Shed advice

So, I’m looking to add about 8’ to the gable end of this shed. Just an open shelter for firewood. The shed is about 14’ long as is. I’ve got used powerline poles for uprights and plenty of lumber to work with for the framing.

Question is: how deep (at all?) to set the poles. We live in US zone 4 and the frost line is at least 4’ deep. But the shed is just sitting on treated runners on the ground, so I’m doubting whether burying the posts even makes sense. My thoughts are that the shed can freely heave with frost, so if I set the posts 4’ deep then theres a breaking/stress point. If I set the posts on rocks or on concrete piers above grade, then everything can heave freely together...

I have almost no building experience. Does this make sense or am I being foolish??

Hey Brody;
If it was my project , I would use the 1' tall piers and bury them so most are in the dirt.
Use a piece of rebar and drill the bottom of the post .
This way the post has to stay on the pier.    
After all its only an 8' roof.  You practically could use a diagonal from the shed to support it.

Your thoughts and concerns mirror mine.  When I had to add a lean-to to a garage on a slab, I used posts 1' deep in the ground with a blob of cement around the base (nails sticking out of post to tie it to the cement blob).  That way if the wind tried to lift the lean-to, the blob (underground) would prevent uplift.  Barring concrete, I'm not sure how to achieve that concept...  

For a small utility shed, frost heave doesn't amount to much. I wouldn't worry about it.

However, wind load does matter. Some sort of deep anchor system will pay off handsomely in the long run.

Mike Haasl wrote:Your thoughts and concerns mirror mine.  When I had to add a lean-to to a garage on a slab, I used posts 1' deep in the ground with a blob of cement around the base (nails sticking out of post to tie it to the cement blob).  That way if the wind tried to lift the lean-to, the blob (underground) would prevent uplift.  Barring concrete, I'm not sure how to achieve that concept...  

Since you brought that up, I’ll run this one by you as well:

We also have a 2 car garage on a concrete slab that I would like to add a lean-to to. I thought burying the posts below the frost line WOULD  make sense in that situation since I dont think the garage heaves, or at least not much. Maybe I could get away with not burying so deep if I do something like you described with concrete and protruding nails.

Douglas Alpenstock wrote:For a small utility shed, frost heave doesn't amount to much. I wouldn't worry about it.

However, wind load does matter. Some sort of deep anchor system will pay off handsomely in the long run.

What do you think of Thomas Rubino’s idea with the 1’ tall piers and posts sitting on a spike of rebar? That was my exact idea.

Brody Ekberg wrote:

Mike Haasl wrote:Your thoughts and concerns mirror mine.  When I had to add a lean-to to a garage on a slab, I used posts 1' deep in the ground with a blob of cement around the base (nails sticking out of post to tie it to the cement blob).  That way if the wind tried to lift the lean-to, the blob (underground) would prevent uplift.  Barring concrete, I'm not sure how to achieve that concept...  

Since you brought that up, I’ll run this one by you as well:

We also have a 2 car garage on a concrete slab that I would like to add a lean-to to. I thought burying the posts below the frost line WOULD  make sense in that situation since I dont think the garage heaves, or at least not much. Maybe I could get away with not burying so deep if I do something like you described with concrete and protruding nails.

I'm actually not sure what makes things heave or not.  I just suspect that if they are above the frost line, they are subject to heaving.  I did a lean-to on my barn and I didn't know if the barn heaves annually or not since it's buried into a hillside and I was putting the lean-to on the side that is buried at one end and not at the other.  So I buried the posts 4' and just assumed that if they heaved differently from the barn by an inch, the flex in how I attached it to the barn would compensate for that tiny bit of movement.  So maybe that's a lazy option...

I have found frost heave to be a very iffy thing.  I have seen structures destroyed by it.  I had a fence post pushed out of the ground by it.   At the same time, I have seen the idea of setting anything below the frost line ignore without negative consequences.  In the case of this shed, I wouldn’t worry.

John F Dean wrote:I have found frost heave to be a very iffy thing.  I have seen structures destroyed by it.  I had a fence post pushed out of the ground by it.   At the same time, I have seen the idea of setting anything below the frost line ignore without negative consequences.  In the case of this shed, I wouldn’t worry.

From my reading, frost heave results from a perfect combination of a bunch of different variables. Temperature, soil type, drainage, snow cover and materials used all come into play, and thats not even considering the actual way things are constructed! But I agree that I probably dont need to worry much about it in this situation.

I would drive in metal T posts I think you call them, and screw your uprights to them.
Wind and falling firewood may be your real issues.

John C Daley wrote:I would drive in metal T posts I think you call them, and screw your uprights to them.
Wind and falling firewood may be your real issues.

Even if the uprights are sitting with rebar up the bases?

everything can heave freely together...

fantastic phrase