Shed roof garage addition

Ugarte · Apr 7, 2012

I'm planning a shed roof addition to our saltbox garage--about 15 x 30, gravel floor, pole or pier-and-post construction, attached to the back of the garage, pitched roof to pitched roof, to house my new Kubota B3300--and I have a few questions: 1.) Do I need to remove the sod, or can I simply lay a moisture barrier and the gravel over the sod? Assuming the sod must go, how thick should the gravel layer be in Maine? 2.) Can I dig holes for the poles or piers with my new backhoe, or should I buy or rent a posthole digger? What would be the technique with the backhoe--will it dig a hole with a 16" bucket straight down to, say, four feet? 3.) Are 4x4's sufficient for this addition as it will be attached to the garage roof and supported by 8 posts, or should I use 6x6's? Thanks for the advice.

clemsonfor · Apr 7, 2012

Ugarte said:
I'm planning a shed roof addition to our saltbox garage--about 15 x 30, gravel floor, pole or pier-and-post construction, attached to the back of the garage, pitched roof to pitched roof, to house my new Kubota B3300--and I have a few questions: 1.) Do I need to remove the sod, or can I simply lay a moisture barrier and the gravel over the sod? Assuming the sod must go, how thick should the gravel layer be in Maine? 2.) Can I dig holes for the poles or piers with my new backhoe, or should I buy or rent a posthole digger? What would be the technique with the backhoe--will it dig a hole with a 16" bucket straight down to, say, four feet? 3.) Are 4x4's sufficient for this addition as it will be attached to the garage roof and supported by 8 posts, or should I use 6x6's? Thanks for the advice.

The 4x4s should be fine, especially if you use tin, but even with shingle weight i feel thats plenty. I would not dig with a back hoe, the ground around will be all loose and not compacted as if you dug a post hole, around the hole the post will go in.

Why would you put a moisture barrior down for gravel? I would just put the gravel if you want gravel and then spray roundup (glyphosate) to kill what grows through it.

Kyle241 · Apr 8, 2012

Well you're likely to get different responses from different people. Personally, I would remove the sod and dig down whatever is required to get rid of at least the topsoil. I would then fit and pack with gravel and top with '3/4 less' and pack. As for the 4x4's, 15x30 is a large area with a shed roof and snow load. I would prefer 6x6 with at least 2"x8" girders. Digging with your BH will work fine. It is difficult however to get a small hole dug with a BH compared to an posthole digger but I used my BH on all the piers for my garage.

clemsonfor · Apr 8, 2012

Sorry i dont even consider snow down here!! I did get as heavy as a snow as we probly will ever get last year no prob on my shed though.

bearcreek paul · Apr 8, 2012

I put a shed up last year about the size your planing.Went with 4x6's post and 2 x6's for the rafters 16 in on center.Used 2x10's to hang the rafters.No problem with the snow load even thought we only had 2 good snows.I live in Pa in the Poconos so not as much snow as you get.Here are some pictures.

300UGUY · Apr 8, 2012

clemsonfor said:
Sorry i dont even consider snow down here!! I did get as heavy as a snow as we probly will ever get last year no prob on my shed though.

We had a foot of wet snow a couple years ago, it took down several old barns around here.