Insulation question regarding exterior walls

[z-bail]

I know it isn't directly a/c related but hopefully someone can help.

I was just wondering if the walls of an attic should have insulation or just have bare plywood?

I have a house with a bonus room in Florida and the bonus room get's real hot in the summer. I happened to go in the attic the other day and it seems to be insulated well (R30 on the floor). However, I have walls in the attic as well and I can see the plywood. On the other side of the plywood is the exterior which is stucco.

There may be insulation between the plywood and stucco although I have know way to tell but I just thought maybe there should be some type of insulation/radiant barrier on the wall instead of seeing bare plywood.

Any thoughts?

[deejoe]

If you are referring to a unlived- in storage type attic, then the answer is no.
No insulation is required on the walls or under roof, just the floor area (the ceiling below)
Make sure there is also adequate ventilation like air entry coming in at the eaves(soffit) and an exiting area at the highest part of the roof.
An attic(storage type) area is best when the temperature within the attic is close to what the temperature is outside.

[sktn77a]

So, the attic in question is above your bonus room? With R30 insulation heat gain through the ceiling should be reasonably low. More ceiling insulation will help some but you may have other sources of heat gain. Do you have south or southwest-facing windows and does the room get adequate cooled air? Keeping the attic cooler (with a radiant barrier) will help but insulating the walls/roof of an unconditioned attic space won't have much effect.

[sb023]

Yes, the bonus room faces south and has quite a large window facing south, it is actually two windows side by side with a large half moon window above those two. It would be difficult to install a radiant barrier I think because the bonus room connects to another room downstairs with a vaulted ceiling. I could put a radiant barrier over the bonus room though. Can a radiant barrier be done partially (over some rooms and not others)?
If it works like window tint I guess that is possible, since not all of our windows are tinted yet but the ones that do have tint are much cooler when the direct sun is hitting the window.

[randyholcomb]

Need more information. If the attic has urethane spray-on barrier AND the ridge rows and sofits have been sealed in with the sray on insulation, is ventilation required? The attic floor is not insulated.
Thanks, < No email addresses in post, please put it in your profile, thank you >

If you are referring to a unlived- in storage type attic, then the answer is no.
No insulation is required on the walls or under roof, just the floor area (the ceiling below)
Make sure there is also adequate ventilation like air entry coming in at the eaves(soffit) and an exiting area at the highest part of the roof.
An attic(storage type) area is best when the temperature within the attic is close to what the temperature is outside.