AWF Blog

Flash and Batt - Is it right for you?

Posted by Dan from AWarehouseFull on Nov 26th 2015

It’s that time of year where you’re sitting in your house; it’s getting chilly; and you realize you need to insulate. When it comes to insulation, you have quite a few options available: from crumpled newspaper, to fiberglass batts, to spray foam, to recycled denim. So which one is right for you? At AWarehouseFull, we recommend looking at a method called “Flash and Batt”’

What is Flash and Batt?

“Flash and Batt” combines the best qualities of two types of insulation, closed cell spray foam and batt insulation such as fiberglass or recycled materials. The combination of these two types seals your walls against water and air infiltration using the spray foamand economically maximizes your R-Value with the use of less expensive batt insulation.

The Flash Component:

The first step in the flash and batt approach is to apply a thin layer, (1 to 2 inches), of a two-part polyurethane, closed cell, spray foam, like Dow Froth Pak, to seal the surface, and provide the initial R value. At 1-2 inches you reach the full benefit of the air sealing qualities of the spray foam. Additional foam will provide an insulation value of R-6 per inch but this makes the cost per R-Value a bit high should you choose to work exclusively with spray foam.

The Batt Component:

Since you’ve sealed your wall against water and air, your concern now is to build R-value to a number that meets your local building code. The cost effective way to do this is by using batt insulation. Fiberglass batt insulation has been around for so long that you can buy it relatively cheap, making it the most economical way to build R-value.

Which insulation do we recommend? Well that leads us to…

Our Batt of Choice:

Batt insulation is made by several manufacturers. You find different variations of the same basic product, spun glass fibers that are bonded together, usually with a paper or foil backing. Traditionally, the binder used was a formaldehyde based chemical. Knowing this, we sought out a product that goes above and beyond the standard available batts. We decided on using Ecobatt Glasswool Insulation with Ecose Technology from Knauf. Ecose Technology is a binder based on sustainable and renewable materials. This eliminates the use of harmful chemicals like phenol-formaldehyde or acrylics normally used in fiberglass insulation. It’s this technology that gives Ecobatt its brown color and makes it an eco-friendly and sustainable product that’s safer for your home.

Any Alternatives to Spray Foam?

Say you don’t feel comfortable using a two-component spray foam like Dow Froth Pak. That’s OK. You may be thinking, “Can I seal my walls against moisture and air without spray foam?” Well it’s your lucky day, because it’s possible. You just use another type of foam, single part foam sealants. The Great Stuff line of sealants from DOW offers several options to seal your wall, namely Gaps and Cracks, Enerfoam, or Window and Door. Our personal recommendation is using Gaps and Cracks in the Pro Can with a Pro Foam Gun. Gaps and Cracks has a higher expansion rate than the other Great Stuff products and can be used to fill voids up to 3 inches wide. The Pro Foam Gun and Pro Cans give you greater control and higher yield than using the consumer cans with a straw. Rather than filling your wall cavity with foam, you simply cover the seam where your wall studs meet the sheathing with a quarter inch bead of Great Stuff foam. You also fill any gaps where the plumbing or electrical lines go through the wall. This seals the wall against air and moisture penetration however it does not add significant R-value.

So let’s compare…

Brace yourself, hypothetical incoming…

So let’s say you need to insulate a small portion of one wall. It’s about four feet wide, so about 3 channels. Let’s also say you’ve purchased R-19 Fiberglass Batt, but also want to experiment with using foam. So, you decide to use a different method in each channel. In the first you just use Batt, the second you use Gaps and Cracks to seal the seams and then use Batt, and in the third and final, you use a one inch coating of Froth Pak Spray foam insulation followed by that same Batt insulation. Each channel will now perform differently. The first will have an R-value of 19 because of the insulation you purchased. The second will have the same R-value, but will also be moisture and air tight from the outside. The third, will not only have an air and moisture tight seal, but will have an added R-value of 6 (remember the one inch of Froth Pak?) bringing the total R-value up to 25. And just in case this whole scenario has confused you, here’s a video that just so happens to completely explain (but this time with visuals!) the exact same scenario.

If you have any question about this or any of our other posts or products, don’t hesitate to give us a call!