Two blocks for a 24 cm wall
Technical data
| Property | BT24 | BTA24 |
|---|---|---|
| Dimensions (length × thickness × height) | 250 × 240 × 248 mm | 250 × 240 × 248 mm |
| Construction | one central grip hole | solid |
| Strength class | 15 / 20 | 15 / 20 |
| Density | 1,4 t/m³ | 1,8 t/m³ |
| Thermal conductivity λ | 0,41 W/(m·K) | 0,65 W/(m·K) |
| Block weight | 19.7 kg | 26.0 kg |
| 24 cm wall weight | 315 kg/m² | 416 kg/m² |
| Sound insulation | Rw 52 dB without plaster, 53 dB with 10 mm gypsum plaster, 54 dB with 15 mm cement-lime plaster | Rw 58 dB without plaster, 59 dB with 10 mm gypsum plaster, 60 dB with 15 mm cement-lime plaster |
| Fire resistance | EI 240 / REI 240 | EI 240 / REI 240 |
| Reaction to fire | A1 — non-combustible | A1 — non-combustible |
| Consumption per 1 m² of wall | 16 pcs with thin-bed mortar · 15.5 pcs with conventional mortar | 16 pcs with thin-bed mortar · 15.5 pcs with conventional mortar |
| Pieces per pallet | 48 | 48 |
| Pallet load weight | 946 kg | 1 248 kg |
BT24 or BTA24 — which to choose
BT24 — load-bearing walls
Insulated external walls and internal load-bearing walls. It has λ 0.41 — the lowest among our formats — and weighs 6.3 kg less than BTA24.
BTA24 — walls between flats
Rw 58–60 dB against the R'A1 ≥ 50 dB requirement of PN-B-02151-3:2015, plus REI 240 for fire-separating walls.
BTA24 — foundations and basements
Solid unit, always with damp-proofing. First course on cement mortar laid over roofing felt.
BT24 1/2 — corners
Half block 124 × 240 × 248 mm with one central hole, 9.8 kg, 96 units per pallet. For corners and wall ends.
How many 24 cm sand-lime blocks for a wall
For 1 m² of wall, you need 16 blocks with adhesive mortar and 15.5 with traditional mortar. Example: a 10 × 2.75 m wall with 4.5 m² of openings gives 23 m² of masonry, or 368 blocks. We sell full pallets, so the order is 8 pallets, or 384 units. Calculate your own requirements using the block calculator.
A 24.5 t flatbed carries 25 BT24 pallets, or 1 200 blocks for about 75 m² of wall, or 19 BTA24 pallets. Zones and HDS unloading: sand-lime block delivery.
BT24 external wall — insulation
Sand-lime masonry carries loads and reduces noise, while the insulation layer determines thermal performance. Calculation according to PN-EN ISO 6946 for BT24 with graphite EPS λ 0.031:
| Insulation thickness | Wall U-value | Reference |
|---|---|---|
| 16 cm | 0,17 W/(m²·K) | WT 2021: U ≤ 0.20 |
| 20 cm | 0,14 W/(m²·K) | margin relative to WT 2021 |
| 30 cm | 0,10 W/(m²·K) | passive-house level |
Masonry work
- First course on cement mortar over horizontal roofing-felt damp-proofing; subsequent courses on adhesive with a 2 mm joint.
- Half-block bond, i.e. 125 mm; BT24 1/2 half blocks at corners and wall ends.
- Vertical tongue-and-groove joints without mortar, gap up to 2 mm.
- A mechanical gripper can be used for the heavier BTA24 (26 kg).
Full rules: how to build with sand-lime blocks.
Documents
We issue a declaration of performance for every delivery. Factory production control is supervised by the notified body KIWA (certificate 0770-CPR-8178-01-17). Download: sound insulation (PDF) and fire resistance (PDF).
Frequently asked questions
How much does a 24 cm sand-lime block weigh?
BT24 weighs 19.7 kg, solid BTA24 26.0 kg and the BT24 1/2 half block 9.8 kg. One square metre of unplastered wall weighs 315 kg with BT24 and 416 kg with BTA24.
How many 24 cm sand-lime blocks are on a pallet?
48 BT24 or BTA24 blocks and 96 BT24 1/2 half blocks. The pallet load weighs 946 kg (BT24) or 1 248 kg (BTA24). We sell full pallets.
How many 24 cm sand-lime blocks are needed per 1 m² of wall?
16 blocks with adhesive and 15.5 with traditional mortar. The 250 × 248 mm block face with a 2 mm adhesive joint gives a 250 × 250 mm module.
Solid or holed 24 cm sand-lime block — how does BTA24 differ from BT24?
BT24 has one grip hole, density 1.4 t/m³ and λ 0.41 W/(m·K). BTA24 is solid, with density 1.8 t/m³ and sound insulation Rw 58–60 dB (depending on plaster), so it is used for walls between flats, foundations and basements.
What are the dimensions of a 24 cm sand-lime block?
250 × 240 × 248 mm (length × thickness × height). With a 2 mm adhesive joint this gives a 250 × 250 mm module. The BT24 1/2 half block measures 124 × 240 × 248 mm.
Is 24 cm sand-lime from Trąbki the same as Silka 24?
No. Silka is Xella's block brand. Our 24 cm sand-lime range is BT24 and solid BTA24: 250 × 240 × 248 mm, class 15 or 20, PN-EN 771-2 standard.
18 or 24 cm sand-lime block — which to choose?
Both blocks suit load-bearing walls and insulated external walls. With 20 cm graphite EPS λ 0.031, both walls have U = 0.14 W/(m²·K), so insulation determines thermal performance. The 18 cm wall is 6 cm thinner, giving more floor area, and BT18 weighs 16.6 kg versus 19.7 kg for BT24. A 24 cm wall has REI 240 even without plaster; an 18 cm wall achieves this after plastering. The designer selects load-bearing wall thickness. 18 cm blocks: 18 cm sand-lime blocks.
Does a 24 cm block wall need insulation?
Yes. A BT24 wall with 16 cm graphite EPS λ 0.031 has U = 0.17 W/(m²·K) and meets WT 2021 (U ≤ 0.20). With 20 cm insulation, U is 0.14; with 30 cm, 0.10.
What fire resistance does an 24 cm sand-lime wall have?
EI 240 / REI 240 according to PN-EN 1996-1-2, for both BT24 and BTA24. Sand-lime material has reaction to fire class A1 — non-combustible.
Prepared by the manufacturer, plant operating since 1920.
Request a quotation
We answer enquiries from the entire West Pomeranian voivodeship, as well as Lubusz and Pomeranian voivodeships. Provide the format, quantity in m² or pallets and delivery location — we will prepare a quotation including transport.