Depending on the thickness of the wall, the density of the units and the amount of grout used, concrete masonry walls can provide up to a four hour fire rating. Additionally, concrete masonry walls pass the hose stream test unlike other fire rated wall systems.
The Cinder Blocks are fire resistant meaning they won’t burn, but they are not fire rated, and prolonged and repeated exposure to fire will make them crumble. Can you use cinder blocks for a fireplace? A cinder block is a type of cement block that contains cinders from incinerated wood.
Another common question is “Are cinder blocks good for fire pits?”.
Some have found that cinder blocks are cheap, light and can withstand high temperatures, so they are very good for making DIY fire pits. Cinder blocks can also be painted with heat resistant paint to create a great looking fire pit for under $100.
You can build a cinder block fire pit directly on the ground. With this type of fire pit, the cinder blocks corral the burning materials. Start with cinder blocks that are fire-rated. Are cinder blocks fire resistant?
An old blog post on a “ Redneck Rocket Stove ” made out of cinder blocks prompted many to suggest that the cinder blocks would explode due to heat. Leon, of the blog Survival Common Sense, does a good job of refuting this notion in a blog post, “ Build a brick rocket stove: Is it safe to use concrete blocks?
What are cinder blocks used for?
Cinder block (also known as concrete masonry units (CMU)) are generally used for building outdoor structures like fireplaces, pizza ovens. Not only do they come in different sizes, but some cinder blocks that are classified with the same size can be a bit different allowing them to be used in a different way.
No more cinders, no more cinder blocks. Around 1910 coal cumbustion produced cinders, and few places burned more coal than Pittsburgh, Pennsylvania. A brick mason from Pittsburgh named Francis Straub realized the potential of this large volume waste product, and experimented with cinders and cement.