Do Ceiling Joists Need Blocking? (Explained!)

When you look up at the topmost part of your room, do you often wonder what it is composed of? Well, it’s made of many structures, which include a broad arrangement of ceiling joists.

Ceiling joists perform a very noble function; they ensure you don’t come back home and meet your ceiling on the floor. That’d be a funny sight to behold.

In this article, we will be taking a close look at why you need to block your ceiling joist from view.

Here’s If Ceiling Joists Need Blocking:

Your ceiling joist needs blocking because it holds your roof up and prevents it from crashing down. Ceiling joists get damaged by termites, water, and old age; blocking them provides strength and support.

This process aims to help the joist carry more weight (if there’s an attic), increase the lifespan and prevent injury.

Do Ceiling Joists Need Blocking?

Ceiling joists are a series of woods hung horizontally across your ceiling, spanning the free space. They are attached to the vertical and slanting wood that holds the roof. Ceiling joists run between the sides of the ceiling providing firm support and attachment.

Ceiling joists can either be blocked or exposed based on what you want.

Exposed ceiling joists can be used as a form of decoration or design while blocking them will reinforce the strength of the joists and help them transfer weight equally.

When you go to a restaurant or visit various buildings with exposed ceiling joists, you’ll notice that they are mostly made from different materials. These materials include:

  • Wood
  • Steel
  • Composite or engineered wood (wood made artificially by mixing wood scraps with chemicals and heating)

Ceiling joists are usually arranged with the larger surface lying in the vertical direction, i.e., facing the roof directly, and the shorter surface in the horizontal direction. This allows for easier and more effective distribution of weight.

There’s no standard length for ceiling joists as it depends entirely on the size of your home. Though most houses use 2 by 6 inches board sizes, the dimensions can be as large as 2 by 12 inches.

Now the main question is, do joists need blocking?

Whether your need to block the ceiling joists in your home or not depends on you.

Exposed ceiling joists are mostly used in recreational centers and outdoor spots to give a cool beautiful outlook. However, in your home, it would be advisable to block them.

Why Do Joists Need Blocking?

Over a long period, ceiling joists get affected by a lot of factors. These factors include:

  1. Age:

With time, ceiling joists get weak from holding the weight of the roof and can begin to lose their power. This weakness might not be noticeable until it is already too late to do anything.

  1. Moisture:

Most ceiling joists are made from wood, and unless it is made from steel, they begin to absorb moisture with time. This moisture can either come from the atmosphere or from a leak in the roof. Water weakens the fibers of the wood and reduces its efficiency.

  1. Termites:

Termites are the worst enemy of any type of wood as they feed on it and cause gradual damage from the inside out. Ceiling joists can get damaged by termites and lose their strength with time.

To check the health of your ceiling joist, you will need the help of a professional

Blocking your ceiling hoists can help reduce the effect of age, termites, and moisture on your joists.

It helps to:

  • Provide maximum support for the ceiling joists by sharing the weight
  • Increase the amount of weight the roof can hold.
  • Prevent the collapse of your ceiling, which may cause destruction and damage.
  • Prevent excessive heat from reaching the house on hot days.
  • Provides space to easily pass electrical cables and wires and keep them out of reach.

If your ceiling joists are not blocked, with time, your joists will begin to:

  • Bend and sag, and it gradually succumbs to the weight of the roof
  • Show cracks and splinters
  • Produce loud creaking sounds.

What Is The Ceiling Joist Blocking Requirements?

The requirements for blocking a ceiling joist are very simple.

The principle behind it is to make sure the size of the block is the same as the size or area of the distance between two adjacent joists.

For example, to ensure a smooth and effective block for two ceiling blocks that are 14 inches apart (i.e., from the center of one block to another), the size of the block to be used will be 12½ inches. Also, for joists that are 20 inches apart, the size of the block will be 18½ inches.

This shows that the size of the block to be used depends on the type and dimension of the joist.

In the case where measuring this distance or fixing the block poses an issue, it will be smart for you to seek the assistance of a professional to ensure the blocking is done well.

How Far Apart Should Joist Blocking Be?

The spacing used for your ceiling joist blocking depends entirely on the space between the individual joists.

There is no specific value for how far apart ceiling joists blocking should be; it depends mainly on the following:

  • The size of the room.
  • The amount of load it will be holding.
  • Its purpose.

On average, the standard spacing between ceiling joists ranges from 16 to 24 inches. This spacing makes it easy to measure out the area using a tape

Bigger apartments might make use of larger blocks due to more space that is needed to cover. However, for your home, the spacing above should do the trick.

If the spacing between joists is not put into proper consideration before the blocks are inserted, there might be mistakes. These mistakes may arise from the block being too short or too long.

A professional can be called to assist in fixing the ceiling joist block. This will ensure it is properly set, firm, and lasts a long time.


Ceiling joists are useful attachments that help to keep the ceiling, roof, and other components in place. It helps to hold the weight of the roof and other objects attached to it.

It can be hidden (blocked) or exposed. Blocking ceiling joists is very important because it provides further support, allows for even weight distribution, and prevents damage and collapse of the ceiling.