Hardly any Chimneys are Built Correctly!

Chimney Inspections - What Is Acceptable?

Members of the American Society  of Home Inspectors (ASHI) are often benefited by the guest speakers that are invited to monthly meetings.  This ongoing education provides pertinent information on many subjects that makes the home inspector more knowledgeable and therefore able to provide a better service to their customers.  Recently, a local Connecticut chapter of ASHI  invited an expert on chimneys to speak at their meeting.  Part of the discussion involved what was considered a properly built chimney for fire safety.

As a result of the information provided to the attending home inspectors, it is possible that a new focus on certain aspects of chimneys may show up in inspection reports that were not dealt with prior to this meeting.  How this is dealt with may vary greatly based on how an individual inspection company decides to relay this information, or whether they deem it as something within the scope of a home inspection at all.

While home inspectors are required to inspect fireplaces and chimneys, there are limitations and exclusions in regard to this inspection outlined in the "Connecticut Home Inspection Standards of Practice."  It is by far much less intensive in scope than that which would be performed by a qualified chimney sweep, and is also left up to a certain amount of interpretation by each inspector.  Most home buyers will not notice any change in reporting on chimneys because they typically are only experiencing their own inspection and therefore do not have any other inspections to compare it to.  Sellers of homes and Realtors on the other hand may find themselves confused.  Houses that sold with no mention of a chimney problem in a past inspection report may now be identified as having an unsafe chimney.  A realtor may find an increase in reported deficient chimneys in inspection reports. 

It may be too early to say that the increase in reported chimney deficiencies will definitely occur, but if the home inspectors at this meeting take at face value what was presented to them, then they will have to report that most chimneys are "unsafe" or "unburnable."  Many of these chimneys have been inspected in the past by home inspectors who did not identify them as deficient; many of these chimneys  have been in use for decades without a problem.

What was told to the inspectors at this meeting that may create this potential increase in identified chimney problems?  Mainly it had to do with the smoke chamber.  By today's building standards a smoke chamber (see diagram below) should be parged smooth.  From the early 1960's and back, unparged smoke chambers become more and more common.  Most older chimneys have smoke chambers with open corabled brick narrowing to its top to meet the flue liner.  This leaves stepped edges in the brick that does not allow a smooth flow of smoke.  The speaker at the ASHI meeting suggested they report fireplaces with unparged smoke chambers as "unburnable", meaning it is not safe to use them.  It is likely that the majority of fireplaces in use today do not have smooth surface smoke chambers. Therefore, to take this persons advice would mean to identify that the majority of fireplaces in use today should not be used. 

We contacted the National Chimney Sweep Guild and asked them if unparged smoke chambers were safe to use. We received the following response:  "If the smoke chamber walls are of sound construction (no cracks, or missing mortar or brick), the proper thickness and have the required 2 inch air space to any combustibles, my opinion would be parging would not be a safety issue but rather a performance factor."  Therefore, according to their definition,  unparged smoke chambers (if built correctly as noted), that have been performing adequately for years, may benefit from parging, but it would not be necessary.

It may be observed that some home inspection companies do just as the speaker suggested, requiring many more repairs then has been common in the past.  It is more likely however that most inspection companies will use a "common practice" approach to this situation.  What does "common practice" mean?  During any given time in building history, there were common, acceptable building practices for that time period.  As time goes on building methods improve.  Therefore, is it more practical to view a new chimney with a smooth surface smoke chamber as "more safe and will perform better" then previously accepted building practices, or view an older chimney as "not safe, with  less than adequate performance" because it does not meet the current accepted building practices?   If we were to to take the later stance, then it would follow that any home with knob and tube wiring be considered unsafe and will not perform its designed use adequately, rather then less safe and less practical .  All homes with two prong ungrounded outlets would be considered the same (all homes before 1960 if not upgraded), rather than less safe and less practical then homes with three prong grounded outlets.  All houses built with balloon framing before deck framing became the accepted norm would have to be completely rebuilt.  In short, major reconstruction would be necessary on most homes ever 20 years or so as the "common building practices" of the day changes.  This is not practical, nor is it the purpose of home inspections to deem older common practices as unsatisfactory.  Suggesting upgrades and improvements may very well be a part of a good inspection, but it should be seen in that light, as an improvement rather then a necessity.

Hopefully, the majority of home inspection companies will take the "common practice" approach in inspecting fireplaces, and document in their report that this is what the scope of their inspection initials.  At the same time it should also be reported that, while any given fireplace may appear to have functioned adequately for years, a smooth surface smoke chamber is "safer and will perform better" and further evaluation, investigation and improvement can be obtained by contacting a qualified mason or chimney sweep if the buyer so chooses. 

Below is a diagram of a properly built fireplace/chimney.  There are several building methods shown that are not found on older chimneys and some not often found on new chimneys -  see comments below.

At the top of this chimney it shows a formed cast concrete crown.  Most chimneys today do not have these cast crowns that overhang the brick work.  Typically, even today, most crowns are  only hand formed concrete on top of the brick.

The diagram also shows and air space between the flue lining and the outer masonry with a flexible sealant at the top.  This is rarely found, even on most chimneys built today.

In the diagram you can see the smoke chamber.  Most newly constructed fireplaces are built with a smoothly parged surface.  Most older fireplaces, accounting for the majority of fireplaces, which have been in use for many decades are not built with a smooth surface smoke chamber.

The conclusion: Almost ever chimney, old or new, could have been built in manner that would make them "safer"