A Common Problem With Roof Caps For Bath Fans

I start every home inspection by giving myself a quick tour of the inside of the house to get an idea of what I need to be looking for while inspecting the exterior.  While doing my brief initial walk-thru of the interior, I also turn on everything that removes air from the house, such as bath fans, kitchen exhaust fans, and dryers.  I do this to create negative pressure in the house so I can later make sure that all of the fuel burning appliances still draft properly, and to make sure that all of the fans exhaust the way they're supposed to.

As I turn the fans on in the home, I make a mental note of how many fans I've turned on, and I account for each exhaust while inspecting the exterior.  I've caught a ridiculous amount of bathroom exhaust fans there were vented in to attics or finished floor / ceiling spaces by doing this.  This is also a way for me to check to see that the fans are actually exhausting air, not just making a lot of noise.

I check the operation of bath fans by just putting my hand at the exhaust and making sure air is blowing out - after first checking for wasp nests, of course.  About one-third of the fans that are supposed to be exhausting through the roof are exhausting to a cap with a backdraft damper that is stuck closed, which causes a good portion of the warm, moist air to exhaust in to the attic space (pictured above).  Most of the dampers that I see are made by Broan, so I'll be talking about their specific roof cap.

Most roof caps for bath fan exhausts have a light aluminum backdraft damper which rests on a sealant strip, which is basically a foam piece of weatherstripping.  This sealant strip is installed to keep cold air from coming in, and according to a Broan customer service rep, it also "helps to prevent unbearable metal on metal chatter."  I'd have to agree!  Unfortunately, when the sealant strip gets hot from the sun beating on the cap all day, it gets sticky.  Eventually, the damper gets completely stuck to the sealant strip, which prevents the damper from opening.  This is what causes the black staining in the attic that you see pictured above.

When I find this defect, I usually take my awl and pry the damper open, which allows the damper to open and close freely again... until the next hot day.  Broan received so many complaints about these dampers getting stuck that they changed the material that was used for the sealant strip in 2006.  Now the sealant strips are made of polyester, and they don't get stuck any more.  If you own a house with older roof caps, you can order a replacement damper and sealant strip from Broan by calling 800-558-1711, part # s7017696.  Click here for damper replacement instructions - they're listed under the Maintenance section.  I'll be recommending this to a lot of my customers.

Reuben Saltzman, Structure Tech Home Inspections - Email - Minnesota Home Inspector


Special thanks to Judi Weber at Broan for contributing information to help write this.

Break The Attic 'Seal'? Yes, Every Time!

One of the biggest sources of contention I’ve had to deal with doing home inspections is whether or not a sealed attic access panel should be ‘broken’ to access the attic; even more specifically, whether or not I should be allowed to break the seal.  If you’re not sure what I’m talking about, here’s a photo of an attic access panel. To understand this issue, you need to understand why this panel is here and why it has been sealed.

First, the access panel is here because it is required by the Minnesota State Building Code.  The panel is here for me (or anyone else) to use to get in to the attic to inspect it, or to do work.  That’s it, plain and simple.  The Minnesota State Building Code, section R807.1 says

“…an attic access opening shall be provided to attic areas that exceed 30 square feet and have a vertical height of 30 inches or greater.”

This covers just about every attic space.  Outside of Minnesota, the building code will typically read the exact same way, as this is taken from the International Residential Code.

So why is the panel sealed?  In a new home, the panel only gets incidentally ‘sealed’.  The panel does not get attached to anything; it just gets set down on the opening. When the ceiling finish is applied, which is often spray texture, the seam between the panel and the rest of the ceiling gets covered over.  This is what people are referring to when they say the access has been ‘sealed.’  There is very rarely any caulking or adhesive keeping this panel in place.

This can become a subject of contention when I inspect a house where no one has been in the attic since the ceiling finish has been applied… or as most people say, the access has been sealed.  I say ‘sealed’ too, just because it’s easier than saying “incidentally covered over with a finished surface.”  My evaluation of the attic is a major part of a home inspection, and it’s important for buyers to know about any defects in the attic.  This is a place that homeowners may never even go in to as long as they own their home.  For this reason, I break the seal on just about every home I inspect, but I never do this without permission from the buyer.

The biggest sources of contention come from parties attending the inspection that are under the impression that attic spaces in new homes don’t need to be inspected.  Well, by that logic, new homes wouldn’t need to be inspected at all.  Please check out my blog on New Construction Inspections, and you’ll understand how important inspections are on newly built properties.  A large portion of the problems I find in new construction homes occur in the attic.  Just for fun, here's a photo I took at a 2004 built Minneapolis townhouse - yes, this attic was completely uninsulated.  Don't listen to anyone that tells you new attics don't need to be inspected, or that attic access panels shouldn't be opened.  They're not looking out for your best interest, or they've been mis-informed.

Missing Insulation

The other common argument I hear about not going in the attic is that the panel will look bad after I open it.  This just isn’t true.  If a knife is used to cut the panel open, it will usually leave a noticeable scar in the ceiling, but if the panel is lightly bumped open, it will usually set back down and look almost identical to the way it did before I opened it.  Much of the time, you can’t even tell the difference between a sealed and unsealed panel unless you look closely.

The bottom line is that attic access panels are there for the attic to be accessed, and this is something that should be done at every home inspection.


Reuben Saltzman, Structure Tech Home Inspections - Email - Minneapolis Home Inspections