05:22PM | 01/02/99
Our 70 year old house is located in a cold northern climate and this is our first winter in it.. While there is no insulation in the attic/roof rafters, fiberglass batting has been placed under the attic floorboards. Earlier this week after retrieving some items from the walk-up attic I noticed one of the cardboard boxes seemed slightly damp. Today while back in the attic I noticed little balls of frost/ice in the tips of the roofing nails that protruded slightly through the roof sheeting. In addition, frost had formed on the inside of one of the gable windows as well as on the underside of some of the sheeting that extends out over the soffit enclosed overhang.

Obviously I’ve got some sort of problem with venting and excess humidity. I’ve partially opened one of the gable end windows and made sure that there’s no insulation blocking the soffit vents. How do I know if this is enough ventilation?

As for the excess humidity, I suspect it’s coming from the second floor bathroom. When the previous owner remodeled this bath, he put ½" drywall over the old plaster ceiling (which I would think would act as an added vapor barrier), but the added vent/heater fan assembly has some gaps around it. What is the best way to make a better seal - can I use expandable foam (e.g. Great Stuff)? Also, should I place some sort of plastic vapor barrier around fan assembly box before laying the fiberglass batting back on top? - (Although it’s a combination heater and vent fan, the metal assembly box doesn’t seem to get hot). Finally, should I replace the plastic flexible 4" vent hose with an insulated vent hose?

Any other things I should do to reduce the attic humidity?

I’m open for any/all ideas.



12:17PM | 01/03/99
You did not mention it, but I hope the exhaust is vented outside. The problem with expandable foam is that is somewhat permanent and you will have to replace that fan in time. It can be a bear to break it loose to remove the existing fan. All of the gaps should be sealed since a shower emits a tremendous amount of moisture. Use a product that remains flexible, something akin to Mortite. You can try a vapor barrier but it may trap the moisture and cause some water spots on your ceiling. A better solution may be to build a false box around and over the exhaust fan with a hole large enough for the vent hose. You can seal this gap with the expandable foam. also use it around all of your vent stacks, electrical wire holes and any other gaos you may run across. An insulated or vinyl duct will also help eliminate the transmission of moisture. It is safe to put insulation around the box itself.


Post a reply as Anonymous

Photo must be in JPG, GIF or PNG format and less than 5MB.


type the code from the image


Post_new_button or Login_button

The “Briolette” faceted glass sink from Kohler measures 17.5” wide and is sure to catch the eye—as it does the light. $707.50 Filling an underutilized area beneath the stairs is a smart way to save space. Doing so with a stash of wood, however, is ... For some decorative recycling, consider burying old bottles upside down to create edging for your garden beds and walkways... Chocolate-colored walls and large window frames allow the exposed wood beams to take center stage in this small screened p... If you're not crazy about the idea of commingling plants and pool, this modern variation may be more to your liking. The s... Yes, a freestanding garage can become its own tiny house. Artist Michelle de la Vega has all the comforts of a modern resi... There’s nothing like a new set of cabinet hardware to refresh a room. The possibilities are endless: Go modern, rustic, or... Filling an underutilized area beneath the stairs is a smart way to save space. Doing so with a stash of wood, however, is ... Like no other floor type, a checkerboard design works wonders to underscore the retro kitchen theme. Vinyl flooring, ceram... Twine lanterns add pops of crafty—but sophisticated—flair to any outdoor setting. Wrap glue-soaked twine around a balloon ... When securely fastened to a tree or the ceiling of a porch, a pallet and some cushioning make the ideal place to lounge. V... Incorporate nature into your lighting scheme by securing a dead tree in a concrete mold and draping your pendant lamp from... For the cost of a can of exterior paint , you can totally transform your porch. Paint the floor a hue that complements yo... In this urban apartment, a standard-issue patio became a serene and green perch by replacing the typical concrete with gro... If you put the washing machine in the mudroom, you can stop the kids from walking through the house in dirty, grass-staine...
Newsletter_icon Google_plus Facebook Twitter Pinterest Youtube Rss_icon