Posts made in April 2011

Five Reasons for Chimney Leaks and What to Do About Them

Causes of leaking chimneys can usually be narrowed down to five reasons. If your problem isn’t solved from addressing the items on this list, your leak probably isn’t from the chimney!

common masonry chimney leak fixes

#1 The Simplest Cause of Chimney Leaking: Rain Going Straight In from the Top

Capless Chimney

Capless Chimney (source: hersheychimneycleaning.com)

It’s not hard to picture that. Chimneys without covers get a lot of rain falling straight down into them. A chimney cover makes sense to most people. Not only does it keep the rain out, but keeps birds, animals and debris out. The greatest value of the chimney cover is really keeping these out because when chimneys get blocked at the bottom, people get sick (or even die) from CO poisoning. While it’s true that sometimes an uncovered flue is the source of water problems, most often this reason for a leak is only when the liner is metal.

How to fix it

Get a chimney cover and have a professional make sure it’s not this simple.

#2 Many Chimney Leaks are from Cracks in the Chimney Crown

cracked chimney crown

Cracked Chimney Crown

The chimney crown is the cement part on top of the chimney. The bricks go up around the tile flue liners, but at the top you need something to stop the rain and snow from just falling in around the tiles. You can see that the very purpose of the chimney crown is to keep rain out. Cracks in the chimney crown can occur from shifting of the structure or from shrinkage dating back to the first day the crown was put on. When your crown has cracks, the water goes right through those cracks.

How to fix it

How to fix a cracked crown depends upon how bad the damage is. Most crowns have small cracks. Even small ones need to be fixed because all big cracks started out as small ones. Water freezes and thaws in the cracks all winter long, year after year, forcing small cracks to eventually become big cracks. There are excellent crown coating materials such as Chimney Saver Crown Coat which cover the masonry and prevent small cracks from becoming a real problem.

Once chimney crown damage is significant, though, the only fix it is to remove and relay the masonry. You can’t put a band aid on a gushing wound and you can’t coat a structurally ruined chimney crown and expect it to work. Best to coat your crown now with Crown Coat and avoid the big hassle and expense later.


chimney inspectionLeaky Chimney? We can fix that! If you believe that your chimney is causing damage to your home please give us a call or schedule an appointment online. We’ll be happy to help you.


#3 Chimneys Leaking From the Inside Out from Condensation

damage from chimney condensation

Damage from Chimney Condensation

I remember a lady whose wallpaper peeled where the chimney ran through the house. She knew it was the chimney because this is the only place with wallpaper peeling. She had tried everything- a chimney cover, flashing, even rebuilt the entire top of the chimney. By the time I met her she’d spent thousands of dollars but nothing fixed it.

This was an older house with an unlined brick chimney. In 1900 when it was built that chimney carried wood or coal smoke I’m sure. Someplace along the way a gas furnace was installed, but the chimney was not lined with a properly sized liner.

How to fix it

Gas fumes are very low temperature and have a lot of moisture in them. These fumes were condensing on the inside of this too-large, too-cold old chimney, literally soaking the bricks and keeping them moist all the time. All it took was a chimney liner and we solved the problem.

#4 Chimney Flashing Causes Leaks

bad chimney flashing

Chimney Flashing Leaks

TThe flashing is what keeps water from going into the place where the brick structure comes through the roof (or otherwise comes close to the roof.) There’s a fairly large gap between the bricks and the roof and water will pour through that hole if it’s not sealed up. Flashing is often aluminum that goes in between a couple bricks and bends to go on top of the shingles. Some sort of water proof “stuff” seals those spots. Though it’s far from the best choice, the “stuff” is often tar. In any event, flashing doesn’t last forever and the tar lasts even less time.

How to fix it

There are better materials for sealing the flashing now. If you get a chimney sweep to fix your flashing, tell him you want Flash Seal by Saver Systems. (As you can see, I like Saver Systems products; but they just work well, so you can’t go wrong!) It seals better and lasts longer.

#5 Chimney Leaks Caused by Leaking Bricks

leaky bricks

Leaky Bricks; Source: doityourself.com

Bricks and mortar both pass water, and often lots of it. The problem here is the same as with the crown- the freezing and thawing all winter long with the resulting damage which causes leaks in the house.

You have probably heard of waterproofing a chimney, but you have to be careful about what waterproofing material to use. When water is absorbed into a brick or a mortar joint in the summer time, the water probably dries out after a while. The exceptions might be for a surface in the shade or on the side of the house where the sun never shines; those walls just stay wet. That water does try to escape by “falling” i.e. the water weight (or head pressure) carries it toward the ground where it forces its way out of the bricks either inside or outside of the house.

If you apply a waterproofing material that physically blocks the pores of the brick or mortar, the water is trapped inside the brick. Some bricks actually get soggy, though it’s more likely that the water will just seep to the inside of the house. To the point, using silicone based water sealants may trap water and cause more damage than you started with. Use polysiloxane type waterproofing agents, such as Chimney Saver by Saver Systems.

How to fix it

To find out if your chimney leaks through the masonry surface, have your sweep do a Masonry Absorption Test (MAT) This is a simple test where a special test tube is attached to the side of the chimney and you record the time it takes for water to be absorbed into the wall. This tells you if you should waterproof the chimney.

Bonus: #6 Chimney Leaks That Aren’t Chimney Leaks

non chimney leak

source: www.orionrestoration.com

Sometimes, a leak starts in a different place but finds its way to the chimney, and then visibly enters the inside of a room at the point of the chimney.

For example, your roof might have a leak through the attic vent or roof shingle at the top.  Water could get into the attic or above your ceiling and either drip to the floor or roll along the stringer (the long piece of wood that spaces out the roof trusses and runs the length of your house). If the stringer is un-level, water can travel a ways – and even wind up at the chimney. It has happened, and usually isn’t discovered until people have spent a terrible sum fixing everything else.

Another event that could happen (although I have never heard of it actually happening) is that you could get so much moisture in your attic that it could condense and roll down the stringer onto your chimney.  This could happen if there were some reason your attic was getting a lot of humidity in it – for example, if your dryer vented into the attic instead of out of a vent perhaps, or if your gas furnace were vented by B Vent but just dumped into the attic (which would be a severe carbon monoxide risk, incidentally).

–Need help with your chimney leak repair in Maryland, DC, or North Virginia? Call High’s!

Chimney Airflow Problems

Understanding chimney draft problems is not necessary for most people. Usually, if you notice smoke not rising from your chimney, you can call on a professional to fix the issues.

chimney draft problems

Draft problems can cause you problems!

This information is for those who really like to understand; it may be too much information for many people. I’ll do my best to keep it as interesting as it can be. If you’re a do-it-yourselfer or the owner of an old home, you’ll probably get a lot of out of it.

Understanding Chimney Draft Issues

To understand the problems, you need to understand what draft is. Draft is what we name the effect of how the air flows up the chimney. It’s measured in “inches of water column.” Draft then is the combination of volume, speed, and pressure of the flue gasses. And temperature of the gasses comes into play here as well.
For matters of this discussion, chimney draft is usually thought of as the speed at which the vented gasses travel up the stack, or pressure of the gasses. This can also be referred to as the stack effect. A common question might be “how strong is the stack effect?” Good draft conditions mean that the vented gasses are traveling up the chimney quickly rather than slowly or not at all.

How Does Chimney Draft Work?

The reason smoke (or other flue gas) goes up the chimney at all is because of the vacuum in the chimney. The question you should ask now is “a vacuum relative to what?” The general answer is that it’s relative to the air in the house. Don’t read too much into that because it gets tricky (for example, how does replacement air get into the house?- because the house environment is a relative vacuum to the outside. Yet the inside of the house is not a vacuum compared to the chimney.) Let’s keep this simple and just talk about the chimney. The pressure in the chimney is typically less than that inside the house. Thus, the draft effect is caused by air inside the chimney being pushed up the chimney by the house air.

And why is there a difference in pressure in and out of the house, or in and out of the chimney? There can be a few reasons, but the biggest and most important reason is the temperature difference from one place to another. Remember that when air is heated it expands? The same amount of air occupies a larger space, or you could say the same amount of space has less air (fewer molecules of air.)

The air outside the house in the winter is colder and heavier than the warmer air in the house. It pushes its way into the house (or is it pulled, depending on how confused you want to be.) The air in the chimney just came from a fire so it’s really hot and expanded and being pushed up the chimney to the cooler air outside where warm air rises, right? That’s buoyancy. Problems occur when these processes don’t happen correctly.

Diagnosing Chimney Draft Problems

Draft is measured with a pressure meter that has a probe which goes into the smokepipe. The meter should register a negative number, and generally speaking for residential heating appliances that number would range between -0.02 to -0.04. Zero or a positive number means the gasses are not going up the chimney. And too large a negative number can have its own set of consequences; but that isn’t usually the problem. Mostly “a draft problem” means the gases are not going up the flue, this is merely a minor chimney repair.

Causes of Draft Problems

Chimney Airflow Issues

Chimney Airflow Issues

Now there are other reasons for draft problems. One is called Dynamic Wind Loading. or “DWL.” DWL is caused when the wind blows on one side of the house and causes a positive pressure, and creates a corresponding negative pressure on the other side of the house.

If the windward side of the house is tight and the lee side (negative pressure side) isn’t, the vacuum resulting from the wind can suck air out of the house. And the most likely source of that air is the chimney; it’ll pull down on the chimney, smoke and all and keep it from exiting your house! Or if a gas furnace is being vented you won’t see smoke but you still get the carbon monoxide.

The way to deal with that is to tighten up the lee side of the house and then put in an outside-air source. There are kits for that or you can just crack a window on the windward side of the house.

Chimney Draft Issues Caused by Fans

Big Kitchen Vent Hood

If your ears pop when you turn on your kitchen fan, you’ll probably have chimney draft issues.

The other large reason for bad draft is when chimneys have to overcome fans in the house. Kitchen fans, bathroom fans, radon fans. It doesn’t take much of a fan to overcome a natural draft appliance (such as a fireplace or woodstove) Again, the best answer is to allow “make up air” into the house.

The problem with that of course is that you don’t want a draft across the floor and you hate to purposefully introduce freezing cold air into the very house you’re trying to heat. It’s a Catch 22, but I can tell you CO poisoning is a bad thing, and smoke in the house is a bad thing. You just may have to make some choices.

Air Flowing Down Your Chimney

Finally, sometimes air actually blows down the chimney, but less frequently than you’d guess- it’s usually something else. But maybe your chimney is short and next to a larger part of the house or a bigger building. The same problem occurs if your house is located at the base of a mountain. If you have this problem, a Vacustack is a good solution if you can’t raise the chimney to the proper height.

What is a Freestanding Woodstove?

What is a Freestanding Woodstove?

A pretty basic definition of woodstoves is that they are metal boxes made in such a way that you can have a wood fire inside so that the metal gets hot and heats the room.

Freestanding Wood Stove

As basic as that definition is, there’s actually a great deal of engineering, new technology and testing involved in making today’s woodstoves. They are very efficient heaters (in the 90% efficiency range, like gas or oil furnaces.) Because they use renewable fuel (wood) which is found everywhere, this “old technology heater” is an excellent choice for home heating in the 21st Century.

A “free-standing” woodstove means that the stove is not installed into a fireplace. (That type of woodstove is called a fireplace insert. Some freestanding stoves are on legs, others on pedestals, but all sit at least a few inches above the floor.

Venting Free Standing Wood Stoves

The wood smoke either comes out of the top or rear of the stove and you use stovepipe to carry the smoke through the room from the stove to the chimney. If it comes out of the back there is often a tee section to get the smoke moving UP. For top-vented stoves the stovepipe goes right into the top of the stove.

Wood is usually loaded through the front door of the stove. The doors often have high-temperature glass so you can also look at the fire as it heats the room.

When installing a freestanding stove, you will generally have three ways to vent the smoke from the house:

  1. The first is “through the wall.” A through-the-wall installation is where you route the stovepipe coming from the stove to the wall, where there may be an existing chimney. Many houses have a masonry (brick or block) chimney in place that you can “tap into” to vent a woodstove. So said, all chimneys aren’t masonry, but many are factory-built sections. If you have no chimney in place, don’t worry about it – you just have a factory built chimney installed. The stovepipe joins the chimney at the wall.
  2. The second method is for when you have a chimney directly above the stove. This is not a naturally occurring event unless by huge coincidence. In most cases This method is for people who decide “I want the stove right here” and the stove probably (though not necessarily) is vented out of the top. In this case you have a factory built chimney installed directly over the stove. This is very common and a good way to do the job.
  3. The final method is what’s called a hearth stove installation. Recall that fireplace inserts are installed into fireplaces, not freestanding stoves. However, you can vent a freestanding stove through a fireplace. This usually means that a rear-vented stove sits in front of the fireplace (on the hearth.) The smoke pipe comes off the back of the stove and the turns up through the throat of the fireplace to vent the smoke through the fireplace chimney. This is a perfectly good way to install a stove. Take note, the hearth stove installation requires a properly sized liner to be put into the chimney. Fireplace chimneys will most assuredly be too large for a woodstove.

A note on properly sized chimney liners: In the 1970s many a woodstove was vented into a fireplace with a flue many times too big for the stove. The result was an extraordinary amount of creosote and tar build-up- of a type that chimney brushes can’t remove and many a house burned down in those days. A word to the wise: follow the rules.

What’s the best kind to buy?

There are good stoves and not as good stoves available to you. There is the low end stuff you can get at a great big mass merchandiser of course. These probably do meet minimum EPA standards, but those minimums are getting higher all the time…but they do work.

Cast Iron

Cast Iron Woodstove

Modern cast iron woodstoves can be very efficient and castings do look good, normally appealing to the eye. Cast iron has a reputation for radiating heat most evenly. So said, cast iron can be problematic in that large-surface castings sometime crack. They are also generally more expensive than the options.

Steel

Steel stoves are very efficient as well, and are generally the most economical option. Steel heats up and starts putting out heat the quickest. The styling on a steel stove nowadays can be very good, depending on the manufacturer’s designer. They may have brass doors for example, or other features to make them visually attractive. Steel has a good track record for longevity; you don’t hear of cracked steel panels very often.

Steel and Cast Iron

Another good option is the combination of steel and cast iron. This probably means that the stove is steel, but the door is cast iron (usually with glass.) It’s a very attractive appearance.

What’s the Difference Between a Chimney Cap and a Damper?

So, you’re wondering about the difference between chimney caps and chimney dampers? There’s a big difference, but as per usual the confusion is in the use of the terms.

Chimney Dampers

A damper is a device which slows down the flow of smoke. In the case of fireplaces, it also slows down the heated house air from going up the chimney. This is the main purpose of a fireplace damper.

Chimney Cap

chimney cap

Stainless Steel Chimney Cap

A rain cap, a chimney cover or an animal guard is something that mounts over the top of the flue. It helps to keep rain and animals out. While you can get a cover made out of ordinary steel, don’t. You absolutely want a stainless steel chimney cover because the other ones rust. A cap also usually has some sort of screen to prevent birds and animals out as it keeps the rain out.

A chimney cap does not stop the flow of air/smoke in the flue. There is nothing to operate; they just sit on top of the chimney and keep rain out. Caps are usually called chimney caps and that pretty well sums it up for them.

Top-Sealing Dampers

So let’s talk about Top-Sealing dampers. These dampers do in fact mount to the top of the chimney; in this way they are the same as caps, and this of course is where the confusion comes from.

The top-sealing damper is a device with a base for mounting on the flue tile and it has a lid which lifts up and down to block smoke, which also helps to keep rain out. The lid is held up by strong springs and it’s natural position is open. The lid has a stainless steel cable attached to it which runs through the chimney and mounts to the side wall of the fireplace below.

Within the fireplace, the damper cable has a handle and the mounting bracket is made in such a way as to hold varying degrees of openness. This openness ranges from fully open to completely closed. To operate the damper just grab the handle and pull it into the position you want it to be in.

Is there any further confusion about chimney caps or chimney dampers? Share your responses below.