Question Using Dek-Blocks

Old 02-22-08, 08:08 AM
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Question Using Dek-Blocks


I am wonder if anyone out there has experience building a deck using Dek-Blocks. These are cement blocks which sit on the ground and hold your deck posts and joists up, as opposed to using normal poured in-ground footings.

I will be building a deck up in a campground in Maine this spring. Because it is a campground, there cannot be any permanent structures - footings, cement walls, etc. I have to use something like the Dek-Blocks. The deck will be 26' wide and 10' deep and 3' high. I will be building the deck in five 4'x10' sections and one 6'x10' section (in case I ever have to dismantle and move it to another location).

The company recommends having a footing under every joists and every 5' along the joists. So every joists will have three footings under it in under foot 1,5, & 10, then times the number of joists.

First off, I am curious if anyone has ever used them and what they tought of it?

Second, has anyone ever used them, but used less blocks and maybe wider joists?

And third, what I would like to do is, pre-build the deck sections (joists only) in my home in Mass and truck them up to Maine, then set out three 26' beams and then lay, and connect the six deck sections to them, then add the decking. So I am wondering if anyone has ever used these blocks with beams (girders).

Thank You
Old 02-22-08, 11:29 AM
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Frost Heave

I'd be real concerned about frost heave on the block as the bottom of the block is just resting on the ground and not below the frost line which I suspect is rather deep in Maine.

As the ground freezes and thaws (not necessarily equally under the entire deck), you could end up with an unlevel deck after the first cold season.

It will be interesting to see if anybody has used these in a cold climate and what issues they have had.
Old 02-23-08, 03:45 AM
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Hi csimone,

Welcome to and the Deck forum.

Frost heave, as mentioned by sgtgerryf would be one issue.

I see a bigger one. The fact that the deck is 3' high means a bldg. permit is required, at least in most jurisdictions. It also means you need railings.

Dek Blocks are not code approved, so you couldn't use them.

Lower the deck to less than 30" above grade and you probably eliminate the need for the permit.

Personally, I wouldn't assume the liability of building the deck the way you initially described it. My liability policy only has a $1M limit.
Old 06-11-12, 05:05 AM
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Hi all. First post here.

Regarding dek blocks, I purchased and installed dek blocks from Home Depot for my 30 in. high deck.
I just realized that the 4x4s are loose and don't fit into the block cavity.
There's about 1/4 in. of space there, which makes the 4x4 wobbly and difficult to attach the joists. Should I shim them or fasten them somehow? Thanks
Old 06-11-12, 01:57 PM
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Welcome to the forums! In your area you are subject to more heave than most below the border. You will have problems. You should have poured proper footings with post bases and then your vertical posts. BUT, since you have it done, you're there. The "give" in the dek blocks is from the mold and won't harm anything. You will have vertical pressure from the weight of the deck and it will firm up the posts on the blocks. DO NOT drill or drive anything into the dek blocks. They will break on their own in a few years without help from a fastener. Wish you had called us earlier.
Old 06-12-12, 04:33 AM
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Yeah. Now that I'm committed, I'll stick to my plan. If the deck goes south after a couple years, I'll rebuild. Thanks for your help. I'm a firdt time homeowner who wants to do things on my own so I think i'll be asking a lot of questions on this forum.

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