How to Inspect the Building Exterior to Detect & Correct Attic Condensation and Ice Dam Leaks in buildings
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How to Inspect the Building Exterior for Wet Site, Sources of Attic Condensation, Moisture, & Roof Venting Problems & Attic Mold
How to detect roof venting deficiencies, attic insulation defects, and attic condensation problems
Questions & answers about attic moisture, condensation & ventilation: how to spot roof venting problmes from outside the building
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.
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A Photo Guide for Inspecting the Building Exterior for Wet Site, Sources of Attic Condensation, & Roof Venting Problems
Here we provide a series of photographs taken of the exterior of buildings, demonstrating visual clues that can predict a problem with ice dam leaks into these homes.
No Soffit Intake Vents on a Roof Means Ice Dams
In freezing climates, as in our photograph at page top, given the age of construction (pre 1900), the brown color of the stains (oils from roof sheathing boards that have been wet),
and the shape of the roof edge (probably there was a built-in eaves trough gutter), it is likely that when we inspect the attic
interior we'll see that despite the perforated soffit covers, the roof has no intake venting and there has been a long
history of ice dam leaks on this building.
Inadequate soffit or ridge venting risks attic moisture, mold, ice dams, as show by these photos
In both heating and cooling climates, insufficient roof ventilation risks attic or roof cavity condensation, mold, rot, and in some cases increased heating or cooling costs for the building. And as we show just below, do not assume that your building has working roof ventilation even if you see perforated panels covering the building soffit underside.
Fake Soffit Vents?
Too often building exterior renovations include covering an existing, solid, un-vented
building soffit or eaves with perforated panels, forming a "faux vent" system since the perforations are not really passing
any air into the building attic.
It's easy to spot this condition both by visual inspection and, where accessible, by
pressing on the perforated panels - if they are over an open space they will move easily.
In our photograph at left, although perforated panels are installed on soffits of this older home, we see extensive leak stains on that material. From outside we posit that either the perforated panels were installed over solid wood - there is no actual soffit intake venting for the attic, or the building simply has little or no attic insulation, resulting in lots of heat loss into the attic during winter months, combined with freezing of melting snow at the colder roof edges.
No Soffits so No Soffit Vents Means Ice Dams and Wall Leaks are Likely
The home shown in our photograph at left was built with no roof overhang whatsoever - or no roof soffits or eaves extension past the building walls. Not only does roof runoff too often run down the exterior wall surface, inviting rot or insect damage or wall leaks, but also this construction makes it tricky to obtain any roof cavity intake venting.
Special products such as the Hicks (TM) starter vent can be used at roof eaves in this location, but an air path must also be provided inside under the roof decking.
The window at the building right corner tells us that cathedral ceilings were probably installed inside this home - under-roof venting would still be a good step to avoid roof cavity condensation, leaks, mold, or related damage.
Tiny Gable End Vents can Predict Ice Dams and Inadequate Attic Ventilation on buildings
The photograph shown at left demonstrates a tiny gable-end vent in an older building.
This home combines stone construction, multiple shingle layers, shaded site with (unseen) no other attic intake or outlet ventilation, to make attic condensation problems and seasonal ice dam leaks likely.
Photographs of Building Siding Stains Can Indicate Ice Dam Leaks
This photo shows siding stains caused by roof ice dam leaks into the wall cavity. Notice that the soffit is un-vented on this older home. Roof leaks into the wall cavity have run down the walls and exited between clapboards, leaving stains and peeling paint.
Roof leaks in this area from any cause, ice dams or work, leaky roofing materials will all produce this effect.
Photos of Use of Heating Tapes on Roof Edges Tells the Ice Dam Story
This photo shows roof edge heating tapes installed by an owner to attempt to melt channels through ice that may accumulate at the roof eaves in winter. This is an inexpensive band-aid that may be sufficient if ice dam formation on a roof is rare and/or it is difficult to install good under-roof venting.
This roof has eaves and a ridge that could have been vented.
If a roof shape prevents easy installation of under-roof venting, or if a home is located where building custom excludes under-roof venting, use of an ice-and-water shield product under the shingles at roof edges, or use of metal covering the lower roof slopes are other measures taken to prevent ice dam leaks into the building interior.
Signs of Roof Ice Dam Problems Can Be Seen in Any Season
In addition to our photos showing missing roof intake or outlet venting, roof leak stains, and similar clues, you may be able to spot evidence of attempts to remove roof ice dams by chopping at the ice itself.
Usually attempts to remove roof ice by chopping at it results in damaged roof shingles and sometimes holes in nearby flashing or gutters as shown in this photo.
You'll also spot chop or cut marks in roof shingles at the lower roof edges when this procedure has been attempted.
A Summary of Inspection Tips for Roof Venting & Ice Dam Problems
The first signs of a probable attic condensation problem may there for observation before even entering a building.
Look at the roof. If you're in a cold climate during winter months you may see areas of snow-melt showing where there is an insulation defect. Or you may see actual severe ice dams at the roof eaves.
If the shingles are exposed look for signs of attic moisture in their condition: if there is a high level of attic moisture, unless the roof is quite young,
you might see puckered shingles in the classic "fishmouth" pattern.
This shingle curling is quite obvious. If you inspect the exterior roof surface first, on an old roof you'll note shingles which are brittle and which may crack or break. (Don't walk on such surfaces.) If the roof sheathing is plywood, you may sense
surface deflection which could simply be thin 3/8" plywood (no longer permitted in most jurisdictions) or it could be damaged from heat or moisture. (Beware of falling through).
Look at the ridge. If there is no ridge vent there is no good outlet for an under-roof attic venting system and this roof will be difficult to ventilate. When you make your inside inspection you will also inspect the roof below any "apparent" ridge vents seen outside, as sometimes we find that a faux ridge vent was installed with no openings cut into the roof cavity. See Inspect the Ridge Vent System from the Attic.
Look at the eaves or soffits. If there are no continuous intake vents at the soffits, this roof will be difficult to ventilate. And when you make your inside inspection you will look for light or other indications that the eave or soffit vents you found are real, not faux. See Inspect Attics for Moisture or Mold.
Critique, contributions wanted: Contact Us to suggest corrections or additions to articles at this website, and if you wish, to receive online listing and credit as a contributor. Particular thanks are due to the many experts and also consumers who read and critique technical articles at InspectAPedia.com.
Alan Carson Carson Dunlop Associates, Toronto, Ontario. Mr. Carson is a home inspection professional, educator, researcher, writer, and a principal of Carson Dunlop Associates, a Toronto home inspection and education firm. Mr. Carson is a past president of ASHI, the American Society of Home Inspectors
Some great illustrations of the proper under-roof ventilation pathways are offered by Carson Dunlop.
Mark Cramer Inspection Services Mark Cramer, Tampa Florida, Mr. Cramer is a past president of ASHI, the American Society of Home Inspectors and is a Florida home inspector and home inspection educator. (727) 595-4211 mark@BestTampaInspector.com 11/06 & 12/08
John Annunziata, P.E. - NY Metro ASHI during informal chapter discussions about roof and attic ventilation options (1986-1996).
Technical reviewers are invited to comment or ask questions - contact us
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Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.
The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 2010, $69.00 U.S., is available from Carson Dunlop. The Home Reference Book is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. InspectAPedia.com ® author/editor Daniel Friedman is a contributing author. Field inspection worksheets are included at the back of the volume.
"The Elimination of Unsafe Guardrails, a Progress Report," Elliott O. Stephenson, Building Standards, March-April 1993
"Are Functional Handrails Within Our Grasp" Jake Pauls, Building Standards, January-February 1991
Access Ramp building codes:
UBC 1003.3.4.3
BOCA 1016.3
ADA 4.8.2
IBC 1010.2
Access Ramp Standards:
ADA (Americans with Disabilities Act), Public Law 101-336. 7/26/90 is very often cited by other sources for good design of stairs and ramps etc. even where disabled individuals are not the design target.
ANSI A117.4 Accessible and Usable buildings and Facilities (earlier version was incorporated into the ADA)
ASTM F 1637, Standard Practice for Safe Walking Surfaces, (Similar to the above standards)
"Energy Savers: Whole-House Supply Ventilation Systems [copy on file as /interiors/Energy_Savers_Whole-House_Supply_Vent.pdf ] - ", U.S. Department of Energy energysavers.gov/your_home/insulation_airsealing/index.cfm/mytopic=11880?print
"Energy Savers: Whole-House Exhaust Ventilation Systems [copy on file as /interiors/Energy_Savers_Whole-House_Exhaust.pdf ] - ", U.S. Department of Energy energysavers.gov/your_home/insulation_airsealing/index.cfm/mytopic=11870
"Energy Savers: Ventilation [copy on file as /interiors/Energy_Savers_Ventilation.pdf ] - ", U.S. Department of Energy
"Energy Savers: Natural Ventilation [copy on file as /interiors/Energy_Savers_Natural_Ventilation.pdf ] - ", U.S. Department of Energy
"Energy Savers: Energy Recovery Ventilation Systems [copy on file as /interiors/Energy_Savers_Energy_Recovery_Venting.pdf ] - ", U.S. Department of Energy energysavers.gov/your_home/insulation_airsealing/index.cfm/mytopic=11900
"Energy Savers: Detecting Air Leaks [copy on file as /interiors/Energy_Savers_Detect_Air_Leaks.pdf ] - ", U.S. Department of Energy
"Energy Savers: Air Sealing [copy on file as /interiors/Energy_Savers_Air_Sealing_1.pdf ] - ", U.S. Department of Energy
Falls and Related Injuries: Slips, Trips, Missteps, and Their Consequences, Lawyers & Judges Publishing, (June 2002), ISBN-10: 0913875430 ISBN-13: 978-0913875438 "Falls in the home and public places are the second leading cause of unintentional injury deaths in the United States, but are overlooked in most literature. This book is unique in that it is entirely devoted to falls. Of use to primary care physicians, nurses, insurance adjusters, architects, writers of building codes, attorneys, or anyone who cares for the elderly, this book will tell you how, why, and when people will likely fall, what most likely will be injured, and how such injuries come about. "
Humidity: What indoor humidity should we maintain in order to avoid a mold problem?
Slips, Trips, Missteps and Their Consequences, Second Edition, Gary M. Bakken, H. Harvey Cohen,A. S. Hyde, Jon R. Abele, ISBN-13: 978-1-933264-01-1 or
ISBN 10: 1-933264-01-2,
available from the publisher, Lawyers ^ Judges Publishing Company,Inc., www.lawyersandjudges.com sales@lawyersandjudges.com and also from the InspectAPedia Bookstore (Amazon.com)
The Stairway Manufacturers' Association, (877) 500-5759, provides a pictorial guide to the stair and railing portion of the International Residential Code. [copy on file as http://www.stairways.org/pdf/2006%20Stair%20IRC%20SCREEN.pdf ] -
How to Clean Moldy Wood Framing & Sheathing How to clean/seal mold from/on exposed lumber or plywood subfloor or roof sheathing indoors - some suggestions based on our field and laboratory research
Lighting, proper use of: proper aiming of a good flashlight can disclose hard to see but toxic light or white mold colonies on walls.
Stuff that is not mold but is often mistaken for it - things you may not want to test. Also, not all "black mold" is toxic - here are examples of harmless black mold.
Mold-Resistant Building Practices, advice from an expert on how to prevent mold after a building flood and how to prevent mold growth in buildings by selection of building materials and by anti-mold construction details.
Slips, Trips, Missteps and Their Consequences, Gary M. Bakken, H. Harvey Cohen, Jon R. Abele, Alvin S. Hyde, Cindy A. LaRue, Lawyers and Judges Publishing; 2 edition (April 2006), ISBN-10: 1933264012 ISBN-13: 978-1933264011
Steps and Stairways, Cleo Baldon & Ib Melchior, Rizzoli, 1989.
"The Dimensions of Stairs", J. M. Fitch et al., Scientific American, October 1974.
"Weather-Resistive Barriers [copy on file as /interiors/Weather_Resistant_Barriers_DOE.pdf ] - ", how to select and install housewrap and other types of weather resistive barriers, U.S. DOE
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