Tips for Brewing Big Beers with BIAB

by Robert Blagg | Updated: May 5, 2016

These statements about Brew in a Bag (BIAB) sound familiar?

  • “Are you doing BIAB to learn about all-grain brewing?”
  • “BIAB is a good stepping stone to real brewing”
  • “You can’t get good efficiency BIAB, you can’t brew big beers”
Full Mashtun

I have heard all the misconceptions about BIAB floating around. Most of the ‘information’ came from genuinely well-intentioned brewers, while some of it from patronizing ones.  

Let me assure you that any beer you can make with a three-tiered rig you can also make with your BIAB setup. You can overcome any of the differences with some small process adjustments and a little creativity.

I don’t see BIAB as being limited as much as a different brewing process. Some parts of the process makes for better beer.

Where BIAB Shines

You can sparge with BIAB, but most of us do no-sparge brewing. No-sparge brewing makes for better and more flavorful wort since it is not watered down by sparge water.  Essentially, you are sticking with the absolute best wort your malted grain has to offer.

Traditional English parti-gyle brewing used no sparge brewing for specialty big beers and then made smaller table beers with the second runnings. That is why BIAB is perfect for most big flavorful beers (and makes for a pretty good parti-gyle platform too) .  

For big beers, like a barleywine, no-sparge brewing provides the rich, malty and flavorful wort you want for a beer that can cellar for years.  

I am still drinking the first barleywine I made in 2012 (in fact, I am drinking one as I write this) and it gets better every year. I re-brewed the recipe in January and the batch is currently aging.

Right after you brew it, the hop bitterness smacks you in the face followed by a hefty malt backbone.  As a young beer, it can be unbalanced.  The hops fade over time as malt flavors and aromas morph into something more interesting and unique. After four years of cellaring, the beer has hints of raisin and caramelized sugar with elements of creme brulee and sherry in the aroma.   

I use a lot of dextrin and caramunich malt since the large amount of sugar thins the body.  Here’s the recipe

Robert’s Big Burly BIAB Barley Wine


American Barleywine — BIAB — 1/9/16

American Barleywine BJCP Style: 19C All Grain

Boil Size: 6.75 gal

Boil Time: 60 min

OG:  1.108

Estimated Efficiency:  75%

ABV:  12.7%

Yeast:  Saf-ale 05 (2 packets rehydrated)


8oz        Rice Hulls

14 pounds     Pale Malt, Maris Otter

1.5 pounds     Caramunich Malt

1 pound     Cara-Pils/Dextrine

4 oz        Caramel/Crystal Malt -120L

2 pounds    Extra Light Dry Extract (3.0 SRM)               

2 pounds     Brown Sugar, Light (8.0 SRM)  


2 oz of Chinook @First wort hop

2 oz Northern Brewer @ 10-mins

Mash at 149F for 90-mins


Pitch at 64F and hold for 48-hours

Allow the temp to rise 1 degree F per day holding 70F for 3 weeks

Keg or transfer to secondary and don’t think about it again for at least three months.  

Tips for Brewing Big Beers with BIAB

When brewing a high gravity BIAB batch, think about your system and combine the techniques below to hit your target gravity.

First, I will start with ways to maximize your mashtun space. Second, I will give you some strategies for adding fermentables.

To make all of this easier, I would highly recommend buying brewing software, such as BeerSmith. The software is easier and less error prone than using pen and paper or spreadsheets.  

Getting the most out of your mashtun space

Here a few ways to maximize the extract from the space you have:

  • Recirculate
  • Stir your mash vigorously to ensure conversion
  • Do a mashout
  • Boil for 90-mins instead of 60
  • Cold steep all of your kilned malts


This option requires a pump.  If you don’t have one, don’t worry, we have you covered with the next option.

I spend at least 20-mins of my mash recirculating my wort.  When I moved to BIAB, I was concerned about efficiency, so I added a port to the lid of my kettle for closed recirculation.

I was pleasantly surprised after a few brew sessions that my efficiency increased. My mash efficiency is typically over 80%.

Don’t get too hung up on efficiency.  As long as it is a fairly consistent number and you are making good beer, you’ve figured it out.  

This step ensures that the enzymes responsible for converting the starch from your grain to sugar are distributed throughout your grain bed while ensuring starch is more available. I typically heat my mash while re-circulating to avoid temperature loss.  It takes practice to get the heating just right.  

I use this to monitor the temperature at my pump:


In my experience, you can get a good jump in efficiency by adding a recirculation step.  

Stir your mash vigorously

This step has the same effect as recirculating, but without a pump.  Before I bought a pump, I would heat my mashtun while stirring vigorously.  

Again, it takes practice to ensure you don’t overheat your mash or create hot spots, so slower is better. It is always easier to heat your mash than to cool it.

If you want some strategies for troubleshooting your mash temp take a look at this post.

Do a mashout at 165-170 degrees and hold for 10-mins

Heating your mash past 165 will denature the enzymes converting your mash and decrease your wort viscosity.  This allows you to extract more sugars from your grains.  I would recommend recirculating or stirring during this step.    

Boil for 90-mins (or 120) instead of 60

There is no magic here. Your wort concentrates as you boil. The longer you boil, the more concentrated the wort.  

I would recommend using software like BeerSmith or a boil off calculator to determine how long to boil to hit your starting gravity.  

Be careful about boiling too vigorously for too long — you could heavily caramelize your wort. This is great if you are making a wee heavy, but not for other styles.  

Cold steep your kilned malts

This one is pretty self-explanatory.  Cold steep your dark grains (crystal, chocolate, cara malts) and leave your mashtun space for malts that require conversion.  

Depending on your recipe, this could allow for a pound or two of additional malt.

Double crush or fine crush your grainMillingGrain

Lautering your mash with BIAB is a lot easier since you don’t have the same worries about a stuck mash or setting a grain bed thanks to a finely weaved filter bag. Many brewers use this as an opportunity to fine crush or double crush their grain.

Fine crushing means you are setting a smaller gap on your mill. Double crushing means you are running the grain through the mill twice.  

I personally have not seen the advantage of double crushing or fine crushing my grain. As I stated previously, my efficiency never suffered when I moved to BIAB.  

Having said that, brewers that I respect and trust swear by it. This probably brings an efficiency increase of a few points.

Now that you squeezed every little bit of efficiency out of your system, why not just add fermentables?

Add what you need to supplement your grain bill:


I have been adding regular table sugar and maple syrup to my beers for a long time. Adding sugar can dry out your beers and thin the body. You can compensate for this by adding dextrin, crystal or flaked malts.  

According to the American Homebrewers Association’s yeast book, yeast produce enzymes early in fermentation to break down maltose (the sugar from malted grain). The presence of too much simple sugar may hinder this production. This can lead to under attenuated beers.  

But when sugar is added a few days into fermentation, it creates a simple sugar party for your yeast when they thought they would have mostly maltose. That’s why I typically add sugar to my fermenter rather than to my kettle.

A good rule of thumb: 1# of sugar adds about 46 points of gravity per gallon or 9.2 points for 5-gallons.  For example, if your wort’s gravity is at 1.080 and you add a pound of sugar, you are now almost to 1.090.  

Tip:  For big beers, if you add sugar to the fermenter, also add yeast nutrient to your sugar addition to reduce yeast stress.

Malt extract

If your setup can only hold enough grain to get to 1.080, then make up for it in the last 15-mins with LME or DME.

You can determine the right amount by using BeerSmith.

A good rule of thumb, 1# of LME adds about 36 points of gravity per gallon or 7.2 points for 5-gallons.  DME adds about 40 points of gravity per gallon or 8 points for 5-gallons.

Tip: Keep the formula above and a few pounds of LME on hand all the time. It is great to have when you undershoot your gravity and want to hit your numbers.

Wrap Up

I have been brewing since college and it wasn’t until reading Gordon Strong’s Brewing Better Beer that I began to value the process of brewing above looking for the one best way to brew.

Spending time perfecting a brewing process with the equipment you have (and re-perfecting it when you get new equipment) brings consistency to your beer.

Create a brewing process that works for what you want out of the hobby, whether it’s small batch brewing, brewing quickly, maximizing repeatability, or just making good beer to share with your friends.

Robert is an avid homebrewer and craft beer aficionado. He loves the gadget side of homebrewing and is constantly tinkering with his two breweries, a 10-gallon eBIAB setup and a 20-gallon three-tier rig. He loves Belgian beers and is known for his saisons. Beyond beer, he is a soccer fanatic and member of the Screaming Eagles (DC United) and the American Outlaws (US National Team) supporters groups. His career path has been strange and varied, including time as a sous chef, political consultant for over 25 campaigns, and more recently as a business intelligence professional at the US State Department and large financial institutions.