Insulation options for roof, looking into spray foam or batting

Question

I have a house built in 1955, it's a ranch. I'm in New York. The attic insulation appears to be pretty sparse. There are floorboards on the floor of the attic, it appears there is some pink fiberglass insulation between the floorboards. There is no insulation on the underside of the roof.

I was looking into insulation options, because:

1. It definitely feels a little drafty in here.
2. We're going through oil pretty quickly (we have a 3 year old burner running at 82% efficiency - not sure if the oil should be going this fast).

I was looking into spray foam as an option, but saw some horror stories about jobs gone wrong and the health impact on residents. Is batting insulation worth pursuing? I was hoping if I have it done professionally, then maybe its performance would be comparable to spray foaming the roof.

Cost isn't my primary concern, with spray foam I'm worried about:

1. Health impact
2. A bad job, seems like it could ruin the house
3. Any wiring etc fixed to the walls will get entombed in the spray foam.

Thanks for any opinions on this.

Answer 1

You first need to decide if you want the attic inside the HVAC envelope or not. Right now it's not, there's insulation on the attic floor (ceiling of floor below) capping the area to be heated there. That's most common/traditional. Making a "hot roof" and putting insulation on the inside of the sheathing would be instead of insulation on the attic floor.

Personally, I first air sealed the gaps in the attic floor and then put 22 inches of cellulose, plus added soffit vents. Made a big difference in energy costs.

Answer 2

This is a common scenario. Normally folks will simply blow cellulose or fiberglass over the existing batts to achieve a modern R (insulation) value. This doesn't help with "drafty", though. For that you'll probably need to look at the condition of your windows, the layout and tuning of your heating system, etc., to determine why there's air movement.

To do spray foam you'd first have to remove all the existing insulation. It would provide a very good air/moisture barrier as well. It's also much more expensive. You could blow cellulose yourself for a few hundred dollars and have a very nice insulation layer.