Question about ventilation

Started by Brad(Guest), April 10, 2006, 09:25:21 AM

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Brad(Guest)

Hi Everyone,

I'm working on a slightly modified version of the Little House plans.  The cabin has 11 windows including 1 in each loft.

I didn't install a ridge vent and was considering either gable and soffit vents or no vents at all.

The house is in Northern VT and I am worried about cold air in the non-summer months.  

With the windows how important is it to add additional ventilation?

Assuming that it is pretty important is there a standard for how many soffit vents do I need?  I was planning on installing small round vents the in the blocking between the rafters.  Do I need a vent between each set of rafters or can I go every 4 rafters?

Thank in advance for any insight.


John_M

The idea of a ridge vent is to allow air above your insulation to fluctuate with the outside air temperature and avoid moisture problems.  

Ideally, you would need an open air space running from your soffits (bottom edge of the roof) to the top (ridge vent).  This would allow the air to cool properly and not get your insulation wet from condensation of warm and moist air inside your home.
...life is short...enjoy the ride!!


John Raabe

Yes, John is right. This is not about ventilation for the house but for the roof and rafter cavity. You should have 1" under the sheathing and above the insulation from eave vent (bottom of the rafter) to the vented ridge.

This will reduce summer heat, make the roof last longer (if asphalt), and reduce ice dams at the eaves.

If you have it all sealed up then pack it full of insulation and make sure you do a very good job on the air vapor barrier in the ceiling. This will work as long as you can keep moisture out of the cavity.

Hint: Don't do can lights in the ceilings.
None of us are as smart as all of us.

Amanda_931

Aha.  John's reply may answer my question on this.

Even if you are using one of the foam insulations--e.g. Icynene or the soybean product?