Seattle Home Inspector's Blog


Missing fire-blocking in older homes—fire hazard and energy waster

Many older homes have missing fire-blocking.  Fire-blocking is just what it sounds like—pretty much.  The idea is that we want to “block” the spread of fire from one level to another. 

Fire-blocking can be made of almost any approved material—even wood blocks if the space is such that a piece of wood will work.  Sometimes it is drywall that covers the opening.  Sometimes it amounts to metal rings like would be necessary around where chimney and gas appliance vents run through ceiling or floor structures.  Sometimes it is spray foam insulation or rockwool insulation stuffed in cracks.

In simplest terms we are looking to minimize the flow of air and thus heat and fire from lower areas to upper areas.  For example we do not want a fire in the living room to have immediate access to the roof structure through missing fire-blocking as is very common at uncapped stair wells, or around chimneys and dropped ceilings.  In the following two pictures we can see missing fire-blocking around a chimney and missing fire-blocking over a stair well.  Also note the missing insulation in the walls around the stairwell and in the walls that enclose the chimney.



When you are in your attic, you should never be able to look down inside a space and see the surrounding walls.  You should never be able to see the top of your fireplace surround etc like in this next picture.


This missing fire-blocking also affects the energy efficiency and comfort of the home.  In the winter missing fire-blocking will allow cold air to drop into the spaces and allow heat from the living space to escape.  Typically the walls around these spaces will not be insulated because, if the fire-blocking was in place, the insulation would be in the attic.

Home Inspectors should always identify these by-passes for both safety and energy efficiency.  Often these breaches are not located, or not visible, if the inspector cannot or does not traverse the attic--or they are hidden for some other reason.

This is a good example of how older houses can benefit from improvement, for fire safety and energy efficiency, even while possibly considered acceptable at the time of construction.  It is doubtful that this would have been acceptable for a very long time, given how long it has been known how fire travels in structures.  It is more likely that there was no oversight to catch it.


Charles Buell, Real Estate Inspections in Seattle

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Comment balloon 9 commentsCharles Buell • December 15 2013 06:41AM


I had an inspector put this request in a report this year, and even tho another inspector and sellers didn't think it was necessary/and was costly, they did it to appease the buyer

Posted by Kristin Johnston - REALTOR®, Giving Back With Each Home Sold! (RE/MAX Realty Center ) over 5 years ago

If an inspector cannot traverse the attic that's one thing.... but if he DOES not do it... shame on him! 

People do not realize how fire can spread and heat can travel up those open areas, and how quickly too! Doesn't take much of an opening either!

Posted by Fred Hernden, CMI, Albuquerque area Master Inspector (Superior Home Inspections - Greater Albuquerque Area) over 5 years ago

Kristin, unfortunately you can never predict when fire-blocking will be necessary for fire safety, but for energy efficiency--especially in your neck of the woods--it is pretty much essential

Fred, I think sometimes the smaller the worse because of chimney effect.

Posted by Charles Buell, Seattle Home Inspector (Charles Buell Inspections Inc.) over 5 years ago


Just had an inspection on a home built in 1920 and had these issues in several locations of the home.

Posted by Bill and MaryAnn Wagner, Jersey Shore and South Jersey Real Estate (Wagner Real Estate Group) over 5 years ago

Bill and MaryAnn.  The first picture above is from a 1947 house, the second picture a 1960 house and the last picture from 2007.  These breaches can be present in any age home but certainly more so the older the home is.

Posted by Charles Buell, Seattle Home Inspector (Charles Buell Inspections Inc.) over 5 years ago

Fire safety and energy efficiency has come a long way the last few decades Charles! It strange to see these large openings that are no longer legal.

Posted by Tom Arstingstall, General Contractor, Dry Rot, Water Damage Sacramento, El Dorado County - (916) 765-5366, General Contractor, Dry Rot and Water Damage (Dry Rot and Water Damage Mobile - 916-765-5366) over 5 years ago

It's hard sometimes for clients to understand that this was "the way they did it then."  I mention the large gaps, but try not to frighten anyone about fire safety.  Some of those holes, like the ones above, are hard to "fire stop" now!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 5 years ago

I agree with Jay. Hard to know if the space was allowed or just an oversight. I mention the energy efficiency stand point of the gaps and discuss the fire safety aspect as well.  

Posted by James Quarello, Connecticut Home Inspector (JRV Home Inspection Services, LLC) over 5 years ago

Tom, they are all too common and obvious that is for sure

Jay, most of these fall typically under the, "In the context of other attic repairs......"  Of course if anyone is interested in improving the energy efficiency of the home it will be essential to fix these bypasses.

Jim, it depends on the age of the house, but fire-blocking goes back a long ways.  In some ways the energy by-passes are almost more important especially in areas prone to ice dams.


Posted by Charles Buell, Seattle Home Inspector (Charles Buell Inspections Inc.) over 5 years ago