Kynar

EHH week 18: metal roofing

The form of the roof for this house was driven by several factors.  Preference for a modern aesthetic dictated that it be flat with a shallow slope, which made it easy to stay under the 25 foot height limit.  We sloped it all to one side of the house, so the interior ceilings rise towards the western view and so the rain water all flows to the other side to simplify collection.  The exception to the main slope is on the street side, where we sloped the roof up in the middle to mark the entry on the front of the house.

 

For roofing material, we chose standing seam steel, prefinished with Kynar, one of only two types of roofing suitable for potable rainwater.  The other type is TPO, a white membrane roofing.  Because of the shallow 1:12 pitch, these standing seams needed to be crimped upon installation, rather than just snapped in place the way they are connected on steeper roofs.  To assure weathertightness, a high temperature underlayment covers the entire roof, a second layer of protection from the incessant Seattle area rain.

 

The color of the roofing is a nice steely gray called “preweathered zinc,” though it is important to note that it is not actual zinc metal but instead a PVDF “paint.”  True zinc would leach off the roofing and sully both the drinking water and the irrigation water.  And of course our roofing color has a Solar Reflective Index of 34, so that it reflects unwanted summer heat.

EHH week 24: metal siding

With the weather enclosure of the house complete, the siding can be installed.  It is very exciting to see the final exterior go on!

 

Most of the siding is prefinished steel, to meet the homeowner’s request for durable, affordable, and zero maintenance.  We chose a corrugated panel with fairly narrow ribs for a more elegant and less industrial look, Custom Bilt Contour.  The ribs are oriented vertically both for looks and to let rain run down easily.  The color is baked on, like an automobile, and should never need repainting. 

 

Various trim shapes (L, Z, J) are employed where the corrugated siding meets windows, corners, or another material.  Each shape has to be lapped over the one below so that rain is shed down and away.  While the metal siding will repel most rain on its own, any rain that does get behind it will then be stopped by the building wrap.  This double barrier approach is essential in the rainy Pacific Northwest.

 

At the corners of the house and garage, we used a back-to-back J trim to keep it visually narrow.  It is common to see corners with a single L that covers both walls with a wide--and to my eyes unsightly--trim.

 

The key to metal siding is to have a craftsperson install it.  Done right, it will look beautiful, especially up close, and will be the most durable.  The crew from Consolidated Roofing, the same folks who installed the metal roofing, is doing a beautiful job.

Smart design begins here.