Hi Gareth - thank you for your question. There isn't any published information on the size of the internal holes for these hollow dense blocks. In addition, the actual products stocked by our merchant network will vary slightly as they come from a variety of different manufacturers depending on location, so it is difficult to provide an accurate answer. To be certain, we would recommend a physical measurement being taken. Once an order is placed and a supplying branch confirmed, we can support with this. As a word of caution, these blocks are very strong in compressive strength, but not necessarily designed to support loads from within the hollow section itself.








215mm Hollow Dense Concrete Block 7.3N
Delivery & Returns Information
Delivery charges vary by product category and order value. Items may ship from different suppliers and arrive separately, so delivery charges can be shown per part of your order at checkout.
Standard (Nationwide) Delivery
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Core Products Core
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|---|---|
| ORDER VALUE | DELIVERY CHARGE |
| Under £300 ex. VAT | £30 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.
| Timber & Sheet, Building Materials, Joinery and Gardens & Landscaping Products | |
|---|---|
| ORDER VALUE | DELIVERY CHARGE |
| Under £300 | £25 ex. VAT |
| Over £300 ex. VAT | FREE |
Express Delivery
| Express Delivery - Insulation and Plasterboard & Drylining | |
|---|---|
| ORDER VALUE | DELIVERY CHARGE |
| Under £400 | £90 ex. VAT |
| Over £400 ex. VAT | £55 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 |
How delivery works
We work with a nationwide network of trusted suppliers. Items in your basket may be supplied by different suppliers and delivered separately. Where this applies, you will see delivery charges shown at checkout for each part of your order. We always aim to group products from the same supplier to keep delivery costs as low as possible.
Delivery areas
Delivery charges apply to mainland UK, excluding: AB, CA, CF, DD, DG, EH, EX, FK, KA, KW, KY, IV, LA, LD, LL, ML, NP, PA, PH, PL, SA, SY, TR, TQ and TD.
If your address is in one of these areas, we will contact you before processing your order to confirm any additional costs. We do not currently offer delivery outside the UK mainland.
What to expect on delivery day
- Deliveries are typically kerbside.
- Please ensure someone is on-site to accept delivery. For heavier items, help with offloading may be required.
- Many building materials arrive on large vehicles. If access is restricted, a specialist vehicle such as a HIAB may be required and could incur an additional charge.
Why delivery can cost more than typical parcel delivery
Building materials often travel on larger vehicles and usually carry fewer drops per run than parcel networks. That is why delivery charges can be higher than standard e-commerce shipping.
Returns
Returns depend on what you have bought and whether there is anything wrong with it. For full details on eligibility, timeframes, and exclusions, please see our full policy.
Key Features
- {{fitness_center}} Provides exceptional structural strength
- {{volume_off}} Excellent natural sound insulation
- {{local_fire_department}} Inherent non-combustible fire resistance
- {{private_connectivity}} Hollow voids can be reinforced with concrete and rebar
Technical Specification
| URN: | 5003188 |
|---|---|
| Product: | Single |
| Application: | Internal & external load-bearing masonry |
| Indoor/Outdoor Usage: | Indoor & Outdoor |
| Material Type: | Concrete |
| Thickness: | 215mm |
| Length: | 440mm |
| Height: | 215mm |
| Weight: | 27.5kg |
| Sales Unit: | Each |
| Sales Unit Coverage: | 0.1m2 |
| Fire Rating: | A1 Non-Combustible |
| Moisture Resistant: | Yes |
| Compressive Strength: | 7.3N |
| Certification: | BBA Certified |
| Product Standard: | BS EN 771-1 |
| Grade: | High Strength |
| Edge: | Square |
| Colour: | Natural / Grey |
Product Overview
215mm hollow dense concrete block with a compressive strength of 7.3N/mm², measuring 440mm x 215mm x 215mm.
Manufactured from a dense aggregate mix with central voids, it combines reliable load-bearing strength with easier handling and reduced dead weight compared to solid units.
The hollow format also allows reinforcement or insulation to be introduced into the cores, making it a versatile option for foundations, external walls, partitions, and structural walls above or below DPC.
Features & Benefits
- 7.3N/mm² compressive strength: Certified load-bearing capacity for residential, commercial, and industrial walls.
- Hollow core design: Reduces block weight for easier handling and installation.
- Dense aggregate composition: Provides long-term durability and resilience against impact and wear.
- Voids for reinforcement or insulation: Allows structural reinforcement or thermal upgrades within the wall.
- High mass per unit: Delivers effective sound insulation for partitions and separating walls.
- Non-combustible (Euroclass A1): Provides inherent fire resistance in line with building regulations.
- Standard size 440mm x 215mm x 215mm: Compatible with UK brick and block modular dimensions.
- BS EN 771-3 compliance: Manufactured to European standards for aggregate concrete masonry units.
Applications
- Can be used with load-bearing walling: Suitable for external and internal structural walls.
- Partition walling: Provides strength and acoustic performance for internal divisions.
- Beam, column, and retaining wall construction: Hollow cores enable reinforcement for added strength.
- Boundary and foundation walls: Versatile option for stable, durable walling solutions.
Installation Guidance
- Mortar bedding: Lay on full mortar beds to ensure load transfer and stability.
- Core reinforcement: Where required, fill voids with concrete or insulation to meet structural or thermal needs.
- Handling and placement: Hollow design makes units lighter than solid blocks but still requires safe manual handling.
Compliance & Performance
- Compressive strength 7.3N/mm²: Provides certified load-bearing performance for structural use.
- BS EN 771-3 compliance: Produced in line with standards covering strength, density, dimensional accuracy, and durability.
- Pallet Charge: Orders requiring a pallet will incur a refundable pallet charge. Our customer service team will confirm if this applies to your order.