R28 Value In 6.25" Cavity

mas

Hi,

Im trying to get r28 value in a 2x8 rafter but there is 'provents' (a 1" plastic air baffel) in the cavity so normal pink insulation will not work..

does anyone know a product i could get an r28 or more value out of that will fit in a cavity of 6.25"

for most of the ceiling i just strapped it down.. to fit normal pink.. but there is a area that i cannot afford to loose any ceiling space

thanks

mdshunk

PIC foam board is roughly R-6 per inch, depending on brand. That might be your only, time comsuming and expensive, option.

house bldr

you might try the spray foam insulation.I have not tried it but as I understand, it is about twice the cost of fiberglass and approx. r-7 per in.

Brushslingers

Sounds like you are looking for a radient barrier.. combined with a standard R type insulation you could get 28 out of it.

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Benn

mas

i have a really bad inspector who is riding my ass because im young... He is making me bring up a 1912 house to modern insulation values. and its very hard.. I have already cladded the full house in 1.5" dow foam and now he is going after the roofs..

im gonna just gonna glue together a few peices of 1.5" foam (like the person above suggested) with a value R7.5 then foam them with some foam2foam inplace.

if he has a problem with that i will have to start the legal route to try and smarten him up