Air leakage causing issues?


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Old 08-22-10, 11:44 AM
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Air leakage causing issues?

I was wondering if there is alot of air leaking out of the topplates on a balloon framed home, will it effect the first floor? Every year we have had nothing but problems with a cold kitchen in winter and hot in summer. It was remodeled probably 10 years ago. There was 6 1/2 inch batts of insulation placed in the walls and a vapor barrier placed over that. I just found compressed cellouse in the attic which I would assume has gotten wet from condensation from air leakage. Some of the holes at the top of the home were more than a square foot in size letting out air. Could this be what has been causing the problems? What effects does a very leaky topplate cause in a home? I'm currently in the process of removing the insulation away from the topplates to foam the gaps shut. One other question, How can I clean the vented soffit from our overhangs in the attic? The overhangs are at least 2 feet deep and I think they have been plugged from the cellouse that was added years ago. The area is hard to get to.
 
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Old 08-22-10, 02:26 PM
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Balloon framed houses generally won't have top plates on the gable ends, or at the division between the first and second floors. If your kitchen walls are insulated but the 2nd story walls or not, then you probably have cold/hot air travelling down the walls and then down the floor joists.

Recently I worked on a home where this was a problem despite the 1st story ceiling and rim being "insulated". The problem was that the floor joists and rim were only partially insulated. Sure there was batt insulation between the joists, but it did not completely block the rim, and it did not completely fill the joist cavity. So cold air would race above and below the insulation all the way across the home, making a cold ceiling in the wintertime.

The solution was to remove about 12" of drywall around all the top plates, remove the fiberglass that partially covered the rim joists and spray foam the rim joist with two-part spray foam.

This problem apparently dated back to the time when the house was originally built. The problem became much more noticeable when can lighting was added to the ceiling, making it obvious that there was a problem with air infiltration! (can lights would actually drip condensation in the wintertime!)

As for your problem with cellulose in the soffits, that's a real pain. Make sure it is a "real" problem and not just a perceived one before you go to a lot of work. A little insulation is no big deal. A lot of insulation might be a different story if it's plugging up your intake. You'd want to use a big 12+ gallon shop vac with the big 2 1/2" hose and drop that down the rafters like an elephant's trunk. Suck up what you can, and dump it out in the attic, and repeat.

If that's not possible, the only solution is to remove the soffit, or remove the soffit vents and do the same thing from the exterior side.
 
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Old 08-22-10, 03:24 PM
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In 1979 the house walls were filled with urea-formaldahyde foam. In the 90's the foam was removed from the kitchen and fiberglass was put in the walls because they placed left over boards in the walls, so the foam wasn't doing its job. So there is foam in the walls of the second story. The one thing I noticed was shrinkage of the foam in the walls on some other remodeling jobs. I have air sealed all the tops of the interior walls in the home in the attic plus all the open cavities. That made a huge difference. Right now there is only 3 or 4 inches of cellulose in the attic which I know is killing us on heating. I need the soffit vents clear because right now most of them are blocked and the attic which is vented on the mansard roof, gets hot. With only a few inches of insulation, is that why the 2nd story gets alot warmer than the first?
 
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Old 08-22-10, 04:44 PM
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If you say there is a mansard roof, then there is no doubt why the 2nd story is hot. Probably little to no ventilation in the rafters, or in the space behind the kneewall between the 2nd story rooms and the roof. And maybe you have a few areas where the rafters ARE the walls, around dormers and such. The house wasn't built with the idea of keeping things a constant 70 degrees, like we are accustomed to nowadays!

Insulation helps keep heat in, but does very little to stop radiant heat. Attic ventilation is the key to removing heat. Some promote radiant barriers, but I don't know much about that, and question their effectiveness.

I've seen some of that urea-foam (white and as light as a feather) and it wasn't always the best at completely filling cavities. Sometimes it would shrink or settle, so i've seen that too. So I would venture to guess that if some was removed, that you might have voids in the cavities where the new meets old. And maybe voids in other areas as well. Just guessing though. And yes, R-38 is recommended in attics, since heat rises, it will radiate right out the attic in winter months.
 
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Old 08-22-10, 05:34 PM
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Theres no kneewalls. There are 2 full 10' stories. None of the rafters are part of the wall. We do have a powered attic vent, but it hasn't been used for a few years now. Last time we used it the house temperature went up everytime we plugged it in. Found out later on, it was sucking air out of the home instead of the attic before I air sealed. Even with it off, theres still a good 2x2 opening at the top of the roof where the vent is. Should we plug the vent back in the summer months when the attic is sealed?
 
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Old 08-22-10, 06:38 PM
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I see. Your temperature difference (power vent not in use) is likely due to uneven air distribution, and return air. Large houses often need many zones and thermostatic controls in order to manage the various conditions in the home.

Your right about powered vents sucking air from the home. Your challenge, besides sealing all attic penetrations, is to make sure you have soffit intake equal to the exhaust of your power vent, correct?

If you don't believe you can attain enough sq in of intake at your soffit (power vents pull a LOT of air) you may need to add additional intake. One product, called cor-a-vent, can be added to the lower portions of a roof, which allows you to cut additional venting in the roof without drastically changing the appearance of the roof. This might be a solution if you are looking to increase airflow in summer months.

One has to remember, however, that adding too much venting to an attic that does not have enough insulation is that it's going to bite you back in the winter months when it gets cold. Thermostatic control on your fan is a good idea so that it only runs when attic temperatures are over a certain temperature.

however, it may be that you need to consult an HVAC technician for his opinion as well, something that we can't really advise you on without being there!
 
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Old 08-22-10, 06:39 PM
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Balloon framed houses have a 1x4 or 1x6 board let-in to the studs to hold the floor joists up. At least you air sealed the attic, (for other readers): How to Seal Attic Air Leaks | The Family Handyman

Compare your intake and exhaust vents for the size of your house, with/out a v.b.: Air Vent: Continuous Soffit Vents Specifications
Need more info on the NFVA.

Find your local insulation requirements: http://www.ornl.gov/sci/roofs+walls/...on/ins_16.html

Is the main floor insulated over the crawl space? Heat doesn't rise. The myth that heat rises was used for many years to justify not insulating floors at all. That led to some very cold feet.
It's hot air that rises. An air mass that is warmer than the air around it will rise in relation to that cooler air. The process of hot air rising is called convection. It's only one way that heat can escape a building. Two others are conduction and radiation. From: Floor Insulation - Oikos

The science: http://www.wag-aic.org/1999/WAG_99_baker.pdf

Be safe, Gary
 
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Old 08-22-10, 06:52 PM
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I'll check on the link for the venting of the attic. The main floor is not insulated. We have a EPA woodfurnace in the basement that keeps the basement around 50-60 degrees with the radiant heat of the unit. I also suspect we are losing alot of heat through the ductwork with the ducting not being insulated. Thats next after the attic. Having a damp basement I have always been afraid to insulate it. We run a humidifier, but I was in a vacant house that every bit of insulation under the floor was dripping wet and everything was ruined.
 
 

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