I'm considering insulating my attic ceiling using a foam kit. Doing a bit of research tells me that air sealing and proper ventilation are key

I live in Long Island NY and currently have about R-19. The house is 2400 sqft and the attic floor is 20' x 26' = 530 sqft. I've not measured the attic ceiling square footage, but its about a 45 degree angle, so I know its going to be more sqft than 530 sqft. The house does have soffits and a ridge vent.

I know I should put baffles before spraying any foam, but I don't know what to do about that ridge vent. How do I ensure the air going into the baffles goes out the ridge vents? I've not heard of a material to get that would connect the baffles to the ridge vent.

My goal is to insulate the attic ceiling since we want to keep the attic floor for storage. I'm considering doing this myself since the quote I received was $6400 and there's no way I can afford that now or in the near future.

  • Why are you insulating the roof? The roof is there to keep rain off the house. Insulation goes on top of the ceiling. That is, the temperature of your attic should be the same as the outside temperature. Unless you are trying to convert it to usable space. If you're using it for storage, you still don't need a heated space. Dec 11, 2012 at 16:30

2 Answers 2


If you are foaming the attic ceiling, you're converting the attic to conditioned space. If you do this, you must cover up the ridge, eave and gable vents (or any other vent, for that matter)

Here is an information link on the subject:


  • You can cover up the vents if you were using closed cell spray foam, but it's also possible to run baffles between the rafters.
    – BMitch
    Dec 11, 2012 at 17:04

Converting an attic space into living space has several issues that I can think of:

  • The floor may not be designed to support the load. This right here is the most likely reason for these projects to be stopped before ever starting.
  • You should remove any vapor barrier under the floor so you don't create a moisture trap.
  • You need to include this space with the HVAC vents and returns.
  • You need to be careful with the insulation under the roof to ensure you have enough and don't create the risk of an ice dam.

For that last part, you need to make sure you can get enough R value out of the insulation between the rafters, and may need to build out these walls to allow more insulation. You have the option of using a closed cell spray foam which can go directly on the underside of the roof, at which point you need to remove the ridge and soffit vents as Matthew PK mentions. Or you can use the baffles to create a channel for air to flow under the roof.

To answer your specific question of how to connect the baffles at the top, I would flatten the ceiling right at the peak with an open space between the baffles to each side and the ridge vent. You only need to come down a foot or so, and you won't get much usage out of this space anyway.

As others have mentioned, to use the space for storage, there's no need to make it a living space, just don't store anything up there that's temperature sensitive.

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