David Agnew
Member
- Messages
- 285
Construction question here.
House built in 1981. Before i bought it, attic was completely finished out w/ cathedral ceilings. The attic/2nd floor has a couple bedrooms, an office, bathroom, a storage room. The HVAC wasn't properly reconfigured for the space so, in the summer, it's always 5*-8* hotter up there than on the main floor. That is the problem I'm trying to solve or, at least, make less severe. Winter, it's fine because heat rises. I live in zone 4, so we swing from 0* to 100*.
4' knee walls create the only remaining unfinished "attic" space. There's approx 9'x25' unfinished space above the front rooms that I can access. I can't access the closed off space at the back of the house.
Insulation is 6" or 8" of blown-in, appears to be rock wool. Only level with the top of the joists. Knee wall is faced w/ fiberglass batt. I have no idea how they insulated the cathedral parts, but it's insulated with something as I can see the can lights ghosting through snow during winter.
Part A of my plan is to roll R30 unfaced batts perpendicular to the joists.
Part B is my specific question:
The knee walls. They have paper faced fiberglass bat affixed to them. Paper side to the interior, fiberglass to the un-insulated space. Since they're only a 2x4 wall, I want to increase the insulation there - due to the cathedralling, it basically acts as an exterior wall. I want to put 1" foam board (R5) over the batts, running perpendicular to the studs. Maybe eliminate some thermal transfer through the studs.
But what foam board to use? Faced? Unfaced? That reflective stuff? Which way would it point (in or out?) Does the foam board itself act as a vapor barrier? I don't have any problems now and don't want to create any by trapping moisture in the fiberglass. That's my major concern; creating a new problem.
Any advice?
Thanks.
House built in 1981. Before i bought it, attic was completely finished out w/ cathedral ceilings. The attic/2nd floor has a couple bedrooms, an office, bathroom, a storage room. The HVAC wasn't properly reconfigured for the space so, in the summer, it's always 5*-8* hotter up there than on the main floor. That is the problem I'm trying to solve or, at least, make less severe. Winter, it's fine because heat rises. I live in zone 4, so we swing from 0* to 100*.
4' knee walls create the only remaining unfinished "attic" space. There's approx 9'x25' unfinished space above the front rooms that I can access. I can't access the closed off space at the back of the house.
Insulation is 6" or 8" of blown-in, appears to be rock wool. Only level with the top of the joists. Knee wall is faced w/ fiberglass batt. I have no idea how they insulated the cathedral parts, but it's insulated with something as I can see the can lights ghosting through snow during winter.
Part A of my plan is to roll R30 unfaced batts perpendicular to the joists.
Part B is my specific question:
The knee walls. They have paper faced fiberglass bat affixed to them. Paper side to the interior, fiberglass to the un-insulated space. Since they're only a 2x4 wall, I want to increase the insulation there - due to the cathedralling, it basically acts as an exterior wall. I want to put 1" foam board (R5) over the batts, running perpendicular to the studs. Maybe eliminate some thermal transfer through the studs.
But what foam board to use? Faced? Unfaced? That reflective stuff? Which way would it point (in or out?) Does the foam board itself act as a vapor barrier? I don't have any problems now and don't want to create any by trapping moisture in the fiberglass. That's my major concern; creating a new problem.
Any advice?
Thanks.