Concerns over attic mold growth is the most common phone call we receive. The humid, cool winters of the Pacific Northwest create the perfect climate for mold growth and wood decay in attic areas. Though unfortunate for the life of the roof, this reoccurring problem provides an excellent database for us to compare different remediation techniques.
In general, these techniques can be distilled into two broad categories, chemical and abrasion. Both techniques seek to address the same problems, but utilize very different approaches. Before we compare the actual techniques, it is important to understand the goal of attic mold remediation.
Goals of Attic Mold Remediation
#1.) Remediate surface mold growth
Successful mold remediation must address the 3 dimensional growth occurring on the surface of the material. This may be fuzzy growth occurring several millimeters beyond the surface or a very thin layer residing only on the material itself.
#2.) Remediate subsurface mold growth
Mold remediation must also address the effects mold growth has on subsurface materials. If the mold is occurring on steel, plastic or other non-porous materials, where mold growth is restricted to surface, subsurface remediation is not necessary. However, mold growth typically thrives on porous materials such as wood and sheetrock. In these situations, mold growth can stain and discolor the material to a depth of several millimeters. This discoloration, however unpleasant, is not usually a sign of diminished structural integrity. This fact will become important when we compare the two most common remediation techniques.
Abrasion
Abrasion techniques run the spectrum from hand sanding or wire brushing to exotic abatement techniques such as dry ice blasting. All of them utilize the same principle - physically removing the contaminated material. There are two main problems mold remediation seeks to address. First, the 3 dimensional mold growth present on the surface of the material. This is the fuzzy growth you see accumulating on top of the material.
Second, mold remediation must address the underlying staining that occurs within the material. Unfortunately, this second aspect can prove problematic because the discoloration can occur several millimeters into the top layer of the material. This discoloration does not effect the structural integrity of the material, though it is aesthetically unpleasant.
Pro’s
- No chemical exposure or residue. Clients with multiple chemical sensitivity disorder may benefit from the chemical-free approach of abrasion techniques.
- Retains original color of material. Abrasion techniques are useful when unusual architectural circumstances, such as exposed lofts, garages or barns require the retention of the original color.
- Leaves no evidence. Abrasion techniques, if done effectively, can leave no trace of any remediation work.
Con’s
- Ineffective in hard to reach places. Unless an attic has an extremely steep pitch, treating the outer reaches of the sheathing with abrasion techniques is difficult and in many cases, impossible.
- Diminished structural integrity of material. Because mold growth can discolor wood several millimeters deep, addressing the discoloration with abrasion techniques requires removing several millimeters of wood. Ironically, this removal of material will cause a much greater loss of structural integrity than the mold growth itself.
- No protection against future growth. While we generally don’t recommend preventative coatings for mold growth, encapsulants will provide a modicum of protection. Abrasion however, will leave the surface as vulnerable as it was in its original state.
- Cross contamination. Spreads mold spores and fragments throughout remediation area
- Difficult to treat uneven surfaces. For example, many attics are riddled with nail penetrations, making sanding or wire brushing extremely difficult.
- Expensive. As the name implies, abrasion remediation requires a large quantity of labor. These labor costs drive the cost of abrasion techniques far higher than encapsulant based approaches, typically 3-4 x more expensive than chemical treatments.
Encapsulation
Encapsulation techniques typically rely on two components.
- Stage 1 Mildicide treatment
- Stage 2 Encapsulanting paint
Pro’s
- Future growth is easily distinguishable from previous growth. Attic mold remediation is not an exact science. Occasionally, mold growth returns and additional ventilation is required. If the attic was encapsulated, it will be very clear if the growth is new and the result of continuing moisture problems, or if it is old growth, and the result of a failed initial remediation.
- Reduces likelihood of regrowth. Encapsulation leaves the affected materials with a white, painted surface. This provides a tougher surface for mold and reduces the potential for future growth. Note: encapsulation alone should never be expected to prevent mold growth. The underlying cause of elevated moisture must be addressed.
- Cost effective. Due to the reduced labor costs the price of a typical attic remediation project is 3-4 times less than the abrasion technique. While cost alone should not be the defining factor, most clients simply do not have the resources to pay for abrasion techniques. This often results in customers simply ignoring the problem and hoping the issue goes away.
- Retains full strength of material. Encapsulant techniques do not require the removal of the existing material. This allows the remediation contractor to address the mold problems without compromising the structural integrity of the roof sheathing.
- Can be performed in areas with difficult access. Attics are difficult places to work. Because encapsulant techniques do not require physically scrubbing or brushing the surface, difficult to reach areas can be successfully treated.
Con’s
- Can draw attention to area. Because encapsulation is typically white, the remediation technique can draw unwanted attention to a previous problem. This is only a problem if the treatment is limited to a portion of the attic.
- Not appropriate for exposed areas. Encapsulation is not appropriate for vaulted ceilings or other areas where the attic/ceiling area a visible part of the interior of the home.
Conclusion
As you can probably guess, we use the encapsulation technique. We’ve tried them all and nothing can beat the efficacy and efficiency of this approach. Environix pioneered the technique nearly 10 years ago and we are happy to see that it has now become the industry standard.
