How to Install Grab Bars on Fiberglass: 10 Steps

When it comes to your safety, you want to ensure that you have done everything possible to keep yourself and your family healthy and happy. One of the most common household accidents is slipping and falling in the shower or bath. This can be especially dangerous for children who are learning to bathe on their own or elderly people. 

A grab bar is a great way to keep people standing upright in the slippery shower. However, you might be wondering how to install grab bars on fiberglass. Is it the same as installing them on drywall? Do you need special materials? Find out all of the steps and materials you need to successfully install grab bars on fiberglass and make your shower safer. 

Curtesy of Charles Owens

How To Install Grab Bars On Fiberglass

Installing a grab bar on fiberglass is a little bit different from installing one on another wall. Fiberglass is more fragile than typical drywall, and it is harder to find the studs in fiberglass. Grab bars made for fiberglass applications need to use special discs to spread out the tension so that the fiberglass does not crack or shatter when the grab bar is used. 

Gather The Necessary Materials

For this project, you will need the following materials:

  • A drill
  • Various types of Phillips and flat-headed screwdrivers
  • A level
  • A stud finder
  • A saw
  • Utility knife
  • A socket wrench
  • Silicone caulk
  • A tape measure
  • A pencil 
  • Painter’s tape
  • Safety glasses
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Find And Mark The Studs

The first order of business is to find the studs. It can be a bit tricky looking for studs through fiberglass, but your stud finder should be able to penetrate the fibreglass and tell you where the studs in your wall are. It is crucial that you install a grab bar over the studs in a wall because otherwise, the bar may come out when you grab it.

In most cases, you can use a stud finder to locate the studs. Some stud finders can work through fiberglass, and others cannot. If yours gets confused by the resin in fiberglass, you should locate the studs on the walled parts of your bathroom and then measure the distance between them, as well as the width of each stud. 

With those measurements, you can guess where the studs will be throughout the room. Once you have located a stud, you should measure up thirty-three inches from the bottom of the tub or shower and mark that area with some of the painter’s tape. Be sure to keep the tape straight as you lay the stip; otherwise, your grab bar will end up being crooked. 

The Nuts And Bolts Of Installation

Once you have marked the studs with painter’s tape, you are ready to start the installation. You will need to decide whether you want to install a vertical grab bar, which is useful for standing in the shower, or a horizontal grab bar, which helps people lever themselves up and down for a bath. These steps assume a vertical screw-in grab bar.

Find Your Center

Compare the grab bar to the tape marking the wall and look for the center mounting flanges. Use your pencil to draw on the tape where those flanges are located when the grab bar is held directly over the tape. Then dot the center of the traced circles. 


Use an ⅛” drill bit to drill holes over the centers you just dotted. You can use a nail to ensure that you have drilled over a stud, just as a precaution. 


Using a saw, you should next saw a hole over the circles you traced. That will make room for the mounting flanges on the grab bar. These circles should be approximately two inches. 


Figure out the distance between the top of the shower wall and the stud. You will need to use that distance to cut the grab bar’s mounting spacers. You can use a utility knife for the precise cutting to ensure that your grab bar will fit your shower perfectly. 

Drilling Part Two

Use your 3/16” drill bit to drill into the very middle of the two-inch holes you cut. You want to drill over the ⅛” drilled holes from before. 


Put the lag bolt and washer into the mounting spacers. Then, put the completed mounting spacer lag bolt into the hole you just drilled. This is where you will need a socket wrench to make sure that the bolt is firmly in the wall. 


Add a small amount of silicone caulk around every hole you have drilled. This caulk will allow the seal to be watertight, which is important since it is a shower. 


Once you have laid the caulk, you want to have each mounting bracket’s disc side facing towards you when you insert it in the mounting spacer. You will need your screwdrivers in order to tighten the mounting bracket onto the spacer. You will need to peer in closely to ensure that the bracket actually touches the shower wall. 

Your grab bar will have screw holes, so then you can just line up the bar’s holes with the mounting brackets. You can continue to use your screwdriver to finish mounting the actual grab bar onto the mounting brackets. 


The final step of the installation is making sure that the grab bar actually works. How do you do that? Easy, just grab the bar and give it a yank. Remember that it needs to be able to hold up a person’s weight if they are slipping and sliding in the shower, so do not be afraid to pull on it with everything you have got.

Suppose the bar comes loose from the fiberglass; that likely means that you did not install it over a wall stud. That might have been a miscalculation when you laid down the painter’s tape, or your stud finder may have gotten confused. You will need to relocate the studs in the wall and begin the process again to anchor the grab bar to your fiberglass firmly.

Although it may seem intimidating to install a grab bar on fiberglass when there is a risk of it cracking, your family will thank you when they can grab ahold of the bar in the slippery shower or bathtub and stop themselves from taking a tumble. With these easy steps, you can ensure that a shower is a safe place for everyone to be.  

Do Suction Grab Bars Work On Fiberglass?

Suction grab bars can work on fiberglass provided that the intended users do not weigh more than 250 pounds. Typically, customers who plan on using grab bars frequently, such as in older households, will prefer grab bars that are mounted through screws because they are more durable and last longer.

However, if you are installing a grab bar for your children and know that you do not want the grab bar to be a permanent fixture in your bathroom, suction cup grab bars can work quite well. As long as you do your research and check out the manufacturer’s installation guides, you should be able to get a suction grab bar on your fiberglass without a problem. 

Suction grab bars do have their uses, though. They are transportable so that if you go on a trip anywhere that the hotel cannot accommodate your needs, you can easily bring your grab bar and use it during your stay. It is also easier to adjust, so if you have someone coming to visit, you can put up the grab bar and then remove it after the guest leaves. 

Steven Abbey

Steven Abbey is a author for Senior Living Headquarters and owns a home in a retirement community. His wife owns a successful family business that has served tens of thousands of people. He also has a electrical technician degree.

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