Insulation Challenge

[showcrop]

My house is roughly 140 years old of post and beam construction. When we bought it in 1989 it had just been rehabbed with new plumbing electrical, mostly new floors many new walls etc. The exterior walls were insulated with cellulose fiber and the attic has fiberglass. However, it is a story and a half so it has slanted ceilings in the second floor, which have no insulation, so I get ice dams whenever we get a lot of snow, not to speak of the heat loss. The cavities are approx. six feet wide by about eight feet down to the knee walls, and they are only about three inches from the plaster lath to the roof boards with a lot of nails sticking through both surfaces. Ten-fifteen years ago I managed to fit some two inch foam board down into one of the cavities, but it doesn't make much difference in the ice daming. I need to get the insulation down more onto the plaster lath, and I also need to maintain a better cold air passage under the roof boards. Today I cut through the plaster knee wall in a closet to see if I could get at the bottom of the cavities from there but I found an outer board wall to the outside of the insulation so there is no access to the bottom of the slanted cavities from there. Has anyone ever encountered and solved a problem like this?

 

[Greg K]

Short of stripping the sloped ceilings and
spray foam insulating them I'm not confident
that you can stop it. Just my .02

 

[Bob Harvey]

From what you are saying, I don't see an easy fix - more like some real 'Reno' work. I know, winter is a bad time for this type of work, AND you are obviously living in the joint. That said, my plan would be to remove the interior ceiling/pony wall plaster, figure out some proper venting, fur down the rafters enough for both venting and insulation. Retired from doing that stuff (35 yrs.) a while ago, it can be done and if you are 'handy' can be done (with help and depending on size) fairly quickly - there will be a mess. HTH

 

[Dick2]

I've watched this on home improvement shows. Seems that the best way to stop ice dams is to spray CLOSED CELL foam into all the cavities for insulation on the underside of the roof, as the closed cell foam will not let moisture travel through to the roof.

The foam board that you used must be open cell foam, which readily lets heat and moisture through the foam, which will cause ice dams. Check your local foam applicator to see if they will spray closed cell foam in the places where you need it.

 

[John(OR)]

I've seen them put a heat cable up and down the bottom few feet of the roof. I have friend
with a thin roof they put down foam panels on roof then metal.

 

[Russ from MN]

I have used the roof heat cable, at our previous house we had a valley on the shaded side that would ice up sometimes, the heat cable worked well. I only plugged it in when I needed to. I wonder how it would work to put at least 2 inch Hi-density foam over the roof sheathing, after removing the old shingles, and then put on OSB with steel or shingles over.

 

[K Effective]

We finished the attic of the farmhouse about 15 years ago during a complete remodel. Ours is of more modern construction, built 1927. We chose to fur out the true dimensional 2X6 roof rafters to about 8 inches (I think we ripped 2X4s lengthwise, coulda been 2X6s). This dropped the ceiling down a couple inches, but gave us room for the foam air channels to attach to the bottom of the roof decking, then installed the spray cellulose insulation (gray paper product with water/sticker in it to hold in place). We drywalled over the fur strips. Outside the knee walls we used quarter-inch luan paneling instead of the drywall for cheaper coverage. The roof is solid ship lap 1X6 with old heavy felt and asphalt shingles with ridge venting. Never had any ice issues.

 

[IA Roy]

My first house was stick built in 1928, in Albert Lea MN. It had an unfinished attic that I wanted to make into living quarters. It had 2 x 4 rafters. I furred down another 1 1/2" with 2 x 2's. I then put a 1x2 on edge screwed to the 1" sheeting halfway between the rafters to allow ventilation. I had vented soffits and roof vents near the peak of the roof. I then insulated the cavities with 3 1/2" fiberglass batt insulation. I then finished with 1/2" sheetrock. I sold the house the next year as I had to move back to Iowa for a new job. I do not know how effective it was, or if I caused anybody any problems. I moved out 35 years ago. The house is still standing according to a google earth picture I looked at last fall.

 

[JD Seller]

I would think they could reach down from the top with a spray foam insulation wand and fill the cavity. I had the exterior walls done on a plastered house and they did it from the second floor reaching down each stud opening on the first floor.

 

[donjr]

Not seeing the house or knowing your exact situation doesn't help I'll just relate to what we did at our old fire house. It was
builtin 1952 when oil was cheap as dirt, and without any insulation. T had a flat roof with about twenty pounds of stone on it,
and the roof started to leak back around 1980. So, we realized we needed a new roof. So, what we did was to strip the stone and
old roof, then we laid down varying thicknesses of foam insulation from 1" to 4', then a layer of butyl fabric, butyl paint and
more farbic and paint, the about 15# of stone. As far as I know, it's still tight, and our heat bill dropped by about 75% the
first winter.Is there any possibility you could replace the roof with steel and a layer of foam under it?

 

[David G]

You did the right thing making them vented.