visited attic of a house built in 1972 in columbus ohio. problem is condensation and frost on underside of roof sheathing in attic. air turnover is 6.6. attic floor has been sealed and all known penetrations from conditioned space to attic have been sealed. attic has five soffit vents in front and 5 in back. homeowner added three aura vents on top of roof. link following if anyone wants information. (http://www.homedepot.com/buy/active-ventilation-12-in-aluminum-aura...)
homeowner had foam blown into walls two years ago. He is not sure when condensation issue began as he only observed 2 years ago. homeowner keeps a humidistat in attic as humidity sometimes runs above 80%.
any suggestions, knowledge, expertise would be appreciate as I do not know what to recommend.
I'm in PA --I forgot about that -- should have remembered about climate differences and referenced accordingly -- thanks. We have frost to only about 4' below ground level here in winter and the site grading is pretty stable. I've seen those berms when traveling -- not around here and wondered about them. Thanks for the info.
The house in question is in Columbus, Oh. I haven't checked, but I would guess it is all but identical to Pa.
Your problem is in design according to what I see in your first picture. The covered entrance section needs to be completely sealed and vented from the main attic from the inside. The moisture collected below the walk in area or patio is trapped at the soffit and has no where to go but up. Remove the travel to the main attic section and you will solve the moisture problem.
thank you. that was my first recommendation. Homeowner did seal passage from porch to attic using polystyrenene boards sealed with dow spray foam. THis was completed 6 months ago before winter began and had no affect on condensation.
OK next is the insulation has become saturated somewhere and you will have to find the area. I would say it might be time to get a scan of the ceiling for cold spots and to check the area with a non invasive moisture meter. I have found situations where there is no evidence on the ceiling because of very good vapor control design. Also test the trusses at the top for extra high levels of moisture.
Before I comment I have a few questions. What is the orientation of the home? How many occupants? The flex duct is for 2 bath fans? Does the home have ridge venting? If so what type? Where in the attic is the moisture, only on some areas or on all surfaces? What type of heating system and how old is it?
2 adults 1 child. flex duct is for 2 bath fans. there is no ridge venting. attic moisture is on plywood on underside of roof only. no wet of damp insulation. heating is forced air gas, I don't know how old. front of house faces due west.
Was just following this conversation, just wanted to add to make sure to check all the penetrations through the roof. Its possible that pipe boots could be failing. They get dry rotted and loose there elasticity. If rain combines with wind to move the pipe, rain will run right down the pipe and drip into the insulation and not be seen on the underside of the roof deck.
I put a HOBO in crawl space that was wet to damp but out side was very dry. The water line was dripping from the fitting from poly to steel 7 places. Water mist ran a 2nd floor 18' into dirt rotted the rim and got floor board very soft then made the floor joust like rubber. This took 20 yr. The HOBO would read 70% when dry and 95% when raining out side.
Does the homeowner humidify his home with unit attached to his furnace? Those devices can over humidify and send excessive moisture even into a well sealed attic.
You absolutely have to identify the source of the moisture. In the winter time, if outside relative humidity levels are low or if below freezing, then the moisture must be coming from the house. Look for bathroom vents or a bypass that could possible be feeding the attic. I don't believe the attic floor CAN be properly air sealed if the air exchange rate is 6.6.