When the big bad wolf comes knocking at your door, which building material will you have wished you had chosen? Concrete and masonry are two materials that come to mind as indestructible, even for this notorious storytime character.
In all seriousness, if you’re looking to build a strong structure that will last a lifetime, concrete masonry units (CMUs)—commonly called concrete blocks or cinder blocks, are the solution. If you’ve chosen CMU for your walls, there are some things to know about the building material and how to properly insulate this wall type.
Concrete Block Wall Basics
A concrete block is basically what it sounds like. It’s a building material made out of concrete that is shaped like a building block. In typical concrete block wall construction, concrete blocks are stacked on top of each other like bricks and held together with mortar. Sizes and shapes can vary, but these units typically come in dimensions of 8” wide by 16” long by 8” height.
Where to Use Block Walls
Concrete block walls are versatile and are used both above and below-grade. Common examples of commercial buildings that are often constructed with CMU walls include grocery stores, schools, and prisons. Below-grade applications are common for residential foundations that form the walls for crawl spaces, and sometimes basements.
There are many benefits to choosing concrete block walls for your project. A few advantages include the following:
Naturally fireproof
Less susceptible to mold, moisture, and pest damage
Wind-resistance
Heavy load-bearing capacity
Inexpensive
Exceptional security
Block Wall Section Materials
Most times, concrete block walls are made up of more than just a stack of concrete masonry units held together with mortar. For example, a brick cavity wall uses brick veneer attached to structural block. Alternatively, metal wall panels, siding, and other materials can be attached to a backup block wall for a premium finish. A functional CMU wall section often includes a range of components, including:
Insulation
Air space
Moisture barrier
Waterproofing (below grade)
Brick veneer
Reinforcement
Flashing
Interior finishes
Exterior finishes
Insulation Techniques for Block Walls
If you’ve chosen concrete block walls for your project, the next step is to consider which components will make up your wall section. Specifically—when choosing materials, you’ll need to decide which type of insulation to use for your block wall. Additionally, you’ll need to select a compatible installation method.
Insulation can be installed inside the CMU block wall, on the exterior side of the block, or on the interior side of the wall. Some contractors choose spray foam, blow-in, or injection-type insulations for concrete block walls. These methods can be messy and cause problems if you need to cut through the wall at a later date. An alternative solution to increase the insulation value of your concrete block walls is a rigid insulation, like polyiso.
Polyiso insulation boards typically come in modular sizes, such as 4’ x 8’, and are easy to cut with a utility knife. They install quickly with versatile installation techniques, including:
Screws and plates
Adhesives
Loose-laid into metal channel or girt supports
Backfilling
Rmax Polyiso for Block Wall Insulation
Insulation is a critical component that is often added to concrete block walls to increase the wall system’s overall insulating value. The insulating R-value for polyiso packs the most punch with R6 per inch—meaning that you can achieve R13.1 with a single 2” thick layer (the facer adds to the R-value).
These Rmax polyiso products are for block wall exterior installations:
Rmax ECOMAXci® FR is a polyiso with aluminum facers used in block wall insulation exterior
Rmax ECOMAXci® FR Ply is a polyiso bonded to fire-retardant treated plywood for a nailable surface
When insulating the interior cavity of a concrete block/brick veneer wall, foil facers are not always necessary. Polyiso provides a high insulating value per inch for this tight space.
Rmax Durasheath® is a polyiso with inorganic polymer-coated glass fiber mat facers for cavity walls and foundation applications
You can also use polyiso insulation for concrete block basement walls to protect waterproofing during backfilling.
Rmax Thermasheath® is a polyiso that is compatible with backfilling and used in many construction applications, including as exterior insulation of concrete block walls
Click here to browse all of our insulation offerings by application or installation method.
Let Rmax Help Pick the Best Insulation for Your Block Walls
Stuck or overwhelmed trying to decide which insulation to use for block walls in your project? Reach out to your Rmax representative today to get expert advice on which insulation solution will complement your design the best. We have a selection of high-quality polyiso products that are specifically designed to meet building code requirements, simplify installation, reduce costs, and accelerate the construction phase of your project’s envelope.