Which heat insulator to use when pouring concrete screed in the outbuilding - expanded clay or gravel?
Hello! Please tell me, when installing a concrete screed, which material is best used as a heat insulator - gravel or expanded clay. I’m building the outbuilding in the country, there are floors left. By the way, I make the outbuilding with a fireplace so that in winter I could relax with friends in it. I want to make an ordinary concrete screed, I know that I need to make a pillow so that there is minimal heat loss across the floor. For this purpose I want to use gravel - the whole trailer lies under the yard. It was with him that the floor in the corridor was made at my place, but does the neighbor say that expanded clay is much better? Buying it in principle is not a problem, but still, it seems to me that a screed with gravel will be stronger.
Good afternoon, let's figure it out.
What is expanded clay?
If you are interested in expanded clay precisely as a heat insulator, then it is ideal in this sense. In the professional literature it is said that it is thanks to it that it is possible to reduce heat loss by up to 75%. This figure has a logical and very understandable explanation: expanded clay is produced by firing clay alloys. The operating temperature during this process is 1400 ° C. Hence the porosity of natural rounded expanded clay granules. And since there are pores, then a high level of both thermal insulation and sound insulation is ensured.
Important! When installing a concrete screed with expanded clay, granules with fractions of 5-20 mm are used.
The minimum recommended layer of expanded clay when creating a floor cake should be at least 10 cm. In this case, it is important to maximize its density to protect the floor from subsidence. For the same purpose, it is worthwhile to use expanded clay, at least 2 fractions of different sizes, and fill the material with a wedging method.
Why is claydite better than gravel?
Now about gravel! It is also about natural material. In principle, this is rock, also crushed into fractions. This material contains various impurities of clay, sand and organic compounds. It is also used in the arrangement of floors, but with regard to thermal insulation qualities, they are slightly lower than that of expanded clay. In addition, gravel is heavier than expanded clay, but in your situation, this is not so important.
Since this is an outbuilding and gravel you still have, then you can safely use it when installing a concrete screed. It is hardly advisable to purchase specially expanded clay from an economic point of view. And, with regard to strength characteristics, both materials possess them to a sufficient degree.
