I have a 30 year old split level that was never ventilated in the attic. The #1 recommendation seems to be inserting styrofoam true vents into the eaves (over the insulation) along with a ridge vent.
It is my understanding that ideally, this will keep the attic temperature roughly at par with the outside temperature. Better for the attic, shingles, etc? Presumably this will allow my house to cool off a little better in the summer?
My main question - will allowing for greater ventilation in the attic have any effect on the cost of heating my house?
Or, to be more complete; if the barrier between the living space and the attic is so poorly insulated and sealed that ventilating the attic has a noticable effect on your heating bills, then you're already loosing so much heat through the top of the house that you need to add insulation there anyway.
Ridge vents are good but easier is a square roof vent. Do you mean you have no vents at all? Does attic wood look dark and moldy ? You will increase heat loss is you don`t have very good insulation. What is your attic insulation, what are your winter temp lows. The attic should be vented to keep it near outside temps to avoid condensation.
Following that logic, it doesn't matter if it's 10 degrees outside or
50 degrees, the cost of heating or cooling a house will always be the same, because the house is insulated.
There's no question that proper attic ventilation will reduce cooling bills. One big difference is the hot air is gone when the sun goes down, not trapped there for hours to slowly cool overnight.
For the OP, you do realize that you need soffit vents in addition to the stryfoam chutes, right?
"Dave Gallant" wrote in message news: snipped-for-privacy@posting.google.com...
Dave: IIRC the recommended CMHC (Canadian Mortgage and Housing Corp) venting for wood frame construction is 0.3 percent of the area. In other words if say your house is 25 feet by 40 (1000 square feet) you need a 'Minimum of 3 square feet of venting. The guide also says "Venting must be distributed so as to ensure cross ventilation". It does not say you must have ridge vents. Over some 30+ years, to this house, we have added additional ceiling insulation and also additional venting along the soffits (bottom of the eaves). All extra to the original vents in the two gable ends. Anyone who adds insulation is always warned, be sure not block any vents. It occurs to me that you must have an excellent vapour barrier, on the warm side of your ceiling insulation, now. Other wise, every bit of warmed and therefore moist house air that escapes up to the attic can condense up there and you can get mould, rot and possibly wet ceiling insulation. We have seen posting on this type of group about attic condensation problems. In one case someone said they had 'toadstools' growing up there on soaking wet roof rafters! Very expensive! Email me if you want to discuss some more. We are in eastern Canada also. Terry in Torbay Newfoundland. Not as cold as many places in North America but cold enough and on a cold stormy winter night; "Me son she can blow some hard".! PS. Page 104; Canadian Wood Frame House Construction, "For both pitched and flat roofs it is important to provide adequate ventilation of the roof space above the insulation. Even where air and vapour barriers are used some moisture will leak (up) around pipes and other openings (e.g. light fixtures) and through the vapour barrier itself. If that water vapour is allowed to accumulate in attic spaces and/or under flat roofs it is likely to condense in cold weather in sufficient quantities to cause damage. ................. etc. etc. .............................. the most practical way to remove the vapour is by ventilation. BTW we were very careful with that ventilation aspect when building our first house, with a partially vaulted ceiling, 43 years ago. That house is still in good shape with its fourth owner. One of the intermediate owners blocked off some of the crawl space vents I had carefully installed in that first house and fairly quickly had moisture and damp problems! Its amazing how people don't understand the concept of warm moist air condensing in the cold; one only has to breathe out on a cold day to see the moisture in one's breath alone. Anyone know the typical amount of moisture each of us breathes out while we sleep. I think it's like a pint or a litre per night, or something?
There is no venting at all. The previous owner told me that there was venting in the eaves, but if there is there are no holes in the soffit to allow air through. A friend who is a contractor looked over the attic, and told me that there was no problems - no sign of mold or previous condensation problems. I'm just looking to give it a long life and bring it up to more modern standards. It could also use a little more insulation, but I want to put in the true vents first.
Winter gets pretty cold here - east coast of Canada.
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