What I'm Seeing Now

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The Bath Fans Huffed And Puffed And Blew The ... Frosty Dew Down?

What did you say - the bath fans huffed and puffed and blew the frosty dew down?

Come again?

This is a 1970s house, and surprisingly has both original bathroom vent fans operating.  But there are no soffit vents, and I noticed no roof or side vent openings anywhere while I was looking at the house outside.

So I was interested in how everything inside exhausts air!

I was not disappointed.

But it was interesting.  I saw something I had never seen before.

Looking into the attic space I saw frosty dew distinctly located in two different places.

Frosty dew?  How does that happen?

Apparently neither vent has a operating interior flap, so heat from the house makes its way out through the vent openings in the two bath ceilings.  Heat seeks cold, and the previous night it was extremely cold.  I arrived at the house and it was 15F.  During the night it was down to 7F or so.

For lack of a better word, frosty dew could be seen extending from the edge of the roof and making its way up the slanted sheathing.  That heat made its way to the edge of the roof and simply rose from there, freezing along its way.

Turning on the fans to make sure they discharged into the attic, as I suspected, an interesting thing happened!

The blowing air gently began melting the frosty dew!

This homeowner had added extra insulation.  On top of the 70s fiberglass was blown additional cellulose insulation.  A good thing!  But it still may have blocked each bath fan's discharge somewhat. Still, the air moves and that evidence can be seen.

Nonetheless, it's always best to vent bathroom air outdoors.  In fact, today that is the code.

What was the code in this county in the 70s?  I don't know.  Apparently to the edge of the roof!  With no soffit vents it has no where to go but up and in.

And as warm air gently seeps out the bath vents and crawls up the sheathing, it creates dew, which in this attic, the night before, had frozen!

My recommendation:  it's good to huff and puff if you are a bathroom exhaust fan!  But it's best to huff and puff that air outdoors.  Even if it is not the current code that would be best.  It causes less stress to the house and roof sheathing!  And doing so is the Best Practice  in any case.  If you are a wolf and want to huff and puff, may I suggest you NOT go down the chimney.  The pigs are waiting.

 

 

Jay Markanich Real Estate Inspections, LLC  

Based in Bristow, serving all of Northern Virginia.

Office (703) 330-6388   Cell (703) 585-7560

www.jaymarinspect.com


Comment balloon 16 commentsJay Markanich • January 14 2015 03:36AM

Comments

Not venting properly is something we see often in older home inspection reports....gotta wonder if there was a code....

Posted by Sally K. & David L. Hanson, WI Realtors - Luxury - Divorce (EXP Realty 414-525-0563) over 3 years ago

Well morning Jay, I had thought you had seen most everything in homes.  To be a first for you it must have been something that doesn't happen often (thankfully)

Posted by James Dray, Exceptional Agents, Outstanding Results (Fathom Realty AR LLC) over 3 years ago

Probably not S&D.  Usually I wonder if there is going to be a fan!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 3 years ago

I am sometimes tempted to think I have seen it all James, and then get very surprised by nature and creativity!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 3 years ago

Brrr, I'm chilly just looking at those photos.

Yes, venting outside is best!

Posted by Kat Palmiotti, The House Kat (Grand Lux Realty, Monroe NY, 914-419-0270, kat@thehousekat.com) over 3 years ago

It was really cold that day Kat!  I actually wore gloves!  I'm a tough guy, I never wear gloves!

Imagine.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 3 years ago

Gloves are recommended, along with socks.

This old home demonstrates the undeniable, that is that an understanding of the laws of physics helps to understand why heat and cold do what they do in our homes.

Posted by Lenn Harley, Real Estate Broker - Virginia & Maryland (Lenn Harley, Homefinders.com, MD & VA Homes and Real Estate) over 3 years ago

Good morning Jay,

Would be nice to have it exhaust onto the windshield here on a day like today!

Make yourself a great day.

Posted by Raymond E. Camp, Licensed Real Estate Salesperson Greater Rochester (Howard Hanna Real Estate Services) over 3 years ago

True Lenn, and as such they have to be controlled.  And can be.

It's cold and snowy here too Raymond.  My daughter needs a ride to math class today.  I hope the windshield stays frost free!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 3 years ago

Jay, sure sounds like this will definitely go on the inspection notice, and always fun to listen to inspectors' findings! 

Posted by Joan Cox, Denver Real Estate - Selling One Home at a Time (Metro Brokers - House to Home, Inc. - Denver Real Estate - 720-231-6373) over 3 years ago

Inspections can be fun Joan.  I learn new things all the time!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 3 years ago

Jay, I'm afraid I often see bathroom fans discharging into the attic. Not a good practice. Usually those homes do have vented soffits and roof vents. Still a bad idea, right?

Posted by Tom White, Franklin Homes Realty LLC, Franklin TN (Franklin Homes Realty LLC (615) 495-0752 or www.FranklinHomesRealty.com) over 3 years ago

I think they were merely using the insulation as a filter, to filter out all those nasty odors before they release them into the atmosphere! Solid theory, don't you think? And you turn on the fans to melt the frost... perfect system!

Posted by Fred Hernden, CMI, Albuquerque area Master Inspector (Superior Home Inspections - Greater Albuquerque Area) over 3 years ago

Tom - venting directly to the outdoors, either roof or siding, is the current code and best practice. 

Fred - I think that filtration thing is also a best practice.  And who doesn't want to get rid of Jack Frost inside the house!?

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 3 years ago

Jay, In one of my rental condos we replace the non vented fans in the two bathrooms. 70's construction. These vent fans are basically useless. They blow the bathroom air through a small filter and vent back into the room. Result, the humidity stays in the room. So we lent the tenant a dehumidifier to combat the extra moister in the air in the upstairs, and checked for leaks.

Hopefully, problem solved.

Posted by Mark Horan, "The Resident Chef" - Resident Team Realty LLC & (Resident Team Realty, LLC & Toni's Property Management LLC) over 3 years ago

That's a lot of work for what seems to be a net zero Mark!  But no leaks is a good thing.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 3 years ago

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