The soft elastic joints in the bathroom and kitchen keep water and dirt out of joints and absorb movement, but they have a limited lifespan. Read here how to replace them.
What are soft joints?
The term “soft joints” is the general term for the kind of joints that retain a certain elasticity and flexibility even in the hardened state. This makes them ideal as a seal between surfaces that work in relation to each other and where there are requirements for water tightness. It can be, for example, in the bathroom or between the kitchen table and sink. Elastic joints are most often silicone-based.
The joints not only protect against water ingress but also help to facilitate cleaning and ensure that dirt and soap residue does not accumulate in the cracks.
Soft elastic joints are, for example, important in the bathroom in the joints where walls and floor meet or in the corners where two wall surfaces meet. Soft joints are also often used where the bathtub and washbasin adjoin the wall, where the toilet bowl meets the floor, and for joints at the shower cubicle or niche.
A soft joint should never be the only waterproofing. In newer bathrooms, there will be a waterproof membrane under the tiles, but in older bathrooms, the joint can be absolutely essential to maintain the tightness.
Missing or bad joints can cause water to seep into the underlying structures and cabinets, which can lead to rot and fungus, an undermined floor, or other unpleasantness that can be expensive to fix.
The kitchen is not as exposed to water and moisture as the bathroom, but the waterproof joints are still often used at the kitchen table, where the worktop adjoins the wall and in joints between worktops. The joint between the sink and the worktop should also be secured with sealing.
When do soft joints need to be replaced?
The soft joints have a limited lifespan and must therefore be replaced every few years. The sealant itself, the quality of the work, the surrounding materials, and the effect of wear and moisture all contribute to the lifespan. It is therefore difficult to say exactly how long a joint can last. That’s why it’s a good idea to check them carefully once a year. As a starting point, you can count on joints to be replaced approx. every 5 years, but in practice, the joints can last much longer if they are done correctly and you provide ongoing maintenance.
Silicone joints dry over time and lose their elasticity. If the joint loosens at the edges, it is a sign that it should be replaced. If it has become discolored and attacked by mold, you can first try to clean it, but you must consider a replacement if it cannot be cleaned.
Especially in older bathrooms, the existing joint between e.g. wall and floor will be a hard mortar joint. If the joint loosens, or if it crumbles because it has not been able to absorb the movements between the surfaces, it is necessary to replace it with a soft elastic joint.
If you suspect that water may have seeped in where you have found a defective joint, you should have it investigated whether the underlying building structure has been damaged by the leak. If, for example, there are wooden structures under the floor, there will be a high risk of rot and fungus developing.
Which sealant is suitable for bathrooms and kitchens?
There are many different jointing materials. When you stand in the building market and look at the cartridges with all the different types of sealant, it is easy to get confused. Some names indicate the purpose for which the mass is intended, while others refer to the content itself.
A distinction is made between plastic and elastic sealants. The former retains a certain flexibility, while the elastic in the hardened state can stretch up to 25 percent.
The plastic sealants are often acrylic-based, easy to use, and can be painted over.
Elastic sealants are typically silicone-based, slightly more difficult to use, and cannot be painted over. It is this type that is used in the bathroom and for sealing in the kitchen at, for example, the sink. Among other things, they go by names such as “Sanitary silicone”, “Wet room silicone”, “Building silicone” and the like, and are available in different colors. These types of silicone adhere well to most materials.
When you have to use a sealant in the bathroom, it is important that it is intended for wet rooms. Joint compound especially for wet rooms has added fungicides, which can prevent fungus from growing on and in the joint.
However, you must be careful with glass silicone. It contains acetic acid and is, among other things, intended for gluing aquariums together with. Although it adheres excellently, the acid content can damage the surrounding materials if you use it in the kitchen and bathroom.
How do you replace joints/grouts in the bathroom?
You cannot repair a defective silicone joint, so if there are problems with it, it must be replaced – and preferably as soon as possible to avoid moisture penetration, which can cause major damage.
In construction, jointing is work that is normally carried out by a specialist, a so-called jointer. You can do the work yourself if you have your hands properly trained. But in wet rooms, it is clearly recommended to get the help of a professional, unless you simply need to make a sealing joint in, for example, your shower cubicle.
It is also recommended to consult with a professional before replacing joints on flat surfaces, in order to determine both the reason why the joint is defective and at the same time to make sure that deeper damage has not occurred.
If you choose to carry out the work yourself, it is important that you do good preparatory work and have all remnants of the old joint removed before you start to perform a new joint. If the side boundaries where the old joint was located are not completely cleaned, dry, and free of dust particles, there is a high risk that the replaced joint will release its attachment to the sides after a short time, and the replacement is therefore useless.
Pay attention to whether the use of a primer is prescribed for the chosen joint material.
How to change the joint
Start by cutting the old joint free at the edges with a sharp knife, but be careful not to cut too deeply – you risk damaging any membrane/backstop underneath.
Pull away the remains of the joint – and possibly back padding underneath –if it needs to be replaced.
Apply silicone remover to the remains of the old joint. Silicone remover dissolves residues of the sealant and must be allowed to sit for up to a day.
Clean afterward with clean water and allow the area to dry.
Then cover the adjacent surfaces with painter’s tape, and press in new joint backfill, if there has been such before. Then you are ready to fill the joint with silicone compound from the cartridge.
Spray the compound completely into the joint and smooth afterward with a joint stick or finger dipped in sulfur water (washing-up liquid diluted with a little water). The sulfonated water acts as a lubricant so that the finger does not get stuck in the silicone. You can also use joint putty, which is specially designed to create neat, uniform joints.
Remove masking tape immediately after the joint is complete.
Old mortar joints can be difficult to remove, especially if a very hard mortar has been used. Very carefully, you can cut out the joint with a hammer and chisel, a fine cutter with a diamond grinding head, possibly supplemented with an angle grinder. You can easily damage the tiles around the joint, so be careful. Here too, all remnants of the old joint must be removed before proceeding.
Old mortar joints must only be replaced with a soft joint if there is movement between the two surfaces on which the joint is held together. In old buildings that have “settled”, i.e. that the materials no longer move significantly in relation to each other, you will therefore typically have to replace or repair the old mortar joint with a new mortar joint.
The shape of the joint
It is important that the new joint has the right shape. It should be wider than it is deep (roughly speaking, twice as wide as it is thick), and it should only be attached at the sides, not at the bottom. In this way, it can best absorb movements and maintain tightness.
This is where the grout backstop comes into play. The grout backstop must only be used in very wide gaps, which will typically be around door and window openings, drains, and in corners.
A backstop is a round strip of foam or similar material, which must be slightly thicker than the joint, so it must be pressed into place. It ensures that the sealant does not reach the bottom of the joint and that the joint takes the optimal shape. Where a joint backstop is required, you should consider having a jointer do the job, as this type of joint can be difficult to do correctly.
Wide joints, i.e. joints that are wider than 8 mm must only be used where significant movement between construction parts can be expected. An example is a tiled floor with underfloor heating in a concrete base. Variations in the temperature of the floor will cause the floor surface to expand and contract depending on the temperature of the floor. It is necessary here that the floor surface has the opportunity to expand, without the floor surface pushing against the walls and thus being able to cause critical displacements and breaks in other building parts.
Large movements require a wide joint. The wide joint makes it possible for the joint to change shape without tearing it loose from the attachment to the two structural parts. When the joint has a maximum width, it will have the shape of an hourglass, i.e. symmetrical. This means that there will be an evenly distributed pull in the two joints and the risk of it being pulled loose from the places where it is attached is reduced. When it has the minimum width, it will bulge up and down against the elastic joint substrate.
It is important that kitchen tables that go up to the wall are sealed with a sealant, otherwise, water and dirt will quickly collect, which could possibly damage the kitchen.
Joints in the kitchen
Most kitchen tables adjoin one or more walls, and unless the wall is very even, it is almost impossible to get a completely tight fit between the countertop and the wall. This is important, as water, dirt, and food residues will otherwise be able to creep down between the kitchen elements and the wall, where it is impossible to clean.
Therefore, it will often be necessary to grout between the table and the wall. It is basically done in the same way as described above with a silicone joint. This type of joint is also called sealing, as it is a fine narrow joint where no backstop is used.
Also between the kitchen worktop and the kitchen sink, there is a joint that is very exposed to water. If the joint is not tight, the water will penetrate and drip into the cabinet under the sink, just as wooden worktops in particular will quickly be damaged by the water.
When a new sink is placed in the worktop, it is therefore usually placed in silicone before it is fastened. When replacing the joint, it is necessary to remove the sink and the drain before the surfaces can be cleaned and a new joint can be applied.
How do you maintain joints?
Once the new joints have been laid, you naturally want them to last as long as possible. The best thing you can do to protect them is to keep them clean and dry to prevent them from scaling, as the scale makes it easier for dirt and grease to settle, which creates good conditions for mold.
The effectiveness of the fungicides found in the grout will diminish over time. It is also important to ensure good ventilation, especially in the bathroom. It also provides a better indoor climate and generally helps to prevent problems caused by moisture.
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