mississippi. The site for the deck is reasonably flat. I get different opinions about how to prepare the ground. One says to lay down plastic sheet over the vegetation; another says to use landscape fabric; Another says to kill the vegetation with a grass/weed killer; others say to lay gravel over the ground cover, others say it is not necessary; others say I can use sand or dirt. As to supports, I want to place concrete piers sunk into the ground at the 4 corners and use flat patio blocks, 12×12x2 spaced approximately 60” apart. I want to use all pressure treated lumber with 2×6’s for the decking and joists; spacing of joists would be 24”. A small portion of the deck is illustrated and a part of Section A-A. I’ve calculated the weight of the deck to be no more than one ton. That comes out to around 125 #/block.


15 replies so far

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chrisstef

17016 posts in 2840 days


#1 posted 05-30-2017 10:43 PM

Have you looked into the helical deck piles? Basically a 50” steel rod on an auger that you drive with an impact gun.

-- Its not a crack, its a casting imperfection.

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bandit571

18603 posts in 2516 days


#2 posted 05-30-2017 10:58 PM

Sono Tubes, dig a hole, set the tubes, fill with concrete, float in an anchor bolt or two. “Margin” trowel to slick finish the top of the pier. Add a little slope to the top edge for water run off. 8” tubes, 24” long. Can be left on after the crete has set, and painted if you like. Much easier than cutting the tube off.

Scrape the ground to bare dirt, layer of plastic, layer of gravel. Done.

Don’t forget the Termite shields where the wood meet the concrete…

-- A Planer? I'M the planer, this is what I use

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DrDirt

4407 posts in 3575 days


#3 posted 05-30-2017 11:14 PM

the grass is going to die under your deck regardless… so not really a need to kill it off.
If the deck were taller, and you might want to get under it… I would use the gravel, since it wouldn’t be as muddy underneath.

depending on the ground stability…. can just use these and support your joists. But you need to have something well compacted underneath to stay level.

They don’t work so well here, because we have a lot of clay.

-- “The two most important days in your life are the day you are born and the day you find out why.” Mark Twain

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Hermit

139 posts in 1158 days


#4 posted 05-31-2017 12:38 AM

My recommendation would be to dig footings 12×12x12. Use a 2×6 pressure treated block about 6” long, one for each footer. Hammer 5-6 16d galvanized nails into one side of the block to be wet set when the concrete footer is poured. Use a torpedo level on the block both ways. This way you can keep the deck as low as possible. You don’t need to put anything down on the ground. Nothing will grow without sunlight. Would also put your joists at 16” on center vs 24”.

-- I'm like the farmer's duck. If it don't rain, I'll walk.

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bandit571

18603 posts in 2516 days


#5 posted 05-31-2017 03:55 AM

Concrete will rot wooden piers. Wood shrinks, allow water to run down between the wood and concrete.

Weeds will grow under a deck….seen it before. Plastic to keep the weeds at bay, gravel ON the plastic to keep the plastic in place.

Those pier blocks never sit still, always wanting to shift a bit. unless you drill through them and drive a rebar down through them…even them, they will lean.

Sonotube can just be buried in the ground. Anchor bolts can be bought ready made, or…just some 3/4” all thread, ad a nut and a washer at one end, and float that end down into the freshly poured ‘crete. Then you can add a bracket to the bolt sticking out of the pier to attach any framing to it. Do not coat the all-thread or the nut/washer, leave them as bare steel…..concrete sticks better that way.

16’ x 16” means there will need to be a “beam” in the center, where the joists cross. either add a beam with joist hangers, or have a pier under each. easier to add a doubled up 2x in the center, add joist hangers and use 8’ joists. less bounce, too, All you would need would be a couple of piers to support the beam.

-- A Planer? I'M the planer, this is what I use

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a1Jim

116559 posts in 3410 days


#6 posted 05-31-2017 04:40 AM

Hi Ron
Part of the reason it’s so confusing is that codes are different in different parts of the country .I live in Oregon a contractor of 30 years, I build up to 20 decks a year. Here we are allowed to build decks on Deck blocks such as the photo Dr Drit has in his post, but there are exceptions you can’t use deck blocks on sloping ground you can only place your peers(uprights) either in the concrete or on a fastener such as what we call wet post anchors. If you use ground contact pressure treated wood it’s rated for 40 years so placing it the concrete is not a problem. In some area’s of the country, deck blocks are not permitted only concrete dug below the frost line with some type of metal fasteners. The issue of what to do with the ground below the deck can be a regional issue also either kill off or scrap off all vegetation and cover with 6 mil vapor barrier (aka black plastic) after that you have to determine how to hold the vapor barrier down this is why some folks put gravel on top of the vapor barrier, some use wire landscape hangers shaped like a “U” but I’ve found them hard to put into ground without them bending,I use 30 penny nails with fender washers to hold the barrier down.
your drawing looks like a reasonable approach unless your deck surface is going to be composite decking then your joist needs to be a maximum of 16” on center per most composite deck manufacturers specs and to prevent the composite decking sagging between joist.Another way to make your deck more functional is to place one or more beams to shorten the span of your joists and help eliminate bounce when you walk on it and add to its strength.

The best approach is to check your codes and the manufacturer’s specs before you move forward building.
Many homeowners make the mistake of building on setbacks or by not obtaining a permit when one is required or other code requirements that regional governments can make you tear down your new deck or make major changes.

-- http://artisticwoodstudio.com Custom furniture

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rwe2156

2710 posts in 1314 days


#7 posted 05-31-2017 03:19 PM

Ron,

I wouldn’t worry too much about codes a deck is not a permanent part of the house structure. However, depending on where you live a nosy neighbor may alert the “authorities”.

I’ve built many decks (in the south). Not a fan of post supports laid on top of the ground due to issues with rain erosion, and the occasional Armadillo which will cause the base to shift. I use 4×4 or 6×6 PT posts 2 feet deep with 4” of concrete surrounding. If there is a railing, take this into account as to length. I do this for all supports, not just corners (especially if there is a railling). Guarantee your deck will be rock solid.

Don’t worry about what’s under the deck, although its possible you may need some Roundup along the outer edges.

Joist hangers make the job neater (no nails showing in outer rim joists) and faster.

Joist spacing: standard is 16”, (consider 12” if using composite decking).

When installing wood decking, do not leave a gap the boards will shrink on their own.

Countersink the screws – well worth the extra time. You can also use galvanized ring shank nails.

Hope this helps.

-- Everything is a prototype thats why its one of a kind!!

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MrRon

4491 posts in 3077 days


#8 posted 05-31-2017 04:26 PM

Lots of good advice. Here where I live, the codes are pretty lax, but I also live out in the boonies with few neighbors on 12 acres of land. My son lives next door, so no problem with noise, either from him or me. I’m thinking to revise my joist spacing to 16”, but I dread having to dig and pour concrete; after all, I’m 82. Maybe I can contract out that part to my grandson who just graduated from high school. He already has a job for the summer, but he may find time to help me.

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Bluepine38

3372 posts in 2918 days


#9 posted 05-31-2017 06:58 PM

With 2X6 joists, I would go 12” on center. Of course I am the type to wear both a belt and suspenders just in
case. The extra cost would be minimal and you would have a deck that would feel solid underneath. Have
fun with the deck.

-- As ever, Gus-the 78 yr young apprentice carpenter

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chrisstef

17016 posts in 2840 days


#10 posted 05-31-2017 07:25 PM

For $50 a pop its these are waaay easier than digging holes and pouring concrete. When I build my ground level deck (someday) ill be using these for sure.

-- Its not a crack, its a casting imperfection.

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woodbutcherbynight

3634 posts in 2242 days


#11 posted 06-02-2017 04:43 AM

Something to consider on height of deck from ground. Will you ever have a need to get underneath. Sure right now you see no need but I promise Murphy will show up. I thought I left enough on a sloped hill deck. NOT. Years later I am not 30 anymore and a larger frame. In order to do any work I have to borrow a neighbors kid and hope they can brave the bugs and get up and follow my instructions. 4 inches higher and this would not be such a issue. The other side is same way and I have on occasion had to get under to run a wire for something I of course added later.

-- Live to tell the stories, they sound better that way.

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Jim Jakosh

19751 posts in 2939 days


#12 posted 06-02-2017 12:28 PM

A1Jim makes some good points . I like the black plastic with gravel on top for looks and long term weed control. I have a high raised deck and I used black plastic and black lava rock on top for looks and it has no growth after 25 yrs.
I do put all the posts in the ground at lest 2 feet with concrete under and around them…and I used 12 posts with beams and stringers. I don’t like to let erosion or mole tunneling enter in the picture.

As for the deck boards, I uses 2×6 treated wood and would never do it again. It cracked, split and warped even after staining it when it dried out. I had to heavily sand it to keep from getting slivers in our bare feet. Composite decking would be better looking over the long run and I’m thinking of going over the 2×6’s with it. Teak is nice but pricey!!.

Cheers. Jim

-- Jim Jakosh.....Practical Wood Products...........Learn something new every day!! Variety is the Spice of Life!!

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a1Jim

116559 posts in 3410 days


#13 posted 06-02-2017 01:34 PM

Jim Jakosh makes a good point about using PT wood for the deck surface a point I missed when first reading your initial post. Pt does all the things Jim said it cracks, twist and warps. Composite decking last a long time but tends to be hot on bare feet and is at least 50% more than say Western red cedar in my area, I would guess Western red cedar may not be available in your area so if your budget allows think about mahogany or EPI or a more local cedar although I find that Port Orford cedar (really a species of cypress) tends to split much more easily than western red cedar when screwed down. Good luck on your build.

-- http://artisticwoodstudio.com Custom furniture

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MrRon

4491 posts in 3077 days


#14 posted 06-03-2017 12:59 AM

At 82, any deck I build will probably outlast me.

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MrRon

4491 posts in 3077 days


#15 posted 06-03-2017 09:03 PM

I only have southern yellow pine available. Composite lumber is too expensive and I’m not able to locate any cypress, my first choice.

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