I’ve been following the various threads on Breaktime regarding insulation, house wraps, and vapor barriers. The discussion has been helpful but has, naturally, focused on attaining maximum R-values. My situation is a little different. I’m looking for insulation for a summer home which will give me, at least, minimal R-values but not rot out the house over the long run.
The house is in Atlantic Canada. Eventually, my wife and I may be there for up to 6 months a year but we won’t be there for the winter. Still, the highs in May and October are in the 50s with lows dropping down to freezing at night. Even in July and August there will be a few days where heating is required. So, it would be nice to have a bit of insulation in the walls. The attic presents it’s own set of problems but I won’t get into that now since I won’t tackle the attic next summer.
Anyway, here’s the situation. The house is an 1880 saltbox which was in sad shape when we bought it two years ago. Over the last two summers, we restored the original 12/12 pitch roof. We resided the whole house with 1″ board sheathing, tyvek, and 3/4″ kiln-dried spruce clapboard and we also added a new kitchen addition. Next summer, I start on the interior. At this point, the stud bays are either completely open in the kitchen addition or easily accessible in the original part of the house by removing some 1/2″ interior board sheathing.
My original intention was to insulate in a conventional fashion. Fill the 2×4 stud bays with un-faced fiberglass bats followed by a 6 mill plastic vapor barrier and then drywall. However, fiberglass has gotten a bad rap in this little village. What was thought to be minor repairs on three older houses revealed sopping wet fiberglass insulation. It’s not clear to me what the problem is and it may not be the fault of the fiberglass at all. It could be the lack of a good vapor barrier when these older homes were insulated. Also, I doubt if these houses had any type of house wrap and wind-blown horizontal rain can be a problem since this village is right on the Atlantic Ocean.
A second approach would be to use 2″ rigid foam panels in the stud bays. That would leave a 1 1/2″ dead air space in the wall for any moisture to evaporate. What do you think, fiberglass bats or foam panels in the walls?
I might consider other alternatives but renting special equipment can get expensive since most of the rental outlets are three hours away. Anyway, I would be interested in any feedback that folks at Breaktime would offer. Thanks.
Chip
Replies
Chip, I think you need to determine the source of the moisture in the walls before you can consider any insulation. I can't believe the fiberglass has been wet forever, or the studs would be gone. Sounds like you may be right with the wind blown/loose construction theory, but you didn't tell us about the ceiling. If it is leaking vapor and condensing on the underside of the roof, then the water may be running into the walls. Look under the house for gaps into walls and floors as well.
Air sealing, walls, attic and under the floor is critical, and leaving a portion of the house non-corrected will just drive the moist air to that area and defeat the purpose. Although you call it a summer house, you are using it during a time of fairly aggresive temperature gradiant and humidity swings. From your experience in the village, sounds like many of the houses are having the same problem...inadequate sealing/ventilation/insulation/seasonal occupancy.That is not the fault of the fiberglass.
If you have sealed the new walls from leakage as you describe the new wall, then foam board and fiberglass would give a good R-val. (I assume closed cell spray foam not available). It sounds like you want only enough insulation for summer occupancy, but with all the work you are doing, I suggest that you insulate/seal the entire structure for year around survival. Hope this is helpful, Paul
Paul,
Thank you very much for your reply to my question. At this point, my own summer home doesn't have any moisture problems since it hasn't been occupied for over 12 years. I just don't want to introduce any by adding insulation.
Regarding the three older homes in this village which had moisture problems with fiberglass insulation, I'm not sure I can add much additional information. I only witnessed the problem in one case when a carpenter-friend was installing a kitchen exhaust fan for a neighbor. In that case, the insulation he pulled out from the wall cavity was sopping wet. I was told of two other similar cases. In one of those, there was some structural damage to one side of the house. The owner resided that side and, I believe, did not put in any insulation the second time around. Again, this was a summer home. I guess the thought was that any moisture which found it's way into the wall cavity would eventually evaporate and not be traped by the fiberglass.
Yes, I agree that air sealing is critical. Realistically, I'm just not sure how well I'm going to be able to do it with this 1880 era home. Even with all of the improvements we've made it's still a pretty leaky old structure. In addition, we've kept certain elements, like traditional windows, in the name of restoration. But, those just add to the problems of sealing up the house. Yes, as you suspected, sprayed foam is not available locally. Thanks again for your response.
Chip