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Georgian attic insulation


grubbygus's Avatar
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IL

12-28-12, 05:59 PM   #1  
Georgian attic insulation

I have a 60+ year old brick Georgian in Chicago. My winter project is to blow in insulation in the attic to bring my value to R-49. I also plan on installing an attic fan once the weather warms up. Here's my question / concern; I have a few roof vents but my house doesn't have any soffit or eave vents. I do plan on installing ventilation channels between the rafters to keep the insulation from reaching the roof and jeopardizing the cold air barrier. Does anyone see any concerns I might have such as airflow or ice dams?

Thanks

 
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czizzi's Avatar
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12-29-12, 06:43 AM   #2  
Ice dams would be caused by not enough insulation and warm air heating the roof and melting the bottom layer of snow. The melted snow then travels down to the eave where it freezes and backs up. R49 should more than take care of the heat loss through the ceiling, so I don't see any problems with ice dams.

Are there gable vents in addition to the roof vents? For the soffet vents, there are formulas to determine amount of vent Square footage needed for the size of your attic. If you let us know a little more about the size of the attic, we can determine your vent needs

 
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12-29-12, 08:55 AM   #3  
In addition to the added insulation, the most important step you can take would be to air seal between the house and the attic. Warm air leaking into the attic transports heat and moisture, both of which represent energy and potential problems. Major leak areas are obviously the highest priority, like can lights, exhaust fans, plumbing vent paths from basement to attic, and more. Once well air sealed, your insulation efforts will improve. Also, the amount of ventilation required goes down.

There are other options for low venting, from edge vents to under shingle vents. czizzi asked about gable vents, so more details will help.

Bud

 
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12-29-12, 09:46 PM   #4  
Welcome to the forums!

I have a 60+ year old brick Georgian in Chicago... Here's my question / concern; I have a few roof vents but my house doesn't have any soffit or eave vents.
What shape roof do you have? Gable, hip, shed, gambrel, mansard...? Does it have soffits or gable ends or a ridge that could have a vent, but don't? What do you mean by "roof vents"?

Some pictures would help us see what you have. See How To Put Pictures In Your Post.

I also plan on installing an attic fan once the weather warms up.
OK. Why? One more mechanical thing to break down. What is the goal that you believe this fan will help you reach?

 
grubbygus's Avatar
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01-05-13, 08:06 AM   #5  
Thanks guys for the responses. I don't have any pictures right now but plan on going in to the attics today so I'll snap some. My original structure is a hipped roof with no soffits There is an addition built off the backside of the house also hipped and attached to existing roof so I have two attic areas but the addition doesn't have an access scuttle. I plan on cutting through the plywood between two rafters to gain access. Nashkat1 what I mean by roof vents instead of a ridge vent just square vents cut in near the ridge of the roof. Bud what do you recommend I seal holes with? I have several can lights can I use great stuff foam around them. I've attached a picture I found online that is a good representation of what my roof looks like although my pitch isn't as steep.
Thanks

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Bud9051's Avatar
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01-05-13, 09:24 AM   #6  
Can lights are an issue. If they are Insulation contact (IC) rated and Air Tight (AT), then no air should be leaking and you can bury them in insulation. If they do not have the above ratings, then my recommendation is they be replaced. Now that I have covered myself , some people have been using pre-made covers that claim to be approved, that once in place seal the leakage and allow for insulation. Others will advise to build a box out of drywall maintaining a 3" clearance and again seal it and insulate over it.

Safety is the overwhelming requirement and new cans with the correct ratings is best. The AT rating is sometimes part of the model number. Local codes can advise.

Here is a link if you haven't seen it on air sealing: http://www.efficiencyvermont.com/ste...ide_062507.pdf

I though I had posted this one as well on fascia vents: GAF | Cobra FasciaFlow Vent (Attic Intake Vent)

There are other under shingle vents and hip roof ridge vents.

Bud

 
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