January Maintenance Reminders

Inspect Attic for Signs of Frost

Seal Attic Bypasses

 Attic bypasses are simply gaps, or passageways that allow house air to leak into the attic.  The most common locations for bypasses are at furnace exhaust vents, plumbing vents, electrical boxes, and electrical wires that pass through top plates.  Of course, bath fans, and kitchen fans must also not be venting into the attic space.

When is the last time you looked into your attic space?  If you're like most homeowners, you have never looked in your attic.  Well now is a good time to do so.  Why?  Because when the cold December and January temperatures roll in, it's possible for frost to form on the attic structure.  This does not occur during the warmer months and evidence of past problems (i.e. stained or decayed wood) is not always present.

Small amounts of frost are common, but if the frost buildup becomes significant, it can lead to problems.  When frost melts, it wets the attic insulation, which lowers the R-value (insulating value).  In some cases, there will be enough moisture to actually stain the ceilings.  Stains are most commonly found at ceiling penetrations, such as light fixtures, or smoke detectors.

Minor frost formation on nail heads

If the frost buildup occurs regularly, the continual saturation of the roof decking can cause the plywood to delaminate and rot.

excessive frost formation on sheathing

Decayed / delaminated sheathing

Why Does Frost Form in Attics?
 

When warm, moisture-filled house air leaks into the attic, it condenses on the cold surfaces.  That is why you may see frost on the roof structure, or on the nail heads that penetrate the roof sheathing.  This flow of warm air can also cause (or contribute to) the formation of ice dams on roofs.  As many of you know, there has been an abundance of ice dam problems in the Twin Cities this winter.

This particular home shows the classic signs of an ice dam problem.  First, there is an excessive buildup of ice at the overhang and the snow melt on the roof above this area is obvious.  There also are streak marks on the siding, which suggest that moisture has backed up below the shingles and has leaked through the soffit area (leakage into the wall / ceiling structure would also be possible in this situation).

In most cases, stopping the flow of house air into the attic is the key to eliminating these problems.

This image shows some of the more common locations for leaks.

Kitchen and bathroom soffit areas are another common leakage source.  In older homes, there often is no drywall covering the openings to these spaces - from the attic side.

 

Attic hatches are often times not insulated, or are inadequately insulated.
Repairs
 
In most cases, gaps can be sealed with spray foam insulation, but when sealing around a heat generating item, such as a furnace exhaust flue, sheet metal is recommended.

For a much more detailed description of thermal bypasses, and recommended solutions, click here.
 

Lower the Humidity in Your Home

 It is nearly impossible to seal every little bypass to an attic, but if most bypasses are sealed, it is unlikely for you to have frost problems if you also maintain normal levels of humidity in your home.  Excessive humidity levels are common if you:

1)     Have a whole house humidifier and set it too high.

2)     Do not operate your kitchen vent while cooking.
 3)     Do not operate your bath fan while bathing / showering (the fan should also run for at least 15 minutes after showering).