Myths of fire-rated walls and doors between house & garage.

A common mistake that home inspectors make when inspecting single family residences is related to opinions stated about the requirements for separation between the home and the attached garage. 

Their comments often leave them “out on a limb” when repairs are called for and a builder or repair person informs them there are no “fire-rated” requirements.

I should clarify, this article is based on 2015 IRC and may not be consistent in every regard with the codes amended or otherwise in your area.

I routinely hear erroneous statements about compromised “fire-rated surfaces” between the house and the garage.  Also common are statements declaring surfaces between the house and the garage are not “1 hr fire-rated,” or that the “1 hr fire-rated surfaces” are in some way compromised.

The wall between the house and the garage–believe it or not–is NOT a fire-rated assembly and is referred to in the code as the “Dwelling-Garage Separation.”

Meeting the “separation” requirements is really quite simple and minimal compared to what would be necessary in an actual “fire-rated assembly”  (As would be required between multiple dwelling units like condos, townhouses and duplexes etc.)

Typically, ½” drywall (or equivalent) is all that is necessary to meet the separation requirement. 

If there is living space above the garage, the ceiling would have to be 5/8” type “X” drywall (or equivalent).  Again, this is not a “fire-rated assembly,” but merely what is required to meet the proper “separation” requirements.

These wall and surface finishes have to have a flame-spread index not greater than 200, however wood frames and trim around doors and windows are excluded from this requirement.

Duct-work inside the garage, or duct-work that runs through these fire-resistant surfaces must be constructed of  minimum No. 26 gauge sheet steel or other approved material and shall not have openings into the garage. So this means no return air registers or heat supply registers inside the garage.

Openings around other types of penetrations in the walls and ceilings (ductwork, pipes, wires, etc) must be filled with an approved material to resist the free passage of flame and products of combustion.  There is nothing in the code, for single family residential construction, that prohibits plastic piping through these fire-resistant surfaces.  This is another common incorrect call-out by home inspectors.  The openings around them merely have to be properly sealed.

Pull-down stairs in a garage ceiling would be required to meet the requirements of 1/2 drywall or equivalent, or have a 20 minute fire-rating.

The door or doors placed in this “separation” are also frequently misunderstood and incorrectly reported on.

For the door between the house and the garage, all that is necessary is to install a door that meets the “separation requirements” of the code.  Of course this door can never lead to a bedroom.

There is nothing that says it has to be a “fire-rated door,” as frequently reported by home inspectors. 

While this may seem confusing, if one looks at the code it becomes clearer.  It also reveals the source of some of the confusion.

To meet separation requirements, the door must be one of three types of doors:  a solid wood door not less than 1-3/8 inches thick, a solid or honeycomb core steel doors not less than 1-3/8 inches thick, or a 20-minute fire-rated door, with a self-closing device.  Another thing to note, is that a 1-3/4″ thick solid wood raised panel door would likely not comply because the minimum thickness at the recesses would likely be less than 1-3/8.”

As a side note, that little comma after “door” in: “door, with a self-closing device,” is consistent with its pertaining to all three choices–not just the 20-minute type door.  If it applied to only that type of door the comma should not be there.

The first two types are fairly self explanatory but the inclusion of the third type has lead to a great deal of confusion because a door that is a “20-minute fire-rated door” leads one to think that the door in general, and thus the walls and ceiling, have to somehow be “fire-rated.”

Also having a “fire-rating” (as all materials in the home do) does not make any of this a “fire-rated assembly.”  It just means the fire-resistant surfaces are specified to be constructed of materials known to have known fire-resistant characteristics.

For a door to achieve a 20-minute fire-rating it has to go through testing procedures by Underwriters Laboratories and then it receives its “UL listing” as a fire-rated assembly. 

All three types of doors will require weather-stripping/seals on all four edges of the door to prevent the passage of gases that may be drawn into the home, as well as meet energy efficiency standards.

Hopefully this post will help clear up some of the confusion.

By Charles Buell, Real Estate Inspections in Seattle

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Thermopane-in-the-Butt Windows

This is a rant that has been simmering for a few years.

However well intentioned, I think the whole notion of thermopane windows is misguided. When I started building houses in the mid 70’s the idea had really taken hold as people became interested in conserving energy and improving the comfort of their homes.

It was not long before the requirements for insulating glass became codified with different requirements varying with climate.

We are now more than 40 years past the time when I started building and most of the seals have failed on those windows. That is, except for the windows that were not sealed thermopane type. Many of the houses I built had Pella type windows with removable interior panels. Those windows are still performing exceptionally.

I do not belief it can ever be economically justified–over the life of the house–to install thermopane windows when you factor in the cost of replacing all that glass in less than 30 years. This becomes even truer if the windows are triple-pane or have funny gasses pumped into them or reflective coatings applied to them.

Some of the newer windows with the “Warm Edge Spacers” are known to fail in less than 15 years.

I think it is time to revisit the whole business of insulating glass windows and see if the use of removable panel type insulating glass–or even old fashioned storm type windows might have some merit–or at least be an option.  Throwing money at the fruit so far off the ground may not have proved to be the wisest path–and is rotting by the time we get to it.

The amount of energy expended to create thermopane windows simply cannot be justified against how long they last. Well cared for windows should last indefinitely, whereas sealed unit, thermopane windows are a version of job security for the windows replacement industry.

I installed thermopane windows in my kitchen about 18 years ago, and this year two of the panes failed.

This is unacceptable in my opinion. The labor and materials to replace these units will easily cost more money and consume more energy than any imagined savings accrued over the 18 years. If the windows had been a removable glass panel type windows, they would have continued to keep on saving energy, eventually even paying for themselves over the life of the home—probably sooner.

I would like feedback from anyone that can make a case for sealed unit, thermopane windows.

Charles Buell, Real Estate Inspections in Seattle

What is a little missing insulation between friends?

Sometimes it is the little things that get you.

However, these little things can end up costing you a lot of money over time.

At a recent inspection I had a house where the insulation details were not well thought out.  Without going into a discussion about the “type” of insulation, lets just discuss in the simplest of terms how the system was working—or not working as the case might be. 

The following sketch shows how the walls are insulated up to the ceiling and then the roof plane itself is insulated.  What got missed was the wall between the roof and the ceiling.  This space above the ceiling is essentially “conditioned” space and the short wall between has to be insulated to have continuous insulation around the conditioned space.

This next picture shows what that un-insulated area looks like with thermal imaging from the exterior.  However this is a space between the second floor and the main floor ceiling.

Going back to the original drawing, here is an exterior view of that un-insulated space—as seen by thermal imaging.  The un-insulated areas appear warmer (the white-yellow areas)

The same areas of the above picture as seen from the inside of the attic space with the un-insulated areas appearing “cooler” (the black areas).

These areas will need to be well-insulated to prevent wasting of energy that increases both heating and cooling loads of the home. 

The fiberglass insulation should be encapsulated, and for more information about that:  All Fiberglass Insulation Must be Encapsulated.

 By Charles Buell, Real Estate Inspections in Seattle

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