I recently got this email, and as The Pole Barn Guru, I am happy to respond to building questions which are not from Hansen Building clients, either prior or future.
I live in Indiana.
I have a pole barn garage. I didn’t build it. It was built when I got the house. It has a metal drop ceiling. I am looking to insulate it. It will only be heated when I am working on stuff in the winter and not all the time. It will not be conditioned in the summer. I am not sure what the best way to insulate above the drop ceiling. Can I use blow in insulation? If I go this route do I need to put plastic down on top of the metal first then blow it in? I am using 1 inch Styrofoam board in the walls board since I can put it directly against the metal and moisture won’t affect it. I will eventually cover it with plywood. What should I do for the drop ceiling?”
The initial step is to find out what the load capacity of the trusses is. Very few pole buildings have trusses which are designed to support the weight of a ceiling and insulation. You should be looking for a minimum bottom chord dead load of five psf (pounds per square foot). If the prior owner did not provide you with the information about the building, the design loads are supposed to be stamped on the trusses.
Assuming the trusses can support the load, an insulated vapor barrier must be placed beneath any roof steel. If the building was not originally constructed with one, reflective radiant barrier (aluminum side up/white face down) can be added to the underside of the roof purlins. It is essential to have all seams tightly sealed. See www.buyreflectiveinsulation.com to calculate needed quantity and price.
Ventilation must be provided for, as you have a dead attic space. Hopefully the eaves have enclosed vented soffits – to provide an air intake. Along with this – a vented ridge is required, in order to give an outlet.
Finally, once all the above have been taken care of, insulation can be blown in directly above the steel ceiling liner panels. You do not want to have a vapor barrier directly above the existing ceiling, as it could allow moisture to collect above the liner panels and this could cause premature deterioration.
Do you have a burning building question (no pun intended) for The Pole Barn Guru? Email me today!