Replies

1. 
   WonderWoman | Dec 28, 2009 05:12pm | #1

   I'm assuming the insulation
   I'm assuming the insulation is in the attic floor, not on the underside of the roof? Do you have any bathroom or other vent fans that blow into the attic rather than being connected to a duct that vents through the roof or wall? If so this needs to be corrected. Also, if any air is able to rise around or through the insulation this will condense on the undersides of your roof and run down to your soffits where it will drip and freeze.

2. 
   DanH | Dec 28, 2009 08:37pm | #2

   You've got a (serious) air
   You've got a (serious) air leak into the attic, I'd wager. Or possibly even your bathroom fan is dumping into the attic.

3. 
   Clewless1 | Dec 28, 2009 10:36pm | #3

   Check for air leaks into the attic. Maybe exhaust fans dumping into the attic or near the soffit vents. All exhaust ducts should be positively connected to an exterior boot. Seal all ducts, too. Another culprit would be e.g. recessed can lights. They are notorious for causing icing. Your new insulation should have taken care of air sealing problems before it was installed. If it wasn't the insulators responsibility, he should have taken the responsibility of telling you about them. At any rate a recessed can should have been boxed and sealed during insulation regardless of other sealing responsibilities that he may not have had. Maybe you have a mech chase somehwere, too? Ice 'dripping' from soffit vents means moisture getting into the attic and then freezing on your metal soffit material as the air pressure moves it out.

1. 
   Jeff_Clarke | Dec 29, 2009 09:34am | #4

   Icicles coming from the vents mean you have liquid water inside the building envelope and are right to be concerned.

   Do you have a carefully sealed roof sheathing-to-fascia/drip edge condition and 3' of ice and water shield under the shingles? If not you are likely getting ice dams which can occur no matter what the insulation in the roof/ceiling.

1. 
   und76xx | Dec 29, 2009 11:49am | #5

   Thanks for the quick answers. Insulation was placed on the floor of the attic. I do have one can light - a shower light that he claimed was boxed before insulation. I also have a whole house fan that has an insulated shield - from inside of the house rated at R19. It is also boxed inside of the attic. There are two vent fans coming form two separate showers. When installed they were vented to the outside. The roof is 15 years old and installed before I bought the house. So I have no idea what exists under the roof. There are several ice build-ups along the length of the roof. I also have an attic fan used to vent the attic during the hot summer months - it is thermostatic controlled fan.

   Could the insulation installer have covered the overhang vents with insulation thereby preventing the roof from breathing? I have seen cardboard cutouts installed between the roof trusses to assist in air movement. They were NOT used as far as I know. He never mentioned any need to caulk anything in the attic.

   Could the excess ice build up be because of my low thermostat setting inside of the house - 61 at night and 65 during the day?

   Should I get another installer view before I complain to the original contract person?

   Thanks, Mike

1. 
   mmoogie | Dec 29, 2009 05:29pm | #6

   Ask your insulation contractor if he does blower-door testing. If he does, have him do one on your house to locate the sources of air-leakage into the attic. If he doesn't, find someone who does.

   Steve

2. 
   DanH | Dec 30, 2009 07:47am | #7

   The insulation contractor SHOULD take appropriate steps to avoid blocking the vents, but that's not something I would TRUST them to do, without checking their work. When I had our attic done with cellulose I installed the vent chutes myself, to make sure it was done right.

   You may get a clue as to where the moisture is coming from from the pattern of ice. The moisture will tend to condense most heavily within 15 feet or so of where the moisture enters (though maybe not directly above, as hot air may prevent it). So the air leaks are apt to be near the largest icicles.

   For our whole house fan I fashioned a cardboard "cap" that sits on top during the winter.

   Several areas to consider for air leaks:

   -- The scuttle hole itself -- should be foam sealed around the edges, and the board covering the hole should be heavy enough (or weighted) that wind pressure can't lift it. (Put a layer of foam on top of it as well.)

   -- Pipe and flue chases.

   -- Oversized holes drilled for pipes and wiring (though these would be unlikely to cause the amount of trouble you're seeing).

   -- Soffits and drop ceilings. These leave the stud wall open (unless the builder takes steps to the contrary) so that air from the inside can be drawn out.

   -- HVAC ductwork in the attic. Any such ductwork should be very tightly sealed (with mastic or foil duct tape) and insulated.

   -- Vent fans dumping into the attic (a big no-no).

3. 
   Clewless1 | Dec 30, 2009 08:07am | #8

   Are you sure the exhaust fan ducts are connected clear to the outside? I would check to see if he blocked some vents along the soffit. This WOULD be his responsibility. A few blocked vents would allow moist air to build up and cause your problem. Not the case if all are blocked. Also, if generally ventilated well, the moisture is still a sign of air leakage somewhere, I think. Definately check the shower light ... perfect source of excess moisture. Depending on orientation of prevailing wind, the ice you refer to may be close by (e.g. the nearest eave), but again, if the wind comes from that side of the house, the moisture/ice could show up elsewhere.

   If he did e.g. cellulose and did NOT use baffles or make some other provision for protecting the soffits from filling up, he didn't do his job right and shouldn't have been paid.

1. 
   und76xx | Dec 31, 2009 10:53am | #9

   The contractor is coming back to investigate - with some reluctance. I have printed all of your responses so my arguments will have merit and back-up. So thanks for that. He thinks my greatest heat loss - now - is through my walls. He could very well be correct. I have 2x4 wall ocnstruction and I have no idea what is in those walls. Maybe nothing. He said he would check on his investigation stop.

   I do not have any HAVC runs in the attic. I do not have any canned lights. I have one exhaust fan/light in two bathrooms - both are the combined type. I do not want to do much to the walls since this house is @ 3400 sq ft and I am now single with all kids gone to college - time to downsize buy a magnitude.

   Any of you guys work in the Grand Rapids, MI area?"

   Mike