Seattle Attic Mold Inspection Reports
Below are recent inspections of attic mold issues we’ve performed in Seattle.
Project Type > Inspection for Attic Mold in Seattle
REASON FOR INSPECTION:
- Client is selling home and recently had a home inspector call out mold growth in the attic space. Environix hired to inspect the attic as well as provide a bid for remediation.
CAUSE OF MOLD:
- Inadequate ventilation in the attic space steaming from an insufficient ridge vent is allowing humid air to become stagnant in the attic and condense on the sheathing during the winter months. Additionally, unsealed ceiling penetrations and can lights are allowing an excessive amount of humid air into the attic.
ACCESSIBILITY & HISTORY:
- Fully Accessible. All portions of the attic were accessible at the time of the inspection.
TYPE AND EXTENT OF MOLD GROWTH:
MOLD ON SHEATHING:
- Moderate mold covers approximately 40% of the attic sheathing.
- Light mold covers approximately 30% of the attic sheathing.
MOLD ON TRUSSES:
- Light mold is present on approximately 10% of the roof trusses.
MOISTURE & LEAKS:
- No elevated moisture detected at the time of the inspection. However, due to the growth pattern of the mold growth, condensation based moisture likely occurs during certain times of the year. The moisture meter will often not detect the thin layer of condensation occurring on the surface of the sheathing. Additionally, condensation only occurs during cold weather. Therefore, the lack of detected elevated moisture does not eliminate condensation as the source of mold growth.
- Blown-in fiberglass
- Minor Mold Observed: Visible mold observed throughout the top layer of insulation in the attic, in a very minor quantity. Mold on the insulation is not a structural concern. Typically, the mold does not grow on the actual insulation, but rather is deposited from the mold growth occurring on the attic sheathing above. Spores may be removed at the customer’s request, but due to air flow dynamics within a building (air is continuously moving upward), the spores are unlikely to negatively impact indoor air quality.
UPPER ROOF VENTILATION:
- Normal pitch.
- Internally baffled ridge vent.
- Inefficient ridge vent: Ridge venting is present but is a low profile, core type material. These core-type ridge vents are not recommended due to the restrictions created by the baffles. This limits the ability to properly exhaust humid air from the attic. Externally baffled ridge vents perform significantly better.
- Contributing to attic mold. Current ridge area venting is insufficient to allow for the adequate ventilation of the attic space. The lack of venting is likely contributing to the condensation and mold growth on the roof sheathing. See 3rd Party Requirements at end of this report.
- Proper ventilation is necessary to minimize condensation and subsequent mold growth. All areas of improper ventilation must be addressed to ensure the effectiveness of our process. Current code calls for 1sqft of ventilation for every 300 square feet of attic space, distributed evenly between the ridge and soffit area (i.e. 1sqft of soffit venting for every 600 sqft of upper floor space).
- Bird blocking. Every 2nd bay.
- Blocked by fallen baffles. In several areas the vents are blocked by the baffles, which have fallen out of place. This limits the influx of fresh air through the attic, leading to excess condensation and mold growth. Environix will address this in the bid, below.
- Restricted by roof architecture. Traditional soffit venting is not possible in significant portions of the attic. This is due to the architectural constraints such as valleys that are created when two roof sections meet at 90 degree angles. Providing venting in these areas is extremely difficult. Therefore, focusing on other techniques such as reducing the indoor RH is preferred.
- Contributing to attic mold. Current soffit venting is insufficient to allow for the adequate ventilation of the attic space. The lack of venting is likely contributing to the condensation and mold growth on the roof sheathing.
- Focus on indoor RH and air sealing. Improving the soffit venting in the area restricted by roof architecture would be costly and difficult. Instead, consider focusing on lowering the indoor RH and air sealing. Lowering the indoor RH will reduce the quantity of moisture in the air infiltrating into the attic. See the suggestions in the ventilation section below. Additionally, air sealing the ceiling will significantly reduce the movement of humid air from the inside of the home to the attic space. Together, this will likely address the condensation and subsequent mold growth issues on the roof sheathing. If these steps prove insufficient, additional low venting will be required.
- Unsealed. The ceiling currently lacks proper air sealing, which can allow excess moisture and heat to escape into the attic area. This air leakage is a key cause of energy loss, attic condensation and mold growth. NOTE: Air sealing was not required by code until recently. Therefore, the lack of air sealing does not indicate a failure of the original homebuilder.
- Likely contributing. The lack of air sealing is likely contributing to the condensation and mold growth in the attic. Environix will address this in the bid, below.
- Air sealed can lights. Five factory air sealed can lights currently installed. This air sealing is not thorough, and leaves gaps where humid air can still pass through.
- Contributing to mold growth. The lack of thorough air sealing around the can lights is a contributing factor in the condensation and mold growth on the attic sheathing. Environix will address this in the bid, below.
- Rodent. Evidence of past or present rodent infestation was noted, contaminating the insulation.
- Relative humidity levels are slightly elevated. Generally, indoor RH levels should remain under 55% or under 50% in homes with poorly insulated exterior walls. During the warmer months (June through September), the indoor RH levels may be elevated due to high RH levels in the outside air. Therefore, care should be taken when drawing conclusions from elevated RH levels during these months.
- Home suffers from insufficient use of the ventilation system. This leads to a buildup of indoor pollutants and increases the relative humidity, creating conditions conducive to mold growth and dust mites.
- No fresh air intake found on furnace system. Fresh air intakes can be very effective at lowering the interior RH in the home.
- Install a relative humidity gauge on an interior wall in a central area of the home (approximately eye level). Monitor the RH for excessive humidity readings. Maintaining an interior RH level of <50% will greatly reduce the probability of future mold growth.