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Chimney crown

The chimney crown is the concrete (sometimes stone) layer that covers the top of a masonry chimney.  It’s one of those classic “out of sight, out of mind” components of your house, since it’s way up high and usually hard to see even if you’re trying to.  But it’s exposed to the elements continuously, so if your chimney is old then there’s a good chance that the crown is deteriorated.  And that means there’s a good chance there’s a problem with the masonry chimney also.

The job of the crown is to keep water out of and away from the chimney, and water is your home’s number one enemy.  Deterioration of the crown and the chimney is certainly a slow process, but if your chimney is old then it’s had a long time to deteriorate.  And even if the chimney’s newer, neglecting a problem because it won’t create havoc until years from now is a rough way to treat your house.  It also signals to a potential buyer that you’re not on top of things. 

Repairing chimneys can be very expensive, largely because to do work up high requires a lot of set-up time and equipment.  So keeping the crown in good condition (and installing it right in the first place) will contribute to the long-term health of your house and reduced maintenance costs down the road.

A good chimney crown should be nice and thick to help prevent it from cracking.  Anything built of concrete can crack of course, but the thicker something is the lower the stresses are likely to be and so the lower the chance of cracks.  And if a crack does develop it’s less likely to go all the way through a thick material, and it’s easier to seal the crack. 

This chimney crown is great. It’s well designed and in good condition, with
rain caps on top of both flues.
This chimney cap is well designed, but it’s cracked. And the masonry below the crack is starting to show signs of damage. This crack should be sealed.

The crown should be pitched towards the edge to help shed water.

The crown should overhang the masonry of the chimney to help shed water away from the masonry.  If the edge of the crown lines up with the bricks then as water drains off it will just run down the chimney.  Much of that water will actually soak into the bricks, and that will cause deterioration. 

This crown is thick (but there’s still a small crack and no rain cap), but it doesn’t overhang the bricks. Water runs off the crown and directly onto the bricks. The mortar joints around the top are pretty badly deteriorated because of this.

There also should be a rain cap on top of every flue.  Allowing water to run down the flue every time it rains will lead to much quicker deterioration.  There’s no reason to have that happen.  A rain cap can also reduce downdrafts that can lead to dangerous backdrafting, and it can help keep animals out of the flue.

This chimney doesn’t even have a crown. It’s had a lot of work done to it recently, and it’s going to need a lot more in just a few years. This is awful.
It can be easy to ignore a chimney crown like this. It’s certainly out of sight. But this is in terrible condition, and eventually the bill will come due.

Grease traps

Many of the older cities in the Chicagoland area have combined storm and sanitary sewers, meaning that the rain water drainage is collected through the same pipes as the sewage from houses.  This type of system is almost never used anymore when constructing a new system, but many of the older cities still operate this way.

In these older cities with combined sewers it’s very common for houses to have a grease trap built in.  Because the sewer system is combined, and because back when the system was built it couldn’t handle grease very well, grease traps were a way to prevent grease from entering the sewer system.  Here’s a brief description of a grease trap.




A grease trap is a pit buried underground where water from the kitchen drain runs to.  The exit pipe to the sewer is elevated a little bit from the bottom so that there’s always some water in the pit.  There’s a trap built over the sewer pipe, so that grease floating on the surface of the water is held back, but the water is able to run under the trap and out the sewer pipe to the sewer main.  Any solid debris will settle to the bottom.

This way the grease is held back out of the sewer system.  Note that only water from the kitchen flows into the grease trap.  There’s no water from any other sink and certainly no water from any toilet coming into the grease trap.  But there might be water from your gutters flowing into the grease trap.  Where your gutter downspouts go underground they generally empty into the grease trap.

With this arrangement you’ll need to clean out the grease every so often.  This used to be a much bigger issue back when we used a lot more grease in our cooking.  Now you should just throw away your grease rather than putting down your kitchen sink drain.  So how often you need to clean out the grease trap depends on a lot of factors, but it’s likely to be many years (probably a decade or more) before anything will need to be cleaned out.  You can hire somebody to do this for you, or you can just lower a bucket on a rope to scoop out the grease and discard it.

In well over half of the grease traps I see now the trap has completely deteriorated, usually to the point where it’s completely gone.  This isn’t a problem anymore and I don’t recommend that you do anything about it.  There’s just no reason to.  And some grease traps have been bypassed, so that the drainage from the kitchen goes directly to the sewer and doesn’t go into the grease trap at all.

These days the biggest issue with a grease trap is the condition of the ring and the lid.  If the top concrete ring is damaged or the metal lid is broken then somebody could fall through.  But as long as the ring and lid are in good condition then you have very little to worry about with a grease trap.

Sump Pump and Ejector Pump

Many houses have a sump pump, and most newer houses (and some older houses) have an ejector pump.  This blog posts describes the purpose of each of these devices and explains some of the differences.

There’s a lot of water in the ground (of course – that’s why plants have their roots there!) and if any part of a house is below ground then that water wants to try to leak into the house.  And there are a couple of ways to deal with water.

You can try to block water out completely and not allow it to get anywhere it’s not supposed to be.  That’s actually not very easy – water will find a way, especially through an underground foundation that you don’t have access to for maintenance.  Or, you can give water a place to go where it can be controlled and won’t do any harm.  This is the point of a sump pump.

A sump is a pit dug at the lowest point of the house that gives water a place to go and collect before it can come through the foundation wall or through the floor slab.  Usually – but not always – there is also some buried drain pipe (usually called drain tile) running around the perimeter of the house and discharging into the sump.  This drain pipe is perforated so that water in the ground will leak into the pipe and wind up in the sump.

Ground water trying to attack the foundation finds its way into the sump.

At the bottom of the sump is a pump.  When the sump fills with water an automatic valve turns on the pump and pumps that water away, usually discharging outside of the house but sometimes discharging directly into a sewer line inside the house.

So ground water that’s trying to attack your house and ruin your basement instead runs into the sump and is pumped safely away.

An ejector has a completely different purpose.  An ejector deals with drain water from the house’s plumbing system, helping to get it out of the house. In Chicago and most of the older suburbs we have combined storm and sanitary sewers.  These cities use the same large sewer pipes to handle rain water and to handle the drain from your house (from sinks, tubs, showers, and toilets).  Here’s what it looks like, with a typical basement and the sewer line out in the street.  The house’s main plumbing drain pipe leaves through the basement floor, and all the drain water from sinks, toilets, and tubs drain by gravity out to the sewer in the street.

A typical older house with the main plumbing drain pipe going out to the sewer through the basement floor.

It used to be that when it rained very hard in Chicago and some of these older suburbs the sewers became overwhelmed with rain water and actually backed up into the basement through a floor drain.  As you can imagine, this was a huge nuisance and it could do a lot of damage.

During a heavy rain the sewer can get overwhelmed and floor the basement.


So the solution was to start using overhead sewers with an ejector pump.  Now instead of the main plumbing drain pipe going out through the basement floor it goes out through the foundation wall elevated a couple of feet.  All the drain water from the fixtures above this exit point can still drain out by gravity, but all the drain water from the fixtures below has to be pumped up (this includes the floor drain which now empties into the ejector sump).  This drain water first drains into the ejector sump, and when that fills up the ejector pump comes on and pumps this sewage up over a high loop where it can then drain by gravity.  An ejector pump is more powerful than a sump pump, and it’s able to grind up the solid waste from the toilet.

A typical newer home with an ejector pump.

Now if the sewers become overwhelmed by rain water, it would have to back up not just to the floor level but to a point about 6-8 feet above the floor before it could spill into the house.  And if that happens then we’ve all got a lot worse problems to worry about than basement flooding.

Now even if the sewer becomes overwhelmed it’s much harder for that sewer water to back up into the house.

A sump pump just needs a simple cover to keep out debris and to reduce the chance of the water evaporating into the house.  But an ejector deals with sewage – including waste from the toilet.  So the cover to the ejector pit needs to be sealed tightly to prevent those odors from getting into the house, and the pit needs to be vented to the outside through the plumbing system’s existing vent pipes.  So there are two pipes coming from an ejector pit – there’s the drain pipe and there’s the vent pipe.

A sump pump should have a battery backup system so that it can continue to work in case of a power outage.  This is when you’re likely to need your sump pump the most, during a big rain storm that might cause a power outage.  But it’s rare for an ejector pump to have any kind of battery backup system and it’s not really necessary.  But keep in mind that if you don’t have power then you don’t want to use any of the fixtures that drain into the ejector.  You’ll only want to use the fixtures at the first floor and above that still drain directly into the sewer by gravity.

Water, Water Everywhere

“Water, water, everywhere” goes the old saying.  And that might be a good thing for a sailor, but not so much for a homeowner.

I tell all my clients that water is their home’s number one enemy. If you keep your house dry, it’ll last for a long long time.  If it gets wet, it goes downhill fast.

Of course, I’ve never met anybody who’d be happy going outside to the well every time they wanted a drink of water or to take a shower.  So we bring water pipes into our houses.  And we don’t (at least none of my clients) live in the desert, so rain water (snow too!) will fall on and around our houses.  We can’t stop water, we just have to control it.

Too much water in the attic. Notice that only the roof sheathing is affected, and not the rafters. That’s because the sheathing is the coldest part of the attic, so that’s where the water vapor condenses.

It’s important to keep in mind that water comes in different forms.  We have to control liquid water of course, but we also have to control water vapor.  And that’s usually the hard part.

When I see mold in an attic I know that there’s too much water in the attic.  The problem might be a roof leak – liquid water getting in.  But the problem might also be water vapor coming up from a wet basement or crawl space.  I saw quite a few cases of moldy attics last year and in all but one case the culprit was pretty clearly a wet crawlspace.


When the basement or crawlspace is wet that moisture easily evaporates into the air.  And that moist air diffuses throughout the entire house.  Water vapor wants to move from areas of high concentration and warm temperature to areas of lower concentration and colder temperatures.  The coldest and driest part of most houses is the attic (at least in the winter) and so the water vapor is going to be driven into the attic by natural forces.

Water in the crawlspace eventually ends up in the attic. Count on it.

Many people seem surprised and even a little dubious when I tell them that a wet crawlspace is the source of their attic moisture and mold problems.  But consider that in a typical house in this area you can expect anywhere from about 0.3 up to 0.7 natural air changes per hour.  This means that the total of cold air leaking in and warm air leaking out of your house will equal somewhere between about 0.3 and 0.7 times the size of your house.  So in about 1.5 hours up to maybe 3 hours the air in your house completely changes over.  Air moves, pretty fast.  And the water vapor in the air diffuses even faster than that.

So in short order that water vapor finds its way up into the attic.  When it hits the cold surface of the roof sheathing the water vapor condenses, and you get just the right conditions for mold to grow.

There are three general ways to control water: source control, ventilation, and dehumidification.  Source control involves stopping water from getting into the attic in the first place, and so stopping it from getting into the crawlspace.  Or we can ventilate the attic to bring in dry outdoor air and remove the moist air.  Or we can install a dehumidifier in the attic to remove moisture and drain it away.

Ventilation is important in an attic, and most home inspectors make a deal out of a lack of attic ventilation.  But I’ve seen so many attics with bad or no ventilation that had no problems.  And really, why let water vapor get into the attic in the first place and then be forced to deal with it.  Why not keep it out in the first place?

By far the best option is source control.  It’s always best to avoid the problem completely if you can.  Source control is the easiest, most dependable, and most robust solution.  Keep water out of the attic – and that means keeping water out of the crawlspace.

The way to keep your crawlspace dry is for another post, but here are the highlights.  There should be a vapor barrier on the ground to keep water from coming up through the ground.  (The ground is very wet – that’s why trees have their roots there!)  The gutters and downspouts should be in good condition to move rain water away from the house.  And the ground around the house should be sloped away so that rain water flows away from the house.

Stay dry my friends.  Your house will appreciate it.


Water, water, every where,

And all the boards did shrink;

Water, water, every where,

Nor any drop to drink.

“The Rime of the Ancient Mariner”  by Samuel Taylor Coleridge