I’m Steve from SKG Renovations, providing you with some important information on the nature of tile and grout, and the importance of grout sealing in a typical tile installation.
As a contractor in the business of renovation, I having personally completed dozens of tiling jobs and observed hundreds more. Because of this, I believe I have good insight into some of the important details that are often overlooked by tilers. One of these important overlooked details, is grout sealing. I beleive that it is one simple extra step, that can ensure that the beauty of your grout lines and the integrity of your tiling assembly as a whole, can last for years to come. In my experience, most people do not take the small amount of extra time to seal the gout lines after a tiling job. I would say that about 90% of both professional, and DIY jobs that I see, neglect this very important step. That is why I felt that it was important to emphasize the importance of grout sealing in this post.
Especially in a shower enclosure or tub/shower surround, where the surrounding tile is exposed to continuous water exposure, the importance of grout sealing cannot by overemphasized. Many people do not recognize that the grout lines are not simply a decorative margin that helps define the tile borders, but also a structural assembly including the tile, mortar and grout. The grout secures the tile matrix together by providing a very hard and unflexible filler between the tile gaps due to it’s high cement concentration. This high cement content helps to stiffen this matrix, but also aids in the bonding between the grout and the tile edge. This strength and rigidity is considered necessary because it becomes part of the finished surface that will be exposed to vaying amounts of water, abrasion, and dirt. Although grout is extremely strong and resistant to abrasion, expansion and contraction, it’s serious limitation is it’s extreme porosity. This means that in the unforgiving environment of a shower, it will absorb a significant amount of water, and retain it for long periods of time, if not treated with a quality grout sealer.
Some of the problems with grout lines absorbing water can be quite obvious and others, not so obvious. The first, and most obvious problem occurs when the appearance of the grout lines deteriorates over time. In a typical shower, water enters and stays within the grout, never drying out completely because of the frequency of water exposure with daily use. This continuous water exposure and warm temperatures, allows bacerial colonies to begin to establish themselves in an environment that is relatively ideal for optimum baterial growth and reproduction. It does take some time for the homeowner to notice this occurrance (after installation) because the waterborne salts within the cement are reducing the viability of the bacterial colonies and effecting their ability to reproduce. This brings me to the next problem.
As I already mentioned, grout lines in a typical, well used shower, will never be allowed to dry fully between uses. In this wet environment, the growth of bacteria is controlled initially, due to the salt compounds that are dissolved in the grout matrix. But this salty environment is not created without a price. The dissolved salts in the water are created when the mineral bonds in the cement deteriorate. As the cement deteriorates, there is a progressively lower salt concentration in the grout, and bacteria populations grow at a progressively faster rate. This is why it takes a fair bit of time before the grout lines begin to discolour significantly. Because the grout is breaking down, there are also other staining and important structural issues to consider.
When bacteria becomes a significant part of the grout matrix between your tile, the bonding between tile and mortar, and the structure of the grout has been deteriorated significantly. It can usually be identified by a roughening of the grout finish and often voids between tle and grout caused by the cement and sand literally washing down the drain. This progressively more permeable grout also allows body oils, dirt and soap scum to more readily absorb, causing discoloration and accellerating the deterioration of the grout matrix. At this point, water freely moves through the grout to the base of the tile where the thinset mortar attaches the tile to the substrate. This can be a dangerous thing, especially with the new, water proof membranes that are used in modern tub/shower installations. The water can easily move behind the tile via capilary flow or via the small grooves in the mortar base (created by the notches in the trowel used to apply the mortar). Water can stay between the membrane and the tile, not effecting the substructure at all, but slowly deteriorating the bond between tile and membrane. This water will also expand and contract with changing temperature, causing more movement, which in turn causes further cracking of the grout, accellerating the structural decline of the entire assembly.
As well, it should be mentioned that the less punishing environment of floor or wall tiling outside of the shower environment, also suffers from unsealed grout lines. The same process can occur as described above depending on the frequency of water exposure however, the primary problem with these grout lines are staining from exposure to dirt and grime. These grout lines, especially floor grout lines, absorb water just as well as those mentioned earlier in a very wet environment. The unique problem here is that whenever anyone attempts to clean the floor tile, the water they are wiping back and forth across the grout lines becomes dirty. This dirty water pools in the grout lines as they are cleaning, and absors into the porous grout matrix causing it to quickly stain. And because the dirty water is so deeply absorbed into the grout matrix, it is very difficult, if not impossible to clean without bleaching (which also deteriorates the cement bonds in the grout, by the way). The irony is, that the more festideous one is about floor cleaning, the more discoloured and hideous the grout lines become. This downward cycle would be eliminated by grout sealing to begin with.
I think I have made it quite clear how a beautiful and expertly installed tile installation can be affected so negatively over time, simply because the tiler made no attempt to reduce water penetration into the grout lines, simply by grout sealing. Ask your tile supplier to recommend a good quality grout and stone sealer. Cost does vary considerably, but I would recommend to avoid the low cost ones because their ability to seal, and their longevity, are usually related to their price. I regularly use AquaMix Sealers Choice Gold. Keep in mind that even with the best grout sealer, you should still allow a day or two ever year or two, to re-apply the sealer. You will see when the grout seal begins to fail when water exposure causes it to darken slightly. Performing this simple step will keep your tiles surfaces looking like new, for years to come.