Now use shears to cut where you marked and you ll have the perfect size piece for that opening.
Tile over basement wall.
Measure the distance from the edge of the wall to the edge of the last full sized tile installed on the row.
Subtract 1 4 inch from that measurement to get the necessary tile size.
For tiling over tiles in bathroom walls you ll need to set up sheets of waterproof membrane in between the concrete wall and tiles.
Ventilate and dehumidify the area before during and after the installation because basement walls are usually susceptible to moisture.
Be sure you double check the fit with the paper backing still on.
You can get this from construction or hardware stores.