adding soffit vents

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You can have vents without adding overhangs. Between each rafter is a block that fills the space between rafters. The rafter ends and blocks may be covered by a facia board. Vents can be drilled through the facia and rafter blocks with a hole saw and a round screened vent installed in the hole. Even better, another type of vent can be installed without soffits, and adds a drip edge (drip edge vent). See this link for ideas: http://www.toolbase.org/tertiaryT.asp?DocumentID=2146&CategoryID=1014 . This vent requires cutting roof sheeting back 1-inch along the lower edge of the roof and repairing or replacing shingles above. If the roof requires repair, this is the best option and a bitumen edge seal can be added.


This ventilates the space between the rafters. The issue then is to be sure insulation does not block that vent. Chances are, you have kneewalls in the second story, and a space behind the kneewalls. Insulation needs to be installed on the floor of that space and up the kneewall. Insulation then normally follows the ceiling slope inside the rafters and runs across the ceiling in the attic.

Installing vents in the rafter blocks, ventilates the space behind the knee wall, but you need to ensure a ventilation channel exists between the insulation and the roof deck, into the attic. In the attic, ventilation is provided by gable end vents or a ridge vent.

Overhangs would be added by removing the rafter blocking and slaving on rafter tails. These are extensions to the rafter that extend about a foot beyond the current facia and attach along the rafter about three feet into the roof. A roof deck, shingles, new facia and gutters are then added along the new outside soffit. It would be much easier to simply ventilate the roof edge with individual block vents, or continuous drip edge vents, than to add soffits.