CMJeff

Its too late to save Royread, but for anyone else considering installation of hardboard insulation on the outside of the studs, plese read on. The purpose of the vapor barrier on the inside of the insulation is to keep water vapor from inside the living space from traveling through the sheet rock and condensing inside the insulation in the wall cavity when it gets close enough to the outside wall for the temperature to reach the dew point. Adding an inch of hardboard insulation to the outside of the studs in the Pacific NW does not provide enough insulating value to keep the temperatures inside the wall above the dew point so it is inevitable that this arrangement will cause condensation within the wall space. Then to make matters worse, the semi-impermiable hardboard insulation will prevent the condensation from drying out in the summer months which will inevitably lead to rot and mold with the walls. Then to add further insult to injury, your contractors liability insurance company will probably refuse to cover the damage based on this configuration constituting a sort of home made EIFS system which is excluded from coverage on virtually all contractor liability policies in the Pacifice NW. To make matters worse, there so far, is not a good solution to the problem of sagging fasteners which are likey to allow movement in the siding and open up gaps which can add further water intrusion into the system which will be trapped behind the hardboard product. Some insulation manufacturers have been sending their sales people around pimping this system based on a study in Alaska where they used 5" of hardboard on the outside of the studs and in an area where most of the precipitation falls in solid rather than liquid form. Anyway, for anyone who has been around for a while, this new idea of hardboard insulation on the outside of the studs is destined to be a painful redux of the EIFS debacle from the 90's where the product manufacturers once again foisted off an untested and conceptually unsound system on bulders and the public.