Attic Mold Is Often Addressed With Ventilation Which Is a Mistake
Attic mold is often looked upon as being caused by poor attic ventilation. This is a fundamental mistake in the industry. Often well ventilated attics harbor mold growth. Attic Ventilation will not prevent mold growth.
Online, December 11, 2013 (Newswire.com) - The real push for better attic ventilation came from the need for roof decks to dissipate heat quickly because the contemporary roofing products were failing. The real mistake is made when attic ventilation is used as an answer to a problem it cannot solve. Before discussing the issues where attic ventilation is used to provide relief, let's look at why attic ventilation is regarded as the answer for moist, moldy attics.
Shortly after the onset of the fiberglass based roofing shingle upon the roofing marketplace, attic ventilation became evident as mandatory for the survival of this heat-vulnerable roofing product. The reason is that the fiberglass reinforcement cannot be saturated to any formidable degree and that these new shingles (circa 1978) were just a one type adherent asphalt applied to the reinforcement. The combination of the cheaper and more brittle type asphalt combined with the the stiff fiberglass reinforcement provided little range for thermal change in the finished product. This is by comparison opposed to the old products based on saturant asphalt applied to more mailable organic mats and then adherent asphalt used just to hold the surfacing materials. The result was a longer lasting roofing shingle, but only if the shingle could transfer its heat into the attic readily and without obstruction. Failures began to be seen with stress cracks within the new roofing shingles early on. Ventilation was necessary to keep these roof alive.
The push for ventilation began to be mandated and even taught as curriculum in sales training. Ventilation became the focus, both intake and exhaust and government bodies adapted the recommendations of the manufacturers. Attic Ventilation is a good thing but it began to be the called upon as an answer for all sorts of issues within the attic. Ice dams can be prevented with proper ventilation. Moisture can be addressed by ventilation, etc.
Ventilation became the answer to seemingly all the tradesmen for resolution to attic issues. The clarion call for better ventilation became the answer because it seemed like a lack of it had caused many of the issues in the building marketplace. Often home improvement contractors were ill equipped to handle issues that arose within the attics of their customers. They only saw the deficit of ventilation when visiting mold issues, ice dam situations and failed roofs. They did not see moisture as the issue on mold complaints. It would seem that one would zero in on moisture if it is the issue, right? Wrong.
Attics across the nation were retrofitted with intake and exhaust ventilation to cure the woes caused by modern construction deficits. In instances of moisture condensation and the presence of mold in attics were becoming more and more prevalent. With the change in roofing shingle design also came simultaneously, the upgrades of attic insulation, tighter windows and sidings in the energy conscious 1980's. These changes were happening all the while manufacturers were pushing for better ventilation to cover their interests. So some of the brightest minds in the industry went with the flow and blamed ventilation, or lack of it as the reason for the onset of mold in attics.
When mold suddenly shows itself in the attic, it is usually the result of a change in the dynamics of the building. Usually in such cases attic mold has arisen because of additional moisture being pushed into the attic spaces during the winter heating months. Even with properly ventilated attics, mold shows up in the attic. Usually, added attic insulation has been added, or new windows, siding, etc. In the case of added attic insulation, no greater frustration can be realized than that of a homeowner just spending good money on insulation to have a mold problem arise.
Adding attic insulation without proper air sealing causes the greater pressure difference between the conditioned space to the newly, colder attic to be realized through existing bypasses in the attic. Many times these bypasses are invisible and cannot be discerned by the layman or inexperienced contractor. Bypasses are defined as any area of the ceiling that allows the conditioned air to leak into the attic. So much emphasis has been put on the "building envelope," in these modern days but we need a new term: THE CEILING ENVELOPE. The warm moisture laden air needs to remain, as much as can be achieved within the conditioned space in the cooler climates. This is a call for "The Ceiling Envelope" to be addressed with air sealing and a vapor retarder placed on the warm side of the insulation. Once this is done, insulation can be added without detrimental effects.
Ventilation will not cure an attic moisture or attic mold problem. Addressing the moisture first is your best bet. Applying a "Ceiling Envelope" is next. Then upgrade all of the items that make for a healthier and more comfortable home.