A comedy of errors can describe events that from a small misunderstanding snowball into a near catastrophe. Thankfully no gets maimed or killed, but some damage is done. Being a home inspector I view quite a bit of what I would call comedic measures that stem from a misunderstanding and a lack of general knowledge. Often the intention is noble, while the result is far from what had been intended.
Climbing through a scuttle hole to inspect an attic not long ago, I was immediately confronted with a large yellow mound. This hill it turned out was a long ridge of fiberglass insulation batts extending a good ways down the attic. Seeing an air handling unit and duct work, I suspected this heap of insulation was made while the HVAC equipment was installed and then never replaced. It was a good assumption as in my experience out of the way places like attics are often where some contractors leave messes.
I entered the attic and wended my way to the end and back. Along the way I saw several items of interest. The most apparent was the black stains on the roof sheathing. The stains were almost exclusively on the rear sheathing, the front was almost clean. This phenomenon is quite common to see in my experience and there is a very simple explanation.
Another item of interest was on some of the insulation that was still where it should be, undisturbed in the ceiling. The mound was created from a second layer which a past homeowner must have added to save energy. The original insulation, which had at one time been covered, was spotted black. Again this a common sight to see with fiberglass insulation. The black stains are sometimes misidentified as mold when in fact they are nothing more than dirt.
This particular house had been previously inspected prior to sale. Based on that inspection repairs had been made. Some of those repairs were in the attic. I knew this by being shown receipts for the work performed. The "repairs" made were two, one was a mold remediation. Apparently the inspector (I never saw the inspection report, all though it was offered. I opted to not view it) had recommend the "mold" on the roof sheathing be addressed. I saw the very detailed receipt for this work. The pictures in this post are the after. This cost the sellers about $1400.
The other "repair was for unblocking the soffit vents. Apparently the second layer of insulation had been cited as blocking air flow from the soffit vents. It must have been surmised this was the cause for the "mold". The repair according to another receipt was to remove the insulation from the soffit areas. So it turns out the heap of insulation was not entirely the result of the HVAC installation. The guy they hired to repair the blocked soffits had simply pulled the insulation away from the soffits and piled it up.
So at the end of day has anything been repaired?
There are several things happening in this attic that no one has correctly identified or as of yet repaired.
First the mold is certainly not a major concern, yes, it is a fungal growth, but it hardly warrants a $1400 dollar suspect remediation. I have said this before, the air in the attic does not, can not communicate with the living space. There are those who will debate otherwise, I'm not in the least convinced. The cause (not a symptom, i.e. the "mold") for the condition is due to several combine factors.
First the reason for the stains is moisture condensing on the roof sheathing and nails. The moisture comes from conditioned air in the living space escaping into the attic through bypasses and in this instance bathroom fans vented into the attic. The black stains on the insulation are due to air movement through these openings in the ceiling and the over all poor performance of the fiberglass insulation. Next the attic ventilation has been incorrectly installed and was also later blocked at the soffits. What no one apparently knew was the gable vents were causing a short circuit in the air flow from the soffit vents. With a ridge and soffit venting system, gable vents are not to be installed, period. This issue, as I said was not recognized.
The reason for black stains on the back of roof only is orientation of the house. The front of the house faces the sun. The sheathing at the front dries because of the sun beating on the roof. The solution for the attic is to first seal all by passes to prevent conditioned air from leaking into the attic. My advice would also be to get rid of the fiberglass batts, but that is not likely to happen. Next seal off the gable vents, install rafter vents and then replace the insulation. Done.
Sometimes the lack of good information and knowledge can pile on additional problems and costs.