Constructing Roof for Shed

It's slightly more complicated than that here. The real advantage is of course the knowledge of the inspectors that is gladly shared to help the novice through what could be a series of bad decisions.

Reply to
Gordon Shumway
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At a prior house, a neighbor build a rather large shed on his second lot. To get around the need for a building permit he couldn't have a concrete floor or any sort of foundation. He put it on skids on gravel and put in a raised wood floor. Worked well, though I don't know if there were long term issues.

A couple of years later (same house), I built a 2-1/2 car garage. I needed drawings for it but since I estimated the cost at less than $10K, I didn't need an architect's or engineer's seal. I did need full inspections, though. The town engineer was very helpful with design decisions but the general inspector (everything but electrical) was a real asshole. He forced me to put in a metal passage door with a metal frame between the garage an house, and an 8" heavy H-beam over the 16' door. He was trying to force me into two 9' doors but it would have looked horrible. Some inspectors can be a real help but others can be real jerks.

Reply to
krw

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With all of the questions you asked, I have a couple for you.

I was framing an addition for a guy in a township just south. TONS of new housing going up and I don't know how the inspectors keep up. There are a couple old timers on the staff who really haven't kept up with modern building technology.

The addition was a simple, long rectangular room, with load bearing walls running the length, and simple trusses for the roof structure. The inspector kept telling us he wouldn't approve it until I ran 2x's across the ceiling to tie the outer walls together to keep the rafters from pushing the walls out. I tried to explain the geometry of trusses to him and how each truss was actually doing that, but also how it was impossible for the "rafters" to push out a wall when using a truss.

I finally begged him to allow the supervising inspector to come by and look at it. I hope he didn't lose his job, but on the other hand, I hope they asked him to retire.

Reply to
-MIKE-

We designed and built our 24'x28' garage back in 2001, then designed and built our own house in 2003. I didn't have any issues getting the permits, other than a few corrections on the plans for seismic requirements and smoke detectors. I had several inspectors, all of whom were helpful and great to deal with.

The only inspector I ever had a problem with was an electrical inspector when we were remodeling my in-laws house. He always passed my work, but he was a very grumpy guy to deal with.

If the garage is attached to the house, I believe an auto-closing fire rated door like that is required by codes now.

Was the door in a load bearing wall? Was it supporting another floor above?

16' is a large span, especially in a bearing wall. Something like that should have been specified and approved/denied when you submitted your plans to the building department.

Was it required for shear strength? I had to install special seismic anchors in the foundation and build shear walls on either side of our garage (we did go with two 8' doors instead of a single large door).

Anthony Watson

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Reply to
HerHusband

The idiot who built my garage put a couple of 2x12s over the 16 foot garage door and oriented the roof so it was a load bearing member. Since that time it has developed a good bit of sag. When I reroofed the place a few years back I should have pulled the whole roof structure off and rotated it 90 degrees but it didn't occur to me until after the job was done.

Reply to
J. Clarke

Condensation and then dripping was a regular occurrence on the underside of the corrugated iron of the original shed on frosty mornings when everything started to thaw. Probably because of our damp climate, but a lot of moisture was probably coming up through the concrete floor which didn't have a damp proof membrane

-MIKE-;3633983 Wrote:

I meant short diagonal bracing timbers joining the studs to the rafters (about a foot in from the ends of both stud and rafter)

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Reply to
Eugbug

In my case, the header has no structural function. It's just a panel to keep burglars out should they pull of the small metal sheet above the door.

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Reply to
Eugbug

Could you jack up the 2x12 headers to get the sag out, then bolt on a steel flitch plate to strengthen the header?

Of course, if the sag developed over time, it would probably be darn near impossible to straighten those 2x12's again. Maybe you could jack it up in the middle just a little bit (1/8 inch or so) each day, so the beam can slowly straighten out?

Either that or build a temporary support wall and replace the original 2x12 headers. No small job for sure.

Anthony Watson

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Reply to
HerHusband

If it ever becomes an issue, you could probably just lift the roof an inch with jacks and a temporary support and sister in an LVL or Parallam beam next to the 2x12s.

Of course, someone who never got the proper engineering specs for a 16' header probably never bothered to put sufficient footings under posts for said header. It would be nice to know if the foundation is correct, too.

Reply to
-MIKE-

The insulation under the metal roofing would prevent that because it wouldn't allow for that temperature difference in the roof and inside ambient air.

Oh, I see now. If you're wanting that for shear strength (to prevent diagonal racking), you could probably do it better by putting some 1/2" sheathing on the inside or outside of those short walls. Doing it on the inside would give you the added benefit of having a great nailing/screwing surface for hanging stuff like shovels and gardening tools, etc.

Reply to
-MIKE-

There are easier ways to break into that shed, believe me. :-)

I hate to keep bringing stuff up, but you asked. That header *is* doing something structural. It's taking the weight of the roof over the opening and transferring it to the studs and down to the foundations.

I realize this is just a shed so it'll probably be just fine. But I'm looking at your pictures and just realized how far your stud spacing is. If that structure is indeed 20' long, then those studs are 32" apart, twice as far as they should be. It looks tome like the building is actually about 17' long and studs are 24" apart giving you a 30-32" door.

In either case, those studs are undersized. But as I said, it's a shed, not a home. I do, now recommend some diagonal bracing on all the walls. The minimal would be a half sheet of 1/2' plywood on all 8 corner wall ends. You could also put 2x4 diagonals on the insides of the walls, similar to the bracing you show in your pictures.

Just a suggestion.

Reply to
-MIKE-

I just don't understand why you keep suggesting sturdier construction techniques. I hopped into my time machine, took a quick trip into the future to check out his shed and everything is fine. See:

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Reply to
DerbyDad03

LOL!, looks a little like my other ship lapped shed (or what it will like if I don't sort it out!)

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Reply to
Eugbug

LMAO! That's actually pretty accurate.

Reply to
-MIKE-

That's really strange. He couldn't see the cross-tie at the bottom of the truss?

The problem with going over the head of an inspector is that he still has the power to make your life miserable.

Reply to
krw

My experience was exactly the opposite. The electrical inspector was really helpful and easy to work with. He did get a little tight jawed when he plugged in his three-light tester and it was dark. I told him that the garage was shut off at the entrance panel. Well, I didn't have a CO! I told him that I only had power on while I was working on the garage. He just shook his head and said I was the only one he'd come across that actually followed the rules.

It certainly wasn't in '84ish. It had to be 30-minute rated, IIRC, but the metal door and frame was rated for 90(?).

No, it was supporting the trusses. A laminated wood beam (3x 2x12s with plywood) was perfectly good. Overkill, actually. The inspector agreed that it would work but said "do it anyway".

The piers on either side were masonry (8" block and brick). No, he was a well known asshole. He'd failed his inspector's exam three times but was still the town building inspector.

Reply to
krw

EXACTLY!! I was looking around for hidden cameras, because I thought I was on some prank TV show.

Reply to
-MIKE-

So I decided to use 6 x 2s for the rafters. This is an example of the metal cladding I'm using, but the actual sheets would span structure from front to back. I've nailed a 6 x 2 to the ends of the rafters at the front and will do the same at the back, plus I've added blocking over the top plate. Could I screw sheets directly to the framing and dispense with purlins? The sheets would be screwed to the front 6 x 2 (which is going to act as a facia), the 6 x 2 at the rear and the blocking.

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Reply to
Eugbug

I would not attach directly to the framing. The sheets need support crosswise and the sheets need a row of screws near the center. Otherwise they tend to flap up and down in the center of each sheet and pull at the screws at the edges. Not a good practice.

The framing looks nice and sturdy.

Reply to
G. Ross

Somewhere there is a nailing schedule for that siding/roofing product. The schedule for corrugated metal roofing almost always is horizontal, not vertical, hence the purlins. If you are framing in those cross members between your rafters at the intervals required in the nailing schedule, you are good. However, the roofing may or may not require more fasteners along the vertical, overlapping seems. If it does, the seems would have to land on a rafter.

Find the nailing schedule for that product and you'll know for sure.

Reply to
-MIKE-

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