Types of Roofing Sealants

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house roof

Plastic roofing sheets are currently the leading choices for residential and commercial roofs. These come in multi-wall and twin-wall polycarbonate sheets that are easy to install, lightweight and virtually unbreakable. Moreover, polycarbonate sheets have insulating properties that will keep your space warm or cool depending on the climatic conditions and can be cut to suit all shapes. When installing the sheets, you should use their dimensions as your guide. Each of them will be joined to a glazing bar.

You can get glazing bars from your polycarbonate roofing supplier in the UK. They often come with the necessary gaskets and fixings you will need for your installation. The sheets will not be actually screwed to the bars but instead clipped onto a glazing system. The glazing systems generally comprise aluminum or PVC bars with top and bottom sections. After clipping the sheets, you will need a sealant for the attachment of capping bars along your roof’s bottom edge. Here are the sealant options you have for your plastic roof’s installation:

Liquid Rubber Sealant

This is a vapor-tight, waterproof and gas-tight product that will perfectly adhere to lightweight surfaces. The sealant is eco-friendly, has high elasticity and forms a seamless and strong bond with your plastic roof. Liquid rubber sealants will also withstand wide temperature fluctuations. The sealants are, however, not as aesthetically pleasing though you can use acrylic paint to cover the white and black marks.

Polysulfide Sealants

These are elastomeric sealants that have been used for ages. Though more costly compared to other sealant alternatives, polysulfide sealants have excellent resistance to harsh weather. They can thus last for at least 20 years in adverse conditions without cracks. The sealants are generally used on primed surfaces since they have long curing periods.

Silicone Sealants

These are among the most commonly used sealants. There are several silicone sealant formulations but acetoxy-cure and oximo-cure formulations are the standard ones. Acetoxy-cure silicone sealants are cheap and resist the fading caused by continuous UV ray exposure. They can nonetheless not be used on metal owing to their corrosive effects. Oximo-cure sealants are expensive but are anti-corrosive. They also have optimal adhesion, and are resistant to all weather elements though UV rays can discolor them without surface protection.

Polyether Sealants

Metal roof

These are moisture-cured sealants that are longer lasting compared to other alternatives. Polyether sealants have optimal adhesion and can be used in cold climates with no material compromise. They are also easy to apply, cure fast, and will last for 20-30 years when properly applied.

Polyurethane Sealants

These are solvent-based products that come in aromatic and aliphatic variants. The aliphatic variant is more stable compared to the aromatic one. Polyurethane coatings are renowned for their high abrasion resistance and can thus be used on roofs with high foot traffic or severe hailstorms.

If you opt for one of these sealants, choose non-hardening variants that are safe for use with plastic sheets. Other sealants might discolor, crack and at times makes your roofing sheets brittle thus decreasing their longevity. You should make sure the sheets are stored in dry areas before their installation to keep moisture from invading their flutes.


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