How to waterproof a building in Tanzania

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How do you waterproof a building?

In Tanzania the climate is aggressive especially on the coast. Water and moisture are a constant threat to buildings.

Nabaki Afrika has over two decades of waterproofing experience in Tanzania. This article is a brief overview of what we have learned. Waterproofing is a complex process, so you will need further technical advice and expertise on a specific project. Contact or visit Nabaki Afrika’s engineers for project-specific advice.

The Basics

Build it right the first time:
Waterproofing is often considered after a building has experienced water damage. Rising damp, leaking roofs, hairline cracks on the walls and structural weaknesses are expensive to repair.

Waterproofing must be considered as you plan and design your building. It is most effective during new construction. Ensuring effective waterproofing at this early stage:

i) Will protect your building’s interior from water damage during construction itself
ii) Will ensure your building is moisture-sealed, promoting long-term comfort and safety and
iii) Will save you money – would you rather invest early in a strong, secure house or pay later for continuous repairs?

Select the right materials, specify effective products and draw up a working guide that considers the project’s waterproofing needs and solutions before construction begins. Remember this rule of thumb: build it right the first time!

Understand the problem:
The important thing to remember is that there is a solution to every problem.

One must identify their building’s waterproofing problems, or their site’s potential waterproofing needs, before being able to explore the range of waterproofing solutions to find one suited for their building. For example, if damp is higher than 1 metre above ground level, this is probably not rising damp but a leak. Being able to identify the cause – a leak, rather than rising damp – enables you to determine the solution.

Below, we examine the three main waterproofing problem areas, and an overview of their solutions. Each problem has a unique solution.

1. The Roof

Ensuring a watertight roof goes a long way to ensuring the interior of your building does not face water damage.

What type of roof is planned? Is it a flat or pitched roof? What materials are used?

A concrete roof would have a different solution from a stone-coated metal roof tile like Decra or Fortiza.

Identifying the materials and orientation of the roof is the first step. For example, a flat concrete roof is best waterproofed with crystalline waterproofing. Xypex Admix C-1000 NF could be added into the concrete at the time of batching, while Xypex Patch n Plug with Xypex Concentrate could be used to repair existing structures.

A pitched concrete roof might be best waterproofed by bituminous membranes, or repaired with an acrylic coating like Bitumat Synroof.

Each material and orientation has a different waterproofing solution, during either construction or repair, and Nabaki Afrika’s engineers can help you identify the right solution.

2. The Walls

Walls could be damaged by water ingress or damp pressure from the water table.

Are the walls fully above the ground or is a portion below the ground?

Our rule of thumb – build it right the first time – comes into play here. This may include using DPC (damp proof course), typically between your foundation and walls. These are waterproof materials like Polyethylene (PE) sheets, PVC ‘water bars’, or bituminous membranes. Including this in your plan ensures your building is watertight.

Concrete or brick walls could also be repaired – usually first from the exterior, then the interior – using a crystalline product like Xypex.

The specifics of each project would require different solutions, and Nabaki Afrika’s engineers have both the experience and the tools to advise you further.

If you are waterproofing after construction then improved drainage may be a solution. This might include the combination of a Marley rainwater system for the roof and an agricultural drain using a slotted pipe wrapped in geotextiles.

3. The Floor

Floors face a huge amount of pressure, as they are low in the building. It is best to deal with floor waterproofing problems during foundation building. The structural integrity of building foundations, whether deep or shallow, can be compromised by hydrostatic pressure and water leakages associated with high water tables. Inadequate waterproofing, cracking and joint failure are problems that will result in the deterioration of concrete and the leaking of water into the substructure. In the short term, this can lead to the loss of sub-structure functionality and, over time, the structural weakening of the building itself. Whether used for new construction or rehabilitation, a crystalline solution like Xypex will ensure your floor is waterproof.

A Note on Waterproofing by Crystallization:

Waterproofing by crystallization is perhaps the most effective way to waterproof concrete since it becomes an integral part of the concrete and reactivates into a crystal barrier every time it comes in contact with water. Xypex developed this technology.

Basic to the development of Xypex Crystalline Technology was a thorough understanding of concrete’s chemical and physical makeup. Concrete is porous. Its tunnel-like capillaries are a natural part of its mass, and permit the passage of water and other liquids. Researchers at Xypex recognized the opportunity for a chemical treatment that would fill these capillaries to prevent the penetration of water and other liquids from any direction. By means of diffusion, the reactive chemicals in Xypex products use water as a migrating medium to enter and travel down the capillaries of the concrete. This process precipitates a chemical reaction between Xypex, moisture and the by-products of cement hydration, forming a new non-soluble crystalline structure. This integral structure fills the capillary tracts rendering the concrete waterproof.

The fact that Xypex Crystalline Technology is now specified and used on thousands of diverse waterproofing projects around the globe – including the Bank of Tanzania’s lift shafts here at home – is a testament to the original concept.

Crystalline waterproofing technology was an idea that grew because Xypex chemists questioned what concrete was all about and found a way to make it better. Today, you can get this world-leading technology here in Tanzania.

It is important to note that while this is often the best option, each problem and project will have its own set of solutions. Feel free to contact Nabaki Afrika’s engineers for free advice or technical support on your specific project.

Parting Shot:

Planning and designing your building with waterproofing in mind will ensure your comfort, secure your building’s structural integrity and save you money in the long run.

Waterproofing is an important but delicate process. Understanding its importance and getting in touch with the right technical expertise and experience means you can do it right. The tips above provide a basic understanding of waterproofing, and our engineers and team are available to chat to you about your specific project and provide free advice on how to waterproof it.