Advice on chimney

[Pr3ssure]

So, ive got a garage that i am aloud to build a chimney/hood in. Some advice is needed though. Ill get some pictures up for reference kater or tomorrow.

Basically its an old golf cart garage for a golf course. Its a big steel building, probably about 70 by 30 feet floor space with probably 20 foot celing at the peak. There are several spots with windows/skylights, whatever its called. One of them doesnt have a window in it towards the back of the building. Its probably about 7 or so feet from the wall.

My questions being the best way to hang/mount everything. I can maybe just mount it on the wall and do a 45 degree angle to get to the hole but i know straight is better. Although im not sure if they will want me to have the forge right up to the wall, they might want me to be directly under the skylight so if thats the case I'm not sure how i would go about mounting everything. I guess i could just run it up and at an angle, mount to the wall and then fo at an angle out but that seems like a lot. There is framework i could use to hang the hood but im jot sure about the ducts.

Hopefully this isnt all too vague, i know the pictures will help with the analysis so i will try to get over there before it gets too dark.

[Frosty]

Good to see you posting again Pr3ssure, I haven't had anybody to give a hard time over sloppy spelling in quite a while. 

You'll need to do some ground work before we can be much help. Hanging stove pipe is rarely a difficult thing but how involved it is depends on some of the things you haven't told us and heck you probably don't know yet.

Are you sure the roof is 20' or are you estimating? 

Have they given you free choice as to where you set up? If so, stay away from the open hole in the roof. You don't want rain on your gear do you? Ask where you can set up and be sure to find out if you can set up permanently or if you'll have to move it to make room and how often. By permanently I mean for a decent length of time, say 6 months or more, not for ever permanent.

If possible go straight up and through the roof. This is the easiest way to run stove pipe, a couple sheet metal screws in each joint and a hanger to keep the weight off the hood and you're golden. You'll need a good roof jack to keep water from raining straight down on the forge.

If you have to start running angles and turning corners with the stove pipe you'll need a different hanger every time it changes direction. Oh, no matter how you penetrate the: roof, wall, old window, etc. you still have to run the pipe at least 3' above the highest point on the roof within (I don't recall) 10' 20' anywhere up wind. I just don't remember but you'll need to check codes to keep things safe and legal. You don't want to be on the hook if a fire damages property, even if it's not your fault insurance adjusters are always looking for a reason to deny a claim and save themselves the money.

Anyway, it'll be nice to see if we can get you set up. Oh, type more slowly so we don't have to figure out what the words are. Okay?

Frosty The Lucky.

[Pr3ssure]

Yeah, ive been away for a little while. As for where i can place it, ive basically just got a little back section of the garage to use since its not mine. As for the hole in the roof getting rain, i already figured im gonna use a skylight opening and use something to fill in any open space. Plywood or a sheet of metal. Im not positive but i dont think he will want me adding any holes to the building, although i can maybe go through the side of the building to run it up the outside which i think would be easiest.

As for height its just an estimate but its in the 20 foot range give or take a few feet.

The main thing about going straight up is im not sure how i would mount the stove pipe, ill need to take a look again but ill probably have to add some mounting spots or something. 

I was not able to get pictures before it got dark but ill update with some tomorrow. As always i appreciate your knowledge. I'm sure once i start really thinking about it and looking I'll figure something out though. It'll just be really nice if i can get it in before the snow comes and i can forge away from the elements.

Also, not sure what a roof jack is. Im about to google it though. Unless youre talking about these things that kind of spin and a shaped to keep water from running in or one that is like a flattened tee pee kinda deal.

Just looked up roof jack, not sure unless you actually mean one of those like beam jacks or something. 

[jlpservicesinc]

If you can rest the chimney right on the forge it makes is a lot easier to setup. If the stack needs to be suspended it makes it more complex. 

I just use a section of 12" sq metal tubing I made up out of bent L sections and welded together at the open sides. this has worked amazingly well.  My stack is about 17Ft tall and it's fabulous and sucks nearly everything up and out. 

Check out the chimney build on the thread here for the trailer. It shows photo's of the build.   No need to do anything inside the pipe. there are no smoke shelfs or the like. 

For ease in water shedding I prefer going though a side wall vs out the roof as then without creating a good cap usually leaves water coming down both the outside and inside of the stack. A vented cap is needed for sure.  I am not a fan of the spinning ones. I have used them in the past and found they don't really do much in a way what makes a difference enough to warrant the cost. 

[Pr3ssure]

I honestly handent even thought about it yet but you said putting it on the forge, i shloud probably just make a table for it so i can just set it right up next to the forge and do one like that instead of hanging. Would help with making it sturdy too, I'd say.

[Frosty]

If you're using regular stove pipe standing it isn't as structurally sound. where the weight is supported by the screws when hanging it. The problem with putting much weight on stove pipe is it's tendency to buckle if the pressure is too great or off line. Even screwed together the joints can buckle.

Hanging stove pipe is as easy as running a couple pieces of cable or even heavy wire down from the roof and hose clamping it to the side of the pipe in a couple places to distribute the weight. The end of the wire is of course screwed into the roof structure.

A roof jack is a fitting that makes up the stove pipe to a roof and provides a reasonably water tight seal. 

After finding the below picture I had to do some more searching. Seems nobody calls them roof jacks anymore, they're called: roof or stove pipe flashing." What isn't shown in the drawing is the large galvanized sheet that lays flat on the roof. Depending on the type of roofing is how it's water proofed. I just troweled mastic under the one on my shop roof and screwed it down. Making a good water tight seal isn't hard if you do it right.

The spinning caps are enhanced ventilation caps not for stove or furnace stacks.  

 

Frosty The Lucky.

[Pr3ssure]

Cool, that gives me a little more of an understanding. And i wasn't meaning to just set the whole weight of it on a table, just maybe have it to help with the load a little. Maybe thats not a good idea though.

That illustration is a good one too.

Ill have to look up what joists are though, have probably seen them before just didn't know thats what it was.

[ThomasPowers]

Also look up the examples show on IFI about running a horizontal pipe to a window and then go up.  IIRC Hoffi does that in his school.  A bit harder to get the draft started but works well after that if you have the horizontal section big enough and the upright section big/long enough.

In my shop I have a hole in the steel 10' side walls, about 7' off the ground, (used to be for a chimney when my walls were a roof...). I stick a piece of 10" diameter spiral seamed duct out through it at a steep angle and put the forge underneath it.  Works well. 

[pnut]

13 hours ago, Frosty said:

The problem with putting much weight on stove pipe is it's tendency to buckle if the pressure is too great or off line

Very true. It doesn't take much horizontal force to collapse a side and make it fold up.

Pnut

[Latticino]

The library at a nearby technical university should have a copy of the SMACNA standards for ductwork.  This will give you info on joints, sealant, hangers and roof thimbles for your penetration.  I've posted before about terminations, but have limited access right now.

Good luck and be careful.

[Ohio]

Pr3ssure, I recently asked a similar question regarding the Uri Hofi side-draft design on another thread. Like you, I'm thinking about the best way to move air out of a shop where I'm forging and I'm pretty sure I'll be building a side-draft style chimney.

My needs are determined by several things, not the least of which is 1) the ease of installation/repair/adjustment and 2) the amount of rain that will come in.

I live in a very wet sorta place, so if I can avoid going through the roof, I'll do it---roof penetrations are to be avoided because no matter how well flashed, they will eventually leak. It's not just the rain or snow, the sun will rot any rubber and many of the mastics used to attach or flash. The metal roofs also expands and contracts and will work loose any screws or other fasteners, leaving a bit of gap for water.

Ease of install is another aspect I'm considering. I do not like going on a roof, especially one with only purlins and no sheathing because if anyone can step through roofing, fall, and make a sickening squashy sound on the floor below, it would be me. I can run stovepipe with wire because I know how and I have another neighbor who used to install woodstoves for a living and I can ask for help if I need it. If I need to replace or remove, or I want a larger diameter or better material, I can do that without going on the roof. And if I were using a space that wasn't mine, I'd be sure to set up something I could quickly take down should someone decide I don't belong there. It's also a lot easier to cover a wall than to cover a roof.

Either way, best of luck with your endeavor.