Flat roof: Roxul + polyiso + EPDM retrofit
I have a 13′ x 18′ half hexagonal single story bumpout with a very low slope uninsulated roof covered in ‘something’.
Plan is to remove the ‘something’ and layer as follows:
roxul comfortbatt in cavities
Tapered 2 x 4s on top of existing to increase slope on top of rafters.
1/2″ Plywood deck
Roof deck seam tape
4″ wood edging (borders foam)
Two staggered layers of taped 2″ unfaced polyiso
6″ HEADLOK flat head wood screws
60 mil white EPDM
Below is a spec from Firestone but confused as to why I need the barriers. Also pictured is bumpout. Third is from densdeck.
Thanks in advance,
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