Waterproof sealant gets the medal

Waterproof sealant for metal: Your essential guide

Is your old metal roofing starting to leak? Waterproof sealant for metal will stop the problem quickly and easily.

What is waterproof sealant for metal?

Waterproof sealant for metal adheres upon contact with metal surfaces, closing the gap on seams, joints, and around fasteners. SMP (silane-modified polymers) sealants, for instance, form a waterproof bond and can be applied on wet substrates. Once applied and cured, they remain flexible and are paintable. They can be used on a variety of surfaces including corrugated and galvanized steel, aluminum, stone, glass and concrete.


It’s quite simple to use! You will need:

  • Caulking gun
  • Some snips 
  • Clean rags
  • Waterproof sealant for metal

Safety first: Work in a well-ventilated area and protect any surfaces you don’t want to get the sealant on. Always wear gloves when working with sealants.

Prepare the surface: Scrape off any old caulk, paint, or rust before applying the sealant. Get rid of any dust or debris. Please note: When removing old paint, it might be necessary to apply a fresh coating before actually utilizing the sealant, since the latter will usually only protect the joint area.

Apply product: Cut the end of the tube with snips or a utility knife so that you will get a nice constant flow of sealant. Force the sealant into any cracks or gaps with constant pressure on the trigger. After applying the sealant, spread it to a smooth consistent bead with a caulk tool or your finger.

If you are joining two pieces of metal, use hybrid products for bonding and sealing, not only a sealant. Apply a layer of about 5mm of the adhesive sealant for metal to one surface and push firmly together, using a spacer. Please check product information for your exact curing time, since it depends on the technology used, the product formulation and the size of the joints.


Loctite Polyseamseal All Purpose Caulk is an excellent general-purpose product. Designed to have the strength of an adhesive and the sealing characteristics of a caulk, this product is great for bonding most indoor surfaces including wood, concrete, metal, ceramic, and more. It is environmentally safe and is water-resistant, mold resistant, and mildew resistant after cure. It’s paintable in just 30 minutes. 

Loctite PL Roof and Flashing Polyurethane Sealant is specially formulated to create permanent weatherproof seals in all exterior gaps and joints. Its flexible elastic characteristics mean it will expand and contract with exterior construction materials. It is also UV-, ozone-, and corrosion-resistant.

If you have a repair project on a boat or an area subject to a harsh climate, Loctite PL Marine Fast Cure Adhesive Sealant may be your best option. This fast-setting sealant forms a permanently flexible bond that can stand up to saltwater. Once cured, it can even hold up below waterline.