Flash and batt is a combination of spray foam insulation with fiberglass batts. It’s a technique used by some insulation contractors where a flash of closed cell spray foam at 1- to 2-inches is applied in an effort to create an air seal and then puts fiberglass batt insulation over it.
What is Flash and batt insulation?
Flash and batt is a hybrid insulation approach combining fiberglass insulation and closed-cell spray foam. Fiberglass devoured the insulation industry in the 1970s, for obvious reasons. It is cheap, simple to install (if not easy to install well), and readily available.
How does a flash-and-Batt system work?
Moisture: Flash-and-batt systems present something of a mixed bag when it comes to moisture control. The 2 inches of spray foam will help maintain a higher temperature in the wall assembly, keeping surfaces above the dew point during the winter. However, some overzealous builders install a polyethylene (plastic) vapor barrier on the interior.
What type of foam is used in Flash and batting?
In a flash-and-batt installation, part of the fiberglass is replaced with closed-cell spray foam and the remainder is either fiberglass or (occasionally) cellulose. The depth of the spray foam depends on the climate zone, with colder zones requiring thicker foam to keep the wall cavity above the dew point during the winter.
What is Flash-and-fill insulation and how does it work?
A variation of this method is called “flash-and-fill” or “flash-and-blow”; these terms refer to an insulation job that combines closed-cell spray foam with a blown-in insulation material like cellulose or blown-in fiberglass. The flash-and-batt approach can be used for walls, floors, or ceilings.
What is batt insulation?
Batt insulation (also known as blanket insulation) comes in flat pieces. It is made of fiberglass or mineral wool which is pre-cut into flat pieces. Batt insulation is an inexpensive way to insulate your home. Some batt insulation comes with a foil or paper (kraft) facing and some comes with no facing.
What does flash and batt mean?
Flash and batt is a combination of spray foam insulation with fiberglass batts. It's a technique used by some insulation contractors where a flash of closed cell spray foam at 1- to 2-inches is applied in an effort to create an air seal and then puts fiberglass batt insulation over it.
Why does flash and batt make sense?
It seals against air infiltration, it boasts more r-value per inch than other forms of insulation, and it blocks the passage of water vapor. It's also the most expensive option, and it requires dedicated equipment for large-scale installations.
Can I use spray foam and batt insulation?
2:384:10Is Spray Foam Insulation with Fiberglass Batts a Good idea?YouTubeStart of suggested clipEnd of suggested clipThat's probably enough insulation to give you a thermal resistance. Also. So again it's probably notMoreThat's probably enough insulation to give you a thermal resistance. Also. So again it's probably not actually cost-effective to add fiberglass on top of that. Now is there ever a time when it does
How do you flash and batt insulation?
4:5610:40Closed Cell Foam + Rockwool- How To Flash & Batt - YouTubeYouTubeStart of suggested clipEnd of suggested clipIn your wall has to be the foam. Portion. Then the rest you're simply filling in the bats i've toldMoreIn your wall has to be the foam. Portion. Then the rest you're simply filling in the bats i've told people you could put gummy worms over the top it wouldn't bother. Me.
Is 2 inches of closed cell foam enough?
Closed cell spray foam should be 4- to 5- inches on the ceiling and 2- to 3-inches in the walls. This might come as a surprise to you, but honestly, this is all the spray foam it takes to get the biggest bang for your buck with the air seal and thermal resistance needed for certain areas of the home.
Can I put fiberglass insulation over spray foam?
First, a thin layer of closed-cell spray foam is applied between the wall studs, at least 2 inches thick. Colder climates should replace more of the fiberglass with spray foam. After the foam has cured, install the fiberglass insulation and finish building the walls.
Can you spray foam over foam board?
0:263:56Can You Spray Foam Over Existing Insulation? | Foam UniversityYouTubeStart of suggested clipEnd of suggested clipIf it's fiberglass. And we spray over that fiberglass it'll lay on it fine.MoreIf it's fiberglass. And we spray over that fiberglass it'll lay on it fine.
Can you spray foam insulation over fiberglass insulation?
So a typical question is whether or not you would need to remove the fiberglass insulation from your home, or if you can simply have foam insulation sprayed over it. The short answer is that you can spray foam over fiberglass, but there are several reasons why you should seriously avoid doing it.
Is spray foam better than batts?
When it comes to which is best in the spray foam insulation vs. fiberglass debate, spray foam wins, hands down. If you're a DIY-er, you may be used to installing fiberglass insulation. But if you're looking for something that will last a lifetime, let a professional install spray foam.
Why is batt insulation so expensive?
The combination of ongoing shortages and increasing demands has led to higher fiberglass insulation prices. Over the past year, the global pandemic impacted the supply chain between China and North America, causing a shortage of many building products, including fiberglass insulation.
Is foam insulation better than batts?
Spray foam insulation has a higher R-value than fiberglass, making it a better insulator. Another difference between them is that spray foam is watertight while fiberglass cracks under moisture. However, installing spray foam requires a professional while fiberglass is easy to install yourself.
What is a batt used for?
One type of insulation is called Batt insulation. This is one of the most common products used to insulate walls, ceilings and attics as well as basements and crawl spaces. It is generally manufactured from fiberglass, Batt insulation can also be made from cotton or stone wool.
How big is a batt of insulation?
Typically batts come in bags and they're sized to fit into standard cavities. Batt widths vary from 3.5 inches (for a 2×4 cavity) to 5.5 inches (for a 2×6 cavity), though they can be thicker. The batt length is normally 48 inches though sometimes you'll see 96 inches.
What is a Flash and Batt Insulation System?
The Flash and Batt insulation system is when Closed-cell Spray Foam and Fiberglass are both used to insulate a space. This hybrid insulation system involves a layer of Closed-cell spray foam sprayed and then overlapped by a layer of standard Fiberglass insulation. This is an effective system that is better than just Fiberglass and less expensive than all Closed-cell spray foam.
What is fiberglass batt insulation?
Fiberglass Insulation. Batts, or Batt insulation is the traditional type of fiberglass insulation you usually see in homes. It's popularity comes from being extremely easy to install as well as inexpensive. While it's the easiest and most common form of insulation, it's the least effective overall. Fiberglass batts alone aren't an air barrier ...
What is spray foam insulation?
Spray Foam Insulation. Spray foam is an expandable foam cellulose product that's sprayed in between the wood joists. After expanding, it solidifies in the wall cavity. It comes in two variants: open-cell and closed-cell. For a Flash and Batt system, open-cell spray foam is used. Spray foam prevents pests such as mice, rats, ...
Is spray foam better than fiberglass?
Spray foam prevents pests such as mice, rats, and insects from finding their way into your home. It also lasts longer than fiberglass. Foam insulation is a bit more expensive than traditional insulation, but it's significantly more effective.
Is fiberglass batt insulation better than spray foam?
While the improvement isn't as drastic as a complete switch to spray foam, using spray foam and fiberglass batt insulation together improves the efficiency significantly. Fiberglass has an r-value of 3.5 per square inch, while closed-cell spray foam has a value of r-6. Replacing even just a few inches depth makes a definite difference.
What is Flash and Batt Insulation?
Flash and batt is spray foam insulation with fiberglass batts. It’s a technique used by some insulation contractors where a flash of closed cell spray foam at 1- to 2-inches is applied in an effort to create an air seal and then puts fiberglass batt insulation over it.
Why Would a Contractor Recommend Spray Foam and Fiberglass Together?
The theory is that the layer of closed cell spray foam gives you an air seal and then the fiberglass on top of that adds the R-Value needed to get to the prescriptive code.
What is R-Value?
R-Value is the capacity of an insulating material’s resistance to heat flow.
Pros and Cons of Flash and Batt Insulation
This hybrid method could work if it was installed properly, but many contractors who recommend this install less than the required 2-inches of closed cell to create an air seal.
Flash and Batt Cost
Just like any insulation project, the size of the area to be insulated determines the cost.
Learning More About Foam Insulation
Now that you have read all about flash and batt insulation, you may be deciding it isn’t the best option for your home.
How to seal a flash and batt?
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.
What is batt insulation?
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.
What is flash and batt insulation?
The flash-and-batt method of insulation combines a layer of spray foam insulation — in this case, the spray foam is blue — with conventional fiberglass batts . The installation method can be used for floors, walls, or roof assemblies; the photo shows a garage ceiling. At this job, the spray foam is on the warm-in-winter side of the insulated assembly; at most flash-and-batt jobs, on the other hand, the spray foam is on the cold-in-winter side.
What is a flash and blow?
A variation of this method is called “flash-and-fill” or “flash-and-blow”; these terms refer to an insulation job that combines closed-cell spray foam with a blown-in insulation material like cellulose or blown-in fiberglass.
How thick is a R19 batt?
Yes, that's right. As the density of the fiber insulation increases, so does it's R per unit of thickness (up to a point.) An R19 batt at ~6.25" thickness is R19, or ~R3 per inch. Compress it to 5.5" (in a 2x6 framing cavity) it's total performance drops to R18, but that is an INCREASE in R/inch to about R3.27/inch.
Do you compress fiberglass batts?
The answer is simple: Compressing fiberglass batts is a good thing to do, since (a) compressed batts have a higher R-valu e per in ch than uncompressed batts, and (b) compressed bat ts are more likely to be in direct contact with the cured spray foam — and that type of direct contact is a code requirement for flash-and-batt roof assemblies.
Does compressing fiberglass batts reduce R value?
Compressing a fiberglass batt reduces the R-value of the batt but increases the R-value per inch of insulation.
Why use flash and batt insulation?
Here are four reasons flash and batt can be a great insulation option: Structural strength. Two inches of closed cell foam in a 2 inch by 4 inch wall can increase the racking strength more than 200%. (Here is a study done by the NAHB.) Air Sealing.
What is SPFA in the US?
The SPFA (Spray Polyurethane Foam Alliance) has put together great resources you can use based on the region where you are installing the foam (they require your email to download). For those working in the southern climates of the US, document 146 is a great guide that can be used to make sure you are doing things correctly. For those in the northern climates, document 147 can be your go-to guide.
Is Flash and Batt a good application?
Actually, both answers are true. Flash and batt can be a great application — when done correctly. When it is not, problems have often occurred. Sometimes those problems are big ones.
Is flash and batt good?
There you have it. Flash and batt can be good, it can be done right, and it can benefit both you and your customer. If you have any other questions on this or other applications, please feel free to reach out to us at IDI. We look forward to earning your business every day.
What is the batt layer?
The batt layer keeps the interior face of the foam cool, insulated from indoor heat. Too cool, however, and it raises the chance of moisture accumulation within the wall cavity. Table R601.3.1 of the IRC 2009, which lists situations where class-III vapor retarders are permitted, can be used to determine how thick the flash-and-batt layers should be. The table shows R-values for sheathing insulated on the exterior, over 2×4 or 2×6 walls. The table assumes that the wall cavity is filled either with batts or loose insulation.
How thick is flash coat?
There’s more to the flash coat than just air-sealing; thickness is important, too. The flash layer must be thick enough so that the inside surface of the foam stays above the dew point (the temperature at which water vapor condenses) except for short periods of time, such as during an extremely cold spell, which the wall assembly can accommodate. According to building scientist Joseph Lstiburek, flash-and-batt installations require at least 1 in. of spray foam in climate zone 5, 1 1⁄2 in. in zone 6, and 2 in. in zone 7.
Is flash and batt insulation good?
If you aren’t willing to address each of these areas, then flash and batt isn’t the system for you.
What is flash and batt insulation?
Is the flash-and-batt technique — where an inch or two of spray-foam insulation is applied to the interior side of roof or wall sheathing before fitting rafter and stud bays with fiberglass batts — a good way to insulate?
How thick is flash and batt foam?
As a rule of thumb, walls with exterior foam sheathing or flash-and-batt closed-cell foam will avoid condensation problems as long as the foam is at least 1 inch thick in climate zone 5 (Pennsylvania, Iowa, Nevada) or 2 inches thick in climate zone 7 (northern Minnesota). Since exterior foam reduces a wall's ability to dry to the exterior, ...
Do batts have higher R values?
In fact, batts that are compressed slightly as they are installed will yield higher R-values than ones that just fill the cavity. Another concern is that in a heating climate, the flash-and-batt method creates a vapor retarder on the wrong side (the cold-in-winter side) of the fiberglass batt.
Can fiberglass batts be used with spray foam?
Some spray-foam contractors dismissively call the technique "flash-and-dash"; they point out that fiberglass batts may fail to remain in contact with the spray foam, creating an air space and the potential for convective air currents through the insulation.
What is flash and batt insulation?
Flash and batt is a combination of spray foam insulation with fiberglass batts.
How many inches of flash insulation?
It’s a technique used by some insulation contractors where a flash of closed cell spray foam at 1- to 2-inches is applied in an effort to create an air seal and then puts fiberglass batt insulation over it. It is always good to look at the big picture to understand the flash and batt insulation pros and cons.
Does flash and batt insulation have air seal?
Flash and Batt Insulation Problems. 1. No Air Seal Is Created. Your contractor may suggest just an inch of closed cell spray foam coupled with the fiberglass insulation, but 1-inch of spray foam isn’t going to create an air seal. That air seal is important because that keeps the air you pay to heat or cool inside and Mother Nature outside.
Is flash and batt cheaper than air seal?
For example, flash and batt can seem like a cheaper option if the air seal is created properly. However, there are still problems with the method from moisture issues to no air seal. RetroFoam of Michigan has insulated thousands of homes across the lower peninsula, and some of those have been fixing problems that arise from flash and batt.
Can fiberglass batts be used in spray foam insulation?
The truth is, the fiberglass adds nothing to the 2-inches of closed cell spray foam. More R-Value isn’t the answer if you aren’t even creating an air seal that will keep your home more comfortable and energy efficient.#N#Solution: If the spray foam is already creating an air seal, there is no added benefit of adding fiberglass.
