Formwork 101 - MEVA USA

What is Formwork?

In a nutshell, formwork is the mold wherein fresh concrete is poured and formed. The mold, which can be permanent or temporary, holds the poured concrete and shapes it until it solidifies and becomes strong enough to support itself and other loads.

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Formwork is also known as “shuttering.” However, in certain parts of the world, shuttering refers to using plywood or timber to create the mold.

Formwork systems can be classified according to the following parameters:

• Types of material used to create the mold (plastic, steel, timber, aluminum)
• Types of concrete structure it supports (slab, column, wall)

Construction costs usually consist of building materials (ca. 45%), labor (ca. 45%), and operating expenses (ca. 10%). Formwork material comprises 15% of the total building material and contributes roughly 44% of the total labor. Meanwhile, formwork construction accounts for up to 25% of the total cost of building the structure. For this reason, many builders and construction companies prefer reusable forms (panel forms). The process of removing formwork is called “stripping.”

2. Column

As the name suggests, column formwork is used in the construction of circular or rectangular columns. Columns have formwork sections with a “closed load transmission,” which is supported by the formwork’s design and the guaranteed tensile strength rather than by using ties.

Steel formwork is often used to form circular columns as it is economical and available in incremental dimensions. Single-use forms, which are destroyed and disposed of during stripping, can be used as an alternative. However, using single-use formwork is not advisable if you need to construct multiple circular columns.

Meanwhile, rectangular columns are formed using three systems depending on their specifications. For instance, classic timber girders with steel walers and a plywood facing are often used when builders need to construct a significant number of columns with special dimensions. The windmill system, which is composed of columns or multipurpose panels of frame formwork systems, is suitable for building single columns with a standard dimension.

Finally, a foldable column formwork is highly suitable for columns with great heights. Because all the essential components (panels, connecting devices, ladders, and access platforms) are integrated into this type of column formwork, it helps builders reduce their construction time and costs.

3. Wall

Wall formwork comes in different types and classifications, as outlined below.

Conventional
Conventional wall formwork consists of boards or sheets and squared timber. It is flexible, but it can be costly and time-consuming as each component must be assembled on-site. In addition, all of its parts should be made according to the project’s specifications, and they must be nailed together and dismantled again after concreting.

Girder

This is a better version of the conventional formwork. Its components, which usually consist of dimensionally stable girders with two chords and one web, have been standardized to facilitate the assembly of identical and ready-to-use panels. The connection of the panels has also been systematized.

Frame
This type of wall formwork helps reduce labor time since its essential components (forming face, support for forming face, and steel walers) are assembled as one panel. The profile nose of the frames protects the edges of the forming face, thereby extending its lifespan. Connecting devices are used when assembling the frame panels to large-sized units, which are then usually transported by crane.

Crane-independent (hand-set)

This type of formwork can be moved by hand. Because of weight considerations, it is usually made of aluminum or plastic. It can take less concrete pressure than crane-dependent formwork, and is often used in housing and municipal construction projects.

Crane-dependent 

Crane-dependent formwork systems feature a large frame and formwork panels, usually made of steel. As a result, they cannot be moved manually. Since they can resist more fresh concrete pressures than crane-independent forms, they are suitable for the construction of commercial buildings and other extensive infrastructure projects.

Two-sided
As the name implies, two-sided formwork is erected on both sides of the wall. Its formwork ties, which are usually sleeved by spacing plastic tubes so they can be reused, take up the fresh concrete pressure. Push-pull props or large heavy-duty braces are attached to the formwork to align and secure it against wind loads during operation.

Single-sided
Single-sided formwork is used when the concrete has to be poured against existing structures or when builders need to do concreting against a hill or soil. This is why it is most suitable for reconstruction jobs. With this type of formwork system, concrete pressure is transferred from the formwork to the base plates through a support structure. 

Prefabricated
This formwork consists of two prefabricated concrete panels which are assembled in advance, and then transported and filled with concrete on-site. Braces and push-pull props are often used to secure the walls, while working and safety scaffolds are installed with the help of special adapters to make the construction process more cost-effective. Prefabricated formwork helps minimize project duration and labor costs. However, pre-planning is required to ensure that it is transported safely to the site.

Circular
Circular formwork is designed for the construction of curved and polygonal walls. It is also quite useful in the construction of specific concrete structures, such as septic tanks and car park ramps. This formwork system comes in three different types:  

• Round girder – timber spacers are added between the timber girders and steel walers so the formwork can be adjusted to the required radius. 
• Flexible girder – ideal for the construction of curved walls with different radii. It comprises timber/steel girders and a spindle, which allows builders to adjust the formwork to the required radius without having to reassemble the panels.
• Polygonal – existing “flat” frame formwork panels can be refurbished as polygonal formwork by adding supplementary radius panels and rails, allowing builders to minimize their project costs.

Climbing
Climbing formwork is quite useful in the construction of high-rise concrete structures, such as control towers and skyscrapers, because it climbs with the wall. It comprises large wall formwork mounted to a climbing scaffold. There are three different types of climbing formwork:

• Crane-dependent – the climbing unit (scaffold and formwork) requires the use of a crane to reach the next cycle.
• Self-climbing – an automatic climbing system that does not require the use of a crane to reach the next suspension point. Hydraulic rams/pumps lift the scaffold, secondary platform, and formwork to the next pouring cycle. It is ideal for the construction of very tall concrete structures.
• Slipform – a two-sided formwork that slides upwards along the structure being built at a rate of 20–25cm per hour. A system of pipe rods, which is integrated into the already-set concrete, supports the slipform.
   

MEVA is an industry leader offering a wide variety of wall formwork systems that provide highly efficient shuttering, flexibility, and reliability. Our products are lightweight and easy to assemble, and therefore will facilitate the rapid completion of your construction projects. Click here to learn more.

Understanding Insulated Concrete Form

To begin with, Insulated Concrete Form (ICF) represents a modern, revolutionary construction method that brings together strength, comfort, and energy efficiency. This construction method utilizes large, pre-formed polystyrene blocks that interlock, creating a form for the structural walls of a building. Once in position, the blocks are then filled with reinforced concrete, creating a robust structure. To better understand this method, let’s delve into why it is becoming the preferred choice in today’s environmentally-conscious building and construction industry.

Key Features of Insulated Concrete Form

This construction technique involves the use of lightweight, hollow blocks that are stacked together, designed to fit like Lego pieces. They are then braced and reinforced with steel bars before pouring concrete into the cavity. Here are the key features of ICF:

• The interlocking modules are made from highly insulating foam.
• Once the concrete sets, it provides a stable, insulated and airtight wall structure.
• The thermostat effect of ICFs ensures that heat is evenly distributed, eliminating cold spots.
• The foam blocks make it easy to cut and shape around utility lines and fixtures.

Components of Insulated Concrete Form

The primary components of an Insulated Concrete Form system include the formwork and the reinforcement. More about them:

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Formwork

The formwork is made of extended polystyrene (EPS), and this is what we commonly refer to when we mention "insulated concrete form." This part of the ICF system provides the insulation, shaping, and support for the poured concrete.

Reinforcement

Steel reinforcement bars (rebars) are laid within the formwork before pouring the concrete. The amount and type of rebar used depend on the engineering requirements of the structure being built.

Construction Process with Insulated Concrete Form

The construction process using an insulated concrete form system is quite structured and straightforward. It follows the following general steps:

• Formwork assembly: The EPS formworks are interlocked to create the desired building shape.
• Reinforcement: Steel bars are placed within the formwork at specified locations.
• Concrete placement: High-quality concrete is then poured into the formwork.
• Curing: Allow the concrete to cure fully. This can take anywhere from 24 to 48 hours.
• Finishing: Once the concrete has harden, the building can then be fit out conventionally with plasterboard, render, cladding, or bricks

Wide-Ranging Benefits of Insulated Concrete Form

The benefits of using insulated concrete form building methods are profound and multifaceted.

Energy Efficiency

ICFs have exceptional thermal performance, which helps to reduce the cost of heating and cooling significantly.

Strength and Durability

Concrete walls made with ICFs are some of the strongest, most long-lasting building materials in existence. They can resist natural disasters such as hurricanes, tornadoes, and even earthquakes.

Sound Insulation

The combination of concrete and foam acts as a natural sound barrier, reducing outside noise.

As we strive towards sustainable building practices, insulated concrete form offers an unparalleled blend of efficiency, durability, and comfort. Builders, architects, and homeowners worldwide appreciate the value of this innovative method for constructing homes and commercial buildings. Embracing the insulated concrete form method can undeniably lay the groundwork for a more sustainable and energy-efficient future.

Frequently Asked Questions about Insulated Concrete Form

How are insulated concrete forms manufactured?

Insulated concrete forms (ICFs) are manufactured using two identical, parallel pieces of foam insulation, connected by plastic webs. These are often made from expanded or extruded polystyrene, much like the material used in coolers. These pieces of foam can differ in thickness based on the needs of the project. The webs spaced throughout the formwork hold the pieces together and offer stability during concrete pouring.

Is working with insulated concrete forms difficult?

Working with ICFs is relatively simple and straightforward. The foam panels are lightweight, easy to handle and can be cut to size with standard carpentry tools. Additionally, the forms are designed to interlock much like Lego blocks, making the entire construction process quite efficient. It's always advisable, however, to engage experienced professionals for a seamless ICF construction project.

Can ICFs be customized to different shapes and sizes?

Yes, ICFs are incredibly flexible and can be customized to suit a variety of structural designs. They can be used to construct curved walls, tall walls, and can even be cut down for smaller walls. The combination of plastic webbing and foam insulation allows them to be easily tailored to fit any design requirement.

How do insulated concrete forms enhance energy efficiency?

Insulated concrete forms are known for their impeccable energy efficiency. The foam insulation panels on either side of the concrete form act as a robust barrier, reducing thermal bridging and hence minimizing heat loss. This leads to a remarkable increase in the overall energy efficiency of the structure, resulting in significant savings on utility costs.

Are insulated concrete forms environmentally friendly?

Absolutely, ICFs are considered highly eco-friendly. Firstly, they optimize energy usage, reducing carbon footprint. Secondly, unlike traditional construction materials, ICFs generate minimal construction waste. Lastly, the primary components – EPS foam and steel – are recyclable, making ICFs a sustainable choice for new constructions.

Is it expensive to build with insulated concrete forms?

While the upfront costs of building with ICFs can be higher compared to traditional construction methods, the long-term savings achieved through decreased energy costs, lower maintenance, and increased longevity can more than offset the initial expense. Considering these factors, ICFs can actually prove to be a highly cost-effective construction solution.

Can you remodel or refinish a house built with insulated concrete forms?

No doubt, homes built with ICFs can be remodeled or refinished like any other home. Although adjustments to the interior and exterior finishings are common, structural changes require careful planning due to the reinforced concrete within the foam structural insulation.

Pros and Cons of Insulated Concrete Form (ICF)

Insulated Concrete Form, commonly referred to as ICF is increasingly being adopted in the construction sector due to its remarkable insulation properties and structurally sound designs. However, like every construction method, ICF has its share of advantages and disadvantages. In the sections below, we will explore the pros and cons of Insulated Concrete Form.

PROS

Ease of Use in Construction

One of the major advantages of the Insulated Concrete Form is the simplicity involved in its use. The ICF blocks are easy to stack and can be cut and shaped using standard tools, making the construction process easier, quicker, and less labor-intensive.

• Reduces the need for specialized labour.
• Cuts down construction time significantly.
• Easier to install services such as wiring and plumbing within the formwork.

Improved Energy Efficiency

The Insulated Concrete Form provides an excellent thermal insulation which greatly reduces energy consumption for heating and cooling.

• Can reduce energy costs by up to 70%.
• Keeps indoor temperatures stable, increasing comfort.
• Helps in reducing carbon footprint.

Highly Durable and Resilient

Structures built using Insulated Concrete Form are incredibly durable and resistant to damage from natural disasters like hurricanes, earthquakes, and fires.

• Increased resistance to wind and seismic forces.
• Fire resistant for up to 4 hours.
• Resistant to termite and pest infestation.

CONS:

Higher Initial Cost

Using Insulated Concrete Form can be costlier upfront compared to traditional building methods. This can be a major deterrent for potential users.

• Costs more per square meter/foot to construct.
• Additional expense incurred from specialized trades and engineers.

Limited Design Flexibility

While Insulated Concrete Form allows for a variety of design options, it does not offer the same level of flexibility as wood or steel framing.

• Modifications and alterations after construction are challenging and costly.
• Not suited to intricate architectural designs.

Insulation Thickness Requirements

To meet energy efficiency levels, ICFs must be of a certain thickness, which can reduce room space, and cause problems when matching up with traditional wall thicknesses.

• May result in thicker walls than conventional building methods.
• Requires additional considerations for window and door installation.

In conclusion, when deciding whether to use Insulated Concrete Form in construction, it is important to consider its pros and cons. By understanding both aspects, one can determine if ICF's superior insulation properties and durability outweigh its higher upfront costs and potential design limitations in their specific project.

Summary

Overall, insulated concrete form is a game-changer in sustainable construction. This innovative technology offers incredible energy efficiency and durability, surpassing traditional construction methods. The impact on heating and cooling costs is substantial, helping to lower overall living and maintenance expenses for homeowners.

Moreover, insulated concrete form is not only about energy efficiency but also about living comfort. The superior insulation it provides contributes to a more consistent indoor temperature, and also helps in sound-proofing the home. In addition, its strength can withstand extreme weather events better than most traditional building materials, contributing to greater safety for the home occupants.

Nonetheless, as promising as insulated concrete form may be, it’s essential that construction stakeholders, like architects and builders, understand how to properly design and install it. This includes making construction workers familiar with new techniques and ensuring that building codes account for these materials. With proper knowledge and application, insulated concrete form can revolutionize how we build for the future.

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