Soffit vents under second floor bath

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Old 01-29-14, 10:59 AM
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Soffit vents under second floor bath

I bought a cape with a 3/4 dormer on the back side. The soffit vents on the lower roof (guess it would be original roof or the non dormer one) are venting cold air between the floor joists. This is creating quite a problem in my upstairs bathroom. The PEX pipes run under the floor and the cold air from the soffits is causing them to freeze. My question is could i simply cover up the soffits under the bathroom?
 
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Old 01-29-14, 11:16 AM
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In a simple roof design without the 3/4 dormer (dust pan), the vents would be necessary to vent the bottom of the roof or an attic space. When the dust pan was built, this should definitely have been sealed off.

Now, there may be a rim joist in there in which case it is already blocked and the rafter ends are just cosmetic. Have you looked in there to see if the joist bays are indeed open to the venting?

Bud
 
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Old 01-29-14, 11:29 AM
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I have looked in there and they are indeed open.
 
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Old 01-29-14, 12:26 PM
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You will want two fixes, insulation for several feet in and a good air seal on the surface where the wall would normally be. Often a piece of 6" unfaced batt insulation folded in half can be pushed into the cavity and form a complete fill. I don't know how good the access is from the soffit area, but if you can, cut and fit a piece of rigid foam insulation to the vertical front to the opening and caulk the perimeter to complete the air seal.

Good find, you should really feel a difference.

One concern would be, if they didn't insulate that exterior end of those cavities, what did they do with the rest of the cavities?

Bud
 
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Old 01-29-14, 12:43 PM
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do you think the surface seal will be enough. I really don't want to rip up my floor.
 
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Old 01-29-14, 01:36 PM
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Closing off any air access will protect the insulation. The insulation will then protect your floor. Air sealing is the number one fix as a ton more energy and moisture can pass along with the air. With some pictures we might be able to get more detailed.
http://www.doityourself.com/forum/el...-pictures.html

Bud
 
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Old 01-29-14, 03:07 PM
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Thank you very much for the responses. I will try and get up there to take some pics, but with all this snow it may be difficult. Now that I think back, I had to replace a section of the subfloor when I moved in and there was fiberglass insulation in there. Maybe just putting the foam insulation in the soffets will do it.
 
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