2021 Good Quality Steel Roof Underlayment - What is breathing paper? What is it used for? How to install it? – JiBao

Breathing paper is a kind of building waterproof and breathable material, mainly used for tile roofs, metal roofs, exterior walls and other enclosure structures. Its excellent tensile strength and anti-aging performance indicators lead the development of the industry.

Breathing paper effect

The breathing paper is installed behind the hanging board, so it is the second line of defense for the building. If we install it correctly, it should be able to perform three basic functions.

The first and most important thing is that the breathing paper is a backup water barrier behind the external board. The external board itself is the first barrier, but wind-driven rain or snow will break through it and infiltrate inward, so a back-up water barrier is necessary.

Secondly, breathing paper can also function as an airtight layer, which can block hot and cold air from penetrating the wall; of course, the prerequisite is that all seams must be fully sealed. An important design function of breathing paper is to reduce the cost of building power consumption, and reduce air infiltration and possible air leakage.

The third function of breathing paper is its third function: to allow water vapor to penetrate freely, so the water vapor inside the structure can evaporate to the outdoors without being trapped in the structure and causing mold and rot. If the breathing paper does not have this characteristic, then it is like putting a thick raincoat on the house: it can block the water from the outside, but it also blocks the water vapor emitted from the inside; on the contrary, the breathing paper is covered by The outdoor jacket is designed to be waterproof and vapor-permeable, so that the building will not cause problems due to water vapor.

What should I pay attention to when installing breathing paper?

Basic bottom line: construction quality is more important than material selection. No matter which breathing paper product is selected, if it is not installed properly, it is a waste of money. The trouble caused by not installing the correct breathing paper is definitely more than it can solve. In fact, it is not so difficult to install it, but it requires a basic understanding of the principle of breathing paper. The detailed installation requirements are usually available on the manufacturer’s website and the dealer.

One of the prerequisite methods for installing breathing paper is to imagine a drop of rain falling on the outer wall of your home. Gravity pulls it down along the wall. If all the seams, cracks, and perforations are all sealed, And the exteriors are installed in the order of being overlapped, then the drop of rainwater will eventually fall to the ground. But once it finds a ruptured or unflooded node, it will penetrate the breathing paper and enter the main structure.

The breathing paper must be installed from the bottom up from bottom to top. At the same time, it is necessary to ensure that all horizontal seams have at least 6 inches (150mm) overlap, and all vertical seams have 12 inches (300mm) overlap. If you want to install breathing paper before erecting the wall, you should reserve enough material under the wall to cover the floor head plate below the erection. It is important to be cautious that vertical laps are as important as horizontal laps, because wind-driven rain will cause rainwater to move laterally, and even move upwards into the correctly lapped breathing paper.