Basic facts about building materials

  • Some facts about everyday building materials you may not know.

    It was pointed out to me yesterday, that to date, my blogs are written in a way that assumes some prior technical knowledge about building. Considerable interest about Efflock is also coming from home owners, 'Do-It-Yourselfers', or from people who have seen the product and would like their builder to use Efflock in their building project. So here are some basics:

    Many people assume that concrete is waterproof.

    It makes sense right? You see concrete on bridges, footpaths, driveways and balconies everywhere, so surely water doesn't affect it??

    The reality is that even concrete of the highest quality contains small micro cracks that allow water absorption. Water that enters concrete will have detrimental affects to it's durability. Water carries pollutants, chloride ions (salt), and of course can freeze to cause frost damage.

    Water passing through concrete also dissolves and can 'wash out' the alkaline properties within the concrete to transform concrete to a more acidic state. This phenomenon is often the cause of concrete cancer. (Alkaline pH protects steel reinforcement, an acid pH promotes rust and corrosion of the steel.)

    Additives for civil building projects such as bridges, have been around for at least 40 years. Such additives are usually a crystalline technology, where tiny crystals are triggered to grow and fill the tiny pores when in contact with water. These same types of additives only work in structural concrete of high quality with strict controls and cannot be used in smaller scale and lesser quality concrete such as tile beds which are highly porous. Efflock is new patented technology that works in all types of concrete with the advantage of easy on-site use for all types of applications. 

    What is a tile bed and where do I find one in a building?

    A tile bed is usually a mix of 4 parts sharp clean sand to 1 part Ordinary Portland Cement. This mix is prepared on site by tilers to quite a dry consistency (very little water content) and is spread over a floor to a minimum thickness of normally 30mm to create an accurate substrate for tiling. In wet areas such as bathrooms, falls are created to direct water to drainage outlets. 

    Tile beds can be found anywhere beneath where there are tiles on a floor; bathrooms, laundries, balconies, paths, driveways and even living areas. Most of these applications are subject to water from an internal shower enclosure or weather, and an ordinary tile bed without an additive will retain water like a giant sponge.

    The pores within the tile bed also promote a very efficient 'wicking' effect for the transportation of water and damp throughout the entire tile bed. A familiar analogy is if you stuck one corner of a household sponge in a puddle of water, slowly the whole sponge would draw the water until it is completely saturated. This is exactly what can happen with a tile bed, and is one of the key reasons why bathroom and balcony leaks are so common. 

    On an exterior balcony tile bed, the same 'wicking' effect occurs. Externally however,this effect is usually the main reason   for efflorescence. Efflorescence is more common externally because of increased evaporation occurring between rainy weather. When water travels through the tile bed (but also adhesive and grout), it dissolves free lime and salt within the concrete. At a point of discharge (such as grout joints, balcony edges, drainage outlets) this salt laden solution evaporates to leave behind calcium carbonate deposits, which are the white efflorescence marks.

    Adding Efflock to the tile bed, adhesive and grout stops all of these problems.

    What about tile grout? The packet says it is hydrophobic, won't that stop water?

    Tile grout is a lot less porous. However, if you were to take a sample of cured tile grout and do an absorption test, you will find that it still absorbs water. There are also thermal movements to consider which may allow water penetration to the tile bed underneath. A tiled shower floor may go from less than 10 degrees celsius to above 40 degrees celsius in the time it takes to turn on a tap. Tiles themselves aren't necessarily impervious either.

    Efflock makes off the shelf grouts very hydrophobic. A sample of a well regarded brand we tested was completely wet after 24 hours submerged in a bucket of water. With Efflock, the same grout was still bone dry beyond a sheet of paper thickness two weeks later! Grout treated with Efflock will resist ingrained mould -something that is a normal occurrence in standard grout. 

    I have a waterproof membrane. Surely that will prevent these problems? 

    Yes, a quality waterproof membrane is still essential. The membrane however is typically located under the tile bed. If there is any kind of compromise in the membrane, it will most likely fail, often causing structural damage to timber or other building elements. The membrane has to work hard under a heavily saturated tile bed that can happily transport water throughout the entire floor. A tiny defect, even a pinhole sized damage which could easily occur during construction can create big problems. Efflock provides a primary layer of protection with excellent moisture regulation to essentially prevent water ever getting to the membrane.

    Most often, a secondary membrane is used over a tile bed to control efflorescence. It is common outdoors and sometimes provided in bathrooms. Unfortunately, all secondary membrane systems have problems:

    1. The cost around 80% more than using Efflock.
    2. Moisture from hydration of the concrete can be trapped, sandwiched between two membranes.
    3. Secondary membranes are often rigid, meaning any shrinkage or movement cracks will inevitably allow water entry into the tile bed.
    4. Extra process required. Extra labour and subject to lengthy weather delays.
    5. Can actually promote the transport of moisture and associated salts to other areas (i.e. an evaporation or exit point) to cause other problems (such as corrosion of aluminium door sills).
    For further questions, information or specific building problems, please feel free to contact Ben. Details are on the 'Contact Us' page of this website.
  • ← Next Post
  • Leave a comment