## Cinder Block Insulation Blocks for CMU Walls
If you want to insulate a cinder block wall above grade there are several ways to do it. One option is to install rigid insulation on the outside of the wall. This can be tricky and is subject to damage when backfilling and waterproofing the block. A second method is to insulate the inside surface of the wall. This is typically done if the owner plans to finish the interior space, but not if the basement is going to remain unfinished for the near future.
The third — and often simplest — method is to use **cinder block insulation blocks**. These are precut blocks of **EPS insulation** sized to the concrete masonry units you are using. They slide into the cores easily and turn hollow CMU into an insulated wall system without changing your standard block details.
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## R-Value Performance for 8", 10" and 12" Cinder Block Walls
Each EPS insert is engineered to fit snugly inside the block cores and deliver reliable thermal performance.
| CMU Size | Typical R-Value with EPS Inserts* |
|---|---|
| 8" block | R-13 (blended wall value) |
| 10" block | Higher than R-13 |
| 12" block | Highest R-value of the group |
*Actual R-values may vary based on block configuration and project details, but inserts consistently improve the thermal performance of standard cinder block walls.
How EPS Cinder Block Inserts Compare to Other Insulation Methods
There are several ways to insulate CMU walls. EPS inserts offer a unique balance of performance, cost and simplicity:
| Method | Location | Install Complexity | Risk During Backfill | Typical Use Case |
|---|---|---|---|---|
| Exterior rigid foam | Outside of block | High | Higher | New construction with full exterior finish work |
| Interior framed wall + batts | Inside of block | Medium | Low | Finished basements and interior spaces |
| EPS cinder block inserts | Inside CMU cores | Low | Low | New walls or retrofits where cores are exposed |
Because the EPS blocks are inside the CMU cores, they are protected from jobsite damage and do not change the exterior profile of the wall.
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## Benefits of EPS Cinder Block Insulation Blocks
- **Fast installation** – Inserts slide directly into the block cores as the wall is being laid.
- **No special tools** – Standard masonry crews can install them with normal workflow.
- **Durable and moisture resistant** – EPS does not support mold growth and maintains R-value even in humid environments.
- **Compatible with multiple block sizes** – Inserts are precut to fit 8", 10" and 12" CMU.
- **Free sample for every project** – A sample block is provided at no charge to verify the fit with your specific cinder block.
A sample block is provided for every project at no charge to make sure the insulation block fits properly into the cinder block you are using.
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## Simple Installation (Video Demonstration)
The accompanying video shows just how easy these EPS insulation blocks are to install in the field. You can see how they drop into place as the wall is laid, with no changes to standard construction methods.
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## Frequently Asked Questions About Cinder Block Insulation Blocks
**Can I use EPS inserts on existing cinder block walls?**
Yes. If the cores of the cinder block wall are accessible, EPS inserts can be added during renovation or repair work to improve the R-value of the wall.
**How much R-value do the inserts add to an 8" cinder block wall?**
An 8" CMU wall with EPS inserts typically achieves a blended R-value around R-13, with higher values for 10" and 12" block.
**Are EPS inserts affected by moisture?** EPS is closed-cell and does not wick water like fiberglass. It maintains its thermal performance in damp basements and other below- or above-grade wall applications.
**Do EPS cinder block insulation blocks change my wall thickness?**
No. The inserts fit inside the hollow cores of the CMU, so the overall wall thickness and exterior appearance remain the same.
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## Ready to Discuss Your Project?
Have questions about using cinder block insulation blocks on your next project, or need help confirming the right insert size for your CMU?
A free sample block is available for every project so you can confirm the fit before ordering.
