Pier Blocks?

[Dantheman]

I am planning on building a deck off our kitchen next weekend and I am considering using pier blocks instead poured footings. Considering this route for a few reasons:

1) It will be fairly small, 17' wide and extend 13' from the house.

2) Winters in SLC are fairly mild, so frost jacking potential is minimal.

3) Our soil is about 85% sand, dig down 6-12" and it becomes 100% sand. This gives me two things:
a. It drains about 15-20 in/hr, so again frost jacking potential is minimal.
b. It shouldn't have a problem supporting the load, especially if I dug
out the upper 6-12" and put in some compacted gravel.

Just to be safe, I would also decrease the span between posts compared to what I would do if I poured footings, so 4-5 pier blocks across the 17' beam.



So, should I go for it or sack up (pun intended) and pour footings?

[Dantheman]

^^^^^^^^^^

[mtcham]

I built a similar size deck about 12 years ago with the pier blocks. My thinking was I could always adjust them if frost heaving occurred.

Only problem I've encountered was last winter I stacked 3 cords of wood on it and I noticed a small crack on the outer plate.

Be sure and check your stress loads and use the appropriate dimensional lumber. Better to overbuild than have it shaky.

Disclaimer-I'm a total amateur

[criscam]

is the deck gonna be low to the ground?
is it that much extra work to pour the footings seein how you gotta dig em out anyway?
i think you'd probably be allright with the piers as long as you compact some decent base material in there.






but i'd go with the footings

[Dantheman]

is the deck gonna be low to the ground?

It will be low, 21" max.

is it that much extra work to pour the footings seein how you gotta dig em out anyway?

Blocks = 4-5 6-12" holes = pretty easy


Footings = 3 2-3' holes + mixing + pouring = a lot more work.

[runethechamp]

If I remember correctly, sand has shitty load carrying capabilities. So go as wide as possible with the footings.

Edit: OK, not that shitty, 2000 psf.

[Turd Ferguson]

Are you securing the deck to the house or will it be freestanding? I think you wouldn't want to attach it if you're not doing proper footings in case it does move at all.

Is a building inspector ever going to see it? Will selling it with non-permitted improvements ever be a problem?

I've been considering doing the same as you b/c code requires 4ft footings where I am and that is labor intensive. On the other hand, any deck more than 1 ft off grade is supposed to be permitted work, and a deck that low isn't exactly what I want to do.

[SorryBro]

I'm studying for my engineering test and I'm going nuts, so:

I would not build a deck with less than 16"x16" footings. Why, because if you get any shifting at all, you're not going to be happy. Most piers are 12"x12" and I can't tell you how many times I get a call from someone who wants to re-pour footings for their old deck that had piers and has now settled. Digging sucks, but re-digging blows ass.

That being said, if you use piers and make the span between them around 3-4 feet, a 12x12 pier wouldn't overstress the soil.

In any case, if you have other questions, let me know. I design stuff like this for a living, so I don't mind helping out.