I have moisture and a moldy smell in my attic. I had someone come out and open up the eaves and soffets more. It did seem to help but I still have some smell and some moisture. I have insulation on the floor of the attic and also on the sides, but perhaps not enough on the wall next to my bedroom.
Insulation in the attic
atticinsulation
Related Solutions
You can buy air ducts that staple to the inside of your roof above the eave vents and fit between the rafters. The will hold open an air gap of approximately 1 inch to allow airflow past a layer of insulation. The ones I've used are made of styrofoam and IIRC they cost around $2. You should be able to find them near the insulation in your home improvement store.
EDIT: They are called baffles or rafter vents; this is how they're installed:
Given that hot air raises, have you considered a Passive Stack Ventilation system. Basically:
- A tall pipe coming out of the top of your loft so the hot air can raise
- You must not have bends in the pipe or it does not work as well
- The topping on the pipe must not add much to the flow resistance
- The sizing of the pipe is important (sorry can’t help on this)
- Too wide you don’t get fast enough upwards air movement.
- Not wide enough, you get to much air resistance
- The pipe must come out of the top of the loft and be high enough above the roof
- Soffit venting of some type so the colder air can get in at the bottom
The system will only tent to pull air though the loft when the outside air is colder than the air in the loft (just what you need).
Given the correct conditions and design, a Passive Stack Ventilation system will work forever with no running cost or maintenance. Get anything wrong and it will not work at all.
Also check that your ceilings are well sealed, otherwise all the expensive cold air from your AC will just go up into the loft and be vented out.
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Best Answer
Karen, this type of question has come up several times. The basic answer to to provide better ventilation and assure there are no water leaks. Humidity will collect in any attic that is not properly vented. It can condense on rafters, roof sheathing and insulation, then drip. As you are seeing, mildew and mold will result if moisture is trapped. If the problem does not improve after the venting situation is corrected, then you may have to consider replacing the insulation. Mold can cause health problems, an air mold spore test may be a good idea. If any toxic molds are present, remediation will be required. DO NOT ADD any more insulation over the existing insulation until the venting and mold tests are done.