Missing Grout In Shower
Missing shower grout can lead to
water damage behind the tile. The water damage can ruin the wood framing
in the walls and floors. People seem to get a false illusion of security
when using building or roofing paper that is water resistant behind the
tile backing, while thinking it is waterproof and won't become damaged.
Building paper over time will dissenigrate if exposed to elements like the weather and water.
I've torn showers apart that were missing less grout than the picture above and needed to replace the wood floor and walls. You are probably thinking that I'm talking about the walls next in the shower and the floor directly underneath the shower but I'm talking about a large section of the floor and part of the exterior framing.
The more often the bath tub or shower is used, the longer the wood framing will stay wet. Moisture attracts termites, ants and will rot the wood eventually.
How does the grout fallout? Through expansion and contraction as temperatures change, long periods of moisture can cause the grout to deteriorate and poor construction methods. I'm sure there are plenty of other ways for this to happen but these are the most common.
Missing grout can be replaced but I would recommend that you keep an eye on the bath tub enclosure in the future and the surrounding areas, behind the shower or bath tub. If you can't reach a conclusion, to how the grout fell out in the first place, make it a point to regularly check for small cracks or missing grout and repair if needed.
If the grout continues to fall out, I would recommend replacing the damaged area or the entire shower or bath tub enclosure.