When Do I Need To Repair My Chimney? - DC Area Chimney Service
8045 Snouffer School Rd. Gaithersburg MD 20879

How Can You Tell If Your Chimney Or Fireplace Needs A Repair?

Let’s cover the obvious and more well known insights about chimney and fireplace repair.

Deteriorated or even missing mortar joints are most obvious of all.

chimney masonry damage in Olney MDAt the top of a chimney you can’t see the mortar well, so be sure anyone who works on your roof inspects this for you. A chimney sweep should look over the mortar as a matter of routine.

Bad mortar joints should be dealt with sooner instead of later. Once the joints start to fail the damage accelerates quickly. Water (from rain and snow) freezing and thawing in a small crack turns it into a larger crack and ultimately the mortar crumbles. If this problem is left long enough, your chimney may collapse.

The story in terms of fireplaces is similar, the difference being that there’s not a freeze-thaw cycle but rather high temperatures causing stress on the mortar. Even though high temperature mortar is used (or even refractory cement,) these materials don’t hold up forever.

There’s more danger below as well. There’s always the structural problem, i.e. the fireplace is supporting a stack of masonry weighing several tons. You want to keep things from shifting! There is also the obvious fire danger of having “holes in the system” either in the fireplace or in the chimney as it passes through the house.

Chimney liners have lots of problems but you can’t see them easily.

In the last 25 years many houses have converted to stainless steel chimney liners, and for many different reasons, some of which are not related to chimney damage. While the reasons for lining a chimney with a stainless liner would fill a very long article of its own, suffice to say that there can be a lot of problems with tiled-lined chimneys. The focus of this article is how to find out if you have those problems.

In a word, it takes a careful inspection by someone who knows what he’s looking at. In the early days of chimney sweeping (1975 we’ll say) we used very bright lights to look down a chimney. “We didn’t know what we didn’t know” because when the ChimScan™ came along and boy did we all get an eyeful. A ChimScan™ is a closed circuit camera put on chimney rods used to get a close in look at the inside of the chimney.

A ChimScan™ inspection will show cracks and other deficiencies that can’t be seen by a visual inspection looking down the flue with a bright light.

So said, a visual inspection is better than no inspection at all.

And what problems are commonly seen? First of course- you guessed it- deteriorated or missing mortar joints, and you probably can’t see them without a ChimScan™ inspection. Another is misaligned flue tiles. You’d be surprised how many chimneys are not built properly, some with tiles an inch or two offset from the one below. This problem can usually be seen by a visual inspection.

Cracked flue tiles are more common than most people realize. Again, the reason why broken tiles are a problem is the subject of a different article, but as for how to tell if you have the problem is by having a ChimScan™ inspection. It’s a serious condition, it may or may not be covered by homeowner’s insurance, and a chimney liner is the solution.

Finally there’s the issue of “shaling” tiles. This is when thin slices of the face of the chimney tile pop away. This is very visual. Just pull the connector pipe from the wall or look in the clean out door (wherever the bottom of the chimney can be found) and see if there are chips of the liner piling up. This is especially common in flues when converting from oil to gas heat. A stainless steel chimney liner is the solution to all of these liner problems.

Spalling Bricks

This is just the term used for the same problem (as shaling tiles) when it happens to the bricks on the outside of the house. The faces just pop off and lands in the yard or on the roof. It’s very visual – you’ll know if you have this problem just by looking at the chimney and the roof. When this happens there’s nothing to fix the problem except to replace the bad brick with a good one and waterproof the chimney so it doesn’t happen again. And check the crown, which is my next point.

Problems with the crown are easy to see if you go on the roof.

The crown of the chimney is the cement at the top that covers the bricks up to the flue tiles. This keeps rain and snow, not to mention birds etc., from getting into the brick chase around the chimney liners. The crown is the first line of defense against the weather and takes the most abuse because it’s horizontal and facing the sun all the time. All you have to do is go up (or have someone who know what to look for go up) and look at it.

Cracks in the crown, like the mortar joints, usually start small but grow as water freezes and thaws in them. Eventually you have big cracks or even missing chunks of the crown. Water which enters through the crown seeps into the bricks and liner. This is where a lot of spalling or shaling comes from.

The crown is the source of a lot of trouble yet it’s easy to catch the problem early, easy to fix. There are superb specialized crown coatings available today. These highly elastic and weatherproof materials cover small cracks so they don’t get bigger and prevent new ones from forming. It’s smart to just have the crown coated on general principles- even if you don’t have a problem already.

Everyone gets a problem on the crown eventually (and for reasons I won’t go into here, many, many crowns are bad from the first day they are laid) and there’s so much expensive potential damage that can follow, it just makes good sense to coat the crown and rest easier about the whole thing. It’ll save a lot of money in the long run.

Broken firebricks and other assorted problems at the fireplace

Firebricks usually break from too much heat or from logs hitting them one too many times. The fix is merely a replacement.

There’s sometimes a gap between the face of the fireplace and a metal firebox, and sometimes you can see framing through the crack. The solution is to pack it with ceramic wool and put refractory cement on that. This problem will reoccur so you’ll have to “repair the repairs” from time to time just because of the nature of the materials involved and their different rates of expansion.

The damper may not work properly for a lot of different reasons, and most of them are leaky anyway. There’s more heat-loss through most dampers than any other “hole in the house.” If the damper isn’t closing well or easily, that’s something you can tell easily by feeling and seeing as you work the damper. The heat loss is more subtle, though you may well be able to detect a draft across the floor of the room with the fireplace. The fix is a new damper, and a top-sealing damper (such as the EnergyTop™) is the best choice. They really keep the heat in the house when conventional dampers cannot.

chimney flashing repair in Travilah MDThe flashing is a common problem too.

The flashing is the metal that keeps rain or snow water from going into the house at the point where the chimney passes through your roof. The top part of the flashing is actually mortared into the brick mortar joints. It’s a problem if the flashing has holes in it or isn’t sealed into the chimney well. This can be seen but usually only if you go on the roof.

Flashings are the source of almost as many problems as crowns are, whenever anyone is on your roof, ask them to inspect the flashing too. Dissimilar materials with different rates of expansion, coupled with ultraviolet light on the sealants, means that flashings don’t hold up forever. The fix is something most chimney sweeps and all roofers can do. Replacement is always a good choice, but there are repair materials available as well.

Have a problem with the wallpaper where the chimney passes by?

There are two reasons for this problem usually (stress usually- there are a few others too) First is the flashing or crown allowing water to enter the brick structure. The fix for that is to fix the flashing or crown, and maybe install a chimney liner as well. The second is excessive condensation inside the chimney, especially common in gas flues. In this case the solution is almost always a new chimney liner (though you can also go back to a less efficient heater, but nobody is going to do that!)

Rust stains from a chase cover

Very visual indeed. If you have a factory-built chimney, the chase cover is a metal top on the chase surrounding the chimney pipes. Builders commonly put up a galvanized one because they’re cheap to get. The chase doesn’t rust until long after your check has cleared. Don’t make the same mistake twice; get a stainless steel chase cover installed to replace the old rusty galvanized cover. More expensive to be sure (and they’re ALL custom made) but it really is the only smart thing to do. A new galvanized chase top is a false economy.