Ventilation

2136 Views 6 Replies 3 Participants Last post by Gary in WA, Jul 9, 2011

Gungho_15

Discussion Starter · Jul 6, 2011 (Edited)

I am sure this topic has been beat to death. I live in a 2 story 2300 square foot house. Last summer I put on a new roof with Shinglevent II ridge vents.(approx 39 feet)

Our upstairs of our house is always hot in the summer. This spring I had a heat pump installed. Best purchase yet. This fall I plan on adding insulation. I currently only have R12, Code is R40. I installed rafter vents and made sure all soffits are open. The attic is approx 1200 square feet.

The soffits currently have 9 - 16"x2.5" vents cut out. 4 on the front of the house, 5 on the rear.The soffits are cedar tongue and groove.

Should I be adding intake vents or just leave it be? I have tried to figure out the math, but it seriously had me dreaming of numbers all night...lol I live in Vancouver British Columbia if that helps.

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Gary in WA

· #5 · Jul 6, 2011

Continuous would be way better than 8x16's as you will vent each rafter bay rather than one vent every 7' (depends on brand 8x16=65NFVA and 2-3/4 cont. is 8-9 NFVA) http://www.lomanco.com/intakemain.html

http://www.airvent.com/homeowner/products/intakeSoffit-specs.shtml

Install it closest to the fascia board for best air pressure, pp. 616: http://books.google.com/books?id=Z8...page&q=attic airflow with gable vents&f=false

Cont. soffit = 1/2 cont. ridge vent plus add the other side soffit = balanced. Be sure to air seal the attic, much more important: http://www.jlconline.com/cgi-local/...e.storefront/4d17fa04053d6e9327170a32100a05c7

Gary

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Gary in WA

· #7 · Jul 9, 2011

The soffit vent location is fine, just expand the amount for continuous. The box stores sell it screened and louvered.

"Does that sound appropriate and will it make a noticeable difference in my house?" ---- It will help, though the added insulation will insulate the house from the attic for a noticeable improvement.

Air seal the attic holes before insulating and after adding venting- what to look for: http://www.finehomebuilding.com/PDF/Free/021105092.pdf

http://www.google.com/url?sa=t&sour...sg=AFQjCNEV_sFpJPB8DwLjAd-t6PJoO842EQ&cad=rja

Check your other pages here also: http://oee.nrcan.gc.ca/residential/personal/heat/keeping-heat-in-chap4.cfm?attr=4

Gary

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