Roof insulation


#1

I need some advice. I own a Cape Cod, story and a half home, built in 1957. For some reason, insulation was installed between the roof trusses underneath the roof decking. Was that a common practice in those days? Was it done to insulate the upstairs bedrooms. I don’t feel that it’s right and would like some advice on what to do. Thanks!


#2

That is probably because it has a knee wall and a cathedral/vaulted ceiling in the upper rooms, which are usually bedrooms and a bathroom.

It was very common.

They did not consider ventilation as dramatically as it needed to be back then, because saving energy was not given a second thought.

If you are re-doing the roof, you need to add Intake Ventilation, Insulation Baffle Vents and a complete installation of Ridge Vents along the entire peak of the roof.

Ed


#3

Ed,
Thanks! That’s pretty much what I figured, but wasn’t 100% sure. I did have the place reroofed, but they only installed the ridge vent. I have vent on the gable ends. Would you recommend removing the insulation between the trusses or not. I know I have to install soffet vents of some sort to get the desired sheet flow. Thanks again!


#4

No, unless the insulation contains mold, there should be no reason to evacuate that out of the rafter bays.

Yes, you do need 100% continuous soffit ventilation.

For that to work and provide a fresh air flowage upwards through the rafters to be able to exhaust out of the ridge vent, you will need to jury-rig something inside and on top of the insulation in each and every rafter bay, so the the insulation gets compressed slightly, like about 1 1/2" to 2? below the roof decking to allow for air flowage.

If you have access inside of the knee wall attic area, you can slide something inside and on top of the insulation.

If not, you may have to remove the gutter and the fascia board to open up an access panel at the eave edge to work from.

Try various things to see what works.

1" x 2" firring strips in up to 16 foot lengths.

PVC tubing, which can be glued together to create the desired length.

Or, whatever you can think of that is inexpensive and rigid enough to circumvent the insulation and kraft paper obstacle in your way.

It will be tedious, but will provide the air space required.

Ed


#5

He can use baffles if i am reading this correctly.


#6

No, he already had the roof done about a year ago and is not going to be pulling up the decking.

IF, and I mean IF, there is enough clearance inside the knee wall crawl space, then he could try inserting the baffles in, but that wil probably be too tight of a fit.

Ed