1

Goal

I need to install 75 cardboard deflectors (baffles) in my attic. I need to do this so that the cellulose does not go into my soffits.

Current Setup

I brought myself up three sheets of 2x10 plywood planks that I will setup for me to lay on. The attic currently contains insulation batts with an R 5.9 value. It is quite low and that is why I'm going to fill my attic up with 14 inches of cellulose.

I have a head lamp and some staples to help with the insulation.

Problem

My issue is I am not sure if I should remove the existing pink insulation in order for me to staple the baffle and then put it back to its place... Or can I just set my cardboard flush / on top of the existing batt and staple it to the attic joist so that it is a flush fit?

Also, there doesn't seem to be much room at all, how in hell do I get in there and install the baffle? I'll be laying on my stomach of course, but it seems that my head will be blocking my body from being able to play around in there.

Any suggestions?

2

The baffles should go in between the rafters against the inside of the roof boards. They should extend from the lower soffit end, centered between the rafters, as far up as you expect the insulation to fill in.

Your description about the existing fiberglass insulation batts seems to imply that these are installed between the attic rafters. If that is indeed the case I guess you would have to remove those before installing the baffles. If those batts are currently installed all the way up to the top of the rafters then you should remove some of that so that the upper end of your baffles are open to the cold air space where the air above the added cellulose insulation can circulate and travel out through your roof vents, gable vents and/or ridge vents.

The whole idea of the baffles is to allow for there to be a free path for air to pass from the soffit (which should have adequate vents itself) up along under the roof material and pass out through the upper area vents as described above.

  • The batts are in between the ceiling joists and not the rafters. So what I meant was would it matter if I rest the baffles on the ceiling joist batts and then staple them to the rafters? – Alex Oct 30 '14 at 14:03
  • If the baffles are designed to span the full width from rafter to rafter then you would staple them to the bottom of the rafters. At the lower end near the soffit the baffle will no doubt come right down to the batts between the joists. It may even be that the batts get compressed slightly in this area. Some baffles are narrower than the rafter spacing and those may need to be stapled to the bottom of the roof boards as opposed to the rafters them selves. In my judgement if you can use the baffle to keep the whole space between the rafters open that would be the best. (continued) – Michael Karas Oct 30 '14 at 14:23
  • (continued from above) Whole rafter width baffles still need to keep the space at the lower end open as much as possible but it is a tradeoff with how much thickness of insulation you can maintain in between the joists by the outside wall and still maintain maximal cold air space from the soffit area up into the attic space over the new insulation depth. It would be great if engineered roof trusses could push the roof line up 2-3 inches above the top of the lower chord of the rafter at the outside wall but unfortunately they are often not built that way. Same for older style rafters. – Michael Karas Oct 30 '14 at 14:31

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