FAQInsulation

Why do you recommend "insulation" for my new stainless steel liner system?

There are two basic conditions where adding insulation to your liner system may be recommended or required. In some cases you will have the choice of adding the insulation or omitting it. In other cases you will not have the choice, due to the requirements of current safety codes.

Reason #1 - Code requirements

Current building codes for masonry chimneys clearly state the requirement for air space to be maintained between the masonry chimney and the combustible framing of the house. Masonry fireplace construction is also outlined to require a minimum thickness of masonry materials at certain locations in the system, such as above the lintel and opposite the smoke shelf.

Unfortunately, it is very common to have a masonry fireplace or chimney in your home that does not conform to these building codes. These codes are in place to help protect the combustible house from overheating and possibly leading to a house fire. When you add a wood stove to your masonry fireplace or chimney you increase the risk of a creosote fire, or a chimney fire. If the masonry structure is not built to conform to the safety codes you increase your risk of a house fire due to heat transfer. Chimney fires can get very hot and masonry materials are an excellent conductor of heat. It simply is too risky to install a wood stove to a non-code-compliant chimney.

Fortunately, there is a solution that allows safe installation of a wood stove to non-code-compliant masonry chimneys. UL laboratory testing has established that properly insulating a stainless steel liner will mitigate the risk of heat transfer from an accidental chimney fire. The insulation keeps the heat inside the liner pipe and away from the combustible building materials that may be touching the masonry structure. Most manufactures of liner pipe offer a UL Listed insulating system that may be used to safely upgrade a masonry chimney to be used with a wood stove.

In short, if we cannot confirm that your chimney conforms to current safety codes for use with a wood stove we will insist on installing a UL Listed insulated liner system. Note that in some cases the masonry mass of the chimney may be sufficient to protect the combustibles without adding insulation to the liner. But this is rare. It is most common that a masonry chimney not only lacks the required air clearances but also lacks sufficient thickness to protect the combustibles. In these cases the only safe way to re-line the chimney is to add the UL Listed insulation to the liner system.

Reason #2 - Performance and Maintenance

If your chimney passes our safety inspection and is considered code-compliant you may have the option to install insulation or not, depending on the conditions surrounding your chimney. The most common reason to install insulation with your stainless steel liner is to protect the new flue from a cold weather environment. When the chimney is exposed to outside temperatures the chimney will lose too much heat to the outside and draft performance may suffer. A hot flue works better than a cool flue. Draft works better when the chimney stays hot.

If your chimney is on an outside wall and at least one side of the chimney is exposed to the outside we will recommend you add the insulation to your liner. This is especially important if you will be starting a fire in your wood stove every day. A cold flue will contribute to difficult start-ups and increased build-up of creosote in your liner. Adding insulation to your liner will allow the flue to heat up quickly and keep the heat in the flue, leading to improved performance for your wood stove.

A hot flue will stay cleaner and cleaning and maintaining the chimney system will be easier and more effective when you have an insulated liner. If you choose not to insulate your liner we suggest you check and clean your chimney more often. If you have excessive creosote build up you will need to work hard to remove it. An insulated liner will simplify your maintenance routine and, in most cases, allow for annual cleaning with a simple brushing. On the other hand, uninsulated liners may require the use of rotary mechanical cleaning to remove stubborn creosote deposits.

Conclusion

Adding insulation to your new liner system may be required or recommended when either of two conditions exist for your existing masonry chimney:

1. You have a NON-code-compliant masonry chimney system. A UL Listed insulated liner system is required to bring your chimney up to current safety codes for use with a wood stove.

2. Your chimney is exposed to the outside and is susceptible to performance degradation due to the cold weather environment. Insulation is recommended to improve draft performance and reduce or eliminate creosote build-up.

We hope this helps inform you of the benefits of adding insulation to your stainless steel liner system. Please contact a sales representative for more detailed information about insulating options that may apply in your particular situation.

The Staff at the

Cracker Mill Hearth & Emporium