Rebedding Deck Hardware Sealants Guide

Deck hardware gets loose over time, and water will begin to penetrate down through the bolts and screws, leading to rotting deck core. 

Rebedding deck hardware sealants guide

When you see or suspect that a particular piece of deck hardware is loose or leaking, it’s time to rebed the hardware as soon as possible. Rebedding involves removing the hardware and applying a watertight sealant around the screw or bolt holes to prevent water from penetrating them once the hardware is reinstalled. Here’s a quick guide to marine sealants for rebedding deck hardware.

Polyurethane Sealant

Polyurethane is the strongest sealant for rebedding purposes. These sealants are compatible with fiberglass, wood, glass and metal, and are suitable for both above and below waterline applications. However, some polyurethane sealants can be softened or damaged when coming into contact with chemicals such as fuel and solvent. 

Recommended polyurethane marine sealants:

3M Marine 5200 sealant

3M Marine 4200 sealant

3M Marine Adhesive Sealant 5200: More adhesive than sealant, 5200 provides a permanent bond between the hardware and the mounting surface. 

3M Marine Adhesive Sealant 4200: Offers a strong bond, but 4200 isn't a permanent adhesive, allowing for the future removal and disassembly of hardware.

Polysulfide Sealant

Not as strong as polyurethane sealants, but far more resistant against chemicals such as fuel and solvent. Polysulfide sealants remain flexible even after curing. They’re good at absorbing the flexing and vibrations experienced by boats, and can be used for above and below waterline purposes. Polysulfide can damage PVC and Lexan plastics, so it shouldn’t be used on those materials. 

Silicone Sealant

Should only be used for above waterline applications, and doesn’t offer the strongest adhesive bond. Silicone is absorbed by fiberglass, so it’s not ideal for fiberglass decks. The only real advantage to silicone sealant is that it’s compatible with certain plastics that other sealants aren’t. 

Star Brite marine silicone sealant

3M Marine silicone sealant

Butyl Tape

Butyl tape consists of a strip of synthetic rubber butyl on a roll of backing tape. It’s safe and easy to use on all types of plastics and most other materials. Drawbacks include low strength adhesion, and a susceptibility to UV rays and oxidation. 

Which Marine Sealant is Best for Rebedding Deck Hardware?

The best sealant depends on the hardware you’re rebedding and what it’s being rebedded to, and that the sealant and material are compatible. 

Rebedding deck hardware sealants

When choosing a sealant, ask yourself whether you’ll ever need to dismantle or remove the deck hardware in future. If the answer is yes, avoid using permanent sealants like the aforementioned 3M 5200 and stick with something like the 4200 instead.




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