How To Insulate Existing Concrete Block Walls

How To Insulate Existing Brick Walls

Concrete block walls go by a number of names, from cement block walls to cinder block walls. However, no matter what you call them, concrete block walls all have the same problem – they are somewhat porous. This means that they tend to let air in and out, leaving you with expensive electrical bills, not to mention a rather uncomfortable home as far as air conditioning is concerned. One way to remedy this issue is to insulate the existing concrete block walls around your home or office.

Learning how to insulate existing concrete block walls involves learning how to use several insulation options. The most common include injection foam insulation, spray foam insulation, foam boards, loose fill masonry insulation, and polystyrene beads. While these are the readily available and most effective options, which one you choose will depend on whether the wall in question has an exposed top or the concrete blocks are covered.

With that in mind, here are some tips and tricks you can use to insulate existing concrete block walls using the above-mentioned options.

Injection Foam Insulation

One of the main reasons injection foam insulation is quite popular is that this type of insulation is well-suited for a cinder block wall. When experienced masons put a cinder block wall together, they mortar the long sides of the concrete blocks. Unfortunately, this leaves a number of openings on both the shorter ends of the blocks and the middle. It’s these openings that allow for the movement of air.

Injection foam does a very good job of filling up those spaces since this foam can easily get to the nooks and crannies as it pushes into the core and creates an air seal that is excellent at preventing air movement.

The idea is to drill holes into your existing concrete block walls (the middle of the wall) then inject the foam into that hole. This foam will then fill up the cavities and spaces left during assembly. The foam will fill up every space in the wall, including the crevices that remain when the walls get mortared together.

Spray Foam Insulation

In many cases, homeowners use put drywall over concrete block walls. If this is your case, using spray foam insulation options would work before putting the drywall in place. You would need to fur out the studs about a quarter to half an inch. Doing this is highly recommended so that when you use the spray foam into the cavity wall, the insulation gets behind the studs preventing thermal bridging.

  • Note: Thermal bridging occurs when one area of the wall or building has a much higher heat transfer when compared to any of its surrounding materials. As such, this results in reduced thermal insulation.

However, if you aren’t too worried about your walls looking like they have been sprayed, then the drywall isn’t going to be necessary.

Foam Board Insulation

While using foam boards won’t necessarily give you the same kind of result as using spray foam insulation, there is something to be said about this method. Many homeowners prefer to use foam boards on the exterior of their concrete block walls before they have the exterior finish done. Another advantage of using foam boards is that they are very easy to install.

All you have to do is apply some foam board adhesive on the back of each foam board using a caulk gun or utility knife. The next step is as simple as placing the foam board in the right spot on your concrete block wall. Remember to use caulk on all of the seams to ensure no missed spaces that could allow air leaks. This is extremely important for two main reasons:

  • If those seams aren’t properly sealed, you will still get air movement which defeats the purpose
  • Worse yet, condensation can occur within the walls as two different temperatures interact inside those spaces. This can lead to mildew or mold.
Image Source: AKuptsova

Loose Fill Masonry Insulation

This particular solution is perfect for those who have concrete block walls with open cavities. Loose fill concrete masonry insulation, also known as mineral loose fill insulation, is a sand-like material that you can easily pour into the cavities of your concrete wall. The idea is that this sand-like material will find its way into the various crevices within the wall, fill them up and create an airtight seal that prevents air movement within those walls.

While this solution is simple and quite practical, it does have a few drawbacks:

  • Should you ever have to cut into the wall for whatever reason, the loose fill masonry insulation will pour out.
  • The second issue is that since you will be pouring this material into the wall from the top, it’s quite difficult to ensure it gets to all the nooks and crannies within the wall. If there’s any obstruction in its way, the material might not make it to the spaces beyond that obstruction.

In an ideal world, this solution works perfectly. However, if it doesn’t get to all the spaces within your cavity wall, your problem won’t be fully solved as there still will be some spaces letting air in and out.

Polystyrene Beads

Polystyrene beads are a lot like loose fill masonry insulation – they are poured into concrete block walls from the top, which means that they work well with walls that have open cavities. These beads make their way through the wall filling up any spaces found within and making them airtight.

As you can imagine, this is an ideal solution since it doesn’t require that much technical know-how. The biggest problem here is the same problem you will experience with loose-fill masonry insulation:

  • The beads will pour out if you ever cut into your wall
  • If there’s an impediment in their path, the beads may not get to some of the crevices beyond that impediment

When it comes to tampering with existing concrete block walls, it’s best to consult a professional contractor who knows exactly what to do. This is mostly because your walls are load-bearing and support the roof and most of your house.

Also, there are things like electrical wires, water, and gas piping to consider before making any major incisions into the wall. That being said, the above methods are excellent ways to insulate existing concrete block walls should you ever need to do so.

How To Insulate Existing Brick Walls
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