Plastic bathtubs are cheap, easy to install, and relatively easy to maintain. Unfortunately, sometimes they can crack. Whether that’s because of stress, if your home was left unheated in the winter, or because of an accident doesn’t matter. You’ll want to see if you can repair the damage and get your tub back in working order.
In most cases, you can repair hairline and other small cracks in a tub with an epoxy or acrylic repair kit. These kits seal the hole with a hardening plastic solution, which you can then cover with enamel. However, the kit you get should depend on the material of your bathtub and the size of the hole.
How to Fix a Crack in a Plastic Bathtub
In most cases, you can start out fixing a plastic bathtub by simply identifying what caused the crack. Here, there are three main reasons that a plastic tub might crack.
- Lack of support. Here, the tub likely tears, usually in an outward direction and from the top or the tub or from a stress point like the drain. If this is the case, you’ll have to support the tub or the tear will simply happen again. This likely means taking the tub out and building support underneath.
- Accidental Damage. If something sharp or heavy hits the inside or outside of the tub, even while moving it into place, it could crack. If this is the case, you probably don’t have to take any further steps other than fixing it ASAP.
- Chemical damage. If you very frequently clean with abrasive chemical cleaners, they could cause hairline cracks over time. However, in most cases, these cracks won’t go through the full tub. If you treat them right away, your tub will suffer minimum damage.
Identify Tub Type
It’s important to check whether you have a fiberglass or an acrylic tub before you purchase a repair kit.
If you have a fiberglass tub, you’ll want a repair kit with tape for larger cracks. In most cases, you should use an epoxy bathtub repair kit on fiberglass tubs.
On the other hand, if you have acrylic, you’ll want an acrylic kit. These are often epoxy as well, but the formula is different and less fibrous than for a fiberglass tub. However, you might still need tape for a larger crack.
How can you tell? Examine the edges of the crack. If there are fibers, it’s fiberglass. If it’s clean plastic, it’s acrylic.
Things you’ll need:
- Bathtub repair kit (epoxy resin)
- Bathtub repair tape or Fiberglass mesh (for cracks larger than about ¼ of an inch
- Sandpaper (600+ grit)
- Matching paint or enamel
- Fine putty knife
- Disposable gloves
You’ll also want a utility knife to cut the mesh to size if you’re using it.
In addition, many epoxy repair kits are designed just for bathtubs. In this case, they may come with a dye kit, allowing you to attempt to dye the epoxy to match the tub.
You shouldn’t worry about this for the first layer of epoxy but you may want to for the second layer or for the layer of enamel. However, dye-to-match kits can be expensive.
It’s also difficult to get an exact shade match because wet and dry epoxy colors will always be different. However, you can decrease how much the patch stands out against the side of your tub.
1. Clean the tub
It’s always important to start with a very clean and dry surface. Use a chemical cleaner or vinegar to fully scrub your tub, paying special attention to the area around the crack.
After cleaning, you’ll want to allow it to dry for at least an hour but hopefully 24 before adding epoxy. You should not use the tub in that time because it’s important that the tub is very dry.
2. Apply a base layer of epoxy
Mix about a third of your epoxy resin to the standards on the package. In most cases, you’ll either buy a half and half mix, in which case you use 50% of each tube or you’ll buy epoxy in a caulk gun.
In this case, you’ll probably add a few drops of a hardening agent. Or, in some cases, it might self mix as it comes out of the tube. Make sure you follow the instructions on your specific tube.
In addition, it’s important not to use more than you need to set the base layer, because epoxy starts to set as soon as you mix it. If you leave it to sit around, you won’t be able to use it.
A base layer should be just enough to fill the back of your crack and to give the mesh or filler tape something to stick to. If the crack is very large, you’ll probably want to start out with a layer of mesh and then add another one once that’s dry. On the other hand, if you’re repairing a hairline crack in your bathtub, a single layer of epoxy might be enough.
Allow the layer to dry according to the instructions on the package. Usually this takes 1-4 hours. However, some epoxy can take up to 24 hours to dry. Importantly, drying is not curing, which can take twice or even four times as long as drying.
Importantly, epoxy fumes can be toxic. Make sure you keep your bathroom open. You might also want a mask.
3. Apply mesh
Cut your fiberglass mesh or bathtub repair tape to size and apply it over the base layer of epoxy. In most cases, the mesh should extend slightly out into the tub but not too far. You’ll want to cover every part of visible mesh with resin later.
4. Add a second layer of epoxy
Add a second layer of epoxy over the first. Here, if your crack is very deep, aim to add several layers. Thinner layers are always stronger than one thick layer.
However, most cracks that you can repair with an epoxy tub kit are small enough that a single layer will do. Use enough epoxy to work into the cracks fully and to cover the mesh. You can scrape away any excess with a putty knife.
5. Sand the epoxy
Allow the epoxy to dry according to the package instructions. Then, wet a fine grit sandpaper and carefully go over the epoxy to smooth it out. You’ll want to carefully avoid scratching the rest of the tub.
6. Apply a final coat of enamel
Use your dye-to-match or whatever enamel came with your bathtub kit to put a final coat over the bathtub. This step is important, because most epoxy will wear away when exposed to cleaning chemicals. In addition, enamel normally colors the patch to match the tub as closely as possible.
In most cases, you’ll have to wait 4-12 hours to use the tub after applying the final coat of enamel. However, you should always read the package instructions on your repair kit to be sure.
Fixing a Cracked Bathtub Around the Drain
If you have a crack around the drain, it usually means there’s not enough support around the bottom of the tub. You may have to fix this before repairing the crack will do any good.
Once you do, repairing a crack around a tub drain is the same process as repairing one in a tub wall. However, if the fiberglass is actually coming apart, you’ll want to take the bathtub drain out.
From there, you can add epoxy to the crack and then use clamps to hold it together while it dries. If you add extra support under the tub afterwards, there’s a good chance your tub will continue to be fine to use.
However, the larger the crack, the more difficult it is to repair it while retaining water tightness. If you’re unable to get your patch to stop leaking, it might just be that the crack is too big.
However, you can always try broadening the layer of epoxy on the top – because epoxy will bond directly to the existing fiberglass. And, if you’re still having trouble, taking the tub out and adding a seal on the bottom as well can help.
Frequently Asked Questions
If you still have questions about repairing cracks in your plastic tub, these answers might help.
What does it cost to repair a cracked bathtub?
If you do the work yourself, you can likely repair a cracked bathtub for around $15 in materials. However, an acrylic tub crack repair kit can cost well over $30. So, it does depend what kind of kit you need, what’s in the kit, and what brand you purchase.
Will Flex Seal fix a cracked bathtub?
Flex Seal will at least temporarily fix a cracked bathtub. However, you’ll want to check that the Flex Seal epoxy you buy is rated for the material of your bathtub. Otherwise, the sealant could lose its grip and come loose.
In addition, Flex Seal doesn’t officially advertise any of its products for bathtub repair.
Can I fix a cracked bathtub floor?
You can always try to fix a crack in a bathtub floor. Here, you may have to take the tub out and clamp the crack together to get a good bond with the epoxy.
In addition, a fixed bathtub floor will never be as strong as it was before cracking. Therefore, you’ll want to add additional support to the bottom of the tub to prevent it from coming apart.
Finally, it can be difficult to get a good watertight seal on a large patch. When in doubt, you can always add more epoxy and tape to the bottom of the tub as well to get a better seal.
Small and hairline cracks in tubs are relatively easy to repair. If you have a larger dent or a crack in the floor, it will be more difficult to fix.
However, epoxy and fiberglass mesh tape will help you fix most tub cracks. At the same time, you should expect to spend several days on the job, because the epoxy will have to dry in between layers.
Good luck fixing your cracked tub.