Seals for PVC windows: an overview, advantages and disadvantages

The sash of the plastic window is pressed against the frame due to the work of the fittings. But even the hardware itself can not provide a hermetic pressure of plastic to plastic. Therefore, another element is added to the design — a sealer.

Materials with high elasticity are used for the production of seals. Due to this, the seal fits snugly to the plastic surface — and the gap is closed as tightly as possible.

Functions of sealing circuits

The profile made of elastic polymer is either produced simultaneously with the plastic profile (co-extrusion), or is mounted in the groove separately. Seals are installed in slots on frames, sashes, imposts and other elements — that is, wherever gaps need to be tightly closed. The design of sealing profiles is also different, but usually they are a combination of two elements:

• Cavities that increase thermal insulation performance due to the air layer.
• Petals that bend easily and fit snugly to the planes.

The main function of the seal is sealing to protect against blowing. In order for protection to be effective, in most profile systems, not one, but two sealing circuits are made. But this is not the limit: systems with high heat—saving indicators, such as WDS 8S, are equipped with three sealing circuits.

Besides:

• The seal protects the room from dust, which can penetrate into the gap between the frame and the sash.
• In addition to dust, the sealing circuit retains moisture. Even with significant pressure or crosswind, water does not seep into the room.
• Sound insulation. The tighter the sash is pressed against the frame, the less noise will penetrate into the room. In addition, the tubular seal increases the sound insulation characteristics of the window due to the presence of an additional cavity.

Types of sealing circuits

Window seals are made of different materials. The main requirement is that the material must be sufficiently elastic, otherwise it simply will not be able to perform its main function. Today they are used:

• Silicone. It serves up to 30-40 years, retains elasticity both in heat and in severe frosts. In addition, high-quality silicone seals are not afraid of ultraviolet radiation, therefore they ensure tightness well even with prolonged outdoor service. Due to the high price, they are rarely used. In addition, silicone is not durable, and after mechanical damage is not repairable — because the slightest defect causes replacement.
• Rubber (natural rubber). It consists of vulcanized rubber mass with the addition of soot, has high elasticity and has served for more than 20 years. Due to the need to add soot, rubber seals are made only in black, which limits the possibilities for design.
• Thermoplastic elastomer (TPE) is the main material used in the production of seals for modern profile systems, including WDS profiles. Advantages — good elasticity, resistance to temperature changes and ultraviolet. With careful treatment and periodic treatment with protective oils, the sealing contours of the TRE serve as much as the window itself. In addition, the elastomer can be soldered and welded — this facilitates both the repair of contours and the production of windows.
• Ethylene-propylene-diene monomer (synthetic rubber, EPDM). An alternative to natural rubber, cheaper, but at the same time maintaining elasticity in a wide temperature range. While maintaining integrity and periodic treatment with protective oils, EPDM can serve for 20 years or more, ensuring high tightness of the window.
• Polyurethane. A foamed polyurethane roller in a protective mesh or solid shell is a rather rare but effective sealer model. In the production of PVC windows is almost not used, but for the manufacture of wooden structures polyurethane sealing circuits are used to this day.

The standard palette of seals is limited. Usually colors are used that are harmoniously combined with the color of the profile lamination — beige, gray, black, brown, caramel, etc. On the other hand, today, due to the development of technologies, it is possible to produce seals in almost any color. This makes it possible to produce designer windows with a perfectly matched color scheme.

How to take care of the sealing contours?

As long as the seal is strong and elastic, it is effective. To maintain the seal in working condition, you need:

• Avoid strong pressing of the sash to the frame — this causes deformation of the sealing circuit.
• Periodically open windows to restore the shape of the seal, which is in a compressed state.
• Avoid the appearance of cracks, ruptures and mechanical damage.
• At least twice a year, clean the seal from dirt and lubricate it with a special compound that is included in the window care kit (an alternative is a silicone—based lubricant).

If the sealing circuit is irreversibly damaged, or has dried up before cracks appear, it is worth contacting a window company to call a window repair specialist. He will dismantle the sealing circuit and install a new seal.

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