Insulation baffle in Hip Roof Corners
Clewless1
| Posted in Energy, Heating & Insulation on
How do I install insulation baffles at hip roof corners? the last trusses are too short to allow me to maintain the air space above the insulation. It’s new construction. Is it OK to simply block off that last bay (actually the 2 opposing bays) and not vent it? It’s a 4:12 roof and I have continuous soffit vent, ridge vent and some Dutch gable end vents. Is it OK to fill the bay to the underside of the sheathing or do I block off the bottom of the top chord of the truss to leave an air space above (albeit not vented?). I’m afraid if I leave a small vent at the apex of the baffle it might result in the insulator blowing insulation into the soffit.
Replies
Use the baffles! It is not OK to fill the rafter bays. The hip ridge can be vented, or cross rafter ventilation provided.
The hip ridge vent is easiest to install. Run the baffles to the hip rafter, make sure that baffles will not interfere with the slots that will be cut in the sheathing.
For cross rafter ventilation on a truss roof, you can use strapping run horizontally across the bottom of the top chord to provide a ventilation channel between bays. Run the strapping from the corner to the rafter bay that will have a regular length baffle. Apply baffle to the strapping, closing the tops at the hip ridge. Air will move sideways from the hip baffles to the full bay, and then into the attic.
Leave the soffit open until the insulation is blown in. You can inspect and clean out any insulation that gets blown into the baffled area.
Update. My roofing is on. No ridge venting done. No cross venting for trusses ... maybe I can apply some strapping ... gives me some food for thought. Much appreciated. I'll get up there and 'check it out'. Soffit is already in place as well, so whatever I do has to be 'golden'. Some of what I've read said venting every other bay is OK ... so I thought maybe not venting the two adjacent corners might be an OK thing to do.
If your finished attic includes knee walls along the lower sections of the space, you only need to install baffles to the area where drywall will be attached directly to the roof rafters. Staple the baffle through the side flanges directly to the roof deck.