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300mm Thermalite Aircrete 3.6N Trenchblock

URN: 5003095
Core
£6.17ex. VAT £65.22 per m2 Get it for £5.80 ex. VAT with CORE+
£6.17ex. VAT
£65.22 per m2
300mm Thermalite aircrete Trenchblocks offer a unique building solution for below-ground construction needs.

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Thu 7 Aug

Order by Monday at 2pm
  • 2days
  • 12hrs
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  • 46secs

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Product Overview

300mm Thermalite aircrete Trenchblocks offer a unique building solution for below-ground construction needs.

URN: 5003095
£6.17ex. VAT

Delivery & Returns Information

How Our Delivery Works

We work with a nationwide network of trusted suppliers. As a result, items in your basket may be supplied by different suppliers and delivered separately. Where this applies, you'll see multiple delivery charges at checkout. We always aim to group products from the same supplier to keep delivery costs as low as possible.

Delivery Areas & Charges

Delivery charges listed on our website apply to mainland UK, excluding the following postcode areas: AB, CF, DD, DG, KW, IV, LA, LD, LL, NP, PH, SA, SY
If your delivery address falls within one of these postcode areas, we’ll be in touch before processing your order to confirm any additional delivery costs.
Please note: We do not currently offer delivery outside the UK mainland.

Standard (Nationwide) Delivery

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Under £300 ex. VAT £20 ex. VAT
Over £300 ex. VAT FREE

Core Delivery charges apply only when all products in an order that have equivalents are accepted as such. If even one product cannot be substituted with an equivalent, the entire order will not qualify for Core Delivery charges.

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Under £100 £15 ex. VAT
Between £100 - £200 ex. VAT £10 ex. VAT
Over £200 ex. VAT FREE
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Between £150 - £350 ex. VAT £35 ex. VAT
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Express Delivery

Express Delivery - Insulation and Plasterboard & Drylining
ORDER VALUE DELIVERY CHARGE
Under £400 £50 ex. VAT
Over £400 ex. VAT £35 ex. VAT
Express Delivery - Timber & Sheet, Building Materials, Joinery and Gardens & Landscaping Products
ORDER VALUE DELIVERY CHARGE
Under £300 £50 ex. VAT
Over £300 ex. VAT £35 ex. VAT

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Returns

We offer a 30 day returns policy on any faulty products.

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Key Features

  • {{check_circle}} Eliminates the need for mortar perpends 
  • {{thermostat}} Contributes to improved thermal performance 
  • {{line_style}} Substitute for constructing cavity walls using concrete infill
  • {{update}} Accelerates the construction of foundation walls below DPC

Technical Specification

Technical Specification
Thickness:300mm
Length:440mm
Height:215mm
Sales Unit:Each
Brand:Thermalite
Manufacturer's Reference: STTG3001103GR
Weight:17.5kg
Compressive Strength:3.6N


Orders large enough to require a pallet will require a £20 ex VAT refundable pallet charge to be paid per pallet. Our customer service team will reach out to you if this applies to your order

What Is 300mm Thermalite Aircrete 3.6N Trenchblock? 

300mm Thermalite Aircrete 3.6N Trenchblock offers a proven and highly economical alternative to traditional foundation construction methods like cavity walls with concrete infill, engineering bricks, or dense aggregate blocks. 

A "Trenchblock" is specifically designed for use in foundation trenches. The key feature of this 300mm wide Thermalite Trenchblock is its ability to form a solid foundation wall in a single leaf, directly replacing the need for constructing two separate leaves of a cavity wall below ground. 

These innovative blocks are designed to simplify and accelerate the construction of foundation walls below Damp Proof Course (DPC) level, while also significantly enhancing the thermal performance of the ground floor.


What is Aircrete? 

Thermalite blocks are a type of Autoclaved Aerated Concrete (AAC), commonly known as aircrete. This lightweight material is manufactured from sand, cement, lime, pulverised fuel ash (PFA), water, and an aerating agent. 

During production, the mix expands, creating millions of tiny, non-interconnected air cells. The blocks are then steam-cured under pressure in an autoclave, resulting in a strong, stable, and highly insulating material.

Applications

The 300mm Thermalite Aircrete 3.6N Trenchblock is primarily designed for:

  • Solid Foundation Walls: Constructing the foundation walls below DPC level for: 
    • Domestic houses (detached, semi-detached, terraced).
    • Extensions to existing properties.
    • Some low-rise commercial or public buildings (subject to structural design).
  • Internal Load-Bearing Walls Below DPC: Can be used for internal foundation walls supporting internal load-bearing structures.
  • Party Walls Below DPC: Suitable for constructing the foundation element of party walls.


Benefits

  • Economical Foundation System: Offers a cost-effective alternative to traditional methods by reducing materials (no cavity fill, fewer blocks than two skins) and labour time.
  • Rapid Construction: Lightweight nature makes blocks easier and quicker to handle and lay.
  • Enhanced Thermal Performance: The micro-cellular structure of aircrete provides excellent thermal insulation properties compared to dense masonry. Using these trenchblocks helps to reduce heat loss through the foundation walls, minimising thermal bridging at the ground floor junction and contributing to the overall energy efficiency of the building.
  • Superior Sulfate Resistance: This specific Thermalite Trenchblock is suitable for use in ground conditions with up to Design Sulfate Class DS-4. This provides excellent durability and protection against sulfate attack in challenging soil environments found in parts of the UK.
  • Lightweight and Easy to Handle: Significantly lighter than traditional concrete blocks, reducing manual handling strain for operatives and allowing for faster laying rates.
  • Workability: Aircrete is easy to cut, saw, chase, and shape on-site using standard woodworking tools, allowing for precise adjustments and detailing.
  • Reduced Waste: Uniform dimensions and ease of cutting can lead to lower material wastage on site.
  • Excellent Fire Resistance: Aircrete is a non-combustible material and offers high levels of fire resistance.
  • Proven Performance: Thermalite trenchblocks are a "tried and tested" solution, widely used and accepted for foundation construction.

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Q&A

Are these tongue and groove blocks?

No - these blocks are square faced and installed in the wall/foundations butted together with mortar.

answer supplied by James Herbert on 23 May 2025

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