This is a job you must do before fastening the overhead’s roof rafters in place. The term reglet flashing refers to an installation method for counter flashing, not a separate layer. The first two layers are called base flashing and step flashing. Where integral flashing isn’t possible, such as on a stucco wall, use Z-flashing and caulk the top edge. Counter flashing is the final layer of a three-part waterproof barrier installed between a roof and a vertical wall or chimney. Unless it will be protected from rain by the house’s eaves or a solid roof, a roof ledger that is fastened directly to a house with wood siding should be capped with galvanized metal Z-flashing that tucks up under siding to prevent water from seeping in behind it. Push or hammer the ledger back onto the bolts, recheck for level (making any needed adjustments), add washers and nuts, and then tighten the bolts. Remove the ledger, and drill bolt holes where the bolt tips have left marks.
![flash a roof to a vertical wall flash a roof to a vertical wall](https://www.doityourself.com/forum/attachments/exterior-paneling-all-exterior-sidings/70046d1472094072-flashing-siding-porch-roof-wall-3a.jpg)
When that is done, the lean-to roof is flashed into the wall for the life of the new roof.
![flash a roof to a vertical wall flash a roof to a vertical wall](http://aconcordcarpenter.com/wp-content/uploads/image-import/_0vuJZhliRZA/TA6zPTGmo7I/AAAAAAAAJNo/QrL5ii_bMgo/s1600/BLOG%2Bpics%2B067.jpg)
At the end of the job, smooth aluminum caulk or gutter seal over the heads of the nails along the lower edge of the bent metal flashing. Drill holes for the expanding anchors every 16 inches or as specified by local codes, insert the anchors, hold the ledger in place, and tap it with a hammer to indent the anchor locations on its back face. Make sure the caulk also covers the heads of the mortar nails. Begin by marking a line across the wall for the ledger’s top edge. Think about the thermal stress a roof membrane goes through (Figures 7 and 8). And to make matters worse, structurally we also tend to have some issues. No vapor control layer and thermal bridging everywhere. Anchor a ledger to a masonry wall with expanding anchor bolts. No air control in either the roof assembly or the wall assembly.