Monks; our home was built in the 70's, 3bdrm ranch full basement with attached garage, the house is not completely sealed from the garage space (?) ceilings are insulated between the joists but there is the open triangular gap of the trusses showing into the garage. (So I can throw a ladder up inside thegarage and walk over top of the living space from the inside of thegarage.) we have intalled roof peak vents when we did the roof, it Seems to me we'd be better insulated if I cut some triangular panels and sealed off the " attic" space from the garage?Or are thetrusses left open for a reason?
As a construction electrician I see more and more so called green houses do isolate the garage attic area from the house proper. They also insulate that transition. Either some sort of access door is provided between the two or there are separate attic access points. But, I do indeed see that done more today than I did 10 to 15 years ago.
Blocking off the access from the garage to above the house is more than acceptable, should save a bit of heating and cooling costs. What you need to do is ensure that the barrier you put up meets fire codes. Not having one there now is suspect under today's rules. It might have met the codes at the time the house was built, but usually if you touch it, you have to bring it up to the latest edition adopted in your jurisdiction. If discovered after a fire, it could interfere with insurance payout. If mons veneris is in an area that has no permitting, then you are probably good to go.
If your insulted between the attic and ceiling of the house the open area aids in venting air of the attic space and reducing the chance of rot and or moister build up.
