Senility check - Garden shed foundation

[Bill Stock]

I was sure I'd asked this question a few months back, but I searched and could not find the original post.

I want to put up a pump house with water wheel for a small pond. I plan on renting a 'Little Beaver' to dig the holes for my supports. I also want to put up a small garden shed. So I was thinking of digging some holes, filling them with compacted gravel and putting foundation blocks on the gravel to support the shed. I'll probably dig the holes about 3' deep for both the shed and the pump house. The shed will have nothing but gravel in the holes and the pump house holes will be started with gravel and then enough concrete to hold the posts in place.

The frost line is about three feet down, although with the warmer weather heaving seems to be less of a concern. It just seems that a concrete slab is overkill for a small (10x8) garden shed?

[aemeijers]

If you're going to that much work anyway, why not just use sonotubes and put down proper piers with anchor bolts on the top for clips to hold the floor system of the shed?

aem sends...

[Bill Stock]

I was hoping not to rent a cement mixer.

I estimate the shed will need 9 piers. Whereas the pump house is only getting four. Mixing cement for four posts by hand will be bad enough.

[Bill Stock]

Thanks,

The shed will be somewhat close to a spruce tree, so I'm hoping the post holes will disturb the roots less than a complete excavation.

[Lawrence]

That's good thinking. A mature tree is impossible to replace if damaged. Are there many trees of this type on your place? Any type of foundation is OK for a shed if you are at risk for damaging an irreplaceable tree. If you have a lot of spruce on your place them you can worry less, I suppose.

[Bill Stock]

Yes trees are a fair age, four spruce trees about 30'. Although They've been dying from the indeide out. I'm not sure if it's because they were planted too close together or if they are suffering from the dry spell a couple of years ago.

I'm considering getting the piers poured, as it's only $20 a pop with digging and cement. Although I'm not sure how the saddles work, since the posts will be horizontal (floor) as opposed to vertical like deck posts? Bummer is that the tractor (54") won't fit through the gate.

[aemeijers]

If it is a tractor-mounted auger, it can be used to pull and replace one of the gate fenceposts to make the hole wider, either temporarily or permanently. Is there a section of fence you can take down for the day? :^/

There are many different types of saddles available. The deck aisle will have the ones to hold joists. Usual practice is to put a J-bolt in the pier, centered, and then add the saddle afterward. Layout is pretty critical. You'll wanna put up stakes and batten boards, and after the holes are dug, put crossed strings over at least the corner pier centers, and marks over the center points of the in-line piers. A plumb bob will show where to put the J-bolt in. It doesn't have to be perfect, since there will lots of oval holes, but it needs to be pretty close. The usual procedures of making the diagonal measurements match will let you square up the string 'box' pretty accurately. Unless the concrete guy will guarantee he can match a layout diagram, you want to be there when they pour. If they are using the cones and tubes, the strings can also be used for placing those accurately.

aem sends....