The problem is that the wall is uneven.
Tiling uneven walls adhesive.
Plastering a wall can be a super straight forward task but if you have no prior plastering experience it may be worthwhile getting a professional in to help achieving a perfectly flat surface for tiling is essential and this isn t always easy on your first attempt.
It must be easy to work with and it must adequately fill in gaps between the tile and the substrate.
Learn how to prep a shower wall for tile.
How to prepare for tiling a wall.
There is also a spot near the window trim where the wall appears to be built up too much enough so that the tile could end up proud of the trim which i m pretty sure won t look so hot.
The mortar is spread.
Remove old fittings such as pins screws rivets etc.
Preparing an uneven wall surface plastering.
Tile adhesive is expected to hold the tile in place not just for years but for decades without fail.
Find the right trowel and mortar here.
Before you start remember that using the correct trowel and mortar is critical to a successful tile project.
It cannot cure too fast.
Demands placed on tile adhesive are both extensive and steep.
Back buttering is a trick used for tiles of uneven thickness like ungauged slate or handmade tiles extremely large tiles or for tiles being installed on an uneven surface.
Otherwise you do not have adequate working time.
Repair or remove unfit plaster get rid of or pre treat wallpaper if present repair any cracks or signs of damage level the surface sand so that the adhesive can bond make sure the surface is dust dirt and.
Things you will need measuring tape tile wet saw leveling spacers and wedges trowel thinset mortar rubber mallet grout grout float grout sponge.
For wet areas such as shower walls you must take certain precautions.