The fiberglass shower and tub/shower units presently in your apartments are valuable assets. They were designed, fabricated and installed to be permanent fixtures, never to have to be replaced. They were formed, tub and shower, into one flexible, seamless piece to eliminate the need for constant recaulking of seams opening from building movement. Because of their size they had to be put into the bathroom before the construction framing was completed and nailed to the studs before the sheetrocking took place.  There's no sheetrock behind them.      Tearing out a seamless fiberglass shower or tub/shower unit and replacing it with a seamed assemblage (e.g.,tub and tile) involves disruption to the tenants, the creation of solid waste (not fashionable these days), and a replacement cost from $1000 to $3000 depending on what you replace it with.  Aside from correctible errors in design and support of the bottoms, the fiberglass units you presently have are well made, sturdier than many of the modular tub-showers presently available for for replacement.  There is no such thing as a fiberglass tub-shower that can't be repaired and refurbished in place for a fraction of the cost of replacement. Problem #1:  The bottom of your tub/shower unit has split and collapsed and is leaking into the down-stairs apartment. What caused it: your tub-shower bottom is suspended sloping above the subfloor with 2-3 inches of air space between it and the sub-floor.  The bottom has hollow fiberglass ribs or particle board planks (sometimes plywood) laminated to the under-side  to provide "stiffening" to support the person standing on it.  Unfortunately, because of weakness and lack of support between the underside and the subfloor, the bottom tends to collapse after years of foot traffic, eventually splitting, or separating from the drain, and leaking. Solution:  Call A-1 Marble & Fiberglass. With a minimum of disruption to the tenant, we will saw out the failing bottom and laminate in a new bottom, permanently supported from the subfloor by our proprietary composite, and gel-coated to match the rest of the unit.  When we are finished, your seamless tub-shower will look the same as it did before, but with a sturdy, rebuilt bottom, solidly supported, which will last as long as the building.  We are in and out in a day, with the tub-shower being useable the next day. Your cost for this: tub bottoms- $525 - $650, (shower bottoms run $625-$750 and include drain area repair and reinforcement as needed. Repairs above the tub-shower bottom range from $150-$300). "DRILL and Foam" doesn't work:  10 Years ago, we used to try to remedy lack of support by drilling through the tub or shower bottom and introducing polyurethane foam between the bottom and the sub-floor.  Unfortunately, the foam will not harden properly wherever there is moisture, the wet and softening particle board continues to soften, and hollow ribs still collapse from above, Because of this, and other foam problems, we abandoned the "drill and foam" method and took the drastic solution of sawing out the bottom and completely rebuilding it from the subfloor up. We have done hundreds of them in this manner with virtually no structural call backs. Problem #2: The plumber has to replace a valve, or the pipes and there is no way to get at the item being replaced but by cutting out part of the fiberglass, (e.g., Brookdale  Apts). Solution: Save the piece! As soon as the plumber is finished, A-1 Marble and Fiberglass can laminate it back in,  reenforc- ing the repair so that is stronger than the rest of the unit and gel-coating it to match the existing finish. Cost: $375 or less. Problem 3: The tub/shower bottom has craze cracks around the drain and the bottom is hard to clean. What caused it: Extremely hot water pouring from the spigot or shower head has caused thermal shock to the polyester gel- coat that the tub/shower is colored with, creating fissures in the *gel coat. (not in the fiberglass).  (the same thing can happen to cultured marble vanity bowls). Solution: Turn the hot water thermostat down, call A-1 Marble and Fiberglass and we'll *re-gelcoat the bottom to match the the surrounding surfaces. We're in and out in a couple of hours, and the tub is ready for use the next day Cost: Less than $200 . *Gel coat is the term used for the colored (white usually) polyester resin coat on your tub-shower. It is the same resin as that which makes up the underlying matrix. It therefore has a similar coefficient of expansion, and with proper preparation,  will bond better and last longer than other dissimilar finishes. Problem #4: The aluminum and glass shower doors get grungy and loose or leaky and develop mold around the track. Solution: Call A-1 Marble and Fiberglass. We will remove the door and track, repair and refurbish the tub/shower (gel coating where needed) and convert it to a shower curtain system.  This will open up the bathroom, making it more attractive, and eliminate the aluminum and caulking maintenance problems. Cost: $300-$350 Remember: There is no such thing as a fiberglass tub that can't be repaired in place and made to look nice for a fraction of the cost of replacement.                                    _________________________                                       A-1 Marble and Fiberglass