because the water could seep through the joints between the new tiles and sit between the two layers and affect the seal and also raise the height of the floor and affect the slope to the waste outlets..but, why do you want to retile if you're not using the bathroom??...for immediate resale consider bathroom wall to wall bathroom carpet, new wall paint, new vanity, taps and light fittings which should also be cheaper than tiling over the top and, if it's not allowed by the body corporate, it will be a risk to future sales as it should not satisfy a proper building inspection

Tile selection can have a big impact on the cost of your bathroom reno. The cost of the tiles per sqm is one thing, but did you know that most tilers charge different rates for the "Type" of tile laid large format and or vitrified tiles will cost more to install These are a few hard and fast rules we give our clients when they are selecting tiles for a bathroom renovation 1 - opt for darker tiles and darker grout for the floor - as a wet area light coloured tiles on the ground are harder to keep clean 2 - If you are opting for a feature tile - let it be the hero. That means make the rest of the tiles plain - large format subway tiles give you enough texture without detracting from the feature 3 - always opt for square tiles on the ground - trying to get the correct falls using rectangular tiles will mean you will have extra cuts and the floor will look a mess. The second reason we opt for square format for the floor is because of subway tiles You see, back when everyone was opting for square tiles on walls, it was easy to install square on the floor and get all the grout lines to match. Now most people are opting for subway tiles, you can never get all the grout lines to match, therefore installing square means you dont have to match grout lines as they are different format. If you are installing your subway tiles vertically, then there is a chance you will still be able to get all grout lines to match if you have selected the same sized square format tile hope this makes sense I have added a link to a blog that explains more about tile selection

Hi there, tiles on the floor of a bedroom? It sounds a bit cold underfoot unless you are having underfloor heating installed, but then perhaps you are renovating in warmer climes than where I live! I would recommend going for a matte or satin finish in the bedroom as the gloss could look a little sterile.also If you have a connecting ensuite, you wouldnt want to run the risk of slipping on the floor if you have wet feet :o

You may be lucky & the tiles may come off easily if just laid (we just did this in our shower). Worst case when they pull them off they may damage the membrane, in which case they will need to repair it, so it is just the time of the repair & drying, before they can relay the tile. If it's important to you, get them to fix it, as long as you can accept the worst case scenario of the extra time (that is what we did, and then the membrane was fine anyway). Good luck.