Thermal washer for fixing cellular polycarbonate

Let’s talk about such a specialized type of fastener for polycarbonate, such as a thermal washer. We will tell you why it was created, what types of thermal washers are available today, for what purposes and where they are used, how they are correctly mounted. We will mention the pros and cons of the options for this mount.

Let’s start with the fact that the scope of application of thermal washers is quite narrow. They were designed to hold polycarbonate sheets in place. It is a popular material today for the construction of greenhouses, canopies, awnings, fences, arbors. Thermal washers together with self-tapping screws allow you to reliably attach polycarbonate to a frame made of plastic, metal, wood.

Why did it take to create special fastening parts for polycarbonate, in addition to the usual self-tapping screws? This is due to the peculiarities of this material. When the temperature rises, polycarbonate expands, and when it decreases, it contracts accordingly. The expansion coefficient is 0.068 millimeters / meter / degree, which at first glance looks like a small indicator.

In fact, for example, a greenhouse in the middle zone of our country is subject to significant temperature fluctuations throughout the year in the range from -30 ° C in winter to +35 ° C in summer. The difference, as we can see, is large and exceeds 60 ° C. Thus, a five-meter polycarbonate sheet can expand by about 20-30 millimeters, depending on the temperature difference. This leads to the fact that an ordinary self-tapping screw, without a thermal washer, can squeeze out oval holes in the material.

Failure to use thermal washers can cause the polycarbonate structure to break in winter and bulge in summer. In addition, at the point of joining the sheet to the frame with self-tapping screws, a greenhouse or a visor will leak.

There are two types of thermal washers:

Thermal washer made of EPDM rubber	Thermal washer made of polycarbonate
Has a special shape, due to which it never leaks	Protects the self-tapping screw leg from direct contact with the polycarbonate sheet
It happens only in black or gray, no other shades are provided	Manufactured to match the polycarbonate sheet itself
	The sealing ring is made of foam rubber, it wears out quickly, which can lead to leakage of the entire structure

Let us state: rubber thermal washers are better in terms of reliability and service life. But thermal washers made of polycarbonate look attractive, merge with the sheet itself, do not spoil the appearance of a visor or fence.

Branded thermal washers consist of the following parts:

1. Leg, the height of which should correspond to the thickness of the polycarbonate sheet.
2. Sealing ring.
3. The thermal washer itself, which is often called a hat.
4. Cover cap that will cover the screw head.

Fastening polycarbonate with thermal washers

This design does not allow the self-tapping screw to press hard on the polycarbonate sheet, eliminates deformation and punching, increases the pressure and contact area, and ensures the sealing of all fasteners.

Important! The diameter of the hole in the sheet should be about two to three millimeters larger than the diameter of the thermowell leg. And the length, as we already wrote, should correspond to the thickness of the sheet itself.

Experts advise taking a step between the fastening nodes of 40 centimeters, and retreating from the edge of the sheet at least four centimeters.

Important! Choose self-tapping screws, respectively, for wood or metal, depending on what material the frame is made of.

Thermal washers are inexpensive – from 2 to 20 rubles apiece, depending on the material, manufacturer and conditions of sale – wholesale is cheaper, of course. Thermal washers are usually sold in packs of 50. Self-tapping screws sold separately.

The two most common questions that arise about thermal washers:

1. Is it possible to do without them during the installation of polycarbonate? Yes. But still, experts advise using at least rubber pan washers or homemade gaskets for self-tapping screws made of rubberized material. In addition, this method of installation will shorten the life of the visor or greenhouse made of polycarbonate, it can lead to leakage.
2. Where else can thermal washers be used? We managed to find feedback from a user who used rubber thermal washers in the process of attaching siding panels to the facade. But in general, this practice is not very common, the scope of application of thermal washers was initially limited.