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VENTILATION in BUILDINGS
AIR BYPASS LEAKS
AIR LEAK DETECTION TOOLS
AIR LEAK SEALING PROCEDURE
AIR POLLUTANTS, COMMON INDOOR
AIR SEALING STRATEGIES
ATTIC LEAKS, CONDENSATION & MOLD
BASEMENT CEILING VAPOR BARRIER
BASEMENT HEAT LOSS
BASEMENT LEAKS, INSPECT FOR
BLOWER DOORS & AIR INFILTRATION
BRICK WALL DRAINAGE WEEP HOLES
CATHEDRAL CEILING VENTILATION
CEILINGS, DROP or SUSPENDED PANEL
COMBUSTION AIR for TIGHT buildings
COOLING LOAD REDUCTION by ROOF VENTS
CONDENSATION on WINDOWS & SKYLIGHTS
DEW POINT CALCULATION for WALLS
FIREPLACES & HEARTHS
FLAT ROOF MOISTURE & CONDENSATION
GREEN BUILDING CONSTRUCTION
HEAT LOSS in BUILDINGS
HEAT LOSS DETECTION TOOLS
HOT ROOF DESIGNS: Un-Vented Roof Solutions
HOUSEWRAP AIR & VAPOR BARRIERS
HOUSE DOCTOR, how-to be
HUMIDITY LEVEL TARGET
ICE DAM PREVENTION
INDOOR AIR HAZARDS TABLE
INDOOR AIR QUALITY & HOUSE TIGHTNESS
INDOOR AIR QUALITY IMPROVEMENT GUIDE
Insulation Air & Heat Leaks
INSULATION INSPECTION & IMPROVEMENT
INSULATION R-Values & Properties
LOG HOME GUIDE
MOISTURE CONTROL in BUILDINGS
ODORS & SMELLS DIAGNOSIS & CURE
ROOF VENTILATION SPECIFICATIONS
SHEATHING, FOIL FACED - VENTS
STAIN DIAGNOSIS on BUILDING INTERIORS
STUCCO WALL METHODS & INSTALLATION
SWEATING (CONDENSATION) on PIPES, TANKS
THERMAL MASS in buildings
THERMAL TRACKING Indicates Heat Loss
VAPOR BARRIERS & AIR SEALING at BAND JOISTS
VAPOR BARRIERS & HOUSEWRAP
VAPOR CONDENSATION & BUILDING SHEATHING
VENTILATION in BUILDINGS
WIND WASHING INSULATION At EAVES
WINDOWS & DOORS
How to inspect an attic for condensation, leaks, or moisture problems: 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. This chapter "How to Inspect in the Attic or Roof Cavity for Signs of an Under-roof Condensation Problem, is part of our article series on "Attic Condensation". Also see CATHEDRAL CEILING INSULATION.
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Check the Entry & Exit Pathways for Attic Ventilation Air
Check for Signs of Attic Condensation & Moisture
If attic stains are from roof leaks, (right photo above) they will usually be much larger and will appear on the sides of rafters, on larger areas of the roof sheathing, and on larger areas of the attic floor.
If you see evidence of extensive roof leaks or condensation leaks, I'd also check the insulation and the attic side of the ceiling drywall for a hidden mold problem.
If you see condensation drip stains in the attic (left photo above), you'll be confirming what you suspected from outside -- inadequate ventilation.
How to Inspect the Attic for Moisture - Stains Around Roofing Nails
Rust or stains around roofing nails that protrude through the attic sheathing (they're supposed to stick through) are a clear indication of high attic moisture.
Our photograph at above left shows roofing nails protruding through plywood roof sheathing visible in an attic where there is no under-roof condensation or moisture problem.
Our photograph at above right shows roofing nails which have rusted and stained the roof plywood in an attic where indoor moisture has risen through the building to condense on the under-side of the roof.
How to Spot Attic Mold Due to High Attic Moisture or Roof Leaks
These photos show mold on attic surfaces due to high moisture in that area. While many inspectors notice dark mold or mold-suspect material on roof framing or roof sheathing, it is at least as important, and often more important to spot the light-colored molds that may also be present - often these are the more hazardous, particularly if building conditions cause air movement downwards out of the attic into the living space or into an attic-located HVAC duct system.
The brown/black attic mold on plywood in the left-hand photo is easy to spot and is often an allergen or problematic attic fungus like Cladosporium sp., Pithomyces chartarum, Ulocladium sp., or Aureobasidium pullulans but the light colored mold on the tongue-and-groove pine roof sheathing in the right photo was found to be Penicillium sp. which is more likely to be airborne and transmitted in the building.
How to Correct High Attic Moisture, Condensation, Leaks
A first step in fixing a wet or moist attic problem is the correct identification of the source of the moisture. Stains or even wet areas on the under-side of roof decking and on rafters can appear to be a roof leak but in fact moisture may be entering the attic not from above (outside and through the roof), but by rising through a building suffering from leaks, a prior fire extinguishment, or most common, a wet basement or crawl space.
Home inspector David Grudzinskiprovided the attic moisture photographs shown below.
From just the photographs, and without having inspected the building exterior, roof, nor other areas, the photos look like a roof that had numerous leaks, perhaps from worn out roofing, possibly even some rotting sheathing. The photos show areas of apparent mold on some rafters. But especially in the 2nd photo at above right, the very extensive condensation stains around the nail protrusions through the roof deck tell us that the whole attic interior has been soaking wet. Now for the big question: is this wet attic caused by roof leakage or is there a building water entry problem?
Mr. Grudzinski provided the additional, crucial diagnostic information about this wet attic:
In other words, an expert roof and attic inspection include an inspection of the entire building, basement to roof, in order to understand where moisture or condensation are originating and what may have been their effects on the building.
A Wet Attic Risks Hidden Mold Contamination of its Insulation
Also, we wonder if, in a soaked area like this where fiberglass insulation is present, because of the risk of hidden mold in the insulation (see FIBERGLASS INSULATION MOLD) it may be worth checking the attic side of the ceiling drywall below the areas of most-apparent-worst leakage into that space - looking for water stains there, mold, &c.
If you find significant levels or large areas of mold in your attic the mold should be cleaned - that is, removed. Do not rely on magic bullets like sprays alone. The spray approach does not remove the problem mold and it may spread it into otherwise uncontaminated materials like insulation.
Don't tear off the roof over a moldy attic: Unless the mold-causing conditions have also rotted framing or delaminated plywood roof sheathing, structural removal/replacement, such as a roof tear-off are unnecessary and inappropriate. But don't forget that if you see attic mold the insulation or ceiling drywall below may also be moldy.
See How to Find, Test For, & Remove Mold in Attics for details about where and how to look for attic mold and what to do about it.
Frequently Asked Questions (FAQs) about attic or under-roof condensation, attic frost, soffit ice build-up, and related leaks or moisture in buildings
Question: diagnosing moisture high on building walls
I have a double wide manufactured home that I'm renovated. It has vinyl siding and perforated soffits common on manufactured homes. We've noticed moisture high in the walls all around the home and can't identify the cause. Any ideas? - T.B., Colorado
What T.B. found was a combination of accumulated snow or frost or ice in the home's eaves, possibly due to wind-washed insulation, moisture and condensation, or snow and ice building up in the eaves, combined with leaks into the house walls when weather warmed and the accumulated snow or ice melted. Details about this Q&A are at >MOBILE HOMES, DOUBLEWIDES, TRAILERS.
Questions & answers or comments about detecting the cause of attic moisture, condensation, frost, leaks, or mold
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