Roof Mold Removal

What's worse is that I have known many, many homeowners that decided to forego mold remediation because they took the advice of a roofer that really did not understand mold .

Reduce the solar heat gain within the home during the summer months.

Provide an avenue for drying out unexpected water intrusions, roof leaks, etc.

The first is important in cold climates, where ice damming and condensation can occur if the sheathing temperatures reach the dew point. The second is critical in hot climates, where extreme attic temperatures heat can radiate into the conditioned space and increase the load on the A/C.

Active attic ventilation is a fairly new invention, necessary only after the advent of tighter construction techniques and lower quality materials. The former occurred when houses converted from skip sheeting and cedar shake to plywood and composition roofs. Skip sheeting with shakes allowed a significant amount of heat and moisture to escape without the need for specific ventilation. This is why in older, turn of the century homes, you'll very rarely find mold problems in the attic. Compounding the problem in recent decades was the move from real wood to manufactured materials such as OSB and plywood. These materials have a much lower resistance to mold growth.

The worst problems typically occur in homes built in the 60's, 70's and 80's. Houses built in this era often contain manufactured wood materials, composition shingles and poor airflow management. Additionally, these homes tend to have no air sealing on the ceiling, allowing a large amount of warm, damp air to enter the attic space.

The need for attic ventilation varies greatly from one home to another. I've observed a number of homes with the exact same layout, roof structure and ventilation, yet one is covered and mold and the other is spotless. Though frustrating at first, after a bit of digging, the compounding factors can often be identified. Perhaps the most common variable is the number of penetrations in the ceiling. Items like can lights, access hatches, etc. provide a very efficient route for warm, humid indoor air to migrate into the attic space and can have a dramatic effect on condensation and mold growth. Unseen penetrations exist as well; everywhere an electrical wire penetrates the top plate of a wall, heat and humidity can escape into the attic.

How does attic ventilation work?

Most residential home rely on passive ventilation to encourage air flow. Passive ventilation requires intake (typically soffit ventilation) and exhaust (ridge vent or roof jacks). Due to the stack effect, as warm air rises, fresh air is drawn in through the soffit vents and out through the ridge area. Occasionally, houses rely on gable end vents to achieve passive ventilation. Problems can occur if any of the ventilation components are not working properly.

Common issues include:

• Soffit vents blocked by insulation


• Gable end vents competing for airflow


• Missing ridge are vents

Heavily gabled roofs, with a wide footprint and minimal ridge area, also suffer from poor passive ventilation and may require an active system. In a commercial setting, mechanical ventilation is often achieved through wind powered turbine vents. These work especially well in areas with consistent wind. However, they are unsightly for residential applications and most homeowners elect to install electrically powered roof vents instead.