bathtub DIY repair kit

How to Repair Large Floor Cracks in Fiberglass Tub Using the Tub Repair Company’s DIY Tub Repair Kit: Your Guide to Seamless DIY Bathtub Repair

Is your fiberglass or acrylic bathtub showing signs of wear and tear, with weight-bearing floor cracks that seem impossible to fix? Don’t spend thousands of dollars on a replacement.   

The Tub Repair Company’s DIY bathtub repair kit is your ultimate solution for tackling even the most severe bathtub repair.

In this article, we’ll walk you through fiberglass tub repair (it works on acrylic tubs too!) using our Level 3 Tub Repair Kit for big damage, weight-bearing floor cracks. Our Level 3 kit is designed to provide the support needed for durable and long-lasting repairs, plus, our color-matching system ensures a seamless blend.


Example of Level 3 damage before and after repair using Tub Repair Company DIY Kit:


Fiberglass bathtub repair, floor crack in tub

Fiberglass bathtub repair kit


Specialty products included in level 3 kit:

  • Floor Support Foam                                       
  • Preval Spray System
  • Glass Putty                                         
  • Putty Hardener
  • Finish Putty (Gray Putty)                                
  • Finish Putty Hardener Cream
  • Resin (Gloss, Gray, Gold, Almond)
  • Catalyst
  • Reducer                                              
  • Primer
  • Acetone                                              
  • Dye (Gold & Black)
  • Orbital Sandpaper (80 & 120)           
  • Hand Sandpaper (80, 120, 600 - 3000)
  • Mesh Tape                                         
  • Putty Spreader
  • Stir Sticks                                                        
  • Mixing Cups
  • Gloves                                    
  • Detailed Instructions  

What you’ll need:

  • Air-Purifying Respirator                                 
  • 5 ½” Orbital Sander 
  • Shop Vacuum                                                 
  • Paper Towels
  • Extension Cord                                               
  • Extension Cord Splitter (3 prong)
  • Scissors or Box Cutter                                    
  • Power Drill (may not be needed)
  • Drill Bits (may not be needed)                       
  • Blow Dryer

    *These items can be found at your local home improvement store and in many cases, they are available for rental.




    Step 1: Drilling Holes & Applying Foam Support

    Start off by grabbing your basic tools: a power drill, 1/4” – 5/16” drill bits, and Floor Support Foam. Drill holes at the crack's ends and middle for even coverage using the two different drill bits. After drilling, start pumping foam into the deep holes first and then the shallow ones. Take it slow and easy, especially when dealing with foam. Too much foam can cause bulging, especially with plastic tubs, so handle it with care. Give it time, around 2 – 4 hours, for the foam to set until it's no longer gooey.

    Watch out for any bulging; if it happens, add some weight on top of the area, keep an eye on the foam coming out of each hole, and let it sit for 2 - 6 hours. This patient and careful approach ensures a strong foundation to your repair.


    Step 2: Prep Damaged Area

    Make sure you have all the necessary tools at your fingertips: 80 grit sandpaper, vacuum, 5 ½” orbital sander, an extension cord, 3-prong splitter, and mesh tape for larger holes. Once you're equipped, start by carefully removing any excess foam and trimming or sanding down any protruding or loose damage. Then, extend your sanding around the damaged area, going about 2 inches beyond the affected part. Thoroughness is key, so after sanding make sure the sanded surface is clean using a vacuum and acetone on a paper towel. And if you're dealing with sizable holes, don't forget to apply mesh tape.


    Step 3: Apply Glass Putty 

    For step 3, you’ll need Glass Putty and Putty Hardener, a mixing pad or cardboard, putty spreader, wooden stir stick, orbital sander, vacuum, and 80 grit sandpaper.

    It’s time to mix the Glass Putty and Putty Hardener, keep a 10:1 ratio of the two products. After application, patience is key – let the Glass Putty cure for at least 30 minutes before you start the sanding process.

    Pro tip: focus on achieving a smooth and feathered edge during application; it'll save you from the hassle of extensive sanding later on.


    Step 4: Match Color 

    When it comes to achieving the perfect color for your bathtub repair, precision is key. Begin by preparing between 1 to 3 oz of mixed resin, ensuring you have an ample supply of Catalyst and Reducer on hand for the task. Start small in the color mixing process, blending modest amounts of resin until you reach the exact shade you desire.

    To ensure accuracy, conduct a simple test: place a single drop of the mixture on the tub's surface, spread it evenly, and then blow dry it. This method allows you to observe the final shade once it's dried. If, by chance, the resin colors don't seamlessly match your tub, use a small amount of dye.


     Step 5: Mix Coating Products

    Once you’ve matched the color, mix resin, Catalyst, and Reducer in the correct ratios according to the chart provide in the instructions. Carefully pour the resin into the Preval jar, followed by the Catalyst and Reducer, and stir to create a well-blended mixture. Before applying the mixture to your repair area, test the Preval spray system to  guarantee that your application will go on smoothly.  


    If you have questions throughout the repair process, our tub repair professionals are just a phone call away at (877)2FIXTUB (234-9882).

    We also offer detailed step-by-step instructional videos at or on our YouTube channel, "Tub Repair Company.”

    When it comes to DIY bathtub repair, Tub Repair Company’s DIY Tub Repair Kits are the ultimate solution. We not only provide the means to restore your bathtub's structural integrity but also prioritize aesthetics with seamless color matching. Say goodbye to the expense of bathtub replacement and opt for a cost-effective solution that can save you thousands of dollars at


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