This article explains how to spot attic ventilation defects in the soffits or building eaves, as visible from the attic or building interior.

This soffit venting discussion is part of "How to Correct Improper or Inadequate Attic or Under-Roof Ventilation in buildings", our discussion of "Attic Condensation". This article describes inspection methods and clues to detect roof venting deficiencies, insulation defects, and attic condensation problems in buildings. It describes proper roof ventilation placement, amounts, and other details.

Inspecting the Soffit or Eaves Vent System from the Attic - look for blockage

Here is our guide to Inspecting Attic and Under-Roof Ventilation - soffit intake vent adequacy. How to Correct Inadequate Attic Venting to Stop Attic Condensation, Ice Dam Leaks, Attic Mold, & Roof Structure Damage. How to detect roof venting deficiencies, attic insulation defects, and attic condensation problems

Inspecting in the building attic, we check to be sure that there is good air flow at the lower roof edges or "eaves". Even when we see apparent vents installed outside, such as soffit vent strips or perforated soffit covering material, the venting may be blocked or otherwise inadequate.

The cost to heat and cool a building is increased and the risk of an under-roof rot or mold problem is increased as well if the roof is not properly designed and vented.

For example, installing exit venting a the ridge without installing adequate intake venting at the building eaves will increase heat loss from the building during winter months. Warm air leaking into the attic or roof cavity from the building creates a convection current of rising air in the building.

When the convection current of warm moist air leaving at the ridge vent is unable to draw dry cool outdoor air into the under-roof space at the building eaves or lower roof edges, it tends to draw more heated air out of the living space.

Look for these insulation and ventilation defects a the building eaves or lower roof edges:

• Inadequate or incomplete insulation in the attic floor or knee walls.


• Insulation up tight against the roof decking - blocking air flow there, no air path along roof sheathing or decking


• Intake venting at the roof eaves blocked by insulation -
  
  See Blocked Soffit Intake Vents


• Intake venting at the roof eaves is only between some rafter pairs, not all rafter pairs -
  
  See Continuous Soffit Intake Venting Needed


• Moisture stains from ice dam leaks or roof leaks, found on rafters and roof sheathing, particularly at the lower roof edges over a poorly-insulated or poorly-vented attic or cathedral ceiling


• Bath vents or kitchen vents that spill moist air into the attic rather than directing it outdoors; vent fan ducts that are not insulated and that slope so that their interior condensate leaks back into the building.


• Mold stains on roof sheathing or rafters in areas of inadequate ventilation and high moisture.
  
  See Inspect Attics for Moisture or Mold for more indications of attic moisture

...

Continue reading at ROOF VENT SOFFIT, CONTINUOUS or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

• ATTIC CONDENSATION CAUSE & CURE
• ROOF VENT SOFFIT, CONTINUOUS
• ROOF VENTIILATION INTAKE-OUTLET RATIOS
• ROOF VENTILATION SPECIFICATIONS
• SOFFIT INTAKE VENT BLOCKED

Suggested citation for this web page

SOFFIT VENTILATION SPECS at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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INDEX to RELATED ARTICLES: ARTICLE INDEX to BUILDING VENTILATION

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