Needing some advice.
climate zone 5
Have an “attic” that’s being turned into a room (conditioned space). will condition the crawl spaces as well.
joists are 2×6 for 5.5in est. in depth. With a new roof I had them add a roof cap for ventilation (turtle vents were a pain & seemed to be a point of failure for leaks)
SO this means i need baffles for ventilation….
We estimate there’s about 420 liner feet of joists, with all of them about 14in wide.
whats the best option? I cut our having it spray foamed (assuming too expensive)
looking at 3 options(open to more) –
- thin plastic baffles from lowes (2.25/piece) along with r21 fiberglass. spray foam along sides and connections of baffles to seal them. slight compression on fiberglass
2)1/2 gap with 1/2 in board on top (R3 value for 1/2 board) spray foam in place for sealing. R21 compressed on that (5.5 into 4.5 space)
3) 1in gap with 1 in foam board cut to fit.(r5 value on board) leaves 3.5 in, would get r15 fiberglass to fill it.
r15 w/ 1″ foam might actually be the cheapest option. BUT its a lot more work for me to make my own baffles.
Im being told fiberglass is better for heat transfer through attics, especially with the plastic baffles protecting it from windwash and moisture.
Take a look at this FHB post with input from Michael Maines: Better Vented-Roof Baffles. It includes a helpful illustration. Mike stresses the importance of air-sealing and gives a couple of ideas for materials to use.