How to create the perfect concrete base for an extension

By April 15, 2024Blogs, News
Cement screed on concrete slab in backyard project

We are suppliers of high-quality barrow mix concrete for extensions to commercial, industrial, and residential building projects in Stockport, Manchester, Cheshire and surrounding areas.

We have over 30 years of experience supplying concrete to a wide variety of users, ranging from general contractors, local authorities, main contractors and even DIYers. Over these thirty years, we have built up a wealth of expertise in the barrowing system of concrete placement, which has led to our excellent reputation among our clients.

Don’t let your dream extension become a cracked nightmare – ensure a solid foundation from us at New Mix for a safe and lasting addition to your home.

Planning Your Concrete Base

Understanding Ground Conditions

Understanding your soil type and potential drainage issues is key to building a strong foundation for your extension. Different soil types have varying strengths, impacting the concrete base thickness needed.

Additionally, poor drainage can cause water to accumulate and crack the foundation. By knowing your soil and drainage situation upfront, you can ensure a stable and long-lasting base for your extension.

New Mix can offer expert advice (during a site visit) on concrete selection based on your ground conditions. Book a site visit here.


Building Regulations and Permits

Thanks to permitted development (PD), it is not unusual to find extensions being built without any need for a formal planning application.

That said, there is still a legal obligation for homeowners to ensure that any construction work complies with building regulations.


Calculating Concrete Needs

Sometimes it is hard to know exactly how much concrete you need for a project.

One way to help with this is to use New Mix Concrete’s easy to use concrete calculator. You can work out how much concrete you may need, and only pay for what you need which eliminates any wastage. Calculate your concrete volume here.

cracked concrete cement sidewalk foundation

Creating the Perfect Concrete Base (Step-by-Step Guide)

Excavation

Excavating the trench for your extension’s foundation is the first crucial step.

Refer to your building plans that will specify the exact dimensions of the foundation.

Clearly mark the perimeter of the foundation using stakes and string.

Begin digging out your foundation, measuring the depth and width as you go according to your building plans. You can hire an excavator of your own to do the digging, rather than manually.


Sub-Base Preparation

A compacted sub-base is essential for creating a strong and stable foundation for your concrete base for several reasons including weight distribution, stability and drainage.

Well graded granular shot type material should be used to form the sub base and once levelled and compacted, a thin blinding layer of sand (no deeper than 20mm) can be used to fill any voids in the surface. Install drainage if it is necessary.

man digging a hole in the ground with shovel and spade

Formwork

Formwork is like a temporary mould that holds the wet concrete in place until it sets and cures. Building the formwork is a crucial step in creating a strong and well-defined concrete base for your extension.

Set up and secure the frame using wooden slats or fabricated metal sheets and then line the walls with plastic sheeting.


Mixing and Pouring Concrete

Ready-mixed concrete is a good option because it provides consistent quality and saves you the time and effort of mixing your own on-site concrete.

At New Mix, we prepare the concrete volumes at your site, making our ready-mixed concrete a significantly more affordable solution. Furthermore, because you only pay for what you use, there is no wastage and no excessive costs.

Our experienced team then wheelbarrows the ready mixed concrete to your foundation site and will pour it for you.

Iron fittings on a wooden formwork with laid pipes are the basis for pouring the foundation of the house with a concrete slab. Construction of cottages, design, engineering communications.

Read our article here about why we go out of our way to wheelbarrow the concrete for you.


Compaction and Finishing

You’ll now need to compact the concrete to ensure a strong and stable foundation. This process removes air pockets that can weaken the concrete and helps achieve a smooth, level surface.

To do this you can use a vibrating plate compactor across the entirety of the newly poured concrete. For the smaller and harder to reach areas such as the corners, you can use a tamping rod.

For further compacting and to create the perfect finish to your concrete base for your extension you can top it off with liquid screed.

Screeding over underfloor heating pipes in residential property

Curing

Curing is essentially keeping the concrete moist for several days after it’s been poured. This allows the hydration process (a chemical reaction between the concrete and water) to continue throughout the concrete, not just on the surface.

To cure your concrete base, the easiest way is to spray it with water several times a day for the first seven days after it has been poured.

slabs

New Mix provides the perfect foundation for your extension with high-quality ready-mix concrete. Our consistent mixes and convenient delivery ensure a smooth pouring process. Our expert advice can help you choose the right concrete type and answer any questions you might have.

By following these steps and using top-notch concrete from New Mix, you can be confident in creating a strong, stable, and long-lasting foundation for your dream extension.

Order Your Ready Mix Concrete Here

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