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Roofing/Attic Ventilation and insulation with attached covered Porch - Mold Issue



I have covered porch at the front door of my house where the roof is part of the main roof/attic.

The porch has two walls one that is the front door of the house and one that is the outside wall of my master bathroom. (read hot moist shower air)

There is insulation over the bedroom and bathroom but the insulation stops where the porch starts. So here is a 6' by 10' or so section of the attic over the open air porch that is not insulated. The rest of the attic is very well insulated.

There are soffit vents around the rest of the house but not on the porch.

I have black mold growing on the roof boards that starts at the porch, extends over the master bathroom, and then stops. The rest of the attic is mold free.

I know this is more than likely a ventilation and moisture issue.

I live in upstate NY where it is hot an humid in the summer and buried in snow in the winter.

My questions are.

1. should I insulate over the open air porch?

2. Should I add some soffits to the roof of the porch into the attic?

By your description it generally sounds like a ventilation issue. Addition the insulation to the porch will likely not impact anything. Adding ventilation is LIKELY the correct answer. Ventilation is a tricky subject. There must be intake and exhaust, and there must be an air space above the insulation of at least 1" to insure that the air moves correctly. Ventilation is to be installed with a 1:150 ratio of ventilation:square feet of attic space (this is according to the IBC - you should check with your local code official to verify).
Without looking at the project, I'd say you're on the right track. Just remember that ventilation is not something that should be taken with a grain of salt. This is one of those times where it would be worth paying a consultant to visit the property and make a recommendation. It may be that they will tell you the exact thing that I am, however this is a specific project and there may easily be other mitigating factors that we are not examining and adding the ventilation may not fix the issue.
Best of luck.


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Aaron Nelson


All types of questions with regard to roofing, waterproofing and sheet metal. This includes commercial and residential buildings, along with the various aspects of the construction means and methods, ventilation, steep-slope or low-slope, code requirements, installation errors and other such problems


I started in roofing fabricating and installing sheet metal flashings out of high school for a large commercial contractor. I worked for the same contractor in the office estimating and project managing commercial project for 10 years. I left the construction side of roofing and now work as a roof consultant, which I have been doing for 8-years.

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I am a Registered Roof Consultant (RRC) and a Registered Roof Observer (RRO) through RCI, Inc. RCI is a international group of building envelope professionals. I am an approved instructor for RCI educational programs.

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We have worked with many local school districts, insurance companies, HOA's, building management companies, and we have a national client with buildings located throughout the US.

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