You can get similar results as doing all closed cell foam but with less cost.
Hybrid flash and batt insulation roof.
The first problem was that one inch of closed cell spray foam insulation wasn t enough to keep the temperature on the surface of the foam above the dew point due to the temperature or conditions the house was experiencing.
The idea is to get all the benefit of the air sealing but then to get the rest of the r value from the much less expensive cellulose.
The hybrid foam installation method combines energy efficient spray foam with conventional insulation to create a lower cost alternative to using foam alone.
The installed r value is approximately r 12 for two inches of high density spray foam 2 0 pcf and r 13 for three and a half inches of fiberglass batt totaling r 25.
Flash fill flash batt using 2 different types of insulation for lower cost.
For this reason in some markets contractors are turning to hybrid insulation systems often referred to as flash and batt insulation.
In a standard 2x6 wall they will spray 1 of closed foam inside the wall cavity and then fill the rest with cellulose.
Let us start by considering the benefits and costs of spray foam insulation vs.
Matt girand a product and program director for residential insulation with owens corning which offers a hybrid air sealing and insulation system says the adoption of air sealing and flash and batt techniques gained momentum slowly but has become widely accepted.
In this case there were two problems.
All of the rigid insulation board products work.
Fiberglass insulation and other standard products such as cellulose wool and other mass type insulation.
If all of the insulation is on the top of the roof sheathing this is pretty much a no brainer.
Flash and batt insulation is one example of a new technique being implemented by insulation contractors.
Fiberglass devoured the insulation industry in the 1970s for obvious reasons.
All insulation above roof deck the big deal with unvented roof assemblies is to control condensation or moisture accumulation on the underside of the roof sheathing.
Avoiding flash and batt condensation problems.
Many insulation companies in our area have begun to sell hybrid insulation systems.
Flash and batt is a hybrid insulation approach combining fiberglass insulation and closed cell spray foam.
It s a great way to get the benefits of closed cell spray foam and save.
I can foresee many potential building science issues with.
To fill a 2 x 6 inch empty wall cavity first add a flash coat of closed cell foam on the exterior wall to a thickness of 1 2 inches then take a low density batt to fill in the space before the drywall is.
