Stucco and sheathing damage

Here is a story…

My clients had their roof replaced in March of 2010. Long storey short, when the roofers removed the old roofing, they also disconnected the chimeny vent…in the attic. For the entire 10 months, the hot water tank, the furnace (in fall and winter) were spewing into the attic, unbeknownst to the homeowners…

This March they found their cellulose insulation saturated, packed down, sheating on roof covered with mold and swelling, exterior sheathing which is made of buffalo board ( a compressed fiber) totally saturated in the attic area. The moisture ran down the exterior walls (to the main floor bottom plate) which in my opinion has caused excessive staining and cracking of the stucco.

We cut out a portion of interior wall to inspect the buffalo board sheathing and the buffalo board is still wet in areas and in other areas is swollen but drying.

Id like to know what other inspectors opinions are on the stucco. We live in a very volatile climate. In summer it can get up to 38C in summer and -50C in the winter. It froze and thawed many times over the winter. Do you think the damaged buffalo board will support the stucco for much longer? Multiple cracks are showing up througout the field of exterior walls. The stains are “brown” in color on the stucco, which I believe are rusting fasteners. Ive been talking to several suppliers which used to sell the buffalo board. Most have been claiming if buffalo board gets wet, it’s toast, as it is only a compressed fiber board. Dont forget that the condensation has been “waterfalling” down the exterior walls for almost one year now… our freezing and thawing climate does not help either…

The attic structure is 78% saturated. (Moisture meter)…

What a mess! All from some dumb roofer disconnecting the chimney vent!

Need photos please.
If you found over 30 percent bad or corrupted. Change the whole thing.
Stucco and other EFIS systems have been around for thousands of years. In Europe it is a much used product and system.
I to live in a climate as yours, with extremes in temperatures and humidity.
If stucco and EFIS hard coat is maintained properly it lasts 100 years. Now there are many other structure deficiency that can cause a negative effect on it outcome.
Please install photos and I will try to help. I have repaired stucco hard coat on older homes.

I would be careful on this it sounds like a huge expense.
I would not say another word to them on your thoughts .
I would get the people to talk to a lawyer who might say to get an engineering report. … Roy