Change over asphalt shingles to metal roofing

Guest User
5/20/2004
I have a 21'x32' Cape Cod house. I have reshingled the front side of the roof and put a ridge vent on 20' of the ridge in 2 sections of 12' and 8'. I'd like to put a metal roofing on the back side of the house (not visible from the street) on top of the existing old shingles and keep the asphalt shingles covered ridge vent for esthaetics. The roof slope is 11:12. I was advised to put 1"x3" purlins 20"o.c. nailed into the rafters to support the metal roof. My question concerns the transition between the asphalt shingles of the ridge and the metal roofing. The thickness of the metal roofing plus the purlins will add up to 1 1/2". Is there a good way to tuck the metal roofing under the shingles and still keep the ventilation? How can I finish the rakes and the eaves ? Is it possible to use the existing lead sheet flashing around the chimney ? Thanks
Guest User
5/20/2004
These questions really need to be addressed by the manufacturer of your metal roofing. However, here are my thoughts. You should be able to re-install your ridge vent on top of the metal roofing. There should be a closure strip available with the roofing for filling the gaps between the low spots of the metal panels and the ridge vent. There should be matching eave and gable trim available with the roofing. If not, you will need to bend matching drip edges and perhaps some flashing depending up the profile of your metal roofing. I would replace the chimney flashing.
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