Shed Roof Support (7'x16')

[kcn0113]

Hi all –

I'm planning on building a shed on a freshly poured concrete slab. It's adjacent to my garage and I'm planning on attaching it to the existing OSB wall. At first I was planning on adding a roof beneath the garage's roof overhang, but that would cut out a bit of height in the shed.

Would it be wise/recommended to remove the flashing on the garage's roof and nail 2x6 shed rafters to it? Would I still need a new wall on the inside to support the extended roof? Any suggestions would be appreciated. The extra height would be really nice vs. cramming a shed roof "inside/underneath" the existing garage's roof.

Pic of the site:

 

[herm0016]

the rim board is not structural and will fail. I would sister 2x4 or 2x6 rafters to the side of the existing rafters. Use structrual screws or find some proper ties in a simpson catalog, I really like the timberlok brand of screws. keep the slope consistent and make sure you tie in your roofing properly.

 

[kcn0113]

the rim board is not structural and will fail. I would sister 2x4 or 2x6 rafters to the side of the existing rafters. Use structural screws or find some proper ties in a simpson catalog, I really like the timberlok brand of screws. keep the slope consistent and make sure you tie in your roofing properly.

That makes sense; will plan on overlapping the garage rafters and extending them down into the shed roof. Thank you!

 

[WilliamM2]

You are going to attach it, and it will be in front of those utility lines of some type? I wouldn't attach it, probably against code without a proper foundation underneath. And of course you'll need permits.

I'd be more concerned that you don't have any house wrap under your vinyl siding. The OSB looks like it's already starting to rot at the bottom.

 

[kcn0113]

You are going to attach it, and it will be in front of those utility lines of some type? I wouldn't attach it, probably against code without a proper foundation underneath. And of course you'll need permits.

I'd be more concerned that you don't have any house wrap under your vinyl siding. The OSB looks like it's already starting to rot at the bottom.

I didn't mention, but there was an existing shed in place of this concrete pad that I had previously torn down. It was roughly attached to the garage and was 1/2 the width, so I'm just doubling the width to the left, towards the door. I'm planning on running electrical so getting a permit for that. Sheds in my city don't require permits unless they're >200sq. ft.

 

[WilliamM2]

I didn't mention, but there was an existing shed in place of this concrete pad that I had previously torn down. It was roughly attached to the garage and was 1/2 the width, so I'm just doubling the width to the left, towards the door. I'm planning on running electrical so getting a permit for that. Sheds in my city don't require permits unless they're >200sq. ft.

Shed's here don't require a permit either under 12'x12'. But if it's attached to the house, it's not a shed, it's an addition. You are even tying into the house roof trusses and electrical.

 

[pcgeek11]

Agree here. Once it is tied to the building it is no longer a shed, but is part of the building and must comply with the same building codes of that building.

 

[kcn0113]

Ah very good to know; assuming that applies to this garage even if it's not a house/dwelling? I'll dig into the codes/permits a bit and see what I can find. Appreciate all the help.

 

[Greenman]

The slab appears to be about flush with grade. That's going to rot whatever siding you put on it, and it creates a perfect path for termites to enter the structure.

 

[mxnerd]

Same here. Like all others have said, once it's attached to the building (even a garage), it's not a shed anymore. It becomes an addition. Permit will be required.

Go to your city hall and ask the clerks, they will give you an answer.

 

[OILFIELDTRASH]

How thick is the concrete? Looks super thin. No rebar? No stakes in the ground to hold form boards in place? You should have also tied the new concrete into the old by drilling into the garage foundation and tying it together with rebar. I wouldn't tie a shed onto that structure via wood on what looks to be a very questionable concrete pour. That foundation is sure to fail and sink whatever you build onto it.

 

[kcn0113]

The slab appears to be about flush with grade. That's going to rot whatever siding you put on it, and it creates a perfect path for termites to enter the structure.

I'm planning to dig a trench around the edges and adding river rock to avoid any water/insect issues.

How thick is the concrete? Looks super thin. No rebar? No stakes in the ground to hold form boards in place? You should have also tied the new concrete into the old by drilling into the garage foundation and tying it together with rebar. I wouldn't tie a shed onto that structure via wood on what looks to be a very questionable concrete pour. That foundation is sure to fail and sink whatever you build onto it.

It's a 6" slab with reinforcement, and the excess dirt kept the boards in place so nothing shifted. Tying the new slab into the garage's would have been a good idea in hindsight, but don't believe it will be an issue as it'll be covered by the new structure.

 

[WilliamM2]

How thick is the concrete? Looks super thin. No rebar? No stakes in the ground to hold form boards in place? You should have also tied the new concrete into the old by drilling into the garage foundation and tying it together with rebar. I wouldn't tie a shed onto that structure via wood on what looks to be a very questionable concrete pour. That foundation is sure to fail and sink whatever you build onto it.

It'll will sink anyways without footings.

 

[PowerEngineer]

Based on my own limited experience, I did find out the hard way ("stop work" notice stapled next to my front door) that building codes do apply to any shed that directly attaches to a house.

I agree that placing a wood sill and siding directly on the concrete slab is asking for trouble. You might consider placing a course of concrete blocks around the perimeter, fill them with concrete and set some lag bolts. Worked for me.

 

[Greenman]

It'll will sink anyways without footings.

Why would it sink? The load from 3 walls and a roof is minimal.

 

[Red Squirrel]

You are making your life harder by having it so close. I would have made the slab about 2 feet further. you'd get an awkward alley but you could use that for extra storage of things that don't necessarily need to be out of the weather, or can just be under a tarp. You'd want gutters on both the shed and garage roof though otherwise you'll have lot of water pool in one area.

The way you are going about now, you almost have to attach it to the garage and redesign that part of the roof to go over shed part too, and that's just more work to do properly. You can't just go attaching rafters to the end of the existing ones as you won't get proper support. that and it will create a valley in the roof where water and snow will accumulate and definitely cause leaks.

IMO what I would do here is extend the slab by a couple feet, you may want to drill in some rebar to the sides before the pour so it stays attached better, and you'll want to do footings too. Then build the shed 2-3 feet away from garage, and the slab part in between will just act as a solid place to store stuff that can stay outside.

For my shed I kinda cheated though, I didn't bother with a slab and just used deck blocks. I leveled them by burring some partially as needed so they all line up, then I put some wood beams across and built on top of that.





One flaw in my design is there is no proper point load support, and it's a sacrifice I made just so I have nothing sticking out all around, just looks nicer. I've seen much larger cabins built this way so I think it's fine, as the part of the beam that extends past the point load support is not that long.

 

[herm0016]

if your neighbors are frendly and not busy bodies, i would just build the thing. its making the one you had a bit larger, yea you could go through the trouble of getting a permit but its likely more trouble than its worth for this. in my zoneing in the county, which is rural residential, i have an acre of land. the permits for a shed over 144 sq feet require a site plan review and would cost over 1500 dollars. more than i was going to buy a large shed for. so i got 2 smaller ones and will build a roof between them for my tractor. and then put a back on it, then probably a door at some point. haha.

 

[Red Squirrel]

I hate the BS where municipalities limit what you can build on your own damn land. Especially when you have large land. I can sort of understand in a small residential area but there should at least be exceptions for larger land.

It's one of the reasons I want to buy land in an unorganized township eventually, they have no rules in those places and you can do what you want. No permits or nothing. Technically it's suppose to be to code, but nobody is going to come see it. You don't need inspections or anything.

I was thinking if I did buy land but it was in a place that requires permits to build something bigger, I could just build 4 sheds and build a building on top, but think they look at the roof foot print and not the actual building foot print, so it would count as 1 big building.