Staples Size For 3/8 Underlayment? (Fully Explained)

You’ve bought the 3/8 underlayment to protect your floors from moisture, impacts, and other forms of damage—now all that’s left is to put it in place and secure it. But what size staples should you use?

It’s an important question and one that’s understandably easy to overlook. After all, there are many things to consider when laying down the underlayment, such as making sure it’s perfectly straight or the same space between each staple. It’s natural for the staple size to take a backseat during installation.

However, ensuring you use the right staples is critical to proper installation. In this article, I will explain everything you need to know when selecting staples for 3/8 underlayment. 

We’ll cover how many staples per square foot are necessary, what type of stapler is best suited for the job—and much more!

What is the Right Staples Size For 3/8 Underlayment

Installing floor underlayment requires a stapler to attach it securely to the subfloor. But what’s the right size for a staple gun for a 3/8″ underlayment?

When selecting the size of the correct staple for 3/8 underlayment, it’s essential to get the right size, both for functionality and safety. 

Too big, and you may find them poking through the flooring or, worse, hurting someone walking by. 

Too small, and they won’t secure the underlayment properly, which could lead to squeaks or even flooring coming loose with time.

What’s the right size?

The best rule of thumb is to use staples slightly longer than the flooring thickness (including underlayments). So for 3/8 inch carpet and underlayments, you’ll want staples at least 1/2 inch long. 

This will ensure that you have no gaps between them when installed and that they hold everything down firmly.

Another tip is to ensure you’re using stainless steel staples, less likely to rust in humid environments.

When looking for a staple gun for this job, you’ll want something with good drive power to penetrate both layers when required. 

Look for an adjustable pressure handle to tweak it according to your surface type—light pressure for softwood floors and heavier pressure for hardwood surfaces like oak or maple. For 3/8″ thick underlayment, we recommend using 9/16″ staples to get a good grip and ensure that your floor stays secure for years to come.

Trick any excess material off with a utility knife when you’re finished stapling your underlayment. 

This will ensure that everything is even and level, making your floors look great when they’re done.

Of course, other factors are also at play here, such as the type of underlayment being used and how much weight it can hold. 

You may also want to consider the type of stapler used when choosing the right staple size – some staplers may not be compatible with specific staples.

1-1/4 wide staples are a great choice when installing 3/8 inch underlayments using a stapler. They’ll provide enough grip and strength to ensure your floorings will last for years.

Common Problems With Staples Size for 3/8 Underlayment

When it comes to staples size for 3/8 underlayment—otherwise, you could end up with some common problems. 

Here are a few of the issues you might encounter if you don’t get the staple size right:

Too Little Support

You won’t have enough support if the staples aren’t long enough for your 3/8 underlayment. 

Without proper support, the movement of the joists can cause the underlayment to crack, which isn’t good.

Too Much Pressure

On the flip side, you don’t want to use too long staples because they’ll put too much pressure on the boards and create holes when they’re driven in. 

This is a surefire way to weaken your underlayment and cause it to wear out much faster.

Size Matters

Ensuring you have the correct size staples for your underlayment is essential—you need staples that will give your boards enough support but not too much pressure. 

The general rule of thumb is to use 1-1/4″ -1-1/2″ for 3/8″ sheathing, but be sure to look up any specific recommendations from your local building codes or manufacturers’ instructions.

Is a Stapler Gun Necessary in Underlayment?

You may be wondering if a stapler gun is necessary when working with 3/8 underlayment. And the answer is no—you don’t need a heavy-duty stapler gun to install your underlayment.

That’s because there are two options for stapling: a hammer tacker and a staple gun. Here’s the difference between the two:

Hammer Tacker

A hammer tacker is generally used for thin materials like roofing and upholstery and is usually less expensive than a staple gun. 

It’s also lighter and easier to handle, with staples about 5/16 inch in size, making them ideal for 3/8 inch underlayment.

Staple Gun

A staple gun requires more force when you pull the trigger, so it’s better for thicker materials like carpet padding or cabinetry. 

The staples are larger than you would use with a hammer tacker, usually from 1/4 to 9/16 inches in size.

So if you need to install 3/8 inch underlayment, don’t bother with the extra weight of a stapler gun—simply use a hammer tacker with 5/16 stables instead!

Benefits of Using 3/8 Underlayment

Using 3/8 underlayment is essential in laying down a hardwood floor, no matter the material. 

It helps to provide added durability and support while also ensuring that your floor’s surface is even and leveled. But what are the actual benefits of using 3/8 underlayment?

Firstly, it ensures that hardwood floors are more durable and less prone to scratches and scuffs. The extra cushioning effect it provides helps to keep your flooring looking newer for longer. 

Secondly, it creates a stable base for the hardwood material so it doesn’t warp or buckle over time. This also helps to minimize noise, especially if you live in an apartment building or multi-family home. 

Lastly, improved insulation is one of the biggest benefits of using 3/8 underlayment. This traps warm air underneath, helping lower heating bills during colder months!

Overall, 3/8 underlayment can offer many beneficial features for your hardwood floors when properly installed. 

Be sure to consult a professional if you’re unsure how to install this material correctly—it’s worth getting it right the first time!


Whether you’re a beginner do-it-yourselfer or an experienced carpenter, using the right staple size for your 3/8” underlayment is critical to the project. 

It’s best always to use at least a 1/2” staple or nail, and you can never go wrong with a slightly bigger one.

The result of proper nailing and stapling is much better than a nail or staple that is too small. Also, the staples may pull out prematurely if they are too short. 

So, while it may seem like a hassle to take a few extra minutes to check the nailing or stapling specifications, it’s time well spent.

Remember, the correct staples for your 3/8” underlayment create a stronger bond and ensure your project looks flawless. 

So don’t take any chances and use the correct size staples for your project.

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