Deck Maintenance Products
Caulk
SIS 440 is TDS's flagship marine deck caulking compound — a one-part, neutral-cure formulation trusted by professional boat builders and refit yards worldwide for over 35 years. It forms a permanently flexible, UV-resistant bond in teak deck seams with no primer required on properly prepared seam walls.
Unlike two-part polysulfide caulks, SIS 440 cures predictably, resists sunlight and saltwater degradation, and remains pliable through thermal expansion cycles. Available in black, gray, and white to match any deck aesthetic, SIS 440 is supplied in both cartridge and sausage formats for jobs of any size — from a single seam repair to a complete deck re-caulk.
For best results, pair SIS 440 with TDS Bond Breaker Tape at the seam base (to prevent three-point bonding) and use a professional-grade sausage gun for consistent bead pressure. TDS-trained installers use SIS 440 on every teak deck project leaving our Sarasota and Barcelona facilities.
SIS 440 Caulking — Black
SIS 440 Black — one-part, neutral cure formulation with no primer required. Stays flexible, cures rapidly, and adheres permanently. The classic choice for traditional dark teak deck seams.
SIS 440 Caulking — Gray
SIS 440 Gray — one-part, neutral cure formulation with no primer required. Stays flexible, cures rapidly, and adheres permanently. Ideal for teak decks where a gray seam color is desired.
SIS 440 Caulking — White
SIS 440 White — one-part, neutral cure formulation with no primer required. Stays flexible, cures rapidly, and adheres permanently. A clean, bright option for white-seam deck aesthetics.
Caulk Yield Calculator
Note: This calculates the exact fill volume. We recommend adding 20–25% overage to account for the slight crown left during application and material lost during the spooning/tooling process.
Common Questions
Teak Caulk FAQ
What makes SIS 440 the right caulk for teak decks?
SIS 440 is a one-part, neutral-cure marine polyurethane developed by TDS for teak seams. It requires no primer, cures rapidly, stays permanently flexible, and maintains a strong bond to teak side walls across wide temperature and UV exposure ranges — conditions that cause inferior caulks to harden, shrink, or crack.
What colour caulk should I choose?
Black is the most traditional for teak decks and the most common. Grey offers a subtler contrast. White is used in specific applications such as cork decking or light-coloured composite seams. Contact TDS if you are unsure which colour suits your material and vessel style.
How do I prepare seams before re-caulking?
Remove all existing caulk using a reefing hook, then sand residue from the seam walls with a seam sander. Clean with acetone on a fresh cloth to remove all oils and contamination immediately before caulking. In deeper seams, lay bond breaker tape at the base before applying SIS 440.
How often should teak seams be re-caulked?
There is no fixed schedule — it depends on the deck's age, UV exposure, and maintenance history. Signs it is time to re-caulk include caulk pulling away from the seam walls, visible cracking, or water entering beneath the deck. Routine inspection once or twice a year is recommended.
Can SIS 440 be used on composite and cork decks?
Yes. SIS 440 is suitable for sealing seams in TDS composite and cork decking systems. Follow the application guidance for each material — seam dimensions and preparation steps differ slightly from teak installations.