Rookie building a base for a shed. Help pls

Deere Dude · Oct 4, 2016

I would scrape any top soil off which should only be a few inches.

I would then get a load of gravel and spread it out level, smooth and a little bigger than the shed by a couple feet.

I would just use a lawn roller and run over it a bunch of times. That will be packed enough because it will have long 6x6 runners on it to spread out any weight.

Make sure it is set high enough that water won't run through it or under it.

/pine · Oct 4, 2016

A straight (no crown) 12' 2x4 turned on edge with a regular 4' spirit level is a good way to make sure your base is actually level...fwiw...

newbury · Oct 4, 2016

A good way to determine level over a long distance is water.

You've got about a 36 foot run, corner to corner. You could run a 50' garden hose, filled, between two 5 gallon buckets which are side by side and establish a siphon such that when you add some water to 1 bucket it fills the other. Mark what the level is and then you effectively have a 50' level.

I use a 50' length of aquarium air hose and a jug of food-dyed color water, but not every has 50' of aquarium air hose.

I've used that to ensure my shed corners are level back in the '80's before laser levels became.so cheap.

pat32rf · Oct 5, 2016

Don't know what part of Ontario he is in, but our driveway heaves about 6" with the frost. Gravel base, but once it freezes and fills with water it's gonna move. As long as it can free float and the doors open all is good.

Cord · Oct 7, 2016

My issue is that the 6x6's are a fairly small contact area for what will be a pretty good sized shed. If he does nothing, like what was suggested, then the timbers will sink into the ground causing uneven settlement. If he removes the topsoil and replaces it with gravel and doesn't properly compact it then the timbers will sink into the ground causing uneven settlement. Personally, I'd cut out the topsoil and replace it with 3/4" clear crushed stone. In small lifts this stone won't settle much and being crushed it won't displace as easily as a round stone. I'm favoring clear stone over a traffic bond because it won't need to be compacted as much as TB and will drain better than a TB. Again, in small lifts a plate compactor will do an acceptable job of compacting the stone. The other advantage to using a stone base is that the base elevation can correct for any cross slope that may be present.

As a side note, you do not need to build a base over the entire width of the shed, only where the 6x6's will bear. Give yourself a little tolerance and make them 2' wider than the 6x6. The other upgrade would be to put a 2x10 on the bottom of the 6x6 to give it a larger bearing area. This will make the shed less prone to settlement because it has a larger "foot" to rest on. Just make sure you get lumber that's rated for ground contact. If you read the tag on the board, it'll tell you.