jar546
Forum Coordinator
After renovating homes in Pennsylvania and crawling around in over 10,000 attics for both code and private inspections and doing work in attics in Florida, I have a very strong opinion.
It is my opinion that a vented attic is just never going to be as good as an unvented attic when you move the thermal envelope to the underside of the roof. Let me explain.
With all of the existing home inspections that I did on buildings anywhere from relatively new to over 100 years old, a high percentage of the time there were problems. Mold growth, black staining, rusted nails dripping onto the insulation and more. Accessing an attic like this is often difficult as you are stepping on insulation and all of the ducts are insulated, making the larger. When I built a new home in Florida 5 years ago the builder used spray foam on the underside of the roof framing. My attic was never super hot and when you went up there, it was easier to move around and work if you were going to do some wiring. You also don't have to deal with all of that fiberglass in the air when you disturb it or the mess you get with blown in insulation that gets everywhere when you open the door.
The wear and tear on an air handler / HVAC unit is less because it is located within the thermal envelope and just adding a little RValue to the duct work, works wonders even though none is required within the thermal envelope. Keeping the heat on the outside of the building makes energy efficiency that much better.
Now I've seen people try to use fiberglass batt insulation with baffles for the entire attic but that creates a whole other issue with the paper-faced insulation being exposed along with the fact that you are still relying on the airflow between the batts and the underside of the roof sheathing.
Anyway, I thought I would just throw this out there. If I ever build a house again, it will have an unvented attic for sure no matter what climate I live in. If you don't agree with me, you are wrong but feel free to post your opinion anyway....
It is my opinion that a vented attic is just never going to be as good as an unvented attic when you move the thermal envelope to the underside of the roof. Let me explain.
With all of the existing home inspections that I did on buildings anywhere from relatively new to over 100 years old, a high percentage of the time there were problems. Mold growth, black staining, rusted nails dripping onto the insulation and more. Accessing an attic like this is often difficult as you are stepping on insulation and all of the ducts are insulated, making the larger. When I built a new home in Florida 5 years ago the builder used spray foam on the underside of the roof framing. My attic was never super hot and when you went up there, it was easier to move around and work if you were going to do some wiring. You also don't have to deal with all of that fiberglass in the air when you disturb it or the mess you get with blown in insulation that gets everywhere when you open the door.
The wear and tear on an air handler / HVAC unit is less because it is located within the thermal envelope and just adding a little RValue to the duct work, works wonders even though none is required within the thermal envelope. Keeping the heat on the outside of the building makes energy efficiency that much better.
Now I've seen people try to use fiberglass batt insulation with baffles for the entire attic but that creates a whole other issue with the paper-faced insulation being exposed along with the fact that you are still relying on the airflow between the batts and the underside of the roof sheathing.
Anyway, I thought I would just throw this out there. If I ever build a house again, it will have an unvented attic for sure no matter what climate I live in. If you don't agree with me, you are wrong but feel free to post your opinion anyway....