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· Registered
1 Posts
Discussion Starter · #1 ·
I am building a 24x32 shed/shop with a second floor and I am constructing it on 4x6 piers approximately 4-6 feet off the ground. I am planning on spacing them every 5 feet and doubled on the corners. Is this sufficient enough for the weight and how much concrete should I place for each pier? I was planning on using an 80lb bag for each, placing approx. 30lbs at bottom for a plate and then using the remainder(50lbs) to place around the pier. I am placing them approx. 2ft in the ground. PLEASE someone give me an opinion!!! Thank you for your time

· Old School
3,634 Posts
Although you will need to get a better handle on this, I can tell you now that you are going to be WAY short in your calculations.

The "average" pad (just the rectangular bottom part) is usually about 24" square, and about 12" thick.

EACH pad of the size I just mentioned will require either about 9 60# bags, or about 6 80# bags of concrete. That's for EACH one... not even counting the piers.

And, NO, I'm not kidding with these amounts.

· Licensed P.E./Home Insp
758 Posts
It doesn't sound sufficient. I also don't see enough info. Building something like this the DIY way can be incredibly fun and rewarding, but a key first step is putting together a proper design. It sounds like you don't have building plans. You need something to guide you. For something like this, I'm sure there are plans available online that you could buy that would provide all the detail you need. Or hire someone to do the plans if you don't have the experience (my state lets you do your own plans). I also don't see how you'd get a building permit for a 2 story structure without a set of plans.

But to address your question on piers: an 80 lb bag of concrete will only be enough for a round footing 12 inches in diameter and 10 inches thick. Around here, that's not enough. Also, piers every 5 feet sounds like a really uneconomical way to build a shop type of building. But again, I don't have a lot of info to go on.

Things you need to consider for sizing the footings:
1. Frost line depth, that tells you how deep to go
2. Loads from the structure transmitted to each pier (you need to know all your loads, dead, live, wind, rain, snow, seismic, if any), to calculate the load on the soil
3. Bearing capacity of soil, to size the pier based on the load you calculated

That's my humble advice. Also post back with more info on the structure, and maybe we can help some more.
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