attic ventilation and mold

I inspected a hundred year old farm house with a slate roof over felt paper and 1x6 that had just been remoded.The structure had good soffit ventilation,but no gable or ridge vents.They had the tops of the double hung windows in the attic opened about 3" instead.There was some small spots of mold growing on the under side of the roof.Could this have been because of prior leaks which have since been repaired.Should I recommend gable vents and have the mold taken care ? Or or is there something else I’m missing?

Ray, please update your profile so we know where your from.
100 year old houses were never designed for ventilation other than the windows. Open them in the spring and close them in the fall.
If this is a timber framed home then most likely the horizontal beam at the base of the rafters and the ridge pole is restricting air but allowing moisture to enter the cavity. If this is the case I would close up the soffit vents and instruct the client to use the windows as intended.

I’m in NH so this advise is depending on your climate.

Peter,Thanks for the reply.I have another question now concerning this problem.When they remodeled this home they put vented vinyl all along the soffits with baffles into attic cavity.Do they need to change all that siding when they remove the baffles ? If so, would it be better to leave all the soffit venting and cut in gable vents and now the windows could be kept closed.Sorry about my profile.I’m still learning on the computer.I’m getting there.

I have a question. I’m going to assume that at one point they added a modern kitchen, laundry, and baths. Did they install any vent fans? They are adding more moisture in to the structure than when it was original. Are the windows in the bathrooms easily operated and are the people using them?

Hi Ray, I wouldn’t be a bit surprised if the siding company went right over the soffits without drilling any holes. Happens all the time around here with piece work paid sub contractors. If they did drill hole’s it’s probably minimal at best. I see many of these type homes in my area that perform just as well or better with no ventilation other than windows. I would leave the soffits in place but definitely check to see how the air/moisture is getting in there.

If you have any pictures posting them would help

Hi Pete,The home has been vacant since prior to the renovation which ended in Nov.2010.I think its a flip.All the new venting terminates outside.Should we leave the soffit venting with the use of the windows or eliminate them?

How do you know the vents terminate outside. Can you physically see daylight out the eaves or can you just see the proper vents in the attic.
Would help to have more info. and or pictures.

Pete, Robert,and all the H.I.'s,Let me first say this is my first time I’ve posted and I sure do appreciate all the input.I hope to be as helpful to other H.I.'s when I am able to share any knowledge I might have.Thanks! I keep kicking this around ,could they have a bat problem?Ilooked all around and couldn,t find any signs (guano,staining on floor,etc.)but you know how good they are at hiding and maybe with someone cleaning up after them I could have overlooked them.But it is winter and the windows were left open at the top with no screens and that’s the little bit of mold I,m seeing is near the windows.So the mold problem was created because of a bat problem?

I doubt it’s bats, not during the winter. If the windows are open it it possible that the area got wet? Plus, in your area, is it cold? not conducive to mold growth in winter.

Hard to help without photo’s. Did you take any?

if you decided to cover the soffits vents, you would need to remove them. just lay something on top.

I attached a picture of all the utility vents exiting the attic. Two pictures of the mold on the roof. One of the soffit vents which are all, for the most part, with baffles and can see drylight. :roll:

That mold looks like more from humidity than roof leaks, or the roof did not leak very much.

Ray, judging from the picture’s it looks like most of the vents are blocked. The framing looks more modern than 100 years old. I agree with James as far as humidity goes. For venting there should be Styrofoam proper vents to allow the air to flow up from the soffits past the insulation.

Ray -

What is the condition of the basement? Damp? Earthen floor? Is there a crawl space?

If an earthen floor or a damp basement/crawl space, moisture intrusion in the basement/crawl space may be migrating up through the living spaces into the attic.

Symptoms would include mold, rusty roofing nails, frost on the underside of sheathing, etc.

Ray That attic is like clean as a whistle compared to the shi^&%T hole I was in last week…haha:shock: