The After-roof roof project

federer

HI all

first just want to thank everyone for their comments and input in my other thread. i know i dragged you all through a whole lot of pictures and stupid questions and what not.

anwyays not getting any replies in the other section-so now that the new roof is in place, i am going to do spray foam insulation for the attic. what do you guys think about this?

thanks for all the input

federer

seeyou

Open cell or closed cell?

OldNBroken

Federer! As annoying as you've been the last few months and that's the only picture you gonna give us of your final handiwork? Geez!!!!

federer

open cell. sorry didnt clarify before

federer

lol you are kidding right..i posted like 13 pics in my other thread...i know it was pretty annoying...i thought most people on here wanted pics though...

OldNBroken

My bad, guess I better head to the other thread. I missed that

rodeo

why do you want to sprayfoam the rafter bays?
is your new roof vented?

sprayfoam is considered "the best", I suppose,
but its not all roses and is best used in spot applications or
difficult situations. Sealing rim joists is one example.

federer

not the rafters-the underneath of decking. i just used that pic as a reference. the reason is because i have a flat roof, so there is not a lot of space between decking and attic floor. so i cant use fiberglass because i can only get like R12 or something.

the roof is not vented-which is also why we are going with foam-otherwise we would need intake and ridge vents,etc.

i do need to seal rim joists too!

rodeo

Spraying the underside of the decking is the same thing as spraying the rafter bays. They mean the same thing.

Did you lay any rigid foamboard above the deck when the reroof was done?

seeyou

Don't use open cell if there is no venting. If I understand correctly, moisture can permeate open cell, but not closed cell.

federer

oh? isnt that why though? just in case there was a leak in the roof the water could come through-otherwise i would never find out until its too late (all teh wood would already rot away)

seeyou

It'll come through where the insulation meets wood or other material. But, if you trap condensation against the wood, it might not show up until serious damage has been done.

federer

so closed cell will prevent condesnsation?

seeyou

Not exactly prevent. But it keeps the water vapor inside from reaching the cool underside of the sheathing where condensation would occur. Open cell lets the vapor through.

Water coming the other way through the roof will find it's way in past either type foam.