Chimney chase, access to

[edwardh1]

my house has a wood sided (lap siding) chimney chase up the side (2 story). Room inside the house there is a 2 story room with a tall ceiling (no attic access to the chimney chase).

Has anyone ever seen any kind of access door or hatch to allow inspection of the inside of the chase (for water leaks etc?)

[Jim Baird]

No.

Does the chase column go all the way to the ground? I have seen some that are cantilevered. If it goes all the way to the ground it should be open to the rest of the crawl.

Even so, firestops should be in place that would block visibility.

[John Kogel]

Edward, we need more info. If this is truly a chimney that serves a wood burning appliance, then the metal flue liner does need to be accessible or made to be accessible, and the Tee needs to be cleaned.

If there is a metal gas vent, there is less of a worry but I would find a way to remove some siding and cut away some sheathing for a look inside.

Sometimes the chimney is just an empty box with a direct vent for a gas fireplace going through the side.

Which one of those do you have?

[edwardh1]

prefab fireplace with metal multi wall flue pipe, , all outside the house wall, has own foundation, so no access from house crawl space, has a prefab flue pipe inside the chase.

whats a Tee?

[Jim Katen]

prefab fireplace with metal multi wall flue pipe, , all outside the house wall, has own foundation, so no access from house crawl space, has a prefab flue pipe inside the chase.

whats a Tee?

In my area, those things never have any access to the inside of the chase. Seems like it would be a good idea, but it's never done.

[Marc]

prefab fireplace with metal multi wall flue pipe, , all outside the house wall, has own foundation, so no access from house crawl space, has a prefab flue pipe inside the chase.

whats a Tee?

T posts and Double T posts

Figures 13 thru 16

Marc

[Jim Baird]

prefab fireplace with metal multi wall flue pipe, all outside the house wall, has own foundation, so no access from house crawl space, has a prefab flue pipe inside the chase.

That separate little crawlspace under the chimney column, especially in your area, is a termite highway. I have seen sloppy builders put blocks under their cantilevered faux chimneys as an afterthought, but all crawl areas should be accessible, especially for annual termite inspections.

[Erby]

Pop the top. Look down.

[kurt]

The average chimney chase will not leak if....

1) The cap drains and has a well profiled drip edge.

2) All other siding & flashing details are correct; very basic stuff one can determine by looking. One can observe a lot by looking.....YB.

Access to verify fireblocking would be nice, but in my entire career, I don't recall ever seeing it; in my market, it's safe to assume fireblocking is not there. Because there's never any access to verify, it's not anything I can intelligently report on, so I don't.

I like the idea of access though.

[Erby]

To clarify, I wasn't advocating that home inspectors should pop the top but if a home owner wants to look, that's the easiest way to look.

Same around here, Kurt. Though I quite often find the outside corner posts lapped the wrong direction letting water run down inside the vinyl.

[edwardh1]

what is the term , in referring to the metal top cap on a chimney "cap", that describes the practice of putting a slight raised crimp(s) or bent up crease into the top metal to make it slightly higher such that it will drain (rather than it being flat??

Thanks

[Erby]

convex?

[kurt]

Good question. I talk about this almost daily, but don't know a specific term.

Sheet metal is bent on a machine called a "brake" or "bending brake", so we (the folks I work with) call it "breaking" the metal, as in...."break the cap to drain".

I don't know what they call it elsewhere.

[Marc]

'Standing seam' seems to fit. My water well pump house has a sheet metal cover formed that way and it's done the same way as standing seam roof panels.

Marc

[kurt]

Standing seam is standing seam; it's not bent/broken sheet metal. You can do it standing seam style, but that's different from what the question is.

I've often described it as "hip roof" style in the old days. Now, we just send dimensions to the sheet metal fabricator and they crank it out and deliver it same day.

I'll ask them what they call it.

[John Kogel]

Those creases in the metal are ridges. So maybe tell them to bend ridges in the cap.?

[Jim Katen]

what is the term , in referring to the metal top cap on a chimney "cap", that describes the practice of putting a slight raised crimp(s) or bent up crease into the top metal to make it slightly higher such that it will drain (rather than it being flat??

Thanks

It's called a cross break or a cross crease. It's not really done to cause the cap to drain as much as it is to stiffen the metal.

[kurt]

It's done to drain.

Cross crease is a hockey play.

Cross breaks are stiffening methods for broad expanses of sheet metal so these same expanses don't oilcan; it adds strength.

One could apply the term to a chimney cap, sort of, but it would be wrong. Cross breaks are usually around 170-175deg and barely discernible. Their main use is stiffening thin gauge sheet metal. Use that grade sheet metal on a chimney and she rusts out in a year. Use a 170deg crease horizontally and it'll still oil can downward.

Chimney caps are bent/broken to drain with a fairly sharp angle (approximately 130deg). We use 24 gauge, or 20 oz copper. (I think it's 20 oz. anyway.)

[Leighton Jantz]

Just called a buddy who has a tin bashing business, they do call it a cross break. It is meant to drain rain with the added benefit of stiffening the metal. The degree of angle doesn't change the name.

[kurt]

My guy said its not technically a cross break, but they call it that because they don't have a better name.

So, I guess we call it a cross break. With a hole for the flue. And a hemmed and drip edged perimeter.