A.Tim Harwood, sales coordinator at Grace Construction Products, responds: Eaves membrane should always be installed first, under the drip edge, in order to provide maximum protection to the roof sheathing. After installing the drip edge, you can install an extra band of eaves membrane over the top of the drip edge, if desired. This second layer is extra insurance for those who want to be sure that all moisture is conveyed onto the drip edge.

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