Chimney Caps for Your Home

How to Buy the Right Chimney Caps for Your Home
If you are a homeowner and you have to replace a chimney cap, chances are, it is your first time you are doing so. If
you do your homework and you’re willing to pay a little more than you probably want to, you can also make it the last time you have to replace your chimney cap. There are only a few key things you need to know about chimney caps to make your purchasing decision quick and painless. In this article we are going to go over those key points and give you some recommendations.

Your Chimney
First of all, what kind of chimney do you have? There are only a few different kinds so identifying your chimney should be easy. Most chimneys have one or more flues that stick up in the middle of the chimney. The flue is typically orange, made of clay, and lines the inside of your chimney and protects the brick from the heat of your fireplace. The shape of the flue or flues will determine what style of chimney cap that you will need to purchase. The three most common shapes are round, square and rectangle.

If you were adventurous enough to climb up on your roof to take a closer look for yourself, you may find that you have a flue that is square or rectangle yet has rounded edges. Some homeowners may consider these to be oval flues, however, for our discussion they are still considered square or rectangle.

• If you have only one flue and it is round, then you need a round, single flue chimney cap.

• If you have only one flue but it is square or rectangle, then you need a standard single flue chimney cap.

• If you have more than one flue, then you need a multi-flue cap. Note: in some instances you can use more than one single flue chimney cap instead of a multi flue chimney cap but it is typically not recommended.

• Many new home builders are installing factory built fireplaces and chimney systems into new homes. If you look at your chimney and you do not have a clay flue but you have a round metal pipe, then you need a chimney cap for a metal chimney.

Chimney Cap Material
Once you have determined what type of chimney cap you need, you will want to consider what type of material you want the chimney cap to be made from. Chimney caps are made from the following materials:
• Stainless Steel
• Copper
• Black Galvanized

Stainless Steel
If you want to purchase a chimney cap made from a quality material, stainless steel is a very good option. The chimney caps are made from 304 grade stainless steel which is going to do an excellent job of resisting corrosion. The finish is a silver color that has a moderate shine to it. Custom colors are also available for stainless steel chimney caps upon request. Because stainless steel is such a durable metal, the stainless steel chimney caps come with a lifetime warranty.

Copper
Copper is also considered a high quality material for chimney caps for much of the same reasons as stainless steel. It is a durable metal, it is structurally rigid and it does not excessively corrode. In addition, copper is aesthetically pleasing and can add an excellent accent to the outside of your home. Once copper is introduced into the environment it will weather and the color will change. Copper is the highest quality metal used for creating chimney caps and comes with a lifetime warranty.

Black Galvanized
Galvanized steel is the third material that is used to fabricate chimney caps. The steel is coated with zinc which helps prevent corrosion. In addition, the chimney cap is painted black which again helps protect the steel from rust and corrosion. However, the galvanized metal does not hold up well after a couple of years. The metal will eventually rust out requiring the cap to be replaced. These chimney caps come with only a three year warranty. This may be a solution for some homeowners, but if you are looking for a cap that you will not have to replace in the near future, you should consider the stainless steel or copper.

Sizing
Once you have decided the type of material you want your chimney cap to be made from, you will need to find the right size. If you are afraid of heights, you may need a little bit of help with this one. The following discusses how to get your measurements for each type of chimney cap.

Round Single Flue Chimney Cap
These chimney caps will fit overtop of a round clay flue tile and attach to the flue using pressure mounting screws.  These screws do not penetrate the clay flue tile but do hold the chimney cap securely in place when they are tightened down. The size that you need depends on the diameter of your flue tile. Be sure to measure the flue tile end to end going all the way to the edge of the flue tile. In other words, you need the diameter of the entire flue tile, not just the diameter of the hole. The flue tile is typically ¾” to 1 ¼” thick, so using the outside dimensions instead of the inside dimensions is very important. Once you know the diameter, view the chimney caps sizing guide which will help you determine the appropriate size chimney cap for your chimney. The round single flue caps will fit a size range. For instance, an 8” round chimney cap will fit a chimney flue that has a diameter of 6” up to 8 ½”.

Square or Rectangle Single Flue Chimney Cap
These chimney caps attach to the clay flue tile using pressure mounting screws. These screws do not penetrate the clay flue tile but do hold the chimney cap securely in place when they are tightened down. The size that you need depends on the outside dimensions of your flue tile. The flue tile is typically ¾” to 1 ¼” thick, so using the outside dimensions instead of the inside dimensions is very important. Once you have the outside dimensions, view the chimney caps sizing guide which will help you determine the appropriate size chimney cap for your chimney. The single flue caps will fit a size range. For instance, the 13” x 13” chimney cap will fit a chimney flue that has a width of 11” up to 13 ½” and a flue that has a length of 11 ½” up to 14”.

Multi Flue Chimney Caps
These chimney caps are used to cover multiple flues or to cover a chimney that does not have a flue tile to attach a single flue chimney cap to. The multi flue cap mounts to the top of the chimney using tap-con screws. Simply pre-drill the hole for the screw using a masonry bit (some chimney caps are shipped with a masonry bit, otherwise you can purchase one at a big-box store) and use a drill to insert the screw through the mounting flange on the cap into the chimney crown. Some people are easily intimidated by having to drill into concrete or brick, but a masonry bit makes it a snap and the job can even be done using a cordless drill.

To get the right size multi flue chimney cap you will need to get the measurements of the chimney crown (see diagram below). The chimney crown is the very top of the chimney; typically it is a cement slab that caps off the brick of the chimney. Measure the length (D) and width (C) of the chimney crown. Now, measure the total length (A) and width (B) around all the flues. Thirdly, measure the height (E) of the tallest flue. This is necessary because you will need to get a chimney cap that has a screen height that is 5” more than the height of your tallest flue. For example, if the height of your tallest flue is 5”, you will need a chimney cap that 10” (5” more than the tallest flue). Having 5” clearance above the flue will allow the chimney to draft properly; without it, you will end up with smoke in your house – trust me, you don’t want that.

Once you have gathered all of these measurements check out the multi flue chimney caps and decide which material you want. You then want to choose the screen size (F) that is going to give you 5” clearance above the tallest flue and a chimney cap size that is smaller than your overall chimney crown dimensions but larger than your flue dimensions. There usually are a few different sizes that will fit inside your two dimensions. You would choose the larger size if you want to have more of the chimney crown protected from rain, or you may want to choose the smaller size if you are trying to stay within a budget.

3/4” or 5/8” Mesh
You may be wondering why single flue and multi flue chimney caps have two options for mesh thickness. The mesh screen serves two functions. First, it keeps rodents and birds from entering into the chimney while still allowing for the chimney to exhaust properly. Secondly, it serves as a spark arrestor, not allowing sparks and embers to escape from the chimney and into the environment where it could cause a fire.

Many localities - primarily California, but also in other areas around the nation - have spark arrestor codes that call for 1/2" spark arrestors.

The California state building code calls for such spark arrestors on all new construction. Other California codes call for it in "wooded areas" or "within 200 feet of wooded areas" and when it comes time to sell your home, you can also bet the inspector will require you to update your chimney cap to comply with the spark arrestor codes.
To make such a reduced spark arrestor that does not clog, chimney cap manufacturers follow the interpretation that a sphere larger than 1/2" in diameter should not penetrate the screen. This is wording the National Fire Protection Association uses, as well as the one being referred to by several California localities.

Thus, the spark arrestor screens on these chimney caps measure 5/8" from center to center, but still won't let a 1/2" sphere through. This makes them somewhat clog resistant while still meeting major code interpretations.

Chimney Caps for Metal Chimneys
These chimney caps are the easiest to determine which size chimney cap that you will need. The chimney pipe is round, so you need to measure the diameter of the chimney pipe. There are a few different types of metal chimneys, and you will need to determine from the list below which type you have.

• Single Wall Chimney – Round chimney with that is only one pipe

• Double Wall Chimney – Round chimney with an inner and outer liner (a pipe within a pipe)

• Triple Wall Chimney – Round chimney with one inner liner and two outer liners

Once you have determined what type of chimney you have, you need to determine if the chimney is air insulated or solid pack.

• If you have a single wall chimney, the chimney cap you need will fall into the solid pack chimney cap category.

• If you have a double or triple wall chimney pipe and there is insulation between the liners of the pipe, the chimney cap you need will again fall into the solid pack chimney cap category.

• If you have a double or triple wall pipe and there is only an air space between the pipes, the chimney cap you need falls into the air insulated (sometimes called air-cooled) chimney cap category.

Now that you have determined if the chimney pipe requires a solid pack or air insulated chimney cap, use the diameter of the inner most pipe to determine which size you need. For example, you have a single wall chimney that is 8” in diameter – you need a Solid Pack 8” Chimney Cap. Another example, you have a double wall pipe that is air  insulated, and the inner pipe has a diameter of 10” – you need a 10” air insulated chimney cap.

The chimney caps for the air insulated chimneys have a collar that is 15 5/8” in diameter. Some chimneys have an outside diameter that is larger than 15 5/8”. If this is the case, you need an “oversized” chimney cap. Simply follow the above steps for determining the chimney cap size that you need and choose the cap that is labeled oversized or “OS”.

This article should put you well on your way to buying that new chimney cap! For more information keep checking back here at Chimney-Caps.com!