fire blocking

The Importance Of Fire Blocking

When working in construction, safety is paramount, not just in terms of working conditions, but your final product. Failing to create a safe structure means harm to your clients and legal risk for your business. Many people may assume that this conversation orbits around structural integrity, but something else that should be covered is fire safety. Practicing safe habits and removing flammable material is one thing, but you may be surprised how gaps/holes in the wall and ceiling allow fires to spread throughout a structure. In addition, the added airflow they have can feed into a fire. Fire blocking for interior walls is essential to help here. But what exactly does this practice entail?

What Is Fire Blocking?

Fire blocking is basically the practice of filling any sort of gaps in the walls and ceilings in order to reduce the chance of fire spread. This is absolutely critical for new construction, but the truth is, there are a variety of different scenarios where you should be either implementing fire blocking or thinking about it. These include:

  • -Basement finishing
  • -Putting an addition onto a finished home
  • -Remodeling rooms
  • -Running piping/wiring through a plate

Sealing any existing gaps or gaps that may be created from this type of work will slow or stop the spread of flames and smoke in the event of a fire. Fire blocking is generally focused on reducing vertical movement of flames, which is why you hear it mentioned a lot with basement work. Of course, smoke and gas can travel horizontally as well. This is called draft stopping and is generally used for installations like drop ceilings.

In general, even if a client of yours isn’t concerned about fire hazards, they will likely need to put in fire blocking in some capacity. This is because it’s required for most framing inspections. Interestingly, draft stopping isn’t always required. It’s best that you explain the cost/benefit ratio to your clients and let them make the decision. For some areas where fire risk is more common in a structure, it may make more sense, where it can be skipped in others. 

fire blocking
Photo By studiovin

How to Implement It

So, now that we understand the nature of fire blocking, what are some of the key fire blocking requirements to get the process started? For a start, it’s a good idea to see the fire blocking code for your state. Most states have similar building codes for things like these to ensure safety, but you always want to be absolutely sure what the requirements are where you live.

Next is finding the right fire blocking material to use. You have quite a few options to choose from here, from drywall to 2x4s to sheet metal. Which is the best fit for your project? You have a bit of wiggle room here, as long as the local building codes allow you to use it. In general, you want something that is easy to cut to the width/length you need and will still pass inspection. Drywall is a good general fit if you’re having trouble making a decision. If you want a more formal example, though, here’s a look at Utah’s acceptable materials for fire blocking.


  • -Two-inch nominal lumber
  • -Two sets of 1-inch lumber with broken lap joints
  • -Wood structural panels (23/32) inches
  • -A set of 3/4 inch particleboard
  • -One set of half-inch drywall
  • -A set of quarter-inch millboard
  • -Blankets of mineral wool/glass fiber
  • -Cellulose insulation

The thing about fire blocking for contractors doing it for the first time is that there’s not just a set tool or material that you can pick up to get the project. The practice of fire blocking is simply taking a viable material and nailing it into the gap between your framed walls and the foundation. This means you need to cut a piece of material, let’s say drywall, at the width of the gap. For a typical residential property, this is generally 4 to 5 inches. However, you just want to make sure you have the measurement tools to take an accurate look for yourself. Even a small gap can lead to flames and smoke spreading.

When you have the right measurement, you can push the material into the space before securing it to make sure that it doesn’t fall. For drywall professionals, this is all going to feel pretty familiar. The main difference is just being able to scout the gaps that cause flames to spread so you can put up your fire blocking accordingly. In some cases, you may see small gaps after you’re done. It’s essential to use fire foam, caulk, or some type of insulation to fill those spaces. This also applies if you are running plumbing pipes/wiring through as a part of a job. You need to apply that caulk/material to make sure absolutely no air can go through the gap at all.

fire blocking
Photo By ungvar

Why it’s Important

Fire blocking insulation is an essential part of any drywall project, meaning that you also need to factor it into your general drywall installation costs. This ranges from the additional expense for fire blocking material to the labor hours that go into putting this together. Failing to account for this means that a drywall job that was profitable to your company at first may all of a sudden cause you to operate at a loss. Ideally, you want to have a method that lets you easily store and access financial data to understand this.

The best method to do this is by utilizing project management software like eSub. We have a full set of tools that you can utilize in order to make sure you are properly calculating bids and actuals for your company benefit. With our modular format, you can also ensure that you’re only buying the programs you need from our comprehensive software suite. 

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