A little short..

[msteger]

Ran across this chimney yesterday. The top of the flues (3) were only 2"~4" above the adjacent ridge vent. I discussed the 10-2-3 rule with the client. A little short, huh?

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[chicago]

Looks to also be near a ridge vent.

[Chad Fabry]

What do the flues vent?

[John Dirks Jr]

Also, the flues should not be so close to each other. There should be a row of brick between them. (wythe)

I am very curious as to when the 10-2-3 rule came into effect. Anyone know what year? If the chimney was built prior to that rule then perhaps it could be approached as a suggested upgrade rather than a defect. My point being that newer codes are not usually enforced upon retroactively.

I see many chimneys in my area on older homes that do not meet the 10-2-3 rule. I am trying to find an option to calling them all defective.

[John Dirks Jr]

Originally posted by chicago

Looks to also be near a ridge vent.

Or is it the ridge vent that is too close to the chimney?

[hausdok]

Dollars to donuts that stack used to be much higher.

Here's what happened: The crown cracked, water permeated the stack and ruined the mortar in the top few feet and made the parapet unstabile. Some enterprising individual said, "Hey, I don't have to rebuild that thing, I can just take it down to good mortar and stick a new crown on it."

Write it up as wrong. Don't try to justify it or to figure out whether it should be "grandfathered" - just write it up.

ONE TEAM - ONE FIGHT!!!

Mike

[chicago]

I was wondering what's going on with the step flashing.

It looks peeled up at the bottom.

[SonOfSwamp]

Originally posted by chicago

I was wondering what's going on with the step flashing.

It looks peeled up at the bottom.

That happens when jackleg roofers put on a new layer of shingles, but just bend the original flashing out of the way, instead of replacing it (which would have been the right thing to do).

WJ

[chicago]

Thanks

[Les]

I am with Mike O. Write it and let someone else do the head work.

[msteger]

To answer a few of the above questions -

The home had 2 wood burning fireplaces (living room and basement) and an oil fired boiler (for a total of 3 flues). The middle flue was also cracked vertically on the side facing the camera (look closely at the photo). I explained the lack of proper chimney height to the buyer and recommended full evaluation and level 2 clean/service by a qualified chimney professional. I also noted the flashing that needed to be repaired.

The chimney is original. The sellers were original owners and claim to not have changed anything regarding the chimney. The home was built around 1948.

As noted in the original post, there is indeed a ridge vent adjacent to the chimney, and only maybe 2' from the top of the closest flue.

As I explained to the buyer, the 10-3-2 rule essentually says that the chimney must pass through the roof at least 3' (on the high roof side) and must be at least 2' higher than anything 10' away from the flues. Did I explain this correctly?

I explained to the client that the 10-3-2 rule may not have existed in 1948 (and may not have until recently in many areas since I am in PA), yet should be addressed for safety reasons. Some of these safety reasons pertained to fireplace/boiler exhaust being able to re-enter the home through the adjacent ridge vent, as well as potential drafting issues.

[hausdok]

Hi,

I doubt that anything from that chimney is going to enter the home through the ridge vent unless the attic ventilation is completely screwed up and simply isn't functioning at all. When it's working, air flows out of a ridge vent - not in. The whole point of a ridge vent is to take advantage of the low pressure area that develops at the crest of the roof as air passing over the ridge must accelerate - think Bernoulli's principle.

ONE TEAM - ONE FIGHT!!!

Mike

[Jim Morrison]

Originally posted by AHI

Also, the flues should not be so close to each other. There should be a row of brick between them. (wythe)

I am very curious as to when the 10-2-3 rule came into effect. Anyone know what year? If the chimney was built prior to that rule then perhaps it could be approached as a suggested upgrade rather than a defect. My point being that newer codes are not usually enforced upon retroactively.

I see many chimneys in my area on older homes that do not meet the 10-2-3 rule. I am trying to find an option to calling them all defective.

Where I come from, a wythe is only required if one of the flues is venting more than one appliance.

[chicago]

Interesting as I never considered the air flow as a one way ride to the top.

Does this apply even if the soffit vents (assuming) are in short supply or over abundant.?

Is there never anything equivalent to back drafting.?

[hausdok]

Sure,

They can backdraft. Read my post again, I said that, "unless the attic ventilation is completely screwed up and simply isn't functioning at all," but that's part of the inspection too. Right? If the attic isn't venting properly, there should be plenty of evidence of that to report.

The chimney height requirement concerns ensuring that there is sufficient height so that the chimney will draw properly and that the chimney won't back draft. Air passing over that ridge will tumble. It's well established - pilots have known for decades not to fly too close to the crest of a cliff face and must take precautions when topping the ridge of a mountain because of it. If the stack isn't high enough, that tumbling air will flow down the flue and cause the fireplace to backdraft.

Making the proximity of a ridge vent a concern is a bad call and just creates inspectlore. Call it because the stack is too short but don't call it because you're afraid that the ridge vent will decide on its own to defy the laws of physics and turn into a vacuum cleaner somehow magically pulling the smoke into the house through a vent where convection currents are already flowing out of the house. That's all I'm saying.

ONE TEAM - ONE FIGHT!!!

Mike

[chicago]

Ok.. so the ridge vent is not part of the equation.

Now you have me thinking about cat four vents near windows which is another subject,but thanks for the insight.

[msteger]

Originally posted by hausdok

Hi,

I doubt that anything from that chimney is going to enter the home through the ridge vent unless the attic ventilation is completely screwed up and simply isn't functioning at all. When it's working, air flows out of a ridge vent - not in. The whole point of a ridge vent is to take advantage of the low pressure area that develops at the crest of the roof as air passing over the ridge must accelerate - think Bernoulli's principle.

ONE TEAM - ONE FIGHT!!!

Mike

Mike,

The home had no soffit vents (only gable vents and the ridge vent that terminated about a foot or so from the top of the chimney), so in certain circumstances, who knows if smoke or exhaust fumes could find their way into the home. I did also report on the potential issue with chimney drafting.

[John Dirks Jr]

I thought the point of having ridge vent was heat rises. With the vent at the upper most part of the structure, all the of the heat can escape. The soffit in turn allows cooler air in to replace the hotter that vents out the top.

Some may think this makes a loss of overall heat for the structure in the winter. Wrong. It actually helps. The colder attic air keeps the ceiling cooler which pushes down the warmer house air in a sort of barrier.

[Jesse]

Originally posted by AHI

Some may think this makes a loss of overall heat for the structure in the winter. Wrong. It actually helps. The colder attic air keeps the ceiling cooler which pushes down the warmer house air in a sort of barrier.

No. The cold air does not create a barrier. If the attic was 100 degrees in the winter, instead of 30, less energy would be required to heat the living space below.

If I should keep my ceiling cold, why should I insulate the attic?

[hausdok]

Originally posted by AHI

The colder attic air keeps the ceiling cooler which pushes down the warmer house air in a sort of barrier.

OK, I'm sorry, but that's just plain silly and downright wrong. Please don't ever, ever, ever tell a client that - I beg of you - 'cuz any client who's ever taken a physical science class is going to think to themselves, "What the hell is this guy talking about?"

You agree that heated air rises, correct? Do you understand why? Think in simple terms of a bubble of air under water. That bubble, being under pressure, is being displaced upward toward the atmosphere where there is less pressure. Pressure moves from higher pressure to lower pressure.

Now, cold air is denser than warm air and it falls to the floor. Because it's denser than warmer air, it's like the water surrounding that air bubble and forces the thinner-warmer air upward - remember higher pressure to lower pressure.

If you have an uninsulated ceiling, you end up with heat loss through convection as well as conduction into the attic, and the heated interior air cools more rapidly, causing you to spend more money re-heating that interior air.

If the ceiling is insulated, so that less heat is given up through conduction and convection into the attic, that convective loop that I described above is slowed down and you spend less on fuel. It has nothing to do with a cold ceiling and a colder ceiling will only accelerate that convective loop and consequently heat loss.

Without any soffit or eave vents, the normal convection that a ridge vent will facilitate is greatly hampered; however, it won't be completely eliminated. Remember, he's got gable end vents in addition to the ridge vent. Colder exterior air will still enter the attic, settle to the floor of the attic, be warmed by the heat being given up from the home below, and then rise to the ridge and move out of the vent - the problem is that it might not be enough to keep the underside of the roof dry and it might only occur near the ends of the attic, leaving the air at the center of the attic essentially stalled.

Still, back to the original question. I just don't see it backdrafting into the house through the attic. Yeah, the chimney will probably not draw well, but I doubt that there's any soot staining in the attic to show that the chimney's been backdrafting into the attic.

ONE TEAM - ONE FIGHT!!!

Mike

[Chad Fabry]

I thought the point of having ridge vent was heat rises

Heat moves to cold. Stand under a radiant heater to prove that.

What Mike said about warm air and convection.

[chicago]

Now correlate that to an AC unit.

[John Dirks Jr]

Mike,

Thanks for setting me straight on my incorrect statement. I don't know where I came up with it. I would much rather corrected then be allowed to bask in ignorance. I appreciate your time.

[hausdok]

Hi,

No problem. Sorry if I came off as harsh, but the business is awash in inspectorlore; we've got to speak up quickly and forcefully when such theories are posted on the net, lest they be read and overnight end up getting taught to folks in these home inspection "schools."

OT - OF!!!

M.

[John Dirks Jr]

What if you have a masonry chimney that only serves gas appliances and will never be used for anything else, do you hold that chimney to the 10-3-2 rule strictly?

The reason I ask is some areas allow B vents serving gas or oil appliances to terminate at 2 feet above the roofline. So if a vent connector from a gas appliance connects to a masonry chimney, what's the difference from having B vent all the way out?