Hi All,
I’ve alrady posted this over in General Discussion but was hoping to get additional perspectives so here it is:
Got a little problem in our circa 1850 farmhouse: The attic currently has no insulation and no venting of any kind -just one big dead air space. The second floor as a result is hard to warm in the winter and cool in the summer. Also I have some ice-damning going on.
I removed a section of soffit board this morning and there is a 6×6 handhewn beam visible with is blocking all access to the rafter bay – I think I’m in checkmate here, there just doesen’t seem to be anyway to vent the soffit – unless someone out there has an idea or two… At any rate, I’m thinking my only options are to install gable end vents and a ridge vent, then insulate the attic to R-38 and just filling up the the the rafter bays right down to the solid soffit board I will be re-installing. Is this making the best out of a not so great situation? Any ideas I’d sure appreciate.
Thanks,
Dave in Rochester NY
Replies
what you propose is what I did in my place (same problem, 100 yr old house and no way to vent soffits due to construction).
Adding insulation to your attic will make the biggest difference to your ice damming issue.
I've got some small (6x8")gable vents and a full ridge vent on a 2 story 1500 sq ft house and 12" of cellulose insulation (and a VERY well sealed attic floor, every penetration sealed & caulked).
There is only one rafter bay that any of the snow/frost ever melts on the roof, and that's right above the bath vent exhaust (insulated duct, but still leaks some heat, I guess - already confirmed the shutter works on the fan). I may add some roof vent baffle to that one bay to keep the warmer air from reaching the roof sheathing but its not that bad.
Not perfect, but this roof setup has worked well for the last 7 years for me, anyway.
Oh, and the shingles are about 10 years old, I'll let you know in another 10 or 20 how well they hold up!
Norm
Norm, thanks for the reply! Couple of questions, do you have any thoughts about using fiberglass batts as opposed to cellulose? Also, is cellulose somehting you have to contract to have done or can you do it yourself. And finally, being as the soffits were obstructed like mine, did you insulate right to the obstruction? Thanks again,Dave
By filling-in the rafter bays with insulation, you will be allowing the "thermal transfer" of heat to the underside of the roof deck. This will only increase the amount of ice dams and the severity.
In my experience, I have found that the combination of gable vents and ridge vents, do not allow for the intended air transfer. You may actually cause "short circuiting" from the gable vent to the ridge vent.
Does the hand hewn beam on the wall plate serve a structural purpose? Possibly putting on a second roof, with 2x4's on end?
If you can insulate down to or on top of the soffit board, there must be an opening?
I recommend to use cellulose or foam because they restrict the movement of air. Fiberglass will not. The reason to insulate the attic is to prevent the warm AIR from flowing up into the attic and warm the roof, causing ice dams.I insulated right up to the obstruction (the structural beam).Remember that sealing up the attic plane is at least as important as the choice of insulation types for this type of situation. You want to prevent all warm air from entering the attic as much as possible, turning the whole attic space into a 'cold roof' as much as you can.Hope this helps,
NormPS I think fiberglass insulation is a poor choice for northern climates for the reason given above. It allows free air movement thru it so its ability to insulate is limited when the air temp is quite different inside/outside and convection currents occur. This is not such a big problem when it is only +40F outside, but can be a very big issue then it is -20F outside.