What to Expect with an Historic Chimney

Most homeowners who purchase historic homes recognize the fact that older structures need a lot of work.

There are structural issues to deal with as well as cosmetic, and the larger the home, the more problems to address. However, few homeowners realize the extent to which the chimneys will need to be restored, and are often surprised to find the amount of work needed to bring a chimney up to current codes and standards while maintaining the historic appearance.

Homes built prior to 1920 may not have chimney flue liners. Flue liners keep toxic and heated gasses and creosote inside the flue, rather than outside the chimney or inside the home. While clay tile flue liners started showing up in the 1860’s in larger homes, liners weren’t required by code until 1927 and many jurisdictions did not adopt or enforce the code until as late the 1940’s.  Since flue liners are so important, this is something that must be addressed in an historic chimney. There are multiple factors involved in determining the correct size and type of flue liner to use, so a professional chimney sweep or chimney contractor should be consulted for advice and installation. This is definitely not a do-it-yourself project.

The second most common area to address in an older chimney is the smoke chamber. This is the area above the damper which leans inward to support the flue liner. It is also the place where some people used to smoke meats. Sometimes you’ll find an unexplained door in a chimney above or inside the smoke chamber which was likely used to access the interior to hang meat. It is critical to make sure that any such door is removed and sealed up with masonry, and that the smoke chamber is parge coated with insulating mortar to keep heat inside, allow for the smooth passage of smoke up the chimney, and offer more protection if there are combustible materials next to the chimney.

Often builders installed built-in wood bookshelves, wood trim, or even cabinets right next to the chimney. This is against current code, and a fire hazard. However by using a proper smoke chamber coating and zero-clearance flue liner, these decorative wood items do not need to be moved.

Next to address is the fireplace. Many fireplaces in historic homes were built very small and shallow. These were either used for coal burning or for small ceramic gas heaters. Many of the gas heaters still in use have missing parts or emit too much Carbon Monoxide, thereby creating a health hazard to the occupants. In some chimneys, there is a very small vent which can only be used for a gas heater of this type and may or may not be something that can be changed.

The smaller fireplaces will not work for wood-burning unless they are true Rumford style fireplaces, or can be modified by a Rumford fireplace builder to a Rumford design. The Rumford design (shallow depth, angled sidewalls and smooth throat) are also much more efficient than the standard box-style fireplace.

The flues for other appliances such as a boiler, gas furnace, or water heater need to be inspected as well. These flues are actually much more important because there are toxic gasses such as Carbon Monoxide involved. If there is no flue liner, or the liner is damaged, CO can leak into the interior structure. This is a severe health risk to the occupants.

Finally, the exterior chimney must be inspected for missing mortar and bricks, a damaged or missing cement crown, lack of chimney cover protection, leaning issues, and flashing. The type of historic bricks used and the building style with very thin butter joints used in Victorian-era chimneys is not a commonly known method today. Therefore, it is important to find a professional chimney sweep and/or mason who knows how to rebuild or repair a chimney using the older style methods. Finding an expert in this area may be a difficult task, and finding matching bricks may be even more difficult. In some cases it can take months to obtain matching bricks.

If the restoration work is cost prohibitive, one solution may be to have an historic look gas direct vent insert installed. This will allow for use of the fireplace without extensive flue or chamber repairs. The DV fireplace has its own smaller liner system which is installed inside the old flue liner if there is adequate room.  If not, another solution is available – an historic look electric insert.

It is always best to have a professional chimney sweep inspect all of the chimneys in the house prior to purchase so a buyer will know what they are getting into before the closing. Historic chimney restoration will often cost much more than any other house restoration project, so it is a good idea to know this in advance. A professional chimney sweep knows the current International Residential Code and National Fire Protection 211 Standard, and the proper restoration methods, unlike most home inspectors or contractors who do not get training on chimneys unless they go outside their industry. 

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