OT: Thought of making a chimney cap out of SS but the footprint is 3' x 5'. Stucco?

rons · Oct 16, 2021

A 3' x 5" square with a ellipse in the middle. A sheet(s) of stainless with a drain slope on all sides (like a ant hill).
All four edges bent 90 degrees down to allow water to drain. Bending a drain slop and a 5' long 90 bend is not going to happen
here using one large sheet. A cool job would look like it was pressed into the shape.

I could easily cut up cardboard and construct a model. Then weld four sections together. A long seam will warp. So maybe no good.

So what about a stucco or concrete solution?
Float in a slope with what? And doesn't the mix need an additive so that there is adhesion to paint. The slope height is 3/4".

rons · Oct 16, 2021

Looking for 2 minutes and this picture is about right. Then I thought, why not buy from these people. Going to be over $600. Why not make one.

Custom Chimney Chase Cover - Economy Chimney Protection

Bill D · Oct 17, 2021

Tile or marble slabs, terra cotta etc. Any chance of freezing?
Bill D

CalG · Oct 17, 2021

A cap will condense the moisture and run a creosote stain down everything. DTDT>

If you burn wood.....

EmGo · Oct 17, 2021

CalG said:
A cap will condense the moisture and run a creosote stain down everything.

Hmmm. Totally common on boats, there's several different styles and creosote is not normally a problem. Maybe you didn't have enough draft ?

rons, they have a page of caps

Navigator Orders & Inquirys

(and yeah, at the prices people get for this stuff I'd make my own too !)

neilho · Oct 17, 2021

Or copper.

The cap could be riveted at the corners instead of welded.

Yeah, people use a lot of stone caps around here too, but 4x5 is a lot of cap. Stainless frame with inserts? Stucco over concrete board or whatever the normal substrate is?

What is there to fasten to?

stephen thomas · Oct 17, 2021

The cap could be riveted at the corners instead of welded.

No reason not to weld copper, either. If he has the means to weld stainless, copper is easy enough though it does take heat due to conductivity. I use scrap ground wire from electric cables for filler. (for architectural stuff) If you do a lot of copper welding, there certainly must be a supplier of filler wire.

smt

rons · Oct 17, 2021

Freezing? Only a few days in Dec, Jan. Remember that at global warming rates it won't matter much in the coming years.

Burning wood? Not much at all.

Fasten to? Just the clay ellipse pipe at the top sticking about 3.5" above a uneven mortar bed. The flat (3' x 5') is uneven
and water does not drain.

I was going to drive up to Alan Steel but even if they are still in business they only have a shear. They don't bend metal.

I got the idea from Home Depot when I noticed that they sell 3' x 3' sheets of thin stainless.

Rudd · Oct 17, 2021

I don't know what you are trying to accomplish with this cap, but stucco/concrete/brick/tile will let some water through. Traditional stucco would be the worst, followed by concrete. Tile probably the least bad. Note they put waterproof membranes down under the tile when building a shower.
I just looked at some architectural "features" on a school a bit south of here, the brick (sloped probably 8:12) had let water in and it had attacked the un-galvanized steel holding it up. Nice thing these "features" are over exit doors, perfectly placed to block a required exit when they collapse, and that is the least bad scenario.
Facilities chief used words he doesn't normally use when I pointed it out.

rons · Oct 17, 2021

EmanuelGoldstein said:
Hmmm. Totally common on boats, there's several different styles and creosote is not normally a problem. Maybe you didn't have enough draft ?

rons, they have a page of caps

Navigator Orders & Inquirys

(and yeah, at the prices people get for this stuff I'd make my own too !)

The opening at the top of that stove looks like my opening. Mine is a little higher and the entire port is not square to the 3x5 top.

GregSY · Oct 17, 2021

No reason you can't weld SS without it warping.

Plus...you haven't shown your chimney but chances are it's high in the sky enough that no one is gonna see minor imperfections. Keep it square and it'll look fine.

rons · Oct 17, 2021

Rudd said:
I don't know what you are trying to accomplish with this cap, but stucco/concrete/brick/tile will let some water through. Traditional stucco would be the worst, followed by concrete. Tile probably the least bad. Note they put waterproof membranes down under the tile when building a shower.
I just looked at some architectural "features" on a school a bit south of here, the brick (sloped probably 8:12) had let water in and it had attacked the un-galvanized steel holding it up. Nice thing these "features" are over exit doors, perfectly placed to block a required exit when they collapse, and that is the least bad scenario.
Facilities chief used words he doesn't normally use when I pointed it out.

Second and third sentences in #1 ...

Stucco with primer and a top coat will not allow water to enter.

rons · Oct 17, 2021

rons said:
Second and third sentences in #1 ...

Stucco with primer and a top coat will not allow water to enter.

Maybe I should have specified the job as a chimney crown, not a chimney cap. I made a custom cap from welded aluminum that is a lot better quality than
most of those cheap ones.

What Is A Chimney Crown? How Do They Work? - ALL PRO CHIMNEY SERVICE

What I'm trying for is the fourth picture. But I will prime and paint my stuff.

deltap · Oct 18, 2021

I built one as you describe for a framed stucco chimney I had in FL. I used stainless and welded the seams. I have sheet metal experience. You could make it flat from one piece. With a welded collar in the center it would not leak. If you want a pitch you must use 2 pieces and use triangulation to create pitch. Subject is covered in sheet metal drafting books. Once you know how it is not difficult. It could be made pitched from one piece of metal with only a seam on one side, but that size would be hard to move around in a brake for the required bends. People tend to work within their knowledge and experience. No reason why a stuccoed and sealed crown wouldn't work. Make sure you maintain prescribed clearance from combustibles if working with framing.

rons · Oct 18, 2021

deltap said:
I built one as you describe for a framed stucco chimney I had in FL. I used stainless and welded the seams. I have sheet metal experience. You could make it flat from one piece. With a welded collar in the center it would not leak. If you want a pitch you must use 2 pieces and use triangulation to create pitch. Subject is covered in sheet metal drafting books. Once you know how it is not difficult. It could be made pitched from one piece of metal with only a seam on one side, but that size would be hard to move around in a brake for the required bends. People tend to work within their knowledge and experience. No reason why a stuccoed and sealed crown wouldn't work. Make sure you maintain prescribed clearance from combustibles if working with framing.

What gauge would you suggest?

Maybe it would be possible for me to build a temporary bending jig from hardwood.
Otherwise weld the angles myself.

deltap · Oct 18, 2021

24 ga. minium. For 90 deg. bends clamp to angle iron and gradually bend over with wood or rubber mallet. Experiment to see what works best for you. Make a full size plan view drawing on cardboard. True line lengths are layed out on a square, plan line on one side of square and height of article on other side with true lay out line length the hypotenuse. Layout progresses on metal you will use from a corner. Make a trial layout on cardboard to gain experience and prevent mistakes. You can use a square piece of plywood to get line lengths. A 4' steel rule and large dividers will aid in layout. Don't forget to add allowances for seams and hems to layout. The chimney tile may not be exactly centered so make sure plan drawing is the same as it is on the roof.

rons · Oct 18, 2021

Deltap & others, thanks.

My plan is using cardboard. It rained the first time last night and this morning since last May. I primed the cap I made from ten years ago.
Welded aluminum and a top shield held with rivets. Four stainless bolts hold it in place on the clay vent.
It was painted with Hammertone Black. The top paint was half gone. This time I'm using two part industrial primer and Centari 5000.
Two days ago I primed the cap. Needed another day to cure before the black top coat. Missed it by that much ...

Rudd · Oct 18, 2021

rons said:
Second and third sentences in #1 ...

Stucco with primer and a top coat will not allow water to enter.

Uh, yeah, I've had contractors and salesmen try to tell me that too. If you used the acrylic coating, it might not leak for a while till the stucco cracks. One thing I have learned is that people do not maintain roofs or anything related to them.

Rudd Long, Architect.

1yesca · Oct 18, 2021

you mite get the metal your looking for from a old used restaurant hood , back splash or help from someone that builds them

rons · Oct 19, 2021

1yesca said:
you mite get the metal your looking for from a old used restaurant hood , back splash or help from someone that builds them

Alan Steel in Redwood City has a yard with dismantled restaurant fixtures from stainless. I asked a general question if anybody has been there.

OT: Thought of making a chimney cap out of SS but the footprint is 3' x 5'. Stucco?

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