Nowadays people are speaking about electromagnetic in-house effect more and more, it is said to be harmful to health but researchers still don’t agree on the health issues concerning this question. Most of the people do not know how electrosmog is formed, and what is it depend on. We have to know the electromagnetic properties of the building materials in order to evaluate the reflection and transmission coefficients, which quantitate the RF reflection and transmission loss. There are some data available, and also different measuring techniques that we can use. In aware of these values we can make steps to effectively calculate and simulate how to shield our room or building, so external electromagnetic field will not able to penetrate into the shielded space, or to reduce it to a required level . The first part of this paper presents the electromagnetic properties of basic building materials, like brick, concrete, wood, glass, and complex material like reinforced concrete, with different reinforcement square grid sizes. The second part of the paper raises the question whether the shape of a building has effect on the inner field radiation and how much. This part presents the effect of the shape of a room to in house electrosmog considering rounded corners, rounded window edges, circle and hexagonal shaped room. It is demonstrated, that this parameters have small effect on the electronic and magnetic field. The last part presents comparative data about a small reference building simulated in CST with different building materials. The data presented, suggests that the complex permittivity does not change significantly for different mixing ratios of similar materials. It seems that the biggest difference observed is between hardened and lightweight concrete samples. In closing Carbon and graphite based shielding techniques, and the importance and solutions for window shielding is presented.