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What Is 5/4 Lumber? (Explained)

Lumber is an essential part of building any house or any building. You can use different types of lumbers, such as tumblers and hardwood boards. If you plan to repair your wood ceiling or rooftop, you should use the correct size lumber.

The size of the lumber would vary since their length and thickness are not the same for all. If you go for the standard lumber, you must ensure that your lumber has more than 1-inch thickness.

What is 5/4 lumber?

Mainly, 5/4 lumber is 1.25-inch thick lumber that people mostly use. However, you will find your lumber in the accurate size when you see them, but in reality, they will give you a 1.036-inch thickness. It’s the only reason people go for five-quarter lumber for their house.

Most of the hardwood is measured quarterly since you won’t find specific hardwood lumber for their usage. When you install or use this lumber in your house, some portion of the lumber will be under the basement or will be worked as the fundamental that you cannot count. 

It’s more like the fabric and dress.

You cannot give your tailor the exact size fabric since they need to have some extra clothes or fabric to do the sewing and keep some extra inside your dress so that you can customize it later. 

Although dress-making and lumber-using processes are not the same, you can create these examples to get an overview. A 5/4 lumber will make things easier since it will give you more than an inch of thickness to get a solid foundation on anything. 

You can start with five-quarter or 1.25-inch hardwood lumber, but the finishing will give you around 1.063-inch thickness, which will be more than enough for your house or rooftop.

Lumber is mainly used for windows, floors, and other wood walls to make them stronger; that’s why it varies from place to place. You can even make your hardwood floor using lumber or timber since they will be your best choice to work with. 

You can make your entire floor using single lumber or timber or join them together.

In both ways, you will clearly see using lumber and timber, ideally hardwood. Once you make that hardwood, you will have ample opportunity to turn the surface into an excellent finish using some wood finisher. You may also apply the wood paint over that timber.

If you use a thick or 5/4-inch-thick lumber, you will have the flexibility to use it for any purpose since it will give you a good relief of doing things efficiently. If you apply the primer over your lumber floors, it will provide an excellent finish. 

There might be some other requirements to using lumber apart from its thickness and size.

You should also consider the length of your timber to get another perfect measurement to make this lumber a perfect one for your house. To make a strong wood-made window, you must use thick lumber more than an inch thick. 

It will ensure safety and help you turn this into a secure one.

Choosing lumber with less than 5/4 inch thickness will give you less than the one-inch thickness at finishing. When selecting the perfect lumber for your construction work or making your hardwood surface, it will be another consideration. 

Besides, durability problems will be there if you use less thick lumber on your ceiling, floors, or windows.

How thick is 5/4 lumber? What is the dimension?

The 5/4 lumber is 1.25 inches thick, but the finishing size would be different because of the different use of this lumber. If you use 1.25-inch lumber, you can expertly get 1.063 inches thick at the finishing task. 

It’s a rule of thumb that 0.20 inch or 0.25-inch wood will be for the attachment and other issues you must deduct from your original lumber size.

It has become a widely accepted rule that you will get less thick lumber at the end of your finishing, So it is always advised to buy a big number that will have a little more thickness than your requirement. 

It will help you to choose the oversized lumber to get the desired thickness at the finishing.

Apart from the thickness, you should also know the approximate dimension of your lumber to calculate the number of lumber for your floors or windows. 

Generally, the dimension of a 5/4 inch lumber is around 1”*5.5”; if you are a DIY worker, you must know these basic requirements or information about hardwood or lumber to calculate the number of lumber you need.

It will help you save the extra cost of hiring a professional to come and do the work for you. You may consider your surface, follow these rules to get the required lumber numbers, and buy them accordingly. 

So, remember this dimension for your 5/4 inch lumber to calculate the total number of lumbers.

Why is it called a 5/4 board?

People mostly know these timber by their thickness and call them by quarter. That’s why it is called a 5/4 or five-quarter board that you can use in different places. Since the lumber is known by its thickness, you don’t need to consider its length. 

You will find the perfect size of your tube, the ideal consistency, or see the quarter of your lumber.

A 5/4 board mainly contains or comes with 1.25-inch lumber or board that you can safely use anywhere. This board will be a safe choice for making your hardwood floors or ceiling. You must get through the quarter of that board or lumber when you choose to use different lumber sizes.

For all these reasons, the 5/4 lumber or timber is called the five-quarter lumber. If you go to a shop to purchase lumber, you must ask them by the lumber’s quarter to get the right one. Otherwise, the seller might fail to understand your desired lumber soon.

What is 5/4 lumber used for?

5/4 lumber is used for finishing surfaces as they are durable, preservative friendly, and cost-effective. This size lumber is used for different purposes, including making your hardwood floor, making windows, and creating the foundation or basement. 

However, people also use this hardwood lumber for the following reasons.


Because the primary function of 5/4×6 planks is to finish the surface of a deck upon which people walk, sit, or recline, this type of lumber is generally of very high quality and is classified as an appearance grade. 


Every component satisfies the most stringent grading requirements for durability and overall attractiveness. This lumber has various applications, from building houses to the most fundamental tasks in interior finishing.

Carpentry, hobbies, furniture, shelves, and general finish work are other uses for boards and shelving. The grain of the wood is consistent and has a smooth appearance overall. 

It contracts very little and is simple to work with, both by hand and with machine equipment.

Preservative Friendly:

The element is friendly to preservatives and has excellent nailing and screw-holding capabilities, in addition to being simple to glue. It has good paint retention qualities and may be treated with preservatives relatively straightforwardly.

Cost Effective:

If two decks of comparable dimensions are constructed, one with 5/4 boards and one with 2×6 boards. 

The deck built with the 5/4 boards will require fewer trees to be cut down to obtain the same quantity of wood as the deck constructed with the 2×6 boards.

What lengths are 5/4 lumber boards available?

You can find several lengths for 5/4 number boards available. There are some standards and popular lengths for 5/4 inch lumber boards that you will find below. They will help you to get your best-matched lumber boards accordingly. 

Stock Pieces:

Interestingly, the length of the boards is typically precisely what you want to order. Despite this, there are typically only exact lengths available.

Popular Lengths:

The most popular lengths are even sizes, for example, 8, 12, 16 ft etc. Larger timbers, such as 2x8s, 2x10s, and 2x12s, are available in longer lengths, up to a maximum of 24 feet in some cases.


The actual dimensions of a piece of 5/4 lumber are 1 inch by 5.5 inches. Therefore, if you utilize 5/4 decking, you will only obtain two-thirds of what you would get from a 2×6 board.

Sawn softwood between 2 and 5 inches thick and 4 and 12 inches wide is the technical definition of dimension lumber. There are multiple lengths of lumber, from 6 to 24 feet long. And the lengths of the 5/4 boards that are typically available are six feet.

Final Thoughts 

A 5/4 lumber is a hardwood timber or lumber with 1.25 inches in thickness. If you use such lumber, you will get 1.063 inches’ thickness at the finishing. This hardwood board, or the lumber, is called the five-quarter board and is safe for most surfaces and hardwood floors.