Roofing Geometry for Unusual Roof Penatrations

Victorian houses are beautiful no doubt, but they often present complicated rooflines that require above average designs for flashing.  This problem is one such example.  We were recently commissioned to rebuild this chimney and flash in properly with permanent roofing techniques.  This means no solder, no sealant, and NO cutting corners.  The difficulty in this fabrication is created by a hip intersecting the chimney on the rear corner.  The roof pitch is 10:12 which would be very simple to flash if there wasn’t a hip cutting through the flashing right where a seam is required.



Since we are using a fillet seam, all the transitions and angles must be found in the flat before the pattern is cut out and formed…

First we draw a plan or top-down view:


From the plan we are able to create two sections or side views:




There is one key ingredient missing here though, and that is the true-on or oblique view of the seam that runs through the hip:


With these four projections we now have every angle and true length we need to create the pattern and start forming!

Top-down view of complete fillet seam:



Mind you, this shot is before the slate above the apron was installed:



All seaming, no propane bottle, no lead solder, no petrochemical sealants:


Casa Buena can provide expert fabrication services for any historic permanent roofing projects involving slate, tile, and standing seam.

You can see the finished project including new copper valleys, slate repair, and various repair work on Princeton Ave in Providence.

Published by

Kurtis Hord

God-honoring permanent building.

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