New chimney cap poured on top of a chimney.
New chimney cap poured on top of a chimney.

The top of your chimney has (but not always) a “cap” or “crown” on top of it. chimney caps can become damaged and/or worn over time and will need to be repaired. This can be a relatively easy repair that you can do yourself as long as you are comfortable with accessing the top of your chimney.

Deciding what type of repair to do.

This is simple. First, you need to determine if the chimney cap repair will require removal of the cap (crown). Often times it is clearly evident that the cap has lifted off of the layer of brick that it was poured upon. However, the cap can be cracked in several places and still have a very strong bond to the brick. 

Photos to help determine chimney cap repair

In this photo, it was determined by the chimney mason (me) that the chimney cap maintained a strong bond to the brick and was, therefore, a candidate for preservation with a brush-on product.

Chimney crown preserved with a brush-on product.
Chimney crown preserved with a brush-on product.

Doing an overlay as a repair

You may have sections of crown that are loose or missing. There may be remnants of the crown that remain strongly bonded to the top of the chimney:

Crown worn away from time and freeze damage.
Sections of the crown missing, remnants still bonded strongly to top of chimney

You can do a crown overlay repair. This is strongly recommended in this case because attempting to remove the remaining crown that is strongly bonded to the top of the chimney could loosen the brick below it. I want to do a crown overlay

Removing the entire cap/crown

The photo below shows a crown that obviously will need to be removed, and a new crown of sand mix, topping mix, or concrete mix will need to be poured on top of the top layer of brick. Sand mix consists of fine particle sand and portland cement, and it can be troweled to a very smooth finish. Topping mix consists of sand, cement, and very small gravel; it can be troweled to a smooth finish, but not a very thin finish.

You need to be careful when purchasing sand mix and topping mix because of the above-stated differences. The concrete mix consists of sand, cement, and larger gravel, and can be troweled to a smooth finish if you are skilled at it or practice with it; one would attempt a smooth finish after laying down a bed of concrete mix that is at least 2″ thick. Pouring the mix into a form would be better yet. The concrete crown is the strongest, in my opinion. If you have broken or missing flue tiles and want to add these tiles to your chimney (so that you can install a chimney rain cap on the tile), go to the flue tile installation page.

Mixing Mud

“Mud” is the generic name in the trade for whatever it is that you are mixing. Often times the easiest way to mix up some mud is in a 5-gallon bucket, with a margin trowel. For larger amounts of mud, a wheelbarrow and a hoe are the way to go.

Loose and deteriorated chimney cap. Can be easily removed.
All of this chimney cap can be easily removed

The remaining crown in the above photo was easily removed with a hammer and a wood chisel. Yes, a WOOD chisel. I used a wood chisel because the edge of the chisel and the chisel itself is thinner than a masonry chisel. This is important because the thinner chisel gets underneath the crown easily when removing the old crown. A word of caution: ALWAYS WEAR GLOVES AND EYE PROTECTION WHEN PERFORMING THIS ACTION. If the crown is not going to remove with relative ease, then use a brush-on product to preserve it.

An alternate mix for pouring a new crown

I frequently use a mix of sand mix (or topping mix), pea gravel and bonding agent as a custom mix for crowns. It tools smooth much easier than concrete mix because it has smaller diameter gravel in it:

A bag of pea gravel.

Pea gravel can be purchased at Lowes in ½ cubic foot bags, in the garden section. Mix ½ of a bag (¼ cubic foot) of pea gravel to a 60lb bag of sand mix or topping mix. Never use mortar mix.  Add water and bonding agent to the mix. mix the bonding agent into the water before pouring the water into the dry mix. It is best to pour the dry sand mix and pea gravel into a wheelbarrow and mix these items together before adding the water and bonding agent solution. Add just enough liquid so that the mud is to a consistency that is somewhat firm but can be made smooth with a trowel (if all else fails, follow the directions on the bag…)

Load the mix onto the top of the chimney without troweling it smooth. When you start to trowel the mix smooth, push it straight down first in order to PUSH THE PEA GRAVEL DOWN AND CAUSE THE SMOOTH MUD (“cream”) TO COME UP TO THE TOP. Then trowel the crown smooth. Trowel the mud as little as possible; you do not want too much “cream” to come to the top. The idea is to have a consistent distribution of the pea gravel within the mud. The mud bonding to the gravel is what keeps the crown from cracking, therefore an even distribution of mud and gravel is critical. 

If you determined to do a chimney cap repair by applying a brush-on product to preserve a crown that still has a good bond, Then go here to explore see your options: Brush-on product options

Equipment, tools, and supplies you will need

If you determined to do a chimney cap repair by applying a brush-on product to preserve a crown that still has a good bond:

An appropriate ladder for getting on your roof and getting up to the top of the chimney (if necessary). If you do not have any experience with ladders, I strongly encourage you to download and study the Oregon OSHA ladder guide. I would also encourage you to search for your state’s OSHA guide on ladder use, as well as the ladder manufacturer’s directions and guides for use.

Know what you are doing before you begin to work with ladders! I always tie off my ladder to a gutter spike when the ladder is against a gutter. There is nothing worse than having a ladder blow over in the wind and you are stuck on the roof.  You can click on the product links below to get to my write-ups on the brush-on products. I recommend you do this in order to choose the right product for you and your situation.

ChimneySaver Cold Weather CrownCoat (can be applied in cold weather).  Or

Tamoseal foundation coating – by Euclid Chemical.  Or

ChimneySaver CrownCoat (for normal weather application).

Your DIY savings

I charge anywhere from $225.00 to $490.00 for an easy-to-reach crown repair. The cost goes up as the job becomes more dangerous and more painful ($600.00 – $900.00).

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