What's a Sonotube?

In Quebec, concrete is used for a variety of purposes, like foundations, flooring, and even kitchen countertops. However, it’s not as commonly mentioned when it comes to piles. Maybe it's due to its utilitarian side rather than its aesthetic one? One thing’s for sure, one can spot concrete-made columns, whether in the city or the countryside. They’re used for both residential and commercial projects. 

What’s a Sonotube?

Source: Canva

Aside from the quality of the material in question, what allows concrete to take a cylindrical shape is the Sonotube mould. Said element is a round cardboard form in which concrete is poured. Sonotube has very project-specific characteristics. For residential projects, it’s used to make piles to support porches and balconies, and it’s shaped like a cylinder.

Any and all persons having the right tools and a minimum amount of skills in construction can carry out its installation. For commercial projects, Sonotube allows you to build structural load-supporting elements. It can also be built in various shapes. Albeit concrete appears to be rather ordinary, it’s a material that has a great number of advantages for both residential and commercial projects.

Sonotube or Screw Piles: What's the Difference?

Sonotubes and screw piles are both used in construction to endow structures with a solid base. Here’s how these two methods differ:

Sonotubes are typically used for small- to medium-scale projects, such as fencing, porch posts, small buildings, or traffic signs. They’re driven into the ground where intended, then filled with cement. Sonotubes are a relatively simple and economical solution to build sturdy foundations.

Piles (or screw piles) are steel or concrete structural elements that are embedded deep into the ground to support significant loads. They’re used during large-scale projects, such as skyscrapers, bridges, or industrial infrastructures. Screw piles are driven into the ground with specially designed equipment, such as drilling or vibrating machinery until they reach a sturdier level beneath the ground, and have elevated load capacity.

Overall, choosing between Sonotubes or screw piles ultimately depends on the specific requirements of the construction project in question.

Using Sonotube for Residential Projects

When it comes to residential projects, it’s best known for its usage in small projects like when installing a fence, balcony columns, and carrying out other medium-scale tasks. Experts recommend using at least 20 cm-wide (8 inches) tubes when pouring concrete. Note that you can purchase Sonotube concrete forms at any reputable hardware store. They’re lightweight, easy to install, and simple to transport.

How to Install a Pile Using Sonotube

Allow it to protrude by at least 20 cm (8 in) from the ground. You can insert rebar into the concrete piles to strengthen them. Next, simply dig into the ground to remove a certain amount of dirt based on the tube’s depth. Lastly, place the Sonotube into the dugout, and fill it with concrete. Carefully monitor the amount of water added to the concrete to avoid compromising its performance.

Naturally, endeavours such as some balcony-related work or when it comes to installing a fence can be DIYed if you’re a bit skilled at manual labour. Otherwise, it’s best to hire a contractor to carry out the intended work.

How deep can a Sonotube mould be embedded?

At most, a Sonotube can typically be embedded at depths between 2 to 3 metres, depending on the condition of the ground and the type of project. If you’re dealing with soft soil, it’s best to embed it 2 metres deep, and in the case of hard soil, a depth of 3 metres is recommended. And, according to the CAA website, due to our harsh East Coast winters, the depth at which concrete footings or piles are built must be at least 1.5 m (5 feet), since the ground freezes at that point.

How to remove the Sonotube

Removing Sonotube is a fairly straightforward process. After allowing sufficient time for the cement to cure, you can attempt to pull up on the tube to slide it off. If that doesn't work, cutting it or peeling it off are the typical methods used. In the event it's being stubborn, try applying some water to soften the material.

Is it ok to leave Sonotube in the ground?

You can leave a Sonotube form in the hole in the ground if it's being used for a construction project, particularly for tasks like pouring concrete footings or columns. It will eventually degrade over time due to exposure to moisture and soil.

However, whether it's advisable to leave the Sonotube in place depends on factors such as the specific project requirements, local building codes, and environmental conditions. In some cases, removing the Sonotube may be necessary for aesthetic or structural reasons, or to comply with regulations.

Before leaving the Sonotube in place, it's essential to consider the long-term implications and consult with relevant professionals, such as engineers or contractors, to ensure that it won't cause any issues down the line.

Installing Sonotube for Institutional Projects

Source: Canva

In regards to commercial or institutional projects, the cardboard cylinder can take various shapes and various project-related possibilities are available. It’s used in big buildings with the involvement of professionals to effectively calculate the loads and also necessitate qualified contractors to carry out the work.

Finish-Free Sonotube

The smooth-finish Sonotube doesn’t leave any imperfections on the concrete, surface-wise, thus avoiding having to carry out any finish work, manually. It’s especially used in public and open spaces. These do give off an interesting effect, aesthetically speaking. Inside the mould, there’s a smooth film that’s used to give off the desired effect. Once the cardboard is removed, you can see the effect of the film. Some models leave an imprint of the cardboard’s streaking to give the pile a different type of finish.

Sonovoid Forms

Sonovoid forms are used to make concrete slabs, beams, bridge decks, piles, and piers. It partly replaces concrete. For example, two tubes are installed in formwork to make a concrete slab. They’re tied down to rebar, held and supported while the concrete is poured. Once the drying time has elapsed, the slab is ready to be installed and the tube leaves two round voids inside the concrete slab. Using said method allows one to minimize the use of concrete without impacting its performance and the structural integrity of the slab.

In a nutshell, for residential projects, Sonotube allows one to DIY construction-related tasks. For large-scale projects, said form tubes have other properties that allow you to build 20 feet columns. They serve two purposes: structural and aesthetics. Furthermore, they’re made with cardboard, which is a recyclable material.

Want to learn how to build a sturdy and durable deck? Check out our article!