Reuben's Home Inspection Blog

Photos Of Attic Bypasses With Explanations

January 17th, 2009 | 7 comments

A few posts ago I included several photos of attic problems in my blog Reasons to Insulate, and said I would come back to them in a later post with explanations.   Here we go!

This photo shows a bypass to the attic space around a furnace flue.  The square piece of metal is not sealed to the drywall, and there is a fair amount of air leaking into the attic space from this gap.  I brushed the insulation away to show the gap for the photo.  The insulation has turned black because of the air leakage – as the warm air passes through the insulation, the fiberglass acts like a filter and collects the dust / dirt particles in the air.  Any time you see darkened insulation, you can bet there is air leakage occuring.  This is often confused with mold because it looks similar.
Attic bypass at furnace vent

In this photo the gap around the plumbing vent is allowing air in to the attic.  Notice the dark insulation?  An easy fix would be to fill the gap with expanding foam.
Attic bypass at plumbing vent

This photo shows several holes that wires pass through to get to the attic.  These holes could easily be sealed up with expanding foam.  I didn’t move any insulation to find these holes – this is exactly how the insulation looked when I climbed in to the attic, so there is obviously missing insulation here too.   The recommended insulation depth for loose fill fiberglass is 18″, but the silver areas have no insulation at all.
Attic bypass at wires

This is another attic space in desperate need of more insulation.  Someone probably moved the insulation away to install a ceiling fan, but never bothered to put it back.
Missing Insulation

There is a major attic bypass around this furnace flue, and this is one of the most common bypasses that I find.  You can clearly see the walls on the floor below, and you can even see the basement ceiling from this opening!  To correct this bypass, the owner will need to install a large piece of wood, metal, drywall, or any other material that air won’t pass through, and caulk all of the joints to make it airtight.  This wasn’t obvious just by looking, but I always make a point of pulling the insulation away around furnace flues to look for bypasses.  The fiberglass batt on the right side of the photo was sitting on top of this opening.
huge attic bypass

Hopefully these photos have helped to illustrate exactly what attic bypasses are and how to correct some of the issues.

Reuben Saltzman, Structure Tech Home Inspections – EmailMinneapolis Home Inspections

7 responses to “Photos Of Attic Bypasses With Explanations”

  1. Ice Dams « Reuben’s Home Inspection Blog
    January 17, 2009, 12:56 pm

    [...] Reuben’s Home Inspection Blog Home Inspections in the Twin Cities « Photos Of Problems With Explanations [...]

  2. Reasons To Insulate « Reuben’s Home Inspection Blog
    January 17, 2009, 12:58 pm

    [...] Related Post: Photos Of Problems With Explanations [...]

  3. Attic Problems On A New Construction Home | Reuben's Home Inspection Blog
    March 3, 2009, 6:48 am

    [...] builder had taken all of the necessary steps to seal all of the bypasses to the attic,  by doing something most builders never do.  Before blowing in loose-fill [...]

  4. My Beef With One-And-One-Half Story Houses | Reuben's Home Inspection Blog
    May 11, 2010, 3:49 am

    [...] traditional insulation, attic bypasses also need to be sealed… and these houses have a ton of them.  Perhaps the largest bypass is [...]

  5. Why Is There Frost In My Attic? | Reuben's Home Inspection Blog
    December 7, 2010, 4:58 am

    [...] Attic bypasses are passageways for warm air to leak in to the attic.  A few common places to find these gaps are around furnace vents, plumbing vents, electrical boxes, and electrical wires coming in to the attic.  Any bath fans, kitchen fans, or dryers venting in to the attic space will absolutely wreak havoc.  Even small gaps in any of these vents can bring a lot of moisture in to the attic.  For more tips on locating attic air leaks and sealing them, download this handout. [...]

  6. Realtor.ioRealtor.io - WordPress for Realtors On-The-Go
    December 8, 2010, 9:44 am

    [...] Attic bypasses are passageways for warm air to leak in to the attic.  A few common places to find these gaps are around furnace vents, plumbing vents, electrical boxes, and electrical wires coming in to the attic.  Any bath fans, kitchen fans, or dryers venting in to the attic space will absolutely wreak havoc.  Even small gaps in any of these vents can bring a lot of moisture in to the attic.  For more tips on locating attic air leaks and sealing them, download this handout. [...]

  7. Thinking of adding more insulation to your attic? Read this first. | Reuben's Home Inspection Blog
    February 15, 2011, 4:42 am

    [...] an older attic, it’s pretty much a guarantee that there are attic bypasses present.  Attic bypasses are passageways for warm air to get in to the attic, and they’re the driving force behind ice [...]

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