I want to sand down and paint the threshold to my front door, pictured below. The wood itself is fine (not rotten).

There is a small gap between where the wood sits on the concrete steps.

I assume I should seal this gap - can anyone please advise what I should use?

Should I seal it before or after painting?

enter image description here


I would use Quad sealant. It is paint-able or comes in colors.

I would use a paint stripper to remove as much paint as you can, I like the citrus based strippers. Mask off the door jamb and the wood floor inside and apply the stripper, use gloves and a disposable brush. After it does it's job of loosening the old paint you can scrape it all off. (It may take a couple of applications) You could also strip the brass threshold piece, it is removable, and polish it up.

Once you get as much old paint off as you can you sand smooth, fill any voids and sand again. Use a the pointy end of a 5in1 tool to clean out the gap, you do not want any old paint, stripper or debris left in there.

The Quad can be applied before or after painting, it depends on if you can get it in the color to match your paint or you need to paint to match.

When you apply the Quad you need to mask off the concrete and the wood, it is tenacious stuff. (* The key is to practice first so you can get a feel for how much to apply, not to much*)

They recommend that you do not tool it, but i find you can smooth it if you dip your finger in a soapy water solution, or better, mist it with a spray bottle) and gently run you finger over the surface. Remove the tape immediately.

  • That's really helpful, thanks. Regarding your last suggestion, are you saying that I could use my finger (after dipping it in, or misting it with, soapy water) to shape or smooth the seal? – user77711 Oct 25 '20 at 19:37
  • It is best to try and get a smooth bead of caulk, without applying to much, right from tip of the caulk tube. This takes practice and if it is not smooth often times you can smooth if with your finger. The Quad product does not smooth easily so if you need to smooth it then you can spray it with a soapy solution, 409 cleaner works well, and then use your finger to smooth it, (tool it). If you do not want to use the Quad you could use an outdoor rated PAINTABLE silicone caulk that is easier to work with. Watch some YouTube videos on how the caulk to get some idea of how to best do it. – Alaska Man Oct 25 '20 at 20:38
  • FYI, Quad is a brand name of polyurethane caulk. You can expect similar performance from almost any such product. – isherwood Nov 24 '20 at 20:24

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