A guide to concrete moulds: Everything you need to know

Concrete moulds are in increasing demand in the world of construction. Use this guide as your holy grail for everything you need to know about moulds.

This article answers the following questions:

  • What is precast concrete?
  • What is precast concrete used for?
  • What are the differences between different mould materials?
  • How long do moulds last and how long can they be used?
  • How can I care for my concrete moulds?
  • What is the difference between precast and sitecast moulds?
  • What are the advantages of precast moulds over sitecast?
  • How is precast concrete manufactured?


  1. The history of concrete moulds
  2. What is precast concrete?
  3. What is precast concrete used for?
  4. Concrete mould through the ages
  5. What are the differences between different mould materials?
  6. Different types of moulds for different climates
  7. How long do moulds last and how long can they be used?
  8. How can I care for my concrete moulds?
  9. What is the difference between precast and sitecast moulds?
  10. What are the advantages of precast moulds over sitecast?
  11. How is precast concrete manufactured?
  12. Choosing a designer/manufacturer for your precast concrete

Being in the concrete mould industry for over 40 years, we are well-known industry leaders. We founded Numold in 1978 with the intention of becoming leading designers and manufacturers of moulds for precast concrete, and that’s exactly what we did. Despite being family-run, we are by no means a small organisation – we’re a worldwide leader in our expertise – so, who better to give you a rundown of everything concrete mould related?

Let’s start with its history.

  1. History of Concrete Moulds

The development of the use of concrete is said to be one of the biggest 20th century trademarks. Over time, designers and architects have developed different techniques to test the limits of concrete when using different types of moulds.

For example, as early as 1899, Thomas Alva Edison famously created moulds that consisted of a huge 2,300 pieces! As they were so difficult to put together, understandably, the project didn’t quite go to plan.

Later, in the 1900s, various concrete moulds were developed to construct panels to connect multi-story buildings across whole cities. These included the implementation of various styles/artistic designs – some of which can still be seen today in places like Russia and Berlin.

More complex mould designs were later developed in 1967, the initial ground-breaking design was the famous ‘Habitat’ which saw the beginning of more modular concrete mould designs.

The late-1970s proved an important era for the development of concrete mould. Moulds were created by two Cuban architects for entire housing units that included furniture and window shutters. Further learnings occurred as these moulds had some restrictions in terms of controlling water and the design didn’t entirely fit in with the surrounding (already existing) houses – let’s just say they would’ve had difficulty getting them through town planning in this day and age.

These were some of the projects that led the way and opened the door to the impressive work we do today. Concrete has always been an incredibly consistent material in the construction/design industry and we’re proud to be a part of its history. The exciting thing about concrete moulds and concrete in general,  is we’re still so far from fully discovering its limits. The versatility of the material means we can keep experimenting with different moulds, finding new ways to lead the way in the industry.

  1. What is precast concrete? https://nitterhouseconcrete.com/what-is-precast-concrete/

Precast concrete is where concrete moulds of different materials are used to shape concrete into a specific form. Examples of products that are developed using these types of moulds are fence posts, concrete posts and so on. These items would require specific fence post moulds and concrete post moulds in order to initially shape them – this is done in a controlled environment, rather than being done directly on site. Once they are cast into the concrete mould, the mould is cured, taken to wherever it’s needed and installed.

At Numold, as we design and manufacture all moulds within our UK-based in-house facilities, it means that the product’s end result is not affected by site conditions, which makes for efficient installation and excellent value for money.

  1. What is precast concrete used for?

One of the reasons that precast concrete is so successful is because it’s incredibly multifaceted. It can be used to create buildings, fencing, paving (and so on) through various different industries (for example, homes, gardens, schools, retail etc.) Some further examples of what precast concrete can be used for are below.

  • Fencing

As leaders within the concrete industry, we commonly deal with designing and manufacturing fence post moulds/concrete post moulds for fencing. We’re able to take your wishes on board to create unique, precise designs that, once manufactured and delivered, are easy to construct. We deal with contractors, homeowners and specifiers to provide moulds for their specific needs. The benefits of using concrete mould for fencing is that they’re secure and private, flexible, durable, cost-effective and versatile with little to no maintenance requirements.

concrete fence post mould
Concrete Fence Post Mould
  • Paving

Concrete paving moulds are extremely popular and are an area Numold specialise in. There are lots of reasons concrete is chosen for paving, but one of the biggest reasons is that it’s extremely resilient in any environment. Your product can also be developed in lots of different colours/sizes/textures and so on. Concrete paving moulds are durable, strong and they look great too!

You have the freedom to pave with the highest quality, most beautifully designed concrete for any landscape. If you’re looking for concrete moulds for sale, Numold can help. Whether you’re looking for temporary, traditional or functional paving, get in touch and we’ll be more than happy to help.

  • Precast walling and copings

Precast walling and copings can be perfect to add finishing touches to an outside space and can normally be purchased in a variety of different designs, colours and textures to fit your needs. They can be designed to blend in, accentuating other areas of your garden, or stand out as feature pieces.

These are just some examples of what precast concrete can be used to create. We also design and manufacture feature kits and accessories and the wonderblock!

  1. Concrete mould materials through the ages

Historically, there have been various materials tried, tested and used to create concrete moulds that have led us to where we are today. In earlier years (up to the 19th century), plaster was used containing materials like gypsum, lime and cement. More complex moulds were usually developed with plaster, timber and terracotta. These would be used to develop sensational versions of original stone/marble work.

Concrete mould materials in the 21st century

Concrete moulds still continue to be developed using a wide variety of different materials, for example, steel, timber and moulded latex. However, it’s most common for concrete moulds now to be made from Thermoplastics and Elastomers that are petrochemical-based.

When detailed undercuts/mouldings are needed, Elastomers are used.

Elastomers themselves consist of Polyurethanes, Silicones and Epoxy Resins – these all come in different shore hardnesses. For example soft or rigid systems for specific uses.

At Numold, we have an advanced, in depth knowledge of the different materials required for plastic moulds for concrete and can expertly pair materials and casting methods for each specific project. Our vast experience, developed over 40 years in our field has enabled us to work to provide such an expert and unique experience.

  1. What are the differences between different mould materials?

We understand that your needs will differ depending on what kind of project you’re working on, the climate and lots of other variants. That’s why we design and manufacture our moulds in a variety of different materials, to support your work. From concrete fence posts moulds in HDPU, to polyurethane moulds for concrete products, we provide our services worldwide and would love to be a part of your project.

Plastic moulds

ABS Plastic (Acrylonitrile Butadiene Styrene). This is a common material used for concrete moulds as it is strong, durable and surprisingly lightweight. The process of using ABS tends to be fast as the material lends it’s self for bulk orders. This can really enhance the productivity of your project.

Plastic has lots of properties which makes it a good choice for use with concrete moulds, including chemical-resistance and strength. At Numold, we’ve spent over 40 years developing our use of thermoplastics, polyurethanes and composites, which enhances the fact that we’re leaders in our industry.

abs concrete mould
Numold ABS Concrete Mould in gang format

Rubber moulds

Naturally, one of the biggest benefits of rubber for precast moulds is its flexibility. Other, harder materials, in comparison are more rigid – not giving the same desired effect. Rubber moulds can usually be cast in different shore hardness’s, meaning they’re tailored to the specific needs of you and your projects. It also decreases the risk of damaging your units when you remove the mould, as rubber is so flexible.

polyurethane paving concrete mould
Polyurethane Paving Concrete Mould
polyurethane concrete mould
Polyurethane Kerb Concrete Mould

Timber moulds

Timber is often used for concrete moulds as it has a whole range of qualities that allow it to work well for various projects. It’s very versatile, tough and strong. Heavy timbers can be stronger, but you can also get your hands on lighter-weight timbers. Another important quality is its elasticity. Meaning it can easily re-form its original shape once not in use.

Steel moulds

On the opposite end of the scale, you have steel moulds. Steel is normally used to create concrete moulds that are required for larger, industrial projects that require strength, durability and resilience. They’re very much designed and manufactured to last.

  1. Different types of moulds for different climates

Unsurprisingly, certain materials perform differently depending on which climate they’re used in. It’s important to consider the climate when developing moulds for concrete. 

Whilst this is important for the practicality of the design, this is also true for the aesthetic design of precast moulds. For example, a concrete mould that encompasses curvestone/stone waves lends itself well to warmer, perhaps meditteranean climates where the importance of outdoor living is accentuated. The same can be said for limestone.

  1. How long do moulds last and how long can they be used?

The beauty of precast moulds, is that their life-span can be enhanced by proper use and care. For this reason, it’s almost impossible to put a number on the amount of years you’ll go on to use them.

Making sure to use the moulds as advised and also care for them properly can add years onto them. We’ve seen instances of moulds lasting for multiple years longer than expected just because they’ve been looked after.

At Numold, we put a great level of detail and attention into each and every one of our moulds to make sure you get the absolute most out of them. Therefore, their life expectancy will vary depending on how you treat them.

  1. How can I care for my concrete moulds?

It isn’t hard to make sure concrete moulds are looked after. There are a few things you could consider to provide them with good care:

  • Physically support them correctly
  • Don’t over-fill them
  • Use a release oil
  • Store them properly
  • Stack them properly
  • Allow concrete to fully set before de-moulding
  • Keep moulds out of direct sunlight
  • Store in a dark cool area when not in use

Caring for your mould properly will add to its life expectancy and help you get your money’s worth.

  1. What is the difference between precast and sitecast moulds?

As we mentioned above, precast moulds are designed and manufactured in a controlled environment, before being transported to their desired location for installation. This means lots of risks are decreased and the creation of the mould will not be affected by on-site conditions.

On the other side of things, site cast (otherwise known as in-situ) concrete is developed on site. This means the concrete is poured, moulded and cured on the very site the final form will be constructed on. Once cured, it’ll be moved into place for installation

  1. What are the advantages of precast moulds over sitecast?

As you’re probably realising, precast moulds and site cast moulds are very different. Here are some advantages of using precast over site cast.

  • Versatility

Designers and manufacturers of precast concrete moulds are well-accustomed to working to the needs of a wide variety of different customers. They’re used to easily transferring lots of different products to various locations. Precast concrete is considered in some ways much more versatile than site cast. Also, in terms of aesthetics, you’re normally able to access precast moulds in a multitude of colours, finishes and so on.

  • High quality

When concrete is cast in moulds within a controlled environment, the quality is usually extremely high. The strength of the product, plus the quality is dependent on how well it is cured. Therefore, being in a climate where the environment is controlled and risks are minimised is very important to the overall quality.

  • Efficiency

As precast concrete is efficiently designed and manufactured within an inhouse environment, the level of efficiency is normally much higher.

  • Affordability

Because precast concrete can be developed in-house and sometimes using similar forms, they can be produced en-mass and at a large scale. This sometimes means it’ll be cheaper for you to purchase precast concrete, especially if you require standard sizing.

  • Tailored to you

One of the biggest advantages of using precast concrete is that because the moulds are developed from scratch, you are able to specify dimensions. This means you can personalise your precast moulds to your specific project.

  • Avoiding sitecast moulds

Whilst sitecast concrete has its advantages, it’s clear that it takes a lot of on-site resources (including time, equipment, staff and space) to fulfil the project. It’s also largely affected by conditions on site including weather – meaning you may be delayed or have unwanted interruptions on a daily basis. Delays due to mishaps can mean changes to scheduling, the availability of certain team members and an increased cost too. Whilst sitecast moulds have their own advantages, these are some things that aren’t missed when using precast.

  • Insulation

You may have requirements for insulation within your concrete to save space and also onsite work. You can sometimes choose to include insulation if you have opted for precast concrete. This is because when working in-house, there is a large speciality of equipment that you simply won’t find onsite. It means that you’d avoid having to manually fit insulation to the building you’re working on because your concrete would have enhanced insulation – saving both time, resource and cost.

This is a big bonus from an sustainability point of view and will see big environmental cost savings for the building once in use.

  • Structural reinforcement

Just like the above, reinforcement can be incorporated within an inhouse environment to help add structural integrity to your project. This will be very important for certain projects where normal concrete just won’t be good enough. This should allow you to reduce additional materials normally needed to support structural integrity and help you reduce your costs and put less strain on your resources.

To incorporate this, consistent conditions are needed which aren’t available onsite, but are standard practice in an inhouse environment. Due to this reason, with precast concrete,  you’re also able to incorporate much higher levels of precision within the design of the mould. This level of precision simply can’t be replicated onsite.

  • A controlled environment

As an inhouse environment is controlled, it means that conditions/curing can be sped up without there being an effect on the mould itself. The same can’t be said for sitecast concrete moulds, as the process of speeding things up onsite tends to incur costs and sometimes inconvenience too. There’s also the risk of the final product being poor quality.

  • Environmentally friendly

Due to the increased efficiency of precast concrete, a lot of waste is prevented, meaning a more positive impact on the environment – and that’s always a bonus! Combine this fact with some sustainable materials and you’re working with a green ethos.

  • Decreased use of labour resource

When work is done within a controlled environment, it means the highest level of efficiency and effort is used. Specialist equipment is also utilised, equipment that may not be accessible onsite. In comparison, when creating sitecast concrete moulds, such tasks would need to be undertaken either by hand or with less reliable tools. Not to mention the work would need to be done by highly skilled professionals. This usually takes a lot more time and a lot more labour to complete the job in comparison to precast concrete.

  • The weather doesn’t matter

The beauty of choosing precast for products like fence post moulds is that the work is completed in-house – or in other words, indoors! As each mould is developed in the same controlled, consistent environment every single time, a sudden change in weather won’t affect production at all. The same can’t be said for sitecast – where a turn in the weather could see production stopped, costs hiked and the project delayed.

  • Strength

Concrete takes some time to set and gain its full strength. When a concrete mould is developed in a controlled environment and delivered to site, it has the time it needs to dry and strengthen. Strength tests are also conducted before shipment to make sure the mould is at the highest quality possible.

When using sitecast, the installation team needs to allow time for the concrete to set and dry on site, plus undertake an onsite strength test – possibly delaying work and raising the budget if the waiting period hadn’t been accounted for. Using precast concrete is definitely more cost and time effective.

  • Precast saves time

As precast concrete is designed, developed and tested in advance by a team of professionals, its delivery is more or less guaranteed for the time when you need it. Conversely, as a lot of onsite labour (plus waiting around) is required for sitecast concrete, the whole process becomes timely.

So for example, if you’re waiting to install precast concrete paving moulds, they could be designed, manufactured and delivered whilst your time is being better spent elsewhere. Whereas if you were using sitecast, a whole lot of work, space and time would be required by several different workers onsite.

  1. How is precast concrete manufactured?

As we’ve established throughout this page, precast concrete is manufactured off-site and within a controlled environment. Here we’re going to take a look at an overview of the manufacturing process behind precast concrete.

Step 1: The concrete is inserted into a mould (of varying material – we use hot and cold cast polyurethane, polypropylene, timber, steel, silicone and ABS moulds for concrete).

It’s poured using reinforcement which adds strength to the concrete.

Step 2: The concrete is then demoulded and cured for at least 7 days in a controlled environment.

Step 3:  Once the concrete has been cured, it’ll be transported to the site where it’s required ready for installation.

  1. Choosing a designer/manufacturer for your precast concrete mould

Picking a precast concrete mould designer and manufacturer for your project is a big decision and we’d always urge you to get in touch with any questions you have. If you’ve opted for precast concrete, you’ll know that you’ll need a specialist in this field to make sure every process is completed to the highest standard. They will need the headquarters, staff, equipment, knowledge and experience in order to get the job done. A professional and reputable manufacturer can be the difference between a high quality result at the end of a project and a low one.

Here are a few tips to consider when you’re trying to choose a precast concrete mould manufacturer:

  1. Ask questions

Ask as many questions you can think of. You need to be confident in their ability to answer your questions and you’ll feel better using a supplier who knows what they’re talking about.

  1. Check their customer service skills

As important as knowledge is, picking a manufacturer for your precast concrete mould is a big deal. You need to be comfortable asking questions – knowing that they will try their best to answer them.

  1. Find out about their headquarters

As we mentioned multiple times above, precast concrete mould is manufactured in a controlled environment. Asking questions about their headquarters/factory and how they control their conditions will make it easier to learn about that environment.

  1. Ask about their team

You want to be confident in the people working on your precast concrete mould, so ask away. Find out how long they’ve been working with concrete, if they have any certifications and so on. For example, we have a strong team who have been working within precast concrete for over forty years. This is something we’re extremely proud of and always fills customers with reassurance.

  1. Find out about their equipment

What equipment do they use? Is it all regularly serviced etc.? Are there certain benefits to using the specific tools they use? Knowledge is power!

  1. Check the materials they use

You may be on a budget, or may not want to sacrifice quality by opting for low cost materials. Ask questions about the types of materials they use, costs and what they’d recommend for what you need. This will give you an idea of the materials they use and whether they’ll be able to complete your project with your desired materials.

  1. Check their reputation

Checking their website for customer reviews/project examples is a great way to boost your confidence about investing in a manufacturer for something you’re not an expert in yourself. Plus, you’ll get a feel for the quality of the work they produce and how happy other clients were with their projects.

  1. Check their capacity

If you’re on a time-scale, check turnaround times and whether you’ll be able to get your precast concrete moulds delivered by the time you need. The last thing you want is to finally decide on a manufacturer and then find out they can’t complete your project for another six months. Also ask whether they ever have unexpected delays and how they deal with them. This will make you more prepared in the future.

At Numold, we’ve been designing and manufacturing concrete since 1978. We’re a highly recommended family-run business based in Gloucester, United Kingdom. But we have over forty year’s experience dealing with customers all across the world. In fact, we’re recognised globally for being a leader in our area of expertise. We use the highest quality materials and equipment and we boast a highly skilled, exceptional taskforce who complete every single project to the highest standard.

We work with hot and cold cast polyurethane, ABS, polypropylene, timber, steel, silicone on a regular basis. If you have any questions about any of these materials and any equipment that we use, please feel free to get in touch. You can also see examples of our high quality work here.

We also offer a pattern-making and tooling service and can produce small runs to full turn key solutions. We particularly specialise in bulk orders. So if you like our work and would like to order en masse to save some money, we can talk you through your options. If you’d like a full brochure to browse, or would like to get in touch, please do so today.

By Georgina Jones