Welcome To Our National Bulk Polystyrene Online Ordering Portal

Johannesburg (Gauteng)

011 678 5626

Cape Town (Western Cape)


021 200 5926

Durban (Kwazulu-Natal)

031 940 7056

East London & PE

087 095 3259

National Sales

Please Note That We Are Now Taking Last Orders For 2021

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PolySlab - Polystyrene Rib & Beam Block Void-Formers For Concrete Slab Construction

SKU PS-Johannesburg-110mm (20DV)-1200mm-25mm Lip x 65mm Cutout
Supplied Nationally In South Africa
In stock
Product Details

Order Polystyrene Rib & Beam Block Void Formers Or Decking Blocks - For Concrete Slab Construction Online Today!


We are currently running a massive online special on this product so don't miss out!

If you are a concrete slab construction company then you will really be excited about the ability to simply order your polystyrene slab void-formers, for your rib & block concrete slab projects, nationally online in seconds!

PolyStab Void-Formers are the perfect alternative to traditional ash blocks because they are lightweight and significantly increase the speed at which concrete slabs can be cast and reduce the weight of the slab resulting in less jacking support costs.

Our standard size PolySlab void-former blocks are also the most cost-effective way to cut polystyrene decking blocks / void formers without any significant wastage.

Please note that we are NOT engineers and we do NOT design or install concrete slabs. We just supply the polystyrene blocks.

Don't miss out on our current PolySlab Block special, check out our google reviews and simply order them nationally online when you are ready. Simple, Reliable & Fast!

Order Collections & Deliveries

Depending on the size of your order and location, we will deliver or you can self-collect from any of our national distribution centers located in:

  • Strydompark in Gauteng
  • Philippi in Western Cape
  • Clairwood in Kwazulu-Natal
  • Wilsonia in East London or
  • Neave Industrial in Port Elizabeth

Order lead time is generally 3 to 5 working days for cutting and delivery, once payment reflects in our bank account. This lead time excludes public holidays and weekends. If you need product faster please call us so that we can try and assist.

Standard Polystyrene Block Sizes & Dimensions:

  • Below you will see our standard blocks dimensions.
  • To avoid wastage and costs the blocks are all 1200mm long.
  • We can custom-cut blocks if necessary.

Estimated PolyBlock Thicknesses Based On Concrete Slab Thicknesses

  • Concrete slabs have to be designed and inspected by qualified engineers to ensure that the design loads of the slab meet the design of the concrete slabs.
  • Consult with your engineers to determine if these blocks are suitable based on you slab design and slab loading requirements.
  • Your engineer will specify the thickness of the blocks required.
  • We will not supply PolySlabs to consumers unless they provide proof that an engineer has done a proper design.

Final Concrete Slab Thickness PolySlab Block Thickness
170mm 110mm
200mm 150mm
255mm 190mm
300mm 230mm
340mm 285mm

PolySlab Design Properties

  • Your engineer can use these properties to finalise your concrete slab design.

Density Compressive Strength Cross-Breaking Strength
X-Grade 60 kPa @ 10% compression 80 kPa @ 1% compression
20DV 110 kPa @ 10% compression 150 kPa @ 1% compression

PolySlab Online Prices:

  • Our Online Prices are blocks prices excluding VAT.
  • If you order is over 1000m2 then we can discuss a better rate.

PolySlab - Rib & Block Void Former Or Decking Blocks

  • PolySlab Blocks are expanded polystyrene decking blocks or void formers used in rib & block slab construction.
  • PolySlab Blocks are used instead of traditional ash blocks and they are placed between the concrete lintels to create a base on which the final concrete slab can be cast.

Benefits of using PolySlab Blocks instead of Ash Blocks

  • PolySlab Blocks are lightweight and easy to lift in multi-story building projects.
  • They significantly reduce they final weight of the concrete slab.
  • They increase the rate at which concrete slabs can be prepared and constructed.
  • Lightweight slabs reduce the amount of jacking supports required and the time that such supports need to remain in place.
  • This means that work can resume faster during the curing period of the concrete slab.
  • They increase the thermal and acoustic properties of the concrete slab.

Order Process:

  • Select the closes distribution Centre to your project.
  • Add the products and quantities you want to you order.
  • Add collection or delivery if available
  • Simply order online or submit your order to us for review.
  • Fast & easy!

Payment Methods

  • Credit Card
  • Instant EFT
  • Invoice & EFT
  • Submit For Review

About Polystyrene Product Company (Pty) Ltd

Polystyrene Product Company, established nationally in South Africa in 2016, is a well known & respected bulk national supplier of polystyrene sheets, blocks, insulation, extruded polystyrene ceilings & void-formers in South Africa & for export.

Since 2016, we have supplied polystyrene to over 14000 customers nationally in South Africa, Botswana, Mozambique, Zambia, Zimbabwe & Mauritius. We have also supplied bulk polystyrene to many of the biggest construction projects in South Africa.

We are the #1 National Online Ordering Platform For Bulk Polystyrene In South Africa, making it easier and faster for architects, builders, bulk buyers & the general public to order polystyrene online in SA.

CO. Reg Number: 2016/072709/07

VAT Number: 4220273447

National Sales & Logistics (Johannesburg) 011 678 5626

Cape Town Sales 021 200 5926

Durban Sales 031 940 7056

East London & PE Sales 087 095 3259


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Polystyrene Product Company

Your Trusted Specialists In Bulk Polystyrene For Concrete Floor Insulation, Cavity Wall Insulation, Concrete Roof Insulation, Thermal Ceilings & Void-Former Applications

National Sales & Head Office


Unit 8, Lower Ground Level, Commercial City, Tungsten Rd, Strydompark, Randburg, 2194

VAT Number: 4220273447

CO. Reg Number: 2016/072709/07

Main Office Number:

011 678 5626


Main Email:

Recently Supplied Projects

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1400m2 of 120mm Extra-High Density Concrete Roof Insulation (PolyRoof Insulation) Laid On Top Of Torch-On Waterproofing With Paving Overlay

Hydroboard Insulation_edited.jpg
PolyVoid - Structural Fill Blocks.jpg

Nelson Mandela Children's Hospital Raised Slab Project 

3000m2 of 50mm Extra-High Density Concrete PolyVoid Fillers To Raise An Existing Concrete Slab By 1m. Extra-High Density Polystyrene Has Incredible Compressive Strength Properties.


Let's Explore Your Polystyrene Building Requirements Together!