Pairoducks

Pairoducks

Friday, September 13, 2013

More Roofing...

The last few days have been clear and beautiful, so I have been focusing on getting the roof completed for the fall rains.  I picked up the metal roofing from Tacoma on Monday, prepped everything and yesterday had a work party to get started.  

 

First we finished blocking between the rafters and above the top plate, then we wrapped a giant roof present.  I used a product called Siga Majcoat that I purchased from The Small Planet Workshop located here in Olympia.  This roofing membrane is almost like fabric.  I stretched it out and used the Siga Wigluv tape to hold it down.  I didn't have to use any staples.  I stretched out the membrane, patched the seams with the tape and will lay down foam to told the roofing membrane in place.  The only penetrations in the membrane are where the furring strip lag bolts mount into the rafters.  The big difference between the Siga Majcoat and regular tar paper is that tar paper is not breathable.  If water gets trapped underneath it, it can rot out plywood and rafters if they are not properly ventilated.  Siga Majcoat is permeable to water, so that when it gets trapped, it can escape.  This is important for the style of roof that I am constructing.  The unventilated roof is designed so there is enough foam on top of the roof that the dew point is outside of the plywood sheeting.  Therefore, one does not need to ventilate rafter space and can keep the building's air seal tight.  If water does get underneath of the roof membrane and on top of the plywood, the Majcoat allows the moisture to pass through and dry out.  




Here is a picture after we got the first piece of 2" foam board insulation up.  


The pictures above and below show 4" of insulation in the front end of the roof with 2 furring strips lag bolted in place, holding down the foam.  


A special thanks to Ben Groves, (neighbor, friend and origami artist) for all the help.