Replies

1. 
   csnow | Oct 27, 2004 12:31am | #1

   Copper caps hold up much better than bare mortar caps.  I see them around New England.  My house had one, though I have since demoed that chimney.

2. 
   Sphere | Oct 27, 2004 12:41am | #2

   Funny, I just gave the dimensions for mine to GreenCu this am..mebbe he'll do ya up too.

    

   Spheramid Enterprises Architectural Woodworks

   Repairs, Remodeling, Restorations. 

3. 
   seeyou | Oct 27, 2004 12:44am | #3

   I make this type thing regularly. 16 oz cu is fine (x'd as you suggested). The actual opening should be much less than you described since it's veneer on framing. Several 2x braces across ( keep the proper distance from the prefab flue) will support the cover.

   I invented the "x" factor.

1. 
   woodchuckc | Oct 27, 2004 04:09pm | #7

   GreenCu,

   Thanks for the info.  I may not have made this clear in my original description; there is no framing inside the chimney at the crown.  According to the mason I'll be using, on these types of chimneys he just makes a rectangular "box" of brick with the pipe in the center (of course, the pipe is secured with support straps a couple of feet down from the crown).  I have attached a drawing looking down on the top of the chimney.

   I am planning on putting some bracing across the top - I was thinking about some 1/2" copper tubing spot soldered on the underside of the crown, which would also hold the copper off of the top of the brick by 1/2" or so and allow some air circulation within the chase.

   I'm guessing that about 2 1/2" to 3" wide lip turned down around the outside of the brick should be sufficient.  I  also think that turning out the bottom 1/2" to form a sort of flange would be good to keep water from running straight down onto the brick would be a good thing.

   We do get some wind occasionally, so I was also thinking about soldering some squares of thicker copper in a few places around the lip near the corners, and drilling and tapping the holes for screws to snug up to the brick faces.

   Thanks again for the suggestions!

   -Chuck

1. 
   seeyou | Oct 27, 2004 05:00pm | #8

   That type of chase/chimney is a new one on me. HMMMMMM.

   The copper pipe is a good idea. All your other design ideas are right on course as far as the way I do it. I also hem the edges so there's no sharp edges.

   I normally attach from the sides with tapcons. I've also tapconned thru the top and soldered pieces of copper over the screws if frequent access is not necessary.

   Good luck.

   I invented the hymnal.

4. 
   hammer1 | Oct 27, 2004 12:59am | #4

   I think I would ask the same question as your brother in law. Lead is most commonly used for flashing brick chimneys. Once the first row or two stick above the roof line, an apron is formed by the mason. Lead can be bent and formed to make some round corners and the first piece is mortared into the row of bricks. As the rows of brick ascend, step flashing is bent in place and successive pieces of flashing are installed, overlapping the one before. At the top there may be another apron or cricket which, again, is bent to form to the existing conditions. Copper does not have the same malleability as lead. It often needs soldered corners. A counter flashing would have to be cut into the brick at the angle of the roof, not following the mortar joints and making corners won't be easy. There isn't a good reason for counter flashing in this application unless you get heavy horizontal rain. It's very rare that a traditionally flashed chimney will leak because of no counterflashing. Unless expertly done, the counterflashing could be a problem. Copper likes to expand and contract so this adds another good reason not to use it. There are also soft copper rolls and hard copper sheets

   As far as using a big sheet of copper for a cap, hows the wind in your neighborhood? Around here we use a large piece of slate or other flat stone supported by bricks on end at the corners. This will help protect the top of the chimney. Mortar should be fine for a long time if covered. I'm sure the masons know how to properly flash a chimney if you let them.

   Beat it to fit / Paint it to match

1. 
   seeyou | Oct 27, 2004 01:55pm | #5

   I'm sure the masons know how to properly flash a chimney if you let them.

   That's a regional thing. Around here, the masons mason, the shinglers shingle, and the flashers flash. Re-read the post. One question is about the top cover for a prefab chimney chase with brick veneer. It has to have some type of metal cover. Nothing better than copper as far as I know. Also, in my area, you almost never see lead. We use copper around here. As far as expansion and contraction, you have to allow for it just like you have to allow for it with most other building materials.

   I invented mason jars.

   Edited 10/27/2004 6:58 am ET by greencu

2. 
   woodchuckc | Oct 27, 2004 03:41pm | #6

   Thanks for the reply.  I think that lead flashing is even more of an unknown around here than copper.  Thin aluminum gooped over with roofing tar seems to be the norm (and I've even seen entire chimneys coated with roofing tar from the crown down onto the roofing shingles).

   None of the masons in my area do flashing - I was very quickly informed that they lay brick and roofers do flashing.  I made it clear to the mason that I have contracted with that reglets need to be left in the mortar joints for the flashing to bed into, however.

   -Chuck