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Looking for some guidance on a sealant/caulk that I can use between a Bilco basement metal door, and the cement base it sits on. Temperatures are between 27°-50°F in the swings from night to day, so I need to use something that can cure while cold.

This is an old door where the old sealant was compromised in a spot or two and letting water in, so I ripped it all out of the gap between the cement and the metal frame, and resealed it all using a product I was told should do the job well. DAP AMP is a hybrid modified polymer their support told me should 100% work in this scenario. Unfortunately water leaked right by, so it must have not have sealed well enough to the concrete even though temperatures were within range. This is supposed to adhere to cement and metal, however the bond wasn't enough to keep water out I guess.

Sealant Recommendations: What is a sealant/adhesive that I can use to seal this space to waterproof it so water can't run between the cement/metal frame, and the sealant. Almost guessing the last sealant was Liquid Nails since it was extremely hard and barely flexible, but it lasted for a long time successfully. Prior to ripping out the old, it was sealing the majority of the door other than 2 spots where it failed prematurely from the metal flexing and working itself loose. So a proper product should in theory be able to do the same job.

Bilco typically recommends a Polyurethane type sealant but the temperatures are too low now.

Needs: -A sealant/caulk type of some sort that will bond to cement, metal, and will cure in colder temperatures. I'm ok if its NOT a specific recommendation, but I can use some guidance on the type of product I am looking for, since the specialized product I researched and attempted to use failed. A hybrid? A glue? Any details on what I need will be helpful.

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  • This is very close to a product recommendation/shopping question, but I'd presume someone could answer with a class/category of sealant that will cure in the low temp range you're looking at...
    – FreeMan
    Dec 15, 2023 at 19:28
  • Thanks @FreeMan, I just added some notes to the request so its more around the "type" of sealant I need, not an exact brand. Since I'm at a loss as I thought the one I researched that was supposed to do the job well failed, so I'm looking for other possible options to achieve a proper water tight seal.
    – RocketManZ
    Dec 15, 2023 at 19:41

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Urethane is the rock star of the sealant world, and it will work fine in your temperature range--I've built many houses in Minnesota's "off season" with good results. It's solvent-based, so temperature isn't much of a problem, and it's really sticky. It's much tougher than silicone and you can over-caulk it. It cures slowly, so don't expect to be able to touch it safely for a day or two.

To help it bond to the concrete, roll or press a layer on firmly, then add a secondary bead. Be sure you locate the bead(s) where they'll actually connect the metal and the concrete. Door thresholds often have channel voids.

There are plenty of one-off brands that might do as well, but this is a type you can look for. Examples are OSI Quad, Sikaflex, and PL S40.

To be clear: once it's on your skin it won't come off without a stout solvent or shedding. Write clothing off that it touches.

Keep it in a warm place before use as it does get very stiff from a workability standpoint if it's cold.

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  • Thanks for confirming Urethane caulk will be ok in these temps. At this rate, I don't have much to loose. Any idea before it can get wet? We are expecting a ton of water about 24 hours after I would be applying the Urethane and I'd like to get it on before the rain if it will not compromise the urethane. If not ideal, I'll wait till we have a stretch of a few dry days.
    – RocketManZ
    Dec 15, 2023 at 20:56
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    If you get good contact I'd expect it to perform well in a day or two. Or maybe immediately. It's that sticky.
    – isherwood
    Dec 15, 2023 at 20:59
  • thanks again I'm going to give it a shot. Lastly, can this caulk be tooled or worked and smoothed out at all, or is it pretty much whatever comes out of the gun is what you get?
    – RocketManZ
    Dec 15, 2023 at 21:19
  • Any caulk I've ever used can be tooled. Wipe your tools off well right away or use wood scrap, etc.
    – isherwood
    Dec 15, 2023 at 21:24
  • Thanks for that. I've seen all sorts of horror stories saying you touch it and it instantly sticks to everything. I've used it before though, its just been a long time. Thanks again for the guidance, heading to buy a few tubes and get to it tomorrow.
    – RocketManZ
    Dec 15, 2023 at 21:48

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