What’s the Best Insulation for a Shed? [Batt, rigid or loose fill?]


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Having an insulated shed will give you a comfortable place to work in and a great place to start your seedlings. Its just a matter of choosing which type of insulation will be best for your shed.

The best insulation for a shed is “batt” insulation, which comes in different sizes and thickness and can be used in walls, floors, and ceilings. As well it is quite easy to cut and install for those who are building and insulating the shed yourself.

In this article I will go over “batt” type insulation, the different thicknesses and width and how to choose the correct batt insulation for your shed. I will also go over calculating how much batt insulation and thickness you will need for your shed.

What’s the Best Insulation for a Shed?

I’ve been building sheds and other outbuildings for years and when it comes to insulating a shed I have found that “batt” type insulation is the best. Here is why it is the best choice:

  • The most cost-effective insulation you can buy.
  • One of the easiest types of insulation to install and is perfect for the do-it-yourself person.
  • Is easily cut to fit into any size space with a basic utility knife and straightedge.
  • You can buy it in multi-packs or rolls and some even come with a paperback vapour barrier already attached.
  • It comes in various thicknesses and 2 widths to fit into 24-inch or 16-inch framing sizes.
  • Can be used to insulate ceilings, floors, walls and can be cut into narrow strips for insulation around windows and doors.

Benefits of Using Batt Insulation

  • Works as a good fire retardant and you can get batt insulation that is fire resistance if you need to provide that protection to your out-building.
  • Also provides good noise reduction especially if your shed is located near a busy highway. You can get batt insulation that is especially made for sound proofing as well.
  • Batt insulation is very resistant to mold and mildew and when a proper vapour barrier is installed over the insulation it’s very effective at preventing mold and mildew growth.
  • Very eco-friendly and most new batt insulation is made from renewable resources which helps lessen your carbon footprint.

Is it Worth it to Insulate Your Shed?

This question comes up a lot, after all its only a shed and why should you spend the money and time to insulate the shed? That depends on what you are going to be using the shed for, if its just for storing lawn equipment or toys and bikes then you likely do not need to insulate it.

On the other hand, many folks use there shed for more then just storage. Some like to use it for gardening or as a workshop and even as an office space or a place to get away for a while. For these situations insulating the shed will provide comfort and quiet place to relax.

Here are some benefits of insulating your shed:

  • Temperature Control… Many folks store paints and canning goods in their shed so you’ll want to keep it at a temperature that won’t allow these types of items to freeze. Insulating the shed and using a small heater will prevent these items form freezing and being ruined.
  • Cuts Down on Moisture… When moisture is in the shed it allows the formation of mold and mildew which can be very unhealthy. Insulating the shed and installing a vapour barrier will prevent mold and mildew from forming.
  • Longer Lifespan… Insulating a shed will also help prevent bugs from finding their way into it. The chances of rot will be less which means your investment will last much longer than a shed that is not insulated.
  • Increased Usability… Another perk of insulating your shed is you can use it for an office space, workout area and even a man cave or she cave. Check out my article “How to Make Your Very Own She Shed Getaway” for turning a shed into a She shed!

How Much Batt Insulation Do I Need?

This will depend on the size of your shed and if you are wanting to insulate the ceiling, walls, and floor. Below I will list the batt insulation amounts for a standard 8’- 0” x 12’- 0” shed.

Floor… This can be calculated by calculating the square footage of your floor area, in the example being used it would be 8 feet times 12 feet would come to 96 square feet of batt insulation for the floor. Use the dimensions for your shed to get the amount needed.

Walls… I will use the example size with 8-foot ceiling height, that would be 2 walls at 8 feet times 12 feet and 2 walls at 8 feet times 8 feet, for a total square footage of 320 square feet. Now subtract the square footage of any windows and doors you have and this will give the amount of batt insulation you will need to insulate the walls.

Ceiling… In most cases the ceiling square footage will be the same as the floor square footage, using the example of the 8’- 0” x 12’- 0” the required amount of batt insulation would be 96 square feet. You can subtract the square footage of any openings in the shed ceiling, such as a skylight.

What Sizes Does Batt Insulation Come in?

Batt insulation comes in 2 widths that are made to fit between the framing members for 16 inch and 24-inch centers. The 16-inch insulation is made [15 inches to fit snug] when using 16 inch framing centers. The 24-inch insulation is made [23 inches to fit snug] when using 24 inch framing centers.

Batt insulation comes in bundles and are 48 inches long, you can also get batt insulation in rolls that come in various lengths to suit your particular needs. They also have different sizes for other applications which are used for other purposes which I will not get into these in this article.

What Thicknesses of Batt Insulation Do I Need?

The thickness also known as the [r-factor] determines which thickness to use for different framing sizes. Let’s look at the 3 main situations for insulating a shed:

Floor… In some cases you will want to insulate the floor in your shed, typically the floor will be framed with either 2x4s or 2x6s or even 2x8s depending on how wide the shed is.

For 2×4 floor joist you can use R-12 batt insulation.

For 2×6 floor joist you can use R-22 batt insulation.

For 2×8 floor joist you can use R-28 batt insulation.

Insulation a shed floor requires more work and planning to be used and will need to be installed before you install the flooring material or if your shed is high enough off the ground you can install in from below. You can read my article 10 Tips For Insulating a Shed where I go into detail on insulation a shed floor.

Walls… It’s very common to insulate the walls and in most cases the walls will be framed with 2x4s and in some situations 2x6s will be used.

For 2×4 walls you can use R-12 batt insulation.

For 2×6 walls you can use R-22 batt insulation.

Ceiling… This will depend on the style of roof you have, you should decide if your going to insulate your shed before choosing the type of roof to use.

If you are using a slanted or lean to roof you likely will be using 2×6 rafters which means you can use R-12 insulation [3 ½ inch] which leaves room for air to circulate.

If you are using a gable roof, then you can use thicker insulation, R-22 works good in this type of roof and leaves room for air circulation above the batt insulation, you’ll also want to be sure to install gable air vents on each gable end.

How to Install Batt Insulation

Installing batt insulation is something that most people can do themselves. Get the insulation size that is made for the framing size you have, either 16-inch centers or 24-inch centers. The batt insulation will be 1 inch narrower. What I mean is if your shed is framed using 16-inch centers then the insulation will be 15 inches wide.

The actual open space between framing members using 16-inch centers is 14 ½ inches. The insulation is made to be ½ inch wider [15 inches]to allow a snug fit between the framing members.

Begin by installing all the full pieces you can, next using a straight edge and a Olfa rachet lock  heavy duty utility knife. Be very careful with these types of knives they are sharp and will cut thru the insulation in one or two passes. When you’re measuring the piece of batt insulation make sure to add ½ inch more to the length before you cut it.

Carefully place the insulation into the cavity and don’t overpack it in, it needs to be flush with the outside of the wall framing and fit snugly into the cavity to ensure a tight fit. You don’t want any gaps that will allow cold air to come into the shed. Follow the same procedure for the ceiling insulation.

Tips When Installing Batt Insulation

1] Don’t compress the batt insulation during installation, compressing cause the fibers to be much less effective and can really affect the R-factor of the insulation.

2] When installing the batt insulation and the piece is too long Don’t fold it or cram it into the space, make sure you cut the pieces to fit snuggly without folding or compressing them.

3] Once completed the insulation job wash your clothes by themselves to remove any residue of insulation dust from them.

What Should You Do Prior to Installing Batt Insulation?

1] Need Permit? Call your local building authority to see if a permit is required.

2] Need Electrical? Are you going to need power to your shed to run heating and cooling devices? Do you need plug outlets and lights? Be sure to add these before you insulate the shed.

3] Need Plumbing? You may want to have water in the shed and maybe even a toilet, make sure you have these installed before insulating.

4] Need Phone/ Cable? These services should also be installed before insulating is done.

5] Need Windows? Decide on windows, doors and even skylights and have them installed before insulating.

How to Protect Batt Insulation From Damage?

Once you’ve gone thru all the work of installing insulation in your shed your going to want to protect it from getting damaged. Applying a 6mm or 10 mm vapour barrier will provide some protection, but it can still be damaged.

I have found the cheapest way to protect it is to install ¼ inch plywood or 3/8 OSB or even ½ inch drywall on the walls and ceiling give the best protection. I like to paint the walls and ceiling a bright white which really gives you the most amount of light.

Do I Need to Install a Vapor Barrier in a Shed?

If your not planning on heating or cooling the shed you won’t need to install a vapor barrier, doing so can cause the growth of mold and encourage moisture. However, you will need a vapour barrier under a concrete slab if your building the shed on a concrete slab, this will prevent any ground moisture from getting into the shed from the ground.

Lets look at the 4 situations of sheds:

Air-Conditioned… If you live in a very hot area and have insulated the shed, apply the vapor barrier on the outside of the insulation. This method stops moisture from getting into the shed causing problems.

Heated shed… Living in a cold area will require you to insulate the shed and you may decide to install some form of heating so you can use the shed in cold weather. In this situation you need to install the vapor barrier on the inside of the shed and will prevent condensation from getting into the insulation.

Not insulated… If you don’t have any type of insulation in your shed you DON’T want to install a vapor barrier on walls and ceiling, as mentioned only use a vapor barrier under a concrete slab.

Insulated… If you still want to insulate your shed for other reasons and it is not going to be heated or air-conditioned DON’T use any vapor barrier. If the issue of rot or mold is possible use a rock-wool batt insulation, make sure you have the shed ventilated, especially the attic.

What Do I Use For a Vapor Barrier?

The number one choice is to use 6mm clear plastic vapor barrier, it is installed over the walls and ceiling and attached to the framing members with staples. All the joints are sealed using tuck tape and the top and bottom is sealed use acoustic sealant. Another good option is 10mm polyethylene vapor barrier which is much more durable and does a better job at keeping moisture out.

Conclusion

Having a shed is great for storage, but for many folks using the shed for other things like and exercise room, office or a place to get away for a while your going to want the shed to be comfortable and usable year round and insulating it gives you a place to use year round. Good luck and I hope you enjoyed reading this article.

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