Unvented 5/12 pitch slate roof built with Zip sheathing and closed-cell spray foam insulation
I am Homeowner building house in Port Washington , NY, ( Long Island )
My Architect will try to go for passive house certification , so “She” needs to be air tight and super insulated .
“She ” will have ERV system and attic floor will not have any insulation , so temperature will be balanced throughout interior of the house
Exterior walls is constructed with 3/4″ zip sheathing over 5-1/2″ LSL Versa studs ,
Interior cavity of wall studs will be 3″ of closed cell spray foam and balance of 2-1/2″ will be open cell spray foam
“She” will also have Rainscreen system on exterior walls installed with 4″ Cascadia clip ( thermal spacers ) and will have 4″ of Roxul cavityrock insulation btw clips . Insulation will be covered with Solitex Mento 100 airtight , vapor open house wrap . Cascadia system have 1″ Z profile track that creates 1″ air space (btw rainscreen surface and Vapor barrier )
Upper portion of house will be 7/8″ IPE siding and lover portion will be stone veneer over 5/8″ Durock fastened to Z profile :
“She ” will be glazed with High efficient Passive house European Doors and Windows
UNVENTED PITCH ROOF ;
About 70 % of the house roofing is 5/12 pitch roof with large 5′ overhangs and other 30% is flat roof .
Pitch portion of roof is getting build with 3/4″ zip sheathing over 11-7/8″ LVL rafters ,
We are planing to spray 3″ of closed cell foam insulation btw rafters & under zip sheathing and than balance (about 9″ )of rafter cavity will be filled with open cell foam ( to save on cost) .
As per manufacture Zip sheathing needs have Grace ice & water shield 2′ all around edges of overhangs and in valleys . Over the entire Zip sheathing we are planing to use vapor permeable roof underlayment (Delta-foxx ) from Cosella Dorken and than Vermont slate for finish
Unvented Flat roof :
32′ x 32′ surface is built with 9-1/2″ LVL framing covered with 3/4″ advantex subfloor .
Underneath Sub flooring , 9-1/2″ cavity will be filed up wit 3″ closed cell spray foam insulation and balance of 6″ will be open cell foam .
Entire surface of subflooring will be covered with Grace ice & Water shield membrane . Over the membrane we will have tapered insulation .First layer ( base ) will be 4″ throughout flat roof surface and than Tapered insulation will start as 1/2″ thick and will grow to almost 6″ maintaining 1/4′ per foot pitch over 32′
Primary waterproofing membrane will be Kemper system
MY BIGGEST WORY IS UNVENTED ROOF AND DEW POINT ISSUE THAT MIGHT CAUSE ZIP SHEATHING ROTTING !!!
We are in stage of roof framing completion and Roof sheeting will start end of this coming week
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