Often times in life, good things are born from seemingly bad situations. And so it goes for homeownership too. We recently had some roofing repairs done to our Spanish tile roof. When the roofers began to tackle a leak around our chimney, I heard the dreaded words you never want to hear from your roofer, “Marc, I think you might want to come up here and take a look at this.” Up the ladder I went, and there to greet me were several gaping cracks in our vintage 1936 brick and stucco chimney. I’m no mason, but I knew it was bad. In fact, I had pretended not to notice them from ground level in the past, but now that I was up close, it looked like the top of our chimney was just about to split in two or three pieces before crumbling down.
This news ground roofing progress to a halt while I got on the phone to find a mason. I had several come out to take a look, and surprisingly a couple opted not to go onto the roof. Our second story roof is pretty high, but if I was willing to climb up there, shouldn’t a mason too? And the “solutions” these guys provided ranged from fiberglass tape to elastomeric paint. Seriously? These cracks were almost big enough for me to put my hand in. I thought it was pretty clear this was a major structural issue well outside the bounds of tape and paint. Long story short, I found a mason who agreed demolishing the top of our chimney and rebuilding was the prudent, albeit painfully expensive thing to do. That mason also provided some great input on the new chimney detail, including the addition of a chimney pot. I’ll detail both the chimney repair and the eventual crowning of a new clay chimney pot, as I learned several important lessons along the way.
Luckily the mason’s crew were pretty surgical with the demolition, especially given that we were hoping to preserve the original flue liner. The old liner was clay, and like most things in our house, made in an unconventional size that’s no longer available. The crew used a relatively small bit and a Makita rotary hammer to break the brick into manageable chunks which were sent to ground level via a bucket and rope. Since the chimney had semi fallen apart already, the demo went pretty quickly.
When rebuilding the chimney, it’s important to follow building code standards. These vary in different regions, so make sure you or your mason know exactly what the code states for your area. The height of the chimney is critical for both proper draft (which helps heat and smoke go up the flue and not into your house), as well as helping avoid roof fires. In many areas, a two, three, ten rule applies. While we recommend reading and following your local codes exactly, basically the rule says that the chimney top needs to be at least three feet above its roof penetration and at least two feet above any roof surface within ten feet. Aside from that, you want a chimney that’s tall enough overall to provide proper draft. More on proper draft later.
Given how precariously high our chimney is, I wanted to minimize how much time I spent in the role as roof stuntman. And since this whole mess started with a water leak around the chimney penetration, it was really important to me that the rebuilt chimney was properly flashed. Both of these facts led me to have a conversation with my mason beforehand. It went something like this: Me – “I’m really concerned about proper flashing up there. You’ll make sure that’s taken care of?” Mason – “Sure, no problem.” Turns out I should have been a lot more specific. After the chimney was rebuilt I went up to check things out. I was surprised to find the old flashing simply left in place but separated from the chimney. My first thought was that maybe I was unreasonable to expect that the mason use counter flashing by tucking the top of the flashing into the mortar joint. Several conversations with knowledgeable folks confirmed this is best practice. My mason, on the other hand, thought best practice is to “avoid liability” by not flashing at all, and leaving that up to the roofers to cut in after the fact. Lets just say we had a lively conversation about this discrepancy in which we agreed to disagree. Long story short, I wound up paying my roofer to send out someone just to install the counter flashing before the stucco was applied. They wound up cutting a groove into the chimney and inserting the counter flashing in that groove. Ultimately that solution worked fine, but from my perspective this should have been part of the mason’s job. Make sure you have a detailed (and I mean detailed) conversation about exactly how your mason will or won’t handle flashing if you ever find yourself in our unfortunate position of having to rebuild your chimney. It’s a critical detail.
Clay Tile / Cove Detail
Luckily, the flashing issue was about the only area that the mason and I didn’t click together. One of his suggestions was to install a clay tile top that was a bit wider than the finished stucco width. This provided not only a surface to prevent water infiltration from the top, but also a cool architectural detail to the chimney. It did make life a little harder for our stucco pro, but ultimately it provided a nice cove effect and added some style to the top of the chimney. This clay tile top also served as the base for the installation of a clay chimney pot.
Chimney Pot Style
If you start researching clay chimney pots online, you’ll be confronted with a myriad of options. From simple designs that literally look like a clay pot, to ornate contraptions that might look right at home on the Taj Mahal, settling on a style can be daunting. Many designs have open tops, which can be a consideration if you have high winds or issues with precipitation coming down the chimney. Even though we get little rain, I opted for a design that has an integrated top (make sure you read the section below on cleaning if you’re considering doing the same). I’d recommend googling “chimney pots” and looking at a lot of styles. If you have a local source, it’s even better to see some designs in person before making your decision. Ultimately, try to select a style that works well with your home’s architecture. In our case, we only looked at terra cotta chimney pots since they tied in nicely with our Spanish tile roofing. Most chimney pots are made from clay, but you can find them in different colors, and some are actually made from metal instead of clay. If you have more than one flue, you might want to consider multiple chimney pots. With multiple pots, you can either do the same style and size for each, or you can vary the sizes and styles to add more visual interest as long as all the sizes you pick fit.
Chimney Pot Sizing
Speaking of things fitting, two things are critical here; the inside and outside dimensions of your chimney pot relative to your flue and chimney cap, and also the height of the chimney pot. For the first, you want to be sure that the inside dimensions of the chimney pot are larger than the outside dimensions of your flue. You also want to be sure that the outside dimensions of the chimney pot fit comfortably on the cap or flat surface at the top of your chimney. The other key sizing component here is height, and your existing chimney height will play a vital role in that decision. Walk around your home and take a look at the existing chimney’s height from different angles. Does it appear tall? If so, you may want to go with a short chimney pot design. If the chimney looks short, a taller chimney pot may be in order. The size and shape of what you choose can also have an effect on chimney draft.
Many people look to chimney pots as a cure for a fireplace that doesn’t exhibit proper draft. Chimney draft is the funneling of hot air and smoke up the chimney. If a chimney is improperly designed, draft can actually force smoke and gases into the home as cold air from the outside pressures its way down the chimney. Although there’s a point of diminishing returns, typically a taller chimney makes it more likely proper draft upward will occur. If your chimney is otherwise well designed and sized but maybe just a tad short, there is a chance that a chimney pot will improve draft performance. Pot designs that taper toward the top are also said to improve draft. Keep in mind, there’s no guarantee here. While chimney pots can help with draft issues, they may or may not in your particular circumstances.
Clay Chimney Pot Installation
In most cases, including ours, chimney pots are simply mortared in place. You (if you’re ambitious) or your mason (if you prefer not risking falling off your roof), will also use the mortar bed as an opportunity to make sure the chimney pot is installed plumb. It’s worth having a keen eye on the ground during installation to make sure things don’t appear askew from street level. In our case, the trickiest part of installation was getting the clay chimney pot up two sets of ladders and into its final resting place. I didn’t manage to weigh it, but I would guess our pot weighed in around 60-80 pounds. That may not sound like much, but when you’re prancing around tile roofing and navigating up ladders then any weight is no joke. It took myself, the mason and one of his crew to get that pot up and into place. There are a lot of things that can go wrong here (not the least of which include the clay chimney pot, or worse yet, you falling to your death), so make sure you have enough manpower and safety precautions in place.
Birds and Sparks
When we first moved into our home, we had the chimney inspected pre-purchase and then swept post-purchase. Apparently they didn’t notice the fact that the top of our chimney was starting to fall apart, but that’s another issue. The old spark arrestor was disintegrating and so we had the chimney sweep install a new one. He didn’t really sweat the fact that there was about a two inch gap in the mesh around the rounded flue corners. It turns out that gap was just big enough for our local finches to find their way into our chimney. As a result, about every six months we’d hear chirping coming from our fireplace. We would then open the damper at which point a panicked bird would proceed to fly into all of our windows and crap all over our furniture, before eventually being guided out an open door. Aside from bird issues, most areas also have code requirements for a mesh to function as a spark arrestor. In our case, we installed the bird/spark mesh directly to the flue which protruded from the top of our chimney. Some others prefer to install the mesh using silicon adhesive or mortar to the top of the chimney pot directly. Regardless of how the mesh is installed, make sure it doesn’t overhang the edges or it may be visible from the street. Permanent or semi-permanent mesh installation also has implications for the future cleaning of your chimney.
In all the research I did on chimney pots, not one of the sites that sold them mentioned chimney cleaning considerations. I made a couple calls to chimney sweeps who generally sounded unenthused about anything that blocks access to the flue from the top of the chimney. I spoke to at least one sweep that said cleaning from the bottom is an option, but that it’s a messier one, and not ideal. All I can suggest here is to do your due diligence before settling in on a chimney pot design. I still remember the local fire department paying an emergency visit to the house I grew up in when we experienced a chimney fire. We lucked out and the fire was contained quickly, with no injuries and little damage. But in 2009, the Chimney Safety Institute of America wrote, “According to the most recent statistics from the Consumer Product Safety Commission, an average of 25,100 chimney fires are responsible for 30 deaths and $126.1 million in property damage on average each year.” Chimney cleaning should be an important part of your decisions related to installing a chimney pot. I’d encourage you to call a few chimney sweeps in your area to discuss how particular chimney pot installations might effect their ability to properly clean your chimney, especially if your pot will have an integrated top and/or permanent spark arrestor. In some parts of the world, chimney pots are the norm, rather than the exception. I have to believe that some chimney sweeps are skilled working with chimney pots in place.
Chimney design is often a complete afterthought, or not considered at all when it comes to the architectural appearance of a home. Worse yet, most people install a cheap and frequently ugly spark arrestor at the top of the chimney. Depending on the architectural style of your home, a clay chimney pot can turn what is normally an eyesore into a feature that adds to the character of the home. As a bonus, it can sometimes contribute to better chimney function in the process. Although I’m not thrilled at the expense of having to rebuild our chimney, I am happy we were able to use it as an opportunity to enhance the style of our home in the process. Most clay chimney pots fall in the $100-$600 price range and can be found online or through speciality local masons’ building material stores.
1 thought on “Clay Chimney Pot Installation and Chimney Repair Tips”
At some point I’d imagine chimneys will be a thing of the past. I just had a new high efficiency furnace installed and it’s vented through pvc. How far behind could the hot water heater be before it’s vented differently to recapture lost heat? Then I’ll have a worthless chimney.