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Why Do Bathtubs Crack?: How to Maintain and Repair Bathtub Cracks

Your bathroom is a place of peace and solitude, then one day, as you ready yourself for a relaxing bath, you notice a small crack in the center of your bathtub. While it may not be a cause of alarm, that small crack can lead to further problems if unaddressed.

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Most common causes of bathtub cracks

There are three main reasons why cracks tend to form in, bathtub materials which is lack of support or if the material is flexible, damage from heavy objects and damage from heavy cleaners.

Some material such as fiberglass is highly flexible, meaning it will bend if weight it placed on it. If this sort of material is installed improperly or without additional support, overtime the weight pressure will cause cracks to form.

Cracks also tend to form when objects are dropped on the bathtub, creating small divots and dents that will eventually spiral out into much larger cracks and crevices over time.

Lastly, with highly abrasive cleaners such as bleach, the finish and gloss of the bathtub can easily be eroded away, allowing more moisture into the material, causing cracks. So why are cracks dangerous? Well, if ignored, even tiny cracks in your bathtub can eventually become much larger cracks down the road.

bathtub cracks

Cracks usually mean that more water and moisture will tract into the inside of your bathtub, causing the integrity to weaken more and more overtime, until eventually the entire bathtub cracks in half. Generally, cracking is commonplace in fiberglass bathtubs.

Though the material is inexpensive, it is highly porous, meaning it will absorb water and it cannot withstand heavy punishment, meaning that fiberglass matches all three criteria for cracks to form.

So how do we fix this problem? Well, though it may be costly in the beginning, investing in higher quality materials early will save you trouble down the road. Stone resin, for example, is very stable and will not bend to any weight placed on it.

Summarily, stone resin can also withstand heavy impacts from objects without chipping or cracks and finally, stone resin bathtubs are 100% non-porous, meaning they will not absorb water nor are abrasive cleaners necessary in their maintenance.

Types of bathtub cracks

  • Stress crack:-Stress cracks form when a heavy object is accidentally dropped in your bathtub. Generally, these types of cracks are surface level and are easy to repair-simply go to your nearest home improvement store and buy an inexpensive repair kit and you can easily patch these types of cracks yourself.
  • Hairline cracks: Hairline cracks form when consistent use and abuse is placed on the material, creating small cracks overtime that eventually can destroy the integrity of your bathtub itself. But, like stress cracks, there are basic repair kits that can patch your bathtub before the cracks spread and cause any further damage. weight is placed on the material and it begins to warp overtime due to lack of supporthairline crack.

How to maintain a bathtub?

To prevent cracking and maintain longevity in your bathtub:

  1. Install your bathtub with proper support so your additional weight will not flex or strain your material.
  2. Avoid cleaning with abrasive cleaners such as bleach
  3. Avoid dropping any heavy material in your bathtub.

How much does fixing a bathtub cost?

Though it will vary from professional to professional, generally contractors and plumbers will cost anywhere from 80 dollars to 150 dollars an hour depending on their specialties. As you can imagine, this is quite costly for fixing your bathtub.

However, with just a small amount of research and fairly cheap repair kits, many of these cracks can be done yourself for less than 50 dollars.

Professional Repair Costs

On average, professional help costs anywhere from 80/hr to 110/hr. The benefits of professional help are two-fold-in addition to assisting with your current problem, they are also a great resource for consultation on future projects along with further advice on proper upkeep. They also come with the added benefit of additional knowledge that will help with installation that might be a bit more complicated for yourself.

Now, here is the tricky part; hiring a trustworthy professional is a bit more complicated than consulting the yellow pages. Though there are plenty of plumbers listed online, be sure to have established quotes from them as well as good reviews along with a plumber license.

In short, these professionals should be able to inform you just how much you are paying them for the job at hand along with an accurate time table.

fix cracked bathtub

Bathtub Crack Repair Kits

On the market, there are two common repair kits-surface repair kits and internal repair kits. Surface repair kits usually come in the form of a polymer based tape or paint that will seal the crack on the outer surface of your bathtub. Internal repair kits usually are glue or paste that will fill in the cracks from the inside.

Both of these are fairly self-explanatory and inexpensive, usually running on average 30-40 dollars each, providing a cheap and easy alternative to hiring professional help.

How to Seal a Cracked Bathtub Yourself

1. Halt the Crack -At the end of each crack, drill a ¼ inch hole, this is known as a ‘stop-drill’ hole.

Halt the Crack

2. Fill the Crack – Using a 2-part polyester filler, mix according to instructions and apply the filler to the crack with a clean rubber spreader until the stop-drill holes and the cracks are completely filled-allow the filler to dry before proceeding.

Fill the Crack

3. Sand the Filler -Once the filler has dried, sand it down with light sandpaper. Rub lightly until the surface matches with the rest of your bathtub. Once finished, wipe the surface with denatured alcohol to prepare it for spraying.

Sand the Filler

4. Spray the Finish -Using your bathtub repair paint, spray a light coat and allow it to dry before adding more coats as necessary.

Spray the Finish

5. Buff the Tub – To finish your tub, you will need an auto polish urethane compound. Apply to give it a harder finish and feather the edges of the paint.

Buff the Tub

Your bathtub is an essential part of your bath space, especially bathtubs for small spaces. Please make sure to properly maintain it and fix cracks and other blemishes as you see them. Otherwise, you may have a bigger problem looming over you down the road.

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4 years ago

Hello, I received a composite bathtub, and it’s damaged. It’s a dat to fix it? If necesarry, i cand send some photos. Thanks

Matlotlo Sello
Matlotlo Sello
4 years ago

Hi, my bathtub has a crack, what should I buy to stop crack

4 years ago

Hi- this tub cracked while installing the shower glass door. Can it be fixed and holds the load of shower glass door?

Cora cordial mutuc
Cora cordial mutuc
4 years ago

Can you show a demo on how to repair a plastic bathtub?

Mary Lewis
Mary Lewis
3 years ago

I have a cravk in bathtub bit its not fiberglass can i use repair kit?

Tulin Demirmen
Tulin Demirmen
3 years ago

We filled the tub full during the storm. Would The weight of the water crack the tub??

Susan Graham
Susan Graham
1 year ago

Can I get kicked out for a Crack in my tub that has already cracked before and he rigged it and now it cracked in the same spot what do I do

Stone Resin bathtubs starting at $2,940

Free material samples and tub templates

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