10:14AM | 07/24/01
Member Since: 03/12/01
40 lifetime posts
Our home is over 50 years old. We have noticed there is a moisture problem in the attic. We think the problem is related to not enough ventilation in the attic.

The attic has 1/2 blown in insulation and 1/2 roll insulation. We put plywood done on the side with roll insulation, but put spacers between the plywood floor and joists to allow air movement. The bottom of the boards are moldy and the insulation is wet.

In the winter, the roof nails are frosty.

We rerouted our plastic bathroom vents to reduce pipe runs in our attic. The west and east side of the house has open louvers for air flow. There is a power fan in the middle which runs all the time. There are no soffit vents on the house. There are a couple of vents along the middle of the roof.

Do we need to install additional roof vents along the base of the roof to get circulation along the base since there are no overhang vents/soffits?

What about roof ridge vents? can these be installed to existing roof systems? Is there a better way to get more circulation into the attic?

Thanks in advance


02:37AM | 07/25/01
Member Since: 01/28/01
171 lifetime posts
Make sure the insulation has a vapor barrier under it. The roll insulation may have the barrier attached to the insulation or a separate sheet under it.

One possibility is that the roof leaked at one time. The insulation is storing the water.

Jay J

06:06AM | 07/25/01
Member Since: 10/26/00
782 lifetime posts
Hi tammys,

LOTS going on here. The moisture-issues are due to warm air condensing out on cold surfaces. Yes, you probably DON'T have a vapor barrier between the 'living space' and the 1st layer of insulation. Usually, it's installed to the UNDERSIDE of the joists before the drywall goes up (in the rooms below.) DON'T add it to the top of the insulation!!! All you'll do is 'trap' what moisture gets through the insulation and cause it to get trapped and begin molding and such!

Consider turning OFF the Power Vent. I'm SURE it's drawing warm air from the house below into the attic (in spite of your open Louvers.) The airflow that the Power Vent 'pushes out' is probably LESS than what is being drawn in through the Louvers. Thus, it needs to 'make up' for the 'missing air' by drawing it from the house. (You can sort of test this by holding a buring cigarette, or an incense stick whereever air might get 'drawn' into the attic from the room(s) below. Start by closing off the attic, from below, and holding something 'smokey' near the Attic Steps. If you see the smoke getting drawn up, then you'll know what I'm talking about. Do this 'test' wherever air might get drawn into the attic. JUST BE CAREFUL not to burn yourself or set the house on fire! Have a cup of water AND an ashtray w/you all the time. Have a friend nearby too.)

You DO want to consider adding Soffit Vents and a Ridge VEnt. BOTH can be added w/o having to do any major work, like re-shingling the entire roof. Be SURE you have vents installed between EACH and EVERY pair of Roof Rafters. Do NOT insulate the underside of the roof either. The purpose of Soffit Vents, working in conjunction w/a Ridge Vent, is to allow the air that's drawn into the Soffit to 'flow' along the UNDERSIDE of the roof to cool it, and right out the Ridge Vent. If you insulate the underside of the Roof, you'll TRAP heat and cause a whole, new set of problems!

Once you've installed Soffit and Ridge VEnts, turn off the Power Vent. Let whatever air and moisture that enters the attic get drawn out by Mother Nature. Again, Power Vents can add to the problem in Winter and/or Summer.

My best to ya and hope this helps.

Jay J Moderator


06:17AM | 07/25/01
Member Since: 03/12/01
40 lifetime posts
Thanks for the info.

How does one know if there is a vapor barrier between the living space and insulation? From the attic, looking down, the flooring looks like the back of drywall. The batt insulation did not have any type of paper backing. So, how do I fix the problem of no vapor barrier or adding new insulation (do I add insulation with backing - paper side on the bottom of the attic floor)?

The roof slopes down to the walls with no overhang. The gutters stick out away from the sides of the house. Can soffit vents still be added?

If I can't do the soffit vents, should I just place roof vents (the square ones) along the bottom edges of the roof, and how often should they be placed?

So, when do you run the power vent?

Many thanks!

Jay J

12:28PM | 07/25/01
Member Since: 10/26/00
782 lifetime posts
Hi tammys,

If you see anything like plastic or paper, under which would be the drywall, then you have a vapor barrier. If, as you say, you can see the back of the drywall from the attic, then you DON'T have a vapor barrier.

When you install Kraft-sided Insulation (w/the Kraft-side facing the living space), it needs to be tucked a little under the joist. Simply laying it in may be OK but it won't have the 'seal' you're looking for. That's why when you look at this type of insulation, you'll see 'ears' on the Kraft Paper that allow the Installer to staple it to the joists (or studs when doing walls.) You'll need long clothes, a mask, and gloves. Do it when it's COOL outside!!! Yes, Kraft-side on the BOTTOM (facing the living space.)

Yes, it's possible to add Facia Vents (vs. Soffit Vents.) I've learned this recently. YOu need to visit possibly a Siding Supplier or Roofing Supply House. (Look in the YELLOW PAGES for either or both.) The Supplier will tell you the BEST and 2nd Best way to do an install.

RE: The power vent, consider adding a thermostat in the electrical line. Have it come on at, say, 105 degrees or something. You really only want to use it when Mother Nature doesn't do the job well. I see them working against you and the house. They may not be properly sized. You particular vent may be working very hard (hence, it draws warm moist air from the house into the attic.) Then, on the other hand, it may be undersized and NOT doing the job. It's hard to say w/o having the Power Vent speced-out along w/the Gable Vents.

For now, my best to ya and hope this helps.

Jay J -Moderator

PS: Your call - You may still need to get rid of ALL the existing insulation in order to have the new insulation installed. As I see it (sight-unseen), that's the best way to go. Talk to a Contractor about doing the removal yourself. YOu may save some $$$. Just be sure he tells you how to 'bag' it and anything else ...

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