Re: Insulating void space, flat roof with balloon structure
Howdy this is a great time to get some estimates. A closed cell foam might give you the best for the $ with limited space and then have cellulose blown in on top of it. The out side walls have a void at the top? What do the roof joists rest on?. You might want to add insulation to the walls but with brick issues with it being able to wick out water or not so again a great time to have a contractor actually several come look an advise you. At the least consider putting some Roxal, it does not give off as many itchy fibers as some competitors rock wool, insulation over the wall voids- it has a great fire rating and cuts like bat fiberglass. Adding rock wool or a 2 by4 or 6 on top of the wall void is to stop chimneying or any fire gas/flame. Moreover. to stop convection of air that sucks the heat or cool out of the house with it depending on the time of year.
Any an all of my comments are just my opinion and not to be confused with facts.