Lean to Shed Roof Angle?

[QwikKotaTx]

Edit: shed is complete, pics on page 2.

I have built the base of my shed (12'x6') and am looking for some advice on the roof pitch before I build the walls. I am trying to tuck the right wall under the garage overhang and use the same color shingles and siding to make it blend in. I would like to maximize the height but allow rain runoff. There are no snow loads to worry about here. I hope to use 2x4's to keep the height maximized but I need to check the span for deflection. Some pictures are linked, the last 2 are basic CAD models of the walls and roof at 3°. Any help is appreciated.

 

[Robby321]

I don't see a problem....just do good side drip edge and gutters.

 

[cdestuck]

No way I'd bother putting in the rt wall against your existing wall. No reason to and waste a small amount of Sq footage. I would just put a ledger high on that wall for the rafters to be attached to.

 

[Thumper68]

With shingles I would not do less than a 3/12 pitch.

 

[dontlifttoshift]

No way I'd bother putting in the rt wall against your existing wall. No reason to and waste a small amount of Sq footage. I would just put a ledger high on that wall for the rafters to be attached to.

If its not attached, he doesn't have to worry about setbacks....?

 

[Dhagan887]

Roofing material?

 

[matt_i]

Shingles don't really work on that pitch, I'm guessing around 1:12. If it were me I'd do metal, or grudgingly do shingles but you'd have to ice & watershield the entire roof as that's what would be doing the water resisting, the shingles just there for the solar protection aspect.

 

[Dhagan887]

If its not attached, he doesn't have to worry about setbacks....?

Or posts 4ft in the ground (or proper footings below the frost line), all thread/steel plates tying the two together, property taxes, or other things your jurisdiction might see fit, as silly as it all sounds.

 

[K'ledgeBldr]

Most manufacturers of fiberglass reinforced shingles require at least a 3/12 pitch. Anything less than that would require additional roofing buildup. What exactly that entails would be the recommendation of the manufacturer.

 

[DougWil]

Shingles don't really work on that pitch, I'm guessing around 1:12. If it were me I'd do metal...

Yep and mastic the laps, and better get it up off the ground more, not enough air flow = rot.

2x4 will make a 6ft span, what is the code required LL in your area?

 

[Cato]

Is that base pressure treated?

 

[Brian80]

I'm just reiterating what cdestuck said, use a ledger and don't waste your money for on the sticks. I'd even suggest standing seam for the roof, just match the color, and it will look fine. That way you don't need to concern yourself with that low of a pitch. Personally I think using the metal roof against the existing shingles will give it some contrast. I see it a lot in our area.

What are your intentions. 8 foot ceiling clearance should be more than sufficient for that small of an area.

 

[SARG]

Just to mention ... my neighbor just had the Amish folks build a three sided shed. They brought it in and stuck it on the back of his garage on blocks. Took them about three hours.

 

[QwikKotaTx]

Thanks a lot, guys. I have modified it to be a 2/12 pitch which is as steep as I can go and still walk upright in the thing without whacking my head on the rafters. As mentioned I am not tying it in to the garage in order to avoid making it a permanent structure and get a permit etc. I had thought about lifting it up more but would loose head room. It will possibly sink on the left side some so we shall see. It's raining today heavily so a good time to see what it does. Yes, the floor joists and the plywood are treated.

 

[FlatRoofGuru]

Self-adhered modified bitumen will work at 1/4" per foot slope, and is available in colors to match the shingles. Just be sure to use the base sheet that goes with it and even at low slope it will stay dry.

 

[38Chevy454]

I am assuming your base is 8x12? As a modification to the wall by the garage: Instead of the studded wall, how about use 4x4 posts and a 4x6 header beam. Maybe three 4x4 posts, each end and one in the middle. it would be overkill, but certainly be strong enough to resist any sag. You could lag into the garage wall, to keep it held tight, but the weight loading is through the posts, not by a beam attached to the garage with no other support. I think that could still get away with being an independent structure and not addition to the garage. It would give the extra space, but still meet the "freestanding structure" rule. Also allow a bit more overhang so rain will not splash right against your wall, and it will match your garage overhang better as well. So maybe 10 ft joists could be about right?

 

[jdsac]

Something that small would be great for rubber membrane roofing- no seams to leak.
As far as pitch goes, with no snow you don't need much. A properly graded parking lot for example only has a few degrees of slope, the water will always find the low
area.

 

[rayra]

Self-adhered modified bitumen will work at 1/4" per foot slope, and is available in colors to match the shingles. Just be sure to use the base sheet that goes with it and even at low slope it will stay dry.

This. And seconding the prior comments about 3/12 pitch and asphalt shingles. You've got to use the right product on that shallow of an angle to prevent water infiltration. So given your height clearance constraints, it's sheet products for you. Or you could use tin in a continuous run from high to low, with no lap joints.

 

[QwikKotaTx]

Thanks, again. If I use standard shingles I will use 2 layers of paper and apply roofing cement to the joints.

I'm trying to figure out how wide my door needs to be. I would prefer 36" but the height may be a concern or weight of the door. 30" should be all I need to get the lawnmower in an out easily. The main thing that will be in there is all of the hurricane plywood for the windows. But that goes in one sheet at a time. Can't wait to get that junk out of the garage.

 

[CNGsaves]

Thanks, again. If I use standard shingles I will use 2 layers of paper and apply roofing cement to the joints.

I'm trying to figure out how wide my door needs to be. I would prefer 36" but the height may be a concern or weight of the door. 30" should be all I need to get the lawnmower in an out easily. The main thing that will be in there is all of the hurricane plywood for the windows. But that goes in one sheet at a time. Can't wait to get that junk out of the garage.

^ ^ ^ Don't mess with 2 layers of paper . . . no real benefit.

I'd just make it whatever slope you want to look good and functional.
It could be as low as 1/12. Then . . . use . . . .
. . . . ICE & WATER DAM . . .underlayment . . . . that comes in rolls and you peel off plastic to stick it down. Available at Lowes, HD & Menards for around $50 to $70 per roll. It overlaps 3 inches and you have forever leak-proof roof. Then you shingle with comp shingles as usual.

I used this product to shingle entire 28 sq roof of my friend's house that has very little slope . . . like maybe 2/12. Previously, house had lots of leak problems from normal tar paper and shingle construction. That Ice & Water Dam roll treatment is simply awesome. I will ALWAYS use it around every roof penetration, and edges of house . . . even if they have more slope. For low slope roofs, it's perfect product to ensure no leaks and still use normal shingles rather than crappy look of roll roofing.

 

[jlckmj]

I would open up the fascia and sister the rafters to the ones on the garage, you will have the same pitch as the garage, and you might be able to sneak the shingles under the old one's to make it blend in. That way you do not have to build the inside wall, and it looks like you would gain another foot or more of height.

Jim

 

[Lunker]

You can shingle a 2/12 with I&W as others have previously mentioned

 

[QwikKotaTx]

Shed is finally done after many weekends of hearing the kids scream inside the house and the wife in hospital for stress related heart issues. Whew, never a dull moment.

I went with 2/12 pitch and heavily overlapped tar paper, the thick kind and used a lot of cement on seams and the perimeters. The last two rows I could not even get a hammer under the eave so they are just cemented on. The outside edge is not crowned, just had a less than straight 2x4 for the fascia board. Had to stack some 2x4 drop pieces on the outside wall as the hardie panel did not line up perfect. That stuff is challenging to work with, all cut with the score and snap method and some oscillating trimmer work for small cuts or reliefs. Not perfect but it will suffice.

 

[kelpaso1]

I would open up the fascia and sister the rafters to the ones on the garage, you will have the same pitch as the garage, and you might be able to sneak the shingles under the old one's to make it blend in. That way you do not have to build the inside wall, and it looks like you would gain another foot or more of height.

Jim

I know I'm a little late to this topic but that is exactly how I did it. Gained at least a foot on the inside height. A little more work but I think it looks nicer.

 

[Slednut]

I have a patio cover that has very little fall to it. It has never leaked, where you run into trouble is the water will wick back under the shingles at the facial board. I cut a piece of cedar so I could attach Z flashing to it so the last 3 inches is at a 4/12 pitch. The cedar is ripped at an 85.5 degree angle.

Now days I would use synthetic roofing underlayment.

Here's a pic of the patio.

 

[pmiranda]

I'd put some fine wire mesh to keep critters and birds from nesting between the two roofs. But maybe that's pointless since there's a gap between the shed and house at the bottom, right? Keep an eye out for wasps and such, too.

 

[QwikKotaTx]

Thanks guys. The mesh will be needed on the inside right area as there is a gap between the sheathing and the top sill plate. I did not put any fascia on the back side but in hind sight I should have extended the plywood back wall sheathing up about 3" to seal that area off but allow for some air to escape. It doesn't get too hot in there. The front soffit has 3 small vents with 3 decent sized holes drilled in each.