View Full Version : Somewhat OT- reroofing the shop

11-13-2011, 07:08 PM
Long story short, the insurance people have thrown a monkey wrench into the renovation plan we had for the property we bought a couple months back, which means that rehabbing the failed roof on the garage has gone from sometime next year to ***NOW***. Well, not exactly **NOW**, but the moment I finish the quick&dirty patching to the stucco (which the recent cold&wet weather made obvious had failed and was causing the paint&spackle I spent the past 2 months on pop off the wall...) the garage is the next project so we can get off the horrendously expensive "vacant property/construction site" insurance and onto the "landlord policy" we had planned on.

Anyway, the garage is roughly 30' x 40' with block walls currently sporting flat roof that failed 10 or 15 years ago and has since had a couple layers of blue tarp added. We're told the previous owner had planned on adding a second floor but never got around to it (due to his passing away), which would explain the complete lack of pitch on the roof and the exposed joists and seemingly half-assed attempt as a flat roof. The roof is supported by a pair of 14" steel I-beams going parallel to the 30' dimension, spaced 14' apart and 12' in from either end (with 2x14" wood on 16" centers going along the 40' dimension). Given the waterlogged beams supporting the current "roof" and their complete lack of pitch, we're thinking a new pitched roof of some sort is called for (in a quick&cheap sort of way given it's too cold here in SE PA for putting down flat roofs).

Seems to me dropping (more than) a couple roof trusses on top of the block walls would be the quick/easy/cheap route (there's 2 local companies that make them)... And while I'm at it, I could frame the walls up 4' or so easy enough to make the attic space usable as 2nd floor/loft. And at that point I may as well do a proper 2nd floor, but then I'm far from the quick/easy/cheap route. I've got 2 months left to do this, of which 2 weeks are already committed to finishing and painting the stucco.

Any advice, particularly about how to spec roof trusses or bumping the walls up a couple feet to gain a second floor?



11-13-2011, 07:30 PM
why trusses if you want a habitable room, would think a cut timber would make sense.
I have the same job to do on a 35 foot square shop [mine], i plan on building gables at the end and putting a ridge and purlins between then sheet and shingles [metal ones over here!], the room upstairs will be divided by a central wall which will act as a central support for the ridge and purlins effectivly dividing the span in half, this wall will sit on the 10 x 6 rsj i have already installed, dormer windows will also be cut in at the same time, and a chimney stack to one end for the stove/forge, ps loads of insulation!! [somewhare warm for me to hide!]

11-13-2011, 08:00 PM
If you are trying to do this to code, then your local building dept. will need an engineered plan. You will need the foundations and block walls inspected by an state licenced engineer. The problem is that existing rebar etc will be hidden.

I'd talk to your buliding inspector and ask what they will require. If you are lucky, they will grandfafher in much of what is there.

If you are dodging code and inspections, just make a measured sketch and take to a local truss company. Indicate the pony walls you want and they may even design these into the trusses, and will print out a design and quoatation on the spot (they do around here). The trusses will meet your local code even if the supporting structure doesn't. ;)

11-13-2011, 08:05 PM
I'm not quite sure how you plan to do a second floor, especially with trusses, but I agree that the simplest thing to do to get a gable roof would be to put trusses across from one wall to another, sheath with plywood, and put on asphalt shingles. I imagine the truss manufacturer would help you figure out what you need, given the support locations, spans, etc.

To get a 2nd floor you'll need to build the 2nd floor (duh!), that is, build a replacement for the cockamamie flat roof, then build walls high enough to give headroom, then put trusses on top of the 2nd floor walls.

Another thought, if you want to go really cheap: build a single-pitch shed roof.

P.S. Lakeside53 posted while I was typing. Good question: how tame is your local building department?

11-13-2011, 08:53 PM
You might check with the local truss companies and see if they have any "mistake" trusses. A few years ago when I was building a garage I found the truss company had some trusses that had been built without tails when the plans called for tails. They were a foot longer then I had planed on using but for the price savings , about 2/3's off,I could live with that.

11-13-2011, 10:47 PM
You can get attic trusses that have a room built in. The taller & wider the truss the bigger the room.

11-13-2011, 11:40 PM
Dutch Gambrel trusses maximise the room when you want an attic space. Combine those with dormers and it's can be a great use of "wasted" space.

11-14-2011, 01:11 AM
Since you have the problem that the existing 'floor' joists are going parallel to the long dimension, they probably can't be used as part of the roof trusses. Since they were initially intended as the floor upstairs, keep it that way. Go with the barn roof style (dual slope) and see if you can get the trusses made up for you. I think you will have a better chance at passing the construction if you go with manufactured trusses. The way your walls are tied together with the steel beams is probably the way your trusses should go.

Of course it won't be cheap, nor easy to shingle, but probably cheaper than building upper floor walls, adding the roof at two story height, siding the walls, and then also doing the roof. You can forgo the sheeting for the upper floor for now, though you might want to at least install the perimeter sheeting so it won't be as much of a hassle later. If you can afford to , buy the sheeting for the floor now and have it craned onto the floor joists to make it easier to finish installing it later once you have the roof done.

Maybe some of this won't make sense. I don't know what shape the joists are in, nor whether they are already sheeted, whether the sheeting is any good at this point, or whether you can pass code if you don't fix this before adding the roof.

You could make your own trusses, but then you would need to have the engineering down pat. It could well be better for you to have someone from the truss-making company come out and assess the situation. You would draw up your plan from that assessment, and that would probably give you a go-ahead from the building inspector.

11-14-2011, 07:54 AM
A quick visit to the building-zoning office re height, stepback, allowable use, etc could save a lot of trouble before you fall in love with an idea that can't be used. Also, since they monitor construction all of the time they may have some ideas for you. I like the truss wall and roof together idea myself and truss companies work with building departments all of the time and would be another good source of information.

11-14-2011, 08:53 AM
14" steel beams and 2" x 14" on 16 inch centers sounds like it was intended as the second floor. Don't know if "waterlogged" means "wet" or "rotted and unusable". I'll assume the latter.

I have a building that is 28' x 40' with roof trussses that create a room on the second floor of 12' x 40'. I've got a 10:12 pitch which is a challenge for the roofers but gives a second floor room with good clearance on the side walls.


You didn't mention how tall the block walls are. If you plan on using it as a work shop, having a ceiling at least 9' is nice. If you ever want an 8' garage door, minimum ceiling height is about 9' 4".

Sounds like options might be to: strip off the existing lumber and I-beams, lay another course or two of block to increase the wall height, install trusses to get the roof and second floor.

The only specs you would need for the truss company is the length of the trusses, width of the room and desired pitch.

There is a magazine called Journal of Light Construction which has a number of articles that will help you out quite a bit. You can buy the Archive CD which has all the past issues.