How to Insulate a Shed Floor and Walls

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You’ve got a lot of good reasons to want to insulate your shed floor. When it’s cold in the winter, your shed will lose lots of its heat to the soil. In that cold weather, anything can happen. If you don’t want to experience problems with machinery, a warm or at least warmer than average shed will be helpful. So, how do you insulate a shed floor and walls?

There are plenty of easy and intuitive ways to insulate a shed floor and walls. Insulation for shed floors ranges from common fiberglass to mineral wood. To install it, you’ll have to familiarize yourself with how to shape it and tear up your current shed floor.

But how do you choose between the various forms of information? Once you know which one to choose, how do you install it? In this article, we’ll go through all the steps to insulating a shed floor, and how to do them. We’ll also look at different forms of insulation and their advantages.

Who Needs an Insulated Shed?

You may be wondering whether or not it’s worth it to insulate your shed. To that, we say- absolutely.

A shed is a place with many uses. Sure, it’s a place to store tools. But it can also be a place to hang out, have a break, or get away from anything. Put a little stove in it, and it can even be a little cabin/getaway during the winter.

Not to mention, your tools and stored materials will thank you for the constant temperatures throughout the year. Having a shed with constant warm temperatures will prevent warping in wood, and keep your machinery in tip-top shape.

So, don’t be afraid to lay down a little insulation- you’ll thank us for it later.

Step One- Find Somewhere to Put Your Tools

To insulate your shed floor, you’ll have to tear some stuff up. To do that, you’ll have to find someplace safe to store your tools. The place where you store your tools will have to be sufficiently warm and dry.

If you’ve got a friend with a shed or barn, ask if you can store them in there for a while. Better yet, if you’ve got a driveway and garage, park your car in the driveway for a while and let your garage turn into a storage unit.

If it’s summertime, and you’re not so concerned about your tools getting wet, you may even consider storing them under a tent. This can be a great, quick way to store your tools in the short-term.

Step Two- Choose Your Insulation

Choosing the best insulation for your shed is always the first step to successfully insulating a shed floor. Different types of insulation have different advantages, and you may be more comfortable working with one over the other.

Let’s go over a few different types of insulation and talk about some of their characteristics.

Insulate with Mineral Wood

Let’s start with a less conventional form of insulation first- just to jog the imagination a little.

Mineral wood is essentially similar to fiberglass in storage and transportation. It has a distinct advantage over fiberglass in that it is much easier to handle.

With fiberglass, many people worry about the fine particles infiltrating their lungs and getting all over their hands and arms. Handling fiberglass can be a real bear, despite its high insulation potential. You’ll still have to wear a mask and gloves with mineral wood, but the irritation risk remains much lower.

With alternatives like mineral wood out there, it’s surprising fiberglass remains as popular as it is (and it is very popular).

Mineral wood is more easily cut and shaped than fiberglass, requiring no special tools. If you’ve got access to a simple hand or drywall saw, you’ll be able to make good, straight cuts in a batt of mineral wood. Plus, you won’t have to worry about those little shards.

Mineral wood does have one distinct disadvantage in its tendency to compress with moisture. Even if you’ve made a nice, snug fit for your mineral wood insulation, compression will result from exposure to moisture, and its insulative properties will gradually become more and more compromised.

Insulate with Fiberglass

It’s the form of insulation we all know and love. Well- we love to have it insulating our structures- maybe we don’t like working with it so much. Either way, fiberglass insulation is a good, cheap, efficient way to insulate any structure, despite how pesky it can be to work with.

Best for wooden Sheds
  • Individual Roll – 15 Inches Wide x 32 Feet Long
  • With less dust than other fiberglass products, EcoTouch PINK Fiberglass insulation has excellent stiffness and recovery characteristics
Best for Metal Sheds
  • 16 in X 25 Ft Roll
  • Two layers of Polyethylene Industrialized Air Bubbles

It’s worth noting that if you have a wooden shed then fiberglass is a great choice but if you have a metal shed then I would consider a reflective bubble wrap style of insulation.

Fiberglass is a rather potent irritant. Its docile appearance has tricked many well-meaning observers into taking a rest on a pile of it or wiping their hands on it. But, ignorance isn’t the only way to fall prey to fiberglass. Builders who drift off or get a little too daring while handling fiberglass might also experience irritation.

Fiberglass is also not so good with water. Insulating walls and ceilings with fiberglass is somewhat of a no-brainer. It has extremely efficient insulation and is easy to put up and maintain.

On your floor, however, things get a little bit more tricky. Fiberglass hates moisture- and the floor is where moisture thrives. Moisture can come up through the ground below, or seep in during storms. Thus, fiberglass in the floor is especially vulnerable to damage.

insulate a shed

Fiberglass is also vulnerable to infiltration by rodents. Strangely enough, while it hurts us humans, rodents seem to not care about it at all. Rats will get into fiberglass and build nests, while raccoons eat it up like it’s cotton candy.

That doesn’t mean fiberglass doesn’t have any advantages. While fiberglass can be pesky to handle, it’s also rather easy to cut and shape with the right tools. Not to mention, it’s cheap as dirt.

So, pick your battles. If you’re comfortable with the possibility of fixing up some moisture damage, go ahead and insulate the floor with fiberglass. In this case, you’d be wise to seal things up tighter than Davy Jones’ locker. Don’t leave any openings where moisture can seek in- whether in the form of groundwater or rainwater.

Also, remember to watch the sides of your shed for holes or evidence of infiltration by rodents. Those nests and holes can seriously decrease fiberglass’s insulative powers.

Insulate with Spray Foam

Spray foam is rather easy to install and work with- but all that ease comes with a pretty hefty price tag. Spray foam can range from $1 to $1.50 per square foot to install, and the preparation process can be quite hard to handle.

Great choice
  • Insulating foam sealant that expands up to 3 inches to take the shape of gaps
  • Expanding to form an airtight, water-resistant seal adhering to wood, metal, masonry, glass, and most plastics.
  • 12 Cans of Gaps and Cracks 24oz, 1 AWF 1000 Standard Pro Foam Gun, 2 Cans of Great Stuff Cleaner 12oz.

We all have dreams of a spray-n-go insulation where you can just drill a hole and pump it in- spray foam won’t do that for you. Actually inserting the spray foam is easy. Prepping the floor for it can be a little tricky.

Spray foam needs something to adhere to no matter where you’re putting it. Even if you’ve tightly enclosed the floor on your shed, you’ll need an adherent surface for the foam to stick to. Sheathing or plywood are your best choices for this.

Spray foam’s high cost comes with a high benefit. Once you’ve prepared the area for spray foam insulation, installing it is easy. Just spray it and go! Also, spray foam has the highest level of insulation out of any of the choices listed here. This is because it completely fills up the area you create for it- no air bubbles or holes.

So, if you’re willing to make a place for it and drop a few bucks, spray foam insulation may just be your best choice.

Insulate with Polystyrene Board

Polystyrene board makes for a good choice for floor insulation for a few reasons.

For one, polystyrene is dirt cheap. It’s probably the cheapest form of insulation you can find by footage, defeating even the infamously cheap fiberglass insulation.

Plus, polystyrene is easy to work with. No pesky, irritating glass shards, no special tools. Just cut it and place it- it’s that simple.

Great choice
  • Energy-efficient expanded polystyrene (EPS) R-value approximately 4 per in.
  • High-impact polystyrene (HIPS) laminate

It’s also resistant to moisture. This is especially useful for a shed, considering the fact that it will likely come into contact with a lot of moisture. If you want something that will hold up well in the moist environment of a shed floor, you want a good few polystyrene boards.

The real problem with polystyrene comes in the form of tedious installation. Polystyrene comes in thin boards and must be layered one on top of another to create really efficient insulation. Cutting these boards over and over and over again can get a little tiresome.

If you’re willing to put in the work and cut your boards, polystyrene board might be the insulation for you. Plus, it works well and doesn’t shrink with moisture. Therefore, if you can get a good, snug fit on your boards, you won’t be losing a lot of heat to spaces between boards and insulation.

Polystyrene boards can be found easily at almost any local hardware store, and can also be bought online. They’re light, easy to cut, and easy to handle.

Step Three- Insert the Insulation from the Top Down

If you’re installing your installation from the top-down, you’re going to want to start by tearing up any existing floor. Insulating from the top is probably the easiest way to insulate your shed floor, despite the arduous process of tearing up an already existing floor.

Here’s how to do it:

  • Move the equipment out of your shed. Every piece of it. By the time you’re done, your shed should be completely empty. You can find new storage in a variety of places, but the best place is in a garage or covered area.
  • Put wood on the bottom of your shed. If you have a floor set atop beams that are raised off the ground, you may need to put wood paneling on the bottom to hold the insulation in. This will also help prevent moisture from infiltrating your insulation if you do it right.
  • Measure the space between joist cavities. This will give you the measurements you need to cut your insulation. Cutting insulation before obtaining measurements can just get you panel after panel of inadequate insulation. Plus, a snug fit will increase your insulation levels.
  • Next, install your measured pieces of insulation. Insulation should be pre-cut to the exact specifications of your joist cavity. Make sure that your panels of insulation fit snugly inside the joist cavities, with little to no openings along the sides.
  • Finally, reinstall your floor. Once reinstalled, you can move your equipment back into your shed and you’ll have a fully insulated shed.

If you can, we recommend a top-down method for insulating your shed floor. When working from the top down, you get lots of headspace and mobility. Plus, not many people are too excited by the idea of rolling around in the dirt below their sheds.

Not only that, but you can get away from little creatures when you’re inside your shed. Under a shed, you may find snakes, mice, and all sorts of other pesky critters. Sure, it can just be a matter of shooing them away- but have you ever found a snake slithering across your neck in the dark beneath a shed?

Not fun.

Step Three Pt. 2- Install From the Bottom

Installing from the bottom is much harder, but if you’ve got some prohibiting factor, you might want to do so. It’s quite a trip, and it can be dangerous- but if you’re cautious about it you’ll be fine. So, without further ado- here’s how to install insulation from the bottom.

  • Jacking your shed is the first step for those with prefab sheds like plastic or metal. Make sure your jack is on level ground and is sturdy as a rock. If it’s not, it might fall down on you and cause serious injury or death.
  • Next, just like with the top-down method and for the same reasons, get under there and measure joist cavities.
  • For this method, you’re likely best to use fiberglass or mineral fiber. We recommend mineral fiber to keep those irritants out of the enclosed spaces you’ll be in. Cut the materials to the sizes you obtained when measuring joist spaces.
  • Next, install the batts. Very simple. Make sure they’re measured to fit the cavity exactly. Compressing them will reduce their insulative ability. Leaving spaces will also cause problems.
  • Next, enclose the cavity. There are a whole variety of materials you can do this with. One of these methods is hardware cloth, which can be easily stapled to joists to keep insulation from falling out. You might have problems with moisture, however.

You may have to install insulation from the bottom for any number of reasons. Perhaps you can’t find a place to put your tools. Maybe you have a prefab shed and can’t remove the floor. Either way, it’s completely doable- although admittedly difficult.

Insulate while building shed – Alternative

If you’re still building your shed, you may have an alternative on your hands. This situation knocks out the need to go from a top-down or bottom-up method. Simply install your insulation as you’re building your shed, and you can void the pain of having to rip things up or jack your shed.

To do this, simply hold off on installing the floor. This is another situation where you’ll have to do a lot of measuring, so make sure you’ve got a tape measure on hand.

First, measure the joist cavities as you’re going. Then, once you have the roof put up (to shelter the insulation from rain and moisture) start cutting your insulation to the measurements obtained.

Next, take those pieces of insulation and fit them to the floor. Again, you’re going to want to put some sheathing down to protect your insulation and keep it in place.

Finally, build your floor over the insulation. Just like magic, you’ve got an insulated floor.

Is Insulating a Shed Worth It?

It is a lot of work, we’ll admit it, but having an insulated shed gives you a lot of great advantages.

For one, you’ll have a place where you can keep lots of valuable machinery and materials. If you work with precious wood, specialized tools, or any other form of expensive material, you’re going to want to keep your shed temperature relatively constant. This will stop warping.

Also, having a place to get out of the house and relax from time to time is a huge advantage. Even if all you want is a place to read or have a beer, an insulated shed can help you out, giving you some privacy for just a moment so you can get back to your responsibilities with new energy.

Lastly, it’s really not too expensive. Even if you’re insulating a 500 square foot area, fiberglass will only cost you about $180


While insulating your shed can be an arduous task, it pays off. There are many choices for insulation, all with their own advantages. Check our list of materials for those advantages. Having an insulated shed is a huge advantage, and will keep rewarding you long after the deed is done.

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