Marble is a great way to add some opulence to your homes window sills. When old, worn out or outdated windowsills are a problem, you can easily replace them by installing a marble sill. Best of all, marble sills can be used just about anywhere from windowsills to bathroom soap sills. And they are easier to install than you think.
Before you begin setting a marble windowsill, you’ll need to remove the old one. In some cases, the windowsill is attached directly to the window. This type of windowsill is very difficult to remove and should only be attempted by a professional window installer. When in doubt, call in the pros or leave it alone.
A wooden windowsill attached to a sub-sill is easy enough to remove. First take off all of the surrounding trim. You can look at the sill and see few small pits from the nail holes. These can be punched through using a nail punch and a hammer.
A thin prybar slipped underneath the sill can provide the leverage needed to remove the old windowsill. Cut a small 2×4 to fit underneath of the sill to the floor. Leave enough room to slide in the prybar and use this board to provide leverage and prevent the wall coverings from being damaged in the process.
Gently work out the sill from face to back. Don’t try to remove the sill from the left or right side; it will just get stuck tighter in place. Once its out, remove any debris and clean it with a shop vacuum.
Now the sill(s) can be measured and cut to length. If you’re doing more than one windowsill, you can buy large stock pieces of marble sill at a cheaper price and cut them yourself using a wet tile saw. If not, have the marble manufacturer cut them to length.
Test fit each piece first, making adjustments as needed. Check for plumb. Now apply tile mastic to the sill using a ¼” notched trowel. You may need to bunch up the mastic on one side if the sill is unleveled.
Set the sill in place tight and let it dry for about five hours before sealing it in place with caulk.