Blocking the soffit under rafter air baffle with foam board and spray foam 

Thank you. I was laying on OSB planks too. I had my iPhone sitting in a little tripod down between the ceiling rafters. I haven’t seen Joe Lstibuek’s work. I’ve been watching a lot of Matt Risinger… “on The Build Show”.

Yep, Matt Risinger is a great resource too!

I did. Some friends helped me remove all of the old 3" fiberglass batt insulation and blown-in that was blown in over that and compacted. Then we vacuumed it all nice and clean. I am considering extending the vent baffle to the ridge and spray foaming under that. Maybe next year.

@@BurkeStanion that’s exactly what I’d want to do!

I believe that it has. My wife was just comparing energy (gas heat & elec A/C) costs. On that front, it's a little early to tell really while trying to account for how mild our fall temperatures have been this year. I also have not completed the job yet. I've been wiring and installing new recessed lighting and sealing those with 3M Fire-Resistant foam under Tenmat covers along with sealing wiring penetrations along the way. I only have one more light on the agenda and I'll be finished with that. As far as blocking the soffits, we have noticed a definite improvement in the drafty exterior walls because air is no longer allowed to just blow down the wall where there are wire penetrations or where framing just didn't match up perfectly. They framed the kitchen soffits completely exposed to the attic too. I spray foamed in foam board sheets to cover those too and that has had a very positive effect so far and the insulation has not been replaced yet over the kitchen. I am working this week (DEC 12) to hopefully get the attic fully finished and finally fully insulated.

I imagine that 3/4" OSB would do the job too. And I wouldn't be concerned about the weight. My issue would be reaching down to the edge with plywood and controlling how it stands there (maybe due to the weight) while you try to foam it in. If you can push it in there somehow as I did the foamboard with the reaching stick, I think it could work. The insulation value of the OSB probably wouldn't be the issue, because you'll insulate behind the blocking. All we're doing here is blocking the unwanted airflow. So, if you can get the 3/4" OSB in there, try it. I'd be interested in seeing the process and result. Please let me know how it goes.

@Burke Stanion for the foam pieces you used I think I would make them out of smaller pieces of osb and screw them to the chute before hand so all i would have to do is wedge the entire chute in place and then foam.

@@TheBalognaPony That sounds like a plan. I hadn’t thought of screwing to the baffles. I’ll be looking forward to hearing (or seeing) how that goes.

I bought the Great Stuff 40” wand. It’s available from Lowe’s, Home Depot and other retailers. www.lowes.com/pd/Dow-Great-Stuff-Pro-14-Xl-Foam-Dispensing-Gun-40-in-Adjustable-Flow-Control-Reusable-Spray-Foam-Insulation-Gun/999980596

@@BurkeStanion Thanks Burke.

That 40” wand is a Great Stuff brand gun that I was able to order through Menards. Lowe’s and Home Depot can get it ordered too. 14 Xl Dispensing Gun 40-in Adjustable Flow Control Reusable Spray Foam Insulation Gun www.lowes.com/pd/Dow-Great-Stuff-Pro-14-Xl-Foam-Dispensing-Gun-40-in-Adjustable-Flow-Control-Reusable-Spray-Foam-Insulation-Gun/999980596

Thank you. Follow-up coming soon. It’s been a long project.

Thank you. I’m zone 5 in East Central Illinois. Champaign County, IL. High humidity in summers with heat index rising above 104 and usually brutal cold in Jan-Feb dipping to the -22F area and staying there day & night sometimes for weeks.

I’ve been using Great Stuff Pro Gaps & Cracks (Red Can).

Yes the attic needs air flow. The air will now be directed up through the plastic baffle towards the ridge vent. Doing this blocking prevents airflow into the wall cavity and into the insulation.

Hey Garret. I’ve been using the Great Stuff Pro Series Gaps & Cracks. Red Can.

I haven’t seen any evidence of the plastic being melted by the spray foam.

I installed baffles between most rafters and blocked the soffit between every rafter. There were a few places between two rafters where there was a vent pipe or in the corners of my hip roof home where baffles didn’t fit, but I still blocked the soffit. I figure the attic will still vent using the other baffles just fine.