Are Vermiculite Fire Bricks Good?

By Vanessa Richards

January 10, 2024   •   Fact checked by Dumb Little Man

are vermiculite firebricks good

Vermiculite Fire Brick Overview

A fire brick, also called refractory brick, is a brick made of ceramic material which can withstand very high temperatures. These bricks usually have a low thermal conductivity which makes them highly energy-efficient. Fire bricks are primarily used to make heat barriers in steel stoves, and the inner surface lining of kilns, chimneys, furnaces, and similar structures that need heat resistance at high temperatures.

Fire Bricks are made from Fire clay. The fire clay’s composition changes based on the usage of the bricks. However, the major components of fireclay are alumina and silica. The silica percentage mostly is in the range of 60-70%, while alumina is in the range of 25-35%. Other constituents may include oxides of titanium, magnesium, iron, calcium and potassium. It needs to be noted that the other constituents normally do not exceed 5% if the clay is of good quality.

There are several kinds of fire bricks available in the market. Of these, Vermiculite bricks are of particularly fine quality especially for use in steel stoves at home. These fire bricks are made from a naturally occurring mineral called vermiculite which exfoliates when heated. Exfoliated Vermiculite is mixed with an inorganic bonding agent. It is then hydraulically pressed into a mould and then heat cured. The fire bricks are then cut from these moulds or boards.

are vermiculite firebricks good

◉ Looks / Appearance 

The fire bricks are yellowish in colour and used to line the inside of the ovens.

If the vermiculite turns pink, then it means that it has been exposed to heat for a prolonged time and may need replacing.

◉ Ease of use 

Vermiculite bricks are available in standard sizes online and offline.

Sometimes, Vermiculite bricks need to be cut from pressed boards You can easily cut bricks of the requisite size by placing an old brick on the board, drawing around it and then using a wood saw to cut it to the desired size.

Vermiculite, when mixed with cement, is easy to use at home to build a pizza oven. This mixture forms the dome of the wood-fired pizza oven. There are plenty of Do-it-yourself videos on youtube that can be used as a reference point while taking on the activity.

◉ Functionality 

Vermiculite firebricks are used as lining in the fire chamber of steel ovens. They protect the steel from the high temperature produced by the fire. Basically, in a steel stove, the firebricks act as a heat barrier. They are lightweight and easy to use. The bricks are porous and apt for insulation purposes. They do not crack when they are subjected to high temperatures.

It is not just steel stoves that benefit from vermiculite, but also wood-fired pizza ovens. Vermiculite concrete is used as an insulation agent for wood-fired Pizza ovens. It is mixed with water and cement to form concrete which is shaped like a dome. This insulation layer protects the heat from escaping the oven.

◉ Pros

  1. The fire bricks are lightweight and porous making them excellent for insulation purposes
  2. Vermiculite bricks can be used to aerate the soil. It can be added to compost and recycled in your garden once the bricks have started crumbling.
  3. These fire bricks don’t have asbestos or any other toxic chemicals.
  4. Vermiculite Fire Bricks are easy to source online and offline
  5. Vermiculite fire bricks don’t crack or crumble easily when exposed to heat over long periods.

◉ Cons

  1. Vermiculite fire bricks are expensive.
  2. They are fragile and break easily. Vermiculite fire bricks need to be packaged with great care during transit or while shuffling them inside the stove.
  3. The inside of the stove has to be cleaned with great precaution so that the bricks don’t get wet and weaken eventually. You cannot use water or water-based cleaning agents.
  4. You can’t put oversized logs inside the stove or the bricks will break.
  5. You can only burn seasoned wood as moisture weakens Vermiculite fire bricks

◉ Price

 Set of 4 at  £24.99

Click here to view Vermiculite Fire Brick

Who Is This Fire Brick For?

are vermiculite firebricks good

These fire bricks are useful for anyone who needs bricks in high-temperature applications. The vermiculite fire bricks can resist high temperatures without cracking or crumbling. They have better energy efficiency than most bricks due to their porous nature.

If you have a steel stove at home, these fire bricks can be used to protect the steel walls of the stove while the stove burns efficiently.

◉ Specifications

  • Size : 9″ x 4.5″ x 1″
  • Weight: 500 gms approximately
  • Colour: Yellow
  • The bricks can also be cut into a size of your choice from pressed boards.

What makes this Fire Brick Different From Other Types of Fire Bricks?

The Vermiculite fire brick is different from other firebricks in many ways :

  1. Vermiculite bricks are more porous in texture than other fire bricks and hence have greater efficiency.
  2. They can be recycled by adding to the garden soil.
  3. They can withstand high temperatures and are suitable for being used as heat barriers in steel stoves.
  4. They are more fragile than other fire bricks and need to be handled with care.

Final Thoughts

are vermiculite firebricks good

Vermiculite fire bricks are suitable for any high-temperature application which also requires great energy efficiency.

They are especially useful in steel stoves where they protect the body of the stove from the high heat thus preventing the stove from getting damaged.

They can be replaced easily if they start to crumble, crack or if they turn pink. In fact, Vermiculite bricks are cheaper if they are bought in sets. You can choose to replace one brick and keep the rest for future use.

While Vermiculite bricks have many pros, they have some demerits too. These fire bricks are fragile and a lot of care has to be taken if you are cleaning them or replacing a cracked fire brick. More often than not, these fire bricks start cracking when you are trying to replace existing cracked bricks in the stove. This is the reason why it is advised to change all the bricks in one go even if not all are showing signs of wear and tear.

The presence of vermiculite fire bricks makes it a tad difficult to clean the inside of the oven. This is because vermiculite fire bricks become weak on getting in contact with water. For this very reason, only seasoned wood is used in stoves using fire bricks.

Care also has to be taken to not overfill the stove or use oversized logs in the stove. Shoving big logs inside the stove can cause the firebricks to break and you would need to replace them more often.

Overall, Vermiculite fire bricks act as excellent heat barriers in preventing your cooking equipment from getting damaged. With a little precaution, these fire bricks can provide value for a long time.

Click here to get Vermiculite Fire Brick Set at a Discounted Price
Vanessa Richards

Vanessa is a mom of 3 lovely children and a software geek. Outside of her career as a health and wellness instructor. She enjoys writing and researching on topics such as finance, software, health and culinary.

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