Chimney Question

[powslut]

Just went through the process of rebuilding an old brick exhaust chimney on my house. Originally the chimney serviced a coal furnace and is now used as an exhaust for my NG furnace and hot water tank. The original chimney had no capstone which caused rain water to leak into my furnace, and also corrode out some of my ducting. Looking around it appears that very few chimneys from that era had capstones on them and I am wondering what the reason behind that would be. Anyone have insight?

[OSECS]

Like Tevia said, Tradi-shun.... Tradition !! Putting capstones or chimney pots or hoods on a chimney was a practice that was usually associated with more wealthy people.

Chimneys (and esp. decorated chimneys) used to be a sign of wealth, the more chimneys the richer you were. It's kind of a carry over from that. I'm guessing a little bit, but I'd be willing to put a fiver on it. Also may be associated with a regional thing. Contractors tend to be creatures of habit, replicating what they did in the past.

The 1900-1930 neighborhood in our town has thousands of chimneys/flues with nothing but clay liners protruding above the surrounding masonry.

[powslut]

That's exactly the era mine was built and all it had was a clay liner protruding. Unfortunately years of weathering and a poorly built cedar box around the chimney with no flashing caused the bricks and mortar to completely rot out.

[mock vomit]

Term "chimney cap" can be confusing... do you mean a cover ON/OVER the actual flue pipe itself to keep rascals/rain out of flue (likely to be metal today but could be stone) -OR- the built-up mortar, stone or poured cement cap covering the remainder of chimney NEXT TO/AROUND the flue???

[powslut]

Term "chimney cap" can be confusing... do you mean a cover ON/OVER the actual flue pipe itself to keep rascals/rain out of flue (likely to be metal today but could be stone) -OR- the built-up mortar, stone or poured cement cap covering the remainder of chimney NEXT TO/AROUND the flue???

Chimney cap, not crown.

[L7]

Don't know why they didn't but the rain is one factor. Preventing downdraft can be helpful with a cap too. Just breaks up a wind enough to keep a low pressure at the top.

Your new furnace may be induction so less of a factor but the rain and rotting not to mention critters is still. I have to get a tin cap for a chimney here too. Should be easy to put on. I'll have to repair the chimney here first as well since it's 100 years old.

[OSECS]

Term "chimney cap" can be confusing... do you mean a cover ON/OVER the actual flue pipe itself to keep rascals/rain out of flue (likely to be metal today but could be stone) -OR- the built-up mortar, stone or poured cement cap covering the remainder of chimney NEXT TO/AROUND the flue???

Well as the OP was concerned about water getting in the actual flue, I assumed he was talking about a cover. Just trying to get that accuracy average up Tim.

[FattyCBR]

If you don't have a cap/hood when the rain comes down the chimney and mixes with the exhaust residue it forms acid that causes your liner or brick to deteriorate exponentially faster. If you don't have a hood you should put one on the extend the life of your liner.

[mock vomit]

Well as the OP was concerned about water getting in the actual flue, I assumed he was talking about a cover. Just trying to get that accuracy average up Tim.

You were spot on. I wondered if actual water penetration was thru cracks in a built up mortar chimney "cap" as it's known in my area... that is a faster way to bust up a chimney with resultant freeze thaw issues. Though in Virginie ye might not have that so bad?

[OSECS]

You were spot on. I wondered if actual water penetration was thru cracks in a built up mortar chimney "cap" as it's known in my area... that is a faster way to bust up a chimney with resultant freeze thaw issues. Though in Virginie ye might not have that so bad?

We sometimes call that a "mortar wash" as a specific type of cap for the chimney, but will refer to flue caps for "hoods/caps" over the actual flue opening.

The freeze thaw cycle is much slower around here (since the global warmings). What we do have to worry about is excess rain saturating the mortar wash/cap and then seeping into the house through the chimney masonry.

With the advent of cored brick, masonry isn't as solid as it used to be so it doesn't take much to get the brick saturated and water to become evident in the house. The last El Nino we had in 1998 was horrible for chimneys around here. Lots of remedial stuff to help keep moisture out. New copper, galv and stone hoods/caps and paraffin coating of the chimney shaft (condalox) sp.??)

Masons also don't like to "step flash" into the masonry like they did back in the day. They'll call it a "bond break" if you want them to actually flash into the body of the mortar joints instead of just running flashing up the face of the brick and sealing it with roofing cement/tar.

[arewolfe]

Damnit I thought this thread was going to involve Scot Schmidt or something, then I remembered I was in the padded room.