Attic insulation in a unvented conditioned attic – GreenBuildingAdvisor

Hi all,

We have an attic space above our house and garage and have built an unvented and conditioned attic with the HVAC heat pumps/ducts in the attic space. We close to the point of installing insulation. We were planning on having fiberglass batts installed at the roof under decking and no insulation on the attic floor as the attic is conditioned.

Our insulation subcontractor does a lot of closed cell spray from for unvented attics but has not done what we are asking with a vapor diffusion port and fiberglass batts at the roof deck undersurface.

What is the best way for insulation to be secured to the sloped surface of the roof deck?

Does the contractor need to do additional air sealing in the attic at the edges of the trusses or is the only thing needed in the attic just the insulation at the roof deck?

We have used OSB sheathing and our contractor is taping the seams of the OSB on the exterior of the house. What other things can I ask of the insulation contractor to ensure we get as airtight as possible of an envelope?

thanks for reading and any help!