If you'd like to do renovations to your basement to transform it into an extra bathroom, here is some advice to keep in mind.
1. Find a basement waterproofing solutions firm and waterproof the entire space
Depending on the waterproofing regulations in the area where your property is located, you may only be legally required to waterproof certain areas of the basement in preparation for the construction of the bathroom. You might, for example, only be required to waterproof the shower cubicle area, the sink and the surrounding walls. However, even if this is the case, you should still seek out a local basement waterproofing solutions firm and have them waterproof the entire basement.
The reason for this is that when you're using a bathroom, water can still get spilled in places other than the shower or near the sink. You might, for example, drip water onto the floor when exiting the shower or you might accidentally point the showerhead at the floor when washing your hair. Having the basement fully waterproofed before you construct the bathroom will mean that when these things happen, you won't have to worry about water seeping past the basement's floor and getting into your foundation. This is important, as a water-damaged foundation can cause all sorts of structural problems in the other areas of the building.
2. Don't rush into the renovations after the waterproofing
After the basement waterproofing contractor is finished, they will probably recommend that you wait several days or so before doing any renovation work, such as painting or tiling. It's essential to follow their advice.
If you don't and instead start hurriedly painting the waterproofing areas before the curing process of the waterproofing membrane is finished, this membrane might end up being semi-permeable. If this happens, you may only find out when the bathroom has already been created and been in use for a while, at which point there could be foundation damage, due to the water passing through the membrane.
Fixing this would involve tearing out the new bathroom, having the waterproofing contractor replace the membrane and then refitting the bathroom fixtures and fittings again, and then repainting it. This could cost a lot, be time-consuming and result in taking your beautiful bathroom apart. As such, you should try to be patient and wait to renovate until a few days have passed after the waterproofing work has been done.