What Is A Floor Joist in Construction: Installing & Replacement Guide

What Is A Floor Joist

The foundation of the floor frame depends on many factors, mainly floor joists. Because this horizontal structure distributes loads to the vertical members.

That makes it strong enough to handle heavyweight. But the question is, what a floor joist really is? Could you install it or not?

According to the report of Building Knowledge University, across all types of floor support, floor joists can handle the highest amount of weight. It’s Amazing!. 

So having all the furniture and appliances in a room will not cause any kind of damage to the floor.

But this depends on the quality of the wooden planks. Also, there are some industry standards for floors. That every manufacturer needs to follow.

But understanding floor joist is a crucial thing. That’s why you should read this complete article. Because in this article I have shared information about the major components of floor joists. 

That combines the whole structure of strong and better floor joists.  Also, I have covered a step-by-step process to install it in your house. 

Looks Interesting!.


What Is A Floor Joist

The floor joist is horizontal structural support. It is built with many strong wooden or steel pieces, placed side by side within the floor.

This structure subsequently transfers the load to the other vertical members.

So when the weight is applied to the floor and then joists. The top and bottom of the wooden fiber start compressing themselves.

That helps the weight to distribute evenly on the floor. That’s simple!. Instead of putting all the weight at one place, joists help it to distribute. 

Even though floor joists have too much empty space. That becomes the cause of leaking heat.

But this space can be used for filling cellulose fiber to get better insulation. This will also increase the stability and prevent the joist from buckling up the load.

Especially engineered wood because it gains more strength from expanding. On the other hand, standard wooden made floor joists have their limitations.

That makes it difficult to survive in extreme weather conditions.


Components Of Floor Frame

Floor joists are only part of the floor frame. So there are some others also that help floor joists to work properly.

That’s why for having better floor joists you should know the autonomy of the floor frame.

  • Rim Joists: These are parallel joists installed at the opening and closing on the floor. These joists will provide lateral support to the whole structure. 
  • Blocking Joists: These are some small wooden sections placed within the floor joists. This way you can easily install subfloor. 
  • Support Beam: If there is a long distance to reach the foundation wall. Then support beam comes up to hold the floor joist first end.
  • Sill Plate: Concrete may become a slippery place for floor joists. That’s why the sill plate places at the bottom of the floor and rim joists. This will handle the major weight.
  • Subfloor: After installing floor joists you need a subfloor on it for waking on the floor. This is a kind of base floor.

Type Of The Floor Joists

Sizing is more like the types of floor joists. That makes the structure strong enough whether what the material is.

You can be assured of the strength by analyzing the size and design of the lumber.

1. Natural Lumber Floor Joists

Natural lumber floor joists are usually made from old-growth trees. That has a limited span distance.

Because these trees can be affected by many factors such as species, sizing, deflection, and so on.

However, these floor joists are commonly used in the house. But the supply of young trees is not enough. So using it continuously will wrap up all the trees completely. 


2. Engineered Lumber Floor Joists

Engineered lumber also called man-made lumber is built from the fine fiber of wood gluing together in a specific direction.

Usually, this kind of lumber is quite strong and environmentally friendly. That’s why instead of having solid wood floor joists, engineered wood is a better option. 


3. I-Joists

I-Joists is also known as TJI joists are engineered lumber floor joists. That can carry heavy weight with less lumber than conventional floor joists.

It eliminates all the problems that you may find in dimensional solid wood floor joints. Because it has better strength and relation with size and weight.


4. Open Web Trusses Floor Joists

Open web trusses floor joists is a completely different perspective for residential houses. Because it has many gaps and is made with multiple wooden strips.

That makes your work easy to pass through electric wires and pipes.


How To Install Floor Joists: Step By Step Process

Installing floor joists requires a deep understanding of the major steps. Because this is a difficult and complicated process. Also, fixing it after installing requires an extra budget.

1. Make Layout & Install Other Components

As you already know that floor joists have other components. Some of them such as support beam, sill plate, and header joists need to install first.

Because they become the base structure where you install floor joists. 

Now, the time comes to leave the most common gaping of 16 inches for most houses. This space is also applied to the floor frame.

That’s why while building the base layout you also need to leave this space. 

Looks Odd!. But it works perfectly to support standard subfloor and other flooring components.

So when you complete the layout and install other components altogether. Then you need to start measuring. 


2. Take Measurements

The first thing you need to measure is the place where you need to place the joists. But make sure to make a “V” and “X” mark instead of straight lines.

Because this can easier to find. Also, it will eliminate the mistakes while nailing lumber plank to the wrong place.

When you complete this measurement then you need to go back to the stairwell. Carefully measure how bigger stairs you want. 

Then according to the need mark down the measurements.

In standard houses, stairwells are calculated at the right end of the house to the edge of the stair chase of about 15 ft. and the chase is about 11 ft wide.


3. Put Joists In Place

Joists usually are very heavy that may require to use machines for this work. But you can also do this by yourself by using a simple strategy.

All you need is when you complete the measurement. 

You only need to take help any person for placing the one joist in the flat position. Then placing another is only required to slide over the neighbor joist.

The same procedure you need to follow for all the joists. So that you can easily place them without any help. But make sure you need to do this carefully.

Because doing this process at a very high place may cause a major accident. 


4. Mark The Direction

So you have put all the joists in their places. But you haven’t noticed all the marks you made earlier.

The marks are “V’ and “X” those come to provide the exact area where you need to nail them. 

However, they were placed incorrectly. But now you need to place them according to the mark.

Because before following the incorrect process doing this in the correct way is very difficult. You will get confused. May also do any mistake. 

That’s why after putting joists between the sill plate and support beam now you are free. So all you need is just match the “V” to the “X” mark that’s all.

But the one thing is left in this step. That will be used in the following step.


5. Start Nailing The Floor Joists

Now, the tough part comes up, in this step you need the help of another person.

Because holding the joists in straight positing and nailing it at the same time, is not possible. Also, this is the left part that you need to follow in this step. 

Because this is impossible to hold them all together in a straight position. You need to do this one by one when you go to nailing them.

So use a nail gun machine and start from the middle joist.

Now, this time I-Joist lumber become helpful for you. Because it has a shape of “I” which provides a little bit of space at the bottom and top.

So you can easily nail otherwise you need a joist hanger. 


6. Install LVL At The Stairs

LVL also known as “Laminated Veneer Lumber” is an engineered wood product.

That combines with too much heat, glue, compression, and veneer. It is mostly used in roof and floor projects. Because it has amazing strength and durability. 

That’s why working with floor joists you should also use it at stairs opening and closing. It will provide more strength.

Because stairs are the place where weight distribution will not work properly.

But these beams are enough strong to handle the weight. Especially, if you have naughty children who up and down many times on the stairs.

You only need to use it at the opening and closing area of stairs. 


7. Install Rim & Blocking Joists

Floor joists aren’t completed without installing rim and blocking joists. Because this small section of joists provides that strength.

I have explained earlier about both of them and where they need to install.

Rim at the opening and closing and blocking between both joists. They will connect the whole structure and distribute weight to others.

Simply you can use a nail gun and attach them to the main joists.

But make sure to leave a significant gap between the two blockings. Or you can take the measurement of the lumber and divide it into four parts.

Then every each part installs a blocking. 

So if you are working with solid lumber joists now you also miss out I-Joists. Because installing blocking in solid lumber joists is not an easy thing. 


How To Repair Floor Joists

Installing the floor joists is finished, but what you will do if you face any uneven joists. Now, the repairing work comes up.

So when you see this kind of problem in your floor joists. Then first you need to cut that part. 

Be careful! 

While fixing these floor joists make sure no one should on the floor. So after cutting that faulty section.

Now you need two strong lumber and make sure one should the same length as the floor joist. 

Then after it, place it as the new floor joist and attach it to the faulty joist. This will help you to attach the cutting part.

Then raise the existing joist with the help of a bottle jack. When it comes to the stable angle. Then nail them together and then install the faulty part. That’s all!. 


How To Replace Floor Joists

Repairing can only work if a part of a joist breaks. What you will do if the floor joist needs to replace?

So for this work, first you need to detach that broken joist from the floor frame. This is a very difficult procedure that’s why, be careful. 

You can use a reciprocating saw or hammer and crowbar. After it, using the back of the hammer simply pry the floor joist.

So when you successfully detach the joist. Now, it’s time to install the new one. 

If you want to properly attach a new joist at the exact place. You should use construction adhesive at the top of the new joist.

Then simply use a jack for raising the subfloor. So after it, carefully place the new joist at the replacement position. 

Then you need a joist hanger if you are using solid lumber. But if not then you can easily nail it into the place. 


How To Calculate Joists Span

Joists span is a measurement of the distance between support structures. Before building any floor frame this is a crucial part to determine.

Although, it is a pre-calculated measurement, but can be affected by some factors. 

  • The Depth Of The Joists: This measurement is the height of each vertical joist from its top and bottom.
  • Wood Species: Redwood, hemlock, yellow pine are the common wood species. That is used to build floor joists.  
  • Load Capacity: This is the whole weight that you going to put on the floor. This is a critical measurement that requires expert knowledge. 
  • Joists Spacing: This is the number that refers to the distance between two joists. Commonly it is about 16 inches. 

Wrap Up On What Is a Floor Joist

Considering the whole floor frame joists are the major ones. Because they handle all of the weight, not subfloor and so on.

That’s why building it properly comes at the top. However, there is a misconception behind the types of floor joists. 

But when it comes to the durability, strength, and installation procedure I suggest you I-Joist.

Because they are simply amazing areas of horizontal and vertical support. Also, have areas that can be used while nailing them up. 

Although, following the above installation procedure will lead to the proper floor joists. But other things also consider such as joists hanger installation and so on.

That’s why working with other types may require following additional steps. 


FAQ: What Is Floor Joists and Complete Guide

These are some of the frequently asked questions about floor joists, their installation, replacement, and repairing. Make Sure To Check Out!. 

Q1. How to calculate the size of the joists?

Ans: Getting the exact size of each joist is very easy. All you need is the average depth of each joist. So minus two from measurement and then multiply by two. Also, if you want to know the depth of the joists. Then do this process in reverse format.

Q2. How much thicker the floor sheeting should be for the floor frame?

Ans: There is no exact size of the floor sheeting. But if you want the best match with the floor joists. Then you can go with the standard size of ¾ inches. Make sure to make a plan otherwise you may do mistakes while selecting the subfloor size. 

Q3. How can I transfer electric wires through floor joists?

Ans: Using the I-Joists you can simply make a hole within each joist. Then pass through anything from it. But don’t make too many holes otherwise it will decrease the strength of the floor joists. But working with solid lumber floor joists is a little bit of difficult work.

What Is A Floor Joist

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