I have an old house (built in 1885) with a very nice walk-up attic that I'd like to make into more living space. I have 6" of blown-in insulation in the floor, however the soffits are not vented and there does not appear to be space left for air to flow up the roof decking even if the soffits WERE vented and there is not ridge or gable ventilation at all...so...

I've framed in 4ft knee walls and raised the crossbeams of the roof up to 8ft (adding the proper valley support where appropriate). I'll be placing an air vent in each of the 4 gables (behind the knee walls) and a powered vent in the peak of the roof.

Next, I will be putting R13 faced fiberglass in the kneewalls and ceiling between the newly installed 16" (center to center) apart studs. Then, I'll run R13 faced fiberglass across the 66" of exposed roof underside, hoping that the rafters will compress the insulation enough to maintain some airspace and allow for airflow from the kneewall spaces to the peak space.

Here's my conundrum: how do I install a radiant barrier? Foil board seems easy to install, but isn't it bad to place it between the faced fiberglass and drywall? How effective would it be to just spray on one of the paints that provides some reflectivity over the primer?

I know that any insulation I can put in will help the comfort level in the new living space (and to some extent the rest of the house), but I don't want to create problems down the road. Can anyone here suggest the best way to proceed now that I have fiberglass purchased (not installed) and framing in place?

Thanks!

Be thankful you live in Iowa. Your climate is warm enough there to get away with a lot of things you can't do in colder climates.

1. Install an insulation system that doesn't require venting.

2. Give the fiberglass to a relative or close friend for their project.

We're considered warm enough here to get by with that?? I have to respectfully disagree, I guess. With an average January high temp of 28 and average low of 7 it sure doesn't FEEL like we're not in a cold climate.

July of course is a different story (85/63), so I really feel like I need some air movement across the underside of my roof. I'm actually having 7 roof vents put in behind my 4ft kneewalls and a power vent in the peak. Hopefully, that's what I need for the air movement.

Do you care to expound on your response about an insulation system that doesn't require ventilation? I haven't worked on a house for so long I'm certainly not up on the latest trends...I just bought the fiberglass because that's what's always used around here.

Thanks,
Chad