I use Quad Window Door and siding sealant. You can get in grey. Mask off the sill so you you do not get it where you do not want it. Fill the gap then take you finger and dip it denatured alcohol and use your finger to smooth it out, do not work it to much.

How do you fill gaps under a window sill?

If you have very large gaps around a window, you can fill them using expanding foam. Expanding foam is perfect for filling large gaps around windows as it allows for a degree of movement without cracking or breaking. It can also provide a good moisture barrier between the brickwork and the window frame.

How do you fill gaps around a window frame?

Quote from the video:
Quote from Youtube video: Place the cartridge in the caulking gun and fit the nozzle to ensure a neat finish and easier cleanup ensure you take both sides of the gap before applying the product.

How do you repair an exterior concrete window sill?

  1. Preparation. Rub the surface of any and all damaged areas with a stiff brush. Remove as much concrete debris as possible. …
  2. Horizontal Surface Repairs. Fix any small or medium cracks in your concrete window sill with caulk. …
  3. Vertical Surface Repairs. Use epoxy, which will not shift, to make vertical crack repairs.
  4. What do you seal a window sill with?

    Caulking outdoor window sills and frames requires a product that will hold up to harsh weather conditions. Your best choice is Loctite PL Window Door & Siding Polyurethane Sealant because it forms permanent, water- and weather-resistant seals in most exterior gaps and joints.

    Should I use expanding foam around windows?

    Sealing around windows and doors is one of the most common uses for expanding foam. But the high-expansion stuff can actually push the jamb inward, making them impossible to open. Avoid this by using minimal expanding foam.

    Where should you not caulk around windows?

    Where to Avoid Caulking Your Windows

    • Avoid the Weep Hole: On the exterior frame of vinyl windows, there is a small hole at the bottom. …
    • Above the Window Frame: If you caulk above the window frame then you stand to block the drip edge.

    Should I use caulk or silicone around windows?

    For long-lasting protection around your windows, choose a high quality caulk made from silicone or polyurethane. 100% silicone caulk or a mix of silicone and latex, is waterproof, flexible, shrink-proof and will last over 20 years.