Insulating Cathedral Ceilings | How To Insulate The Roof Ridge

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Hello,

We are in the process of insulating a cathedral ceiling in our remodeled house. We had to pony up to all the existing rafters with 2 x 8's as they were too small (house was built in the 60's with rough sawn fir... good tough stuff, but 2 x 4's don't allow much airflow, with proper R value insulation!) We put in the "rafter buddies" in every space from the very peak to the soffits. (We just had the roof redone so there are many vents, and we just redid the soffits with the alum kind instead of the vents in solid material that was there before!)

My question: how do you insulate at the very peak? Insulation is square, the peak is not... do you just stuff more in that triangular gap? Like I said, we have put the foam rafter vents in the entire length from the big peak beam to soffit. I just don't know how much to stuff in that space. Fill it up with scrap? If so, does it matter what direction the scrap goes in? I would think the gap needs to be filled, but want to make sure its done properly before my other half puts the vapor barrier up!!

Thanks!!

Jo-Ann

Normally with vaulted or cathedral ceilings you would start insulating from the top and work your way down. The batt of insulation is butted against the ridge beam (peak). Because of the angle you will have a small triangular area that could use more insulation where the batt meets the beam. Using pieces of scrap insulation would be perfectly fine. Be sure to remove any kraft facing (paper) first. You would want to place the scrap pieces for a snug fit but don't mash it down or it will lose some of it's R-Value.

Speaking of scrap insulation, sometimes there is a lot of it depending on the project. When insulating new homes we used to pride ourselves in not having too much scrap and stuffed it in different areas such as behind bath tubs, smaller odd shaped wall cavities, etc. A good insulation job should result in only a handful, if any, scrap when the job is done.

Getting back to your question, you will have added extra insulation near the beam by using the scrap. This isn't normally done so you're taking an extra step in adding the additional insulation and it will help reduce air flow. Good luck with your project.

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