How To Install A Chimney Cap Without A Flue? All you need to know about DIY installation

It’s always better to have a cap over your chimney than to get bad weather and wildlife inside your home. But there is a question how to install a chimney cap without a flue? Don’t worry, such a solution exists and we are here to fully deal with it!

Installing A Chimney Cap
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What Is a Chimney Cap And What Does It Do?

Round caps are often seen on roofs and chimneys on homes with fireplace heating. This detail serves not only a decorative function, but also protects the chimney from the elements and debris from outside. Also consider how installing a chimney cap affects draft and airflow.

To have a place to start, let’s consider whether chimney cap needed. So, the chimney cap serves as an umbrella for your vent. There’s a reason for this comparison, because a rain cap is mounted on the top of the flue, not inside it as an internal damper.

Whether you have a tall chimney flue on your roof or not, chimney caps are always made of fire-resistant materials. In a typical wood-burning fireplace, the temperature of the combustion gases passing through the vent can reach 1000°F.

Advantages of chimney caps

The most important feature of chimney caps is protection from leaves, twigs and other natural flammable debris that can lead to a fire if caught in the chimney. If your chimney cap is also equipped with a copper mesh, you will prevent animals or insects from entering the fireplace.

Like a real umbrella, your chimney cap protects the inside of the vent from rain

This is important because moisture inside the chimney provokes increased creosote buildup on its walls. Creosote is a black tar-like substance that adheres inside the chimney. Creosote is highly flammable and poses a fire hazard. So, less moisture means less creosote and less hassle with chimney sweeps.

Another benefit of chimney caps is downward draft protection. This is especially relevant for locations with strong winds, when the air flow enters the chimney and prevents gases and combustion byproducts from escaping.

You might argue that common flue caps do the same thing and you don’t need to complicate your life by installing a chimney cap without a flue. But in fact, chimney caps drain water directly onto the crown of your chimney and significantly shorten the life of your chimney. Just look at these pictures to see the difference:

Comparing flue caps and chimney caps
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Controversial issues with chimney caps

Despite the important pros, there are some cons to installing a chimney cap. Firstly, every time you want to clean the duct, you will first have to remove the chimney cap. This leads to a somewhat more expensive chimney sweep service.

Moving forward, a wrong chimney cap can narrow the chimney outlet. Then, the combustion gases will not leave the chimney completely and will remain in the living space. This may reduce heating efficiency, and may also have a negative effect on the health and well-being of the household.

Also, if your area experiences cold winters, chimney cap installation can cause icing around the vent. And it can prevent proper ventilation and even lead to complete blockage of the chimney outlet. Keep in mind that mesh chimney caps are prone to particularly rapid icing.

See How to Install a Chimney Cap without a Flue

Ideally, installing a chimney cap should be planned during the construction phase of the fireplace. The more complex the design of the chimney cap, the more influence it can have on the draft force and heating efficiency. Of course, this rule works the same whether you install a chimney cap without a flue or with one.

It’s also worth considering that a project completed by hired professionals from start to finish will have a warranty and service. But since you’re already here, let’s see what steps you need to take for a DIY installation of a chimney cap.

Step #1 Measure your crown

The first thing to evaluate is the type and shape of your chimney outlet. There are single flue chimneys and double flue chimneys. In terms of shape, there are oval and square chimneys, but the round flue is the most common.

When taking measurements on the roof, take care of proper safety equipment

Then pay attention to the small protrusion between the roof and the flue opening. This protrusion around the opening is called the chimney’s crown. It is the mounting point for the future chimney cap. Carefully measure its external dimensions in length and width, or diameter.

Never attach chimney cap to single-flue chimneys flush to the crown!

Well, all you have left to do is the third height measurement. For double-flue chimneys, focus on the tube that rises higher. There should be enough distance between the chimney opening and the chimney cap.

Measure the crown to Install a chimney cap without a flue
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Step #2 Purchase a chimney cap and proper fasteners

By and large, installing a chimney cap without a flue is not difficult. It should effortlessly cover the chimney crown, but should not be too wide, otherwise the fasteners will not reach from the cap to the crown. Stainless steel and copper are considered the best materials for chimney caps.

As a general rule of thumb, the chimney cap that fits you should be higher than the tallest flue by two inches

As for the installation, focus on the material from which the chimney crown is made of. Usually it is a clay or metal tube, so choose fasteners that match your material. Accordingly, you need masonry screws or self-tapping screws for metal.

Installing a chimney cap that is too tight for the flue liner is fraught with a chimney fire

It is a good idea to look at the accessories recommended by the manufacturer when choosing a cap. You may need the following tools:

  • Power drill
  • Hammer drill
  • Impact driver
  • Caulking gun
  • High-temperature sealant
chimney cap made of copper
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Step #3 Secure the cap

Try the purchased cap on the crown so that it sits clearly centered and does not bunch up in the corners. Drill pilot holes in the cap for mounting on screws or self-tapping screws. Use a masonry bit or hammer drill to do this.

To adjust the depth you need to drill pilot holes, use this trick:

Before you drill, lay the screw along the power drill bit or masonry bit. Apply duct tape to the bit where the screw ends. That way you mark the correct depth and don’t drill deeper than you need to.

If you plan to use a construction adhesive, thoroughly clean the crown from debris and dust with a stiff bristle brush. Chimney cap installation becomes easier and faster with the adhesive mount. But on the other hand, chimney cap replacement becomes a problem to handle annual chimney maintenance.

So, to avoid disassembly, try purchasing a new chimney cap with a hinged top mount cap

For metal flue, it is preferable to use galvanized steel screws. If you have a clay flue, consider a combo with masonry screws and adhesive, as clay is more brittle and can break apart. Using high-temperature sealant, try not to get glue in the pilot holes to screw head’s location or you will never be able to undo the fasteners. Not implying anything, but just check out How much does it cost to repoint a chimney.

In any doubt, consult a pro

Sometimes it’s better to be reassured and consult with professionals. If you are in doubt about screw hole locations or have problems with pre-drilled holes, just make a video call to a specialized company. If your pilot holes and masonry screws don’t match, the pros will tell you how to get out of this trap.

Secure the chimney cap
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Other Things about Installing a Top Mount Chimney Cap

Let’s cover some points that apply both to double and single flue chimneys. This works for any material equally for metal and clay flues.

Ventilation is critical for chimneys. Obviously, it vents smoke and combustion products away from the chimney. In addition, proper ventilation is important for moisture drainage when condensation occurs.

Thus, it’s necessary to vent properly the entire crown to avoid creosote accumulation

Rain caps designed to be installed directly on chimney flues already have the necessary spacing. But when you install the cap on the crown, never do it in flush single flue chimney. If you are to install a common cap over double flue at once, make an interval from the tallest flue.

Chimney cap installation & safety considerations

Working at height is potentially dangerous, so never disregard safety rules. When working on a roof, make sure you follow these precautions:

  • Avoid the A-frame ladder in favor of an extension ladder equipped with a ladder stabilizer. A ladder stabilizer is an accessory with protective coverings on the wall of the house. It is recommended that the height of the extension ladder be three rungs higher than the gutters.
  • Do not rely on non-slip shoes, always use a safety harness. A roofing safety harness is a strap that passes through your shoulders, waist and legs at one end and attaches to a secure element at the other.
  • Find a companion to help you install the chimney cap. That way you’ll have a helper to hand the needed tool or call for help.

Maintaining your chimney cap

Chimney caps require little maintenance. If the chimney works properly, it is enough to perform a simple check once a year.

Make sure that the mesh on the cap is intact. This will prevent wildlife from entering your home. During leaf season, you can make sure that your cap is not clogged with leaves and other natural debris.

Also check if there is too much creosote accumulated, as its deposits are a fire hazard. Otherwise, the service life of construction adhesive, metal or clay flue, and quality fasteners is measured in decades.

Chimney cap for masonry stove pipe
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FAQ: How to Iinstall a Chimney Cap without a Flue

Can you use a chimney without a flue?

Yes, you can use a chimney without a flue, but it’s still better to use one. The inner tube will protect the masonry joints from damage. It is really easier to adjust the flue’s length or replace it than to rebuild the masonry.

Can you just cap a chimney?

Yes, it is OK to cap a chimney. To say more, it is worth installing a chimney cap even if you already have a damper installed. It is possible to make a chimney cap for a single flue chimney or a double flue chimney at once on the entire crown.

Does a capped chimney need ventilation?

A cap top chimney needs ventilation just as much as a chimney without a cap. So, sealing damper chimney cap really is a bad idea. Proper venting helps to get rid of excess moisture and keep the chimney in working order.

Is a flue cap the same as a chimney cap?

It’s very similar, but there’s a nuance. Flue caps cover only the flue opening, while chimney caps cover the entire chimney and crown. Thus, a chimney cap can be installed without a flue.

To Finalize: How to Install a Top Mount Chimney Cap

As final words, nothing forbids you to install a chimney cap without a flue in your own hands. If you feel confident on the roof, you will definitely succeed! To help you with your purchase, attached is this video by Ceaser Chimney Service, Inc.

If, however, the roof of your house is uncomfortable or slippery, it is better to hire professionals. It won’t cost much, but it will save you a lot of time and effort. Any way, hope you enjoy caretaking your home!

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