Partition Walls: Hollow Bricks or Large-Format, How to Choose

Clay partition walls: hollow brick or large format

A partition wall is the interior wall that divides spaces and, in principle, does not carry the building's loads. To build one in clay you have two routes: hollow brick in the traditional format, easy to handle and to cut, and large-format pieces, which cover more surface with fewer pieces and fewer joints. The choice depends on the thickness you need, the weight you can move on site and the time you have.

These are the five pieces in the Vetonek range designed for partition work, with the data from their technical sheets.

Hollow brick for partitions: Irun, Zarautz and Hondarribia

The Irun single hollow brick is the light partition brick: 32 x 14.5 x 4.5 cm (±10 %), 1.92 kg and about 20 pieces per m². At just 4.5 cm thick it takes up very little space and suits partitions, wall linings, closing off openings and boxing in ducts. It is sold by the pallet of 480 pieces (24.12 m²).

The Zarautz double hollow brick measures 24.5 x 11.5 x 8.1 cm and weighs 1.68 kg. Laid “a tabicón” it gives a partition of about 8 cm with ≈33 pieces/m², and its double row of cavities improves thermal and acoustic performance compared with a single hollow brick. It is sold by the pallet of 472 pieces (14.22 m²).

The Hondarribia hollow brick is the 50 x 20 cm format: 10 pieces per m² and three thicknesses, 7 cm (about 5 kg), 5 cm (about 3.5 kg) and 4 cm (about 3.2 kg). The 50 x 20 cm formats carry CE marking and, according to their sheet, are laid with mortar without wetting the pieces. There is also a 28 x 12.5 x 4 cm format (about 1.1 kg, 25 pieces/m²), very manageable in flat renovations without a lift.

Eibar machetón: sturdier partitions

The Eibar machetón brick is a large-format hollow brick with thick walls. Format 33 (32.2 x 14.2 x 6.6 cm, 2.48 kg, ≈20 pieces/m²) is for openings, door jambs and finishing details; format 50 (48.8 x 19.5 cm, 6.8 cm thick, 4.55 kg, ≈10 pieces/m²) is the one for large areas. At 6.6-6.8 cm thick it is sturdier than a thin partition. Many professionals combine both formats to reduce cuts and waste.

Mutriku large-format clay partition

The Mutriku large-format clay partition measures 70.5 x 51.5 cm and covers 1 m² with only 2.77 pieces, so there are fewer pieces, fewer joints and less mortar than with a conventional brick. It is made of red clay, for interior use, with a regular surface that makes finishing easier, and it cuts with an angle grinder. It allows chases for services. It comes in four thicknesses: 10 cm (20 kg per piece), 7 cm (15 kg), 5 cm (13.6 kg) and 4 cm (12.5 kg). With pieces of 12.5 to 20 kg, its sheet advises working in pairs with the 7 and 10 cm thicknesses.

Single, double-leaf or wall lining: which thickness to choose

• Single partition: Mutriku in 10 and 7 cm; Hondarribia in 7 cm; Irun (4.5 cm) or Zarautz “a tabicón” (about 8 cm) for light room divisions.
• Double-leaf and double partitions: thicknesses of 5 and 4 cm, offered by both Hondarribia and Mutriku.
• Wall lining: covering an existing wall with a leaf of brick; it is done with the thin thicknesses (5 and 4 cm) and also with Irun, Zarautz and the Eibar machetón.

If the partition has to support more than its own weight, or if you are unsure of its role in the structure, consult the project engineer or architect before deciding.

Pieces per m² and weight: quick comparison

• Irun: ≈20 pieces/m², 1.92 kg per piece.
• Zarautz (“a tabicón”): ≈33 pieces/m², 1.68 kg per piece.
• Hondarribia 50 x 20 cm: 10 pieces/m², 3.2 to 5 kg per piece.
• Eibar format 33: ≈20 pieces/m², 2.48 kg; format 50: ≈10 pieces/m², 4.55 kg.
• Mutriku: 2.77 pieces/m², 12.5 to 20 kg per piece.

For example, for a 24 m² partition in Hondarribia 50 x 20 x 7 cm you need 24 × 10 = 240 pieces, that is, 1 pallet of 160 pieces and 1 pack of 80 pieces. For 30 m² of 7 cm Mutriku, 30 × 2.77 = 83.1, so 84 pieces, exactly 3 pallets of 28 pieces. Always add a margin for cuts and breakage.

Laying: keys to a straight partition

1. Set out the partition on the floor and mark the door openings.
2. Bed the first course level on mortar: with large formats, errors carry through.
3. Lay the pieces with mortar or plaster (according to each model's sheet), staggering the vertical joints.
4. Check plumb and flatness with a straightedge and spirit level every few courses.
5. Make cuts with an angle grinder and open the chases before finishing.
6. Finish against the slab above with plaster or foam, leaving a small gap and without loading the partition.

Frequently asked questions

Which brick is used for an interior partition wall?

Usually a hollow brick, either in the traditional format (Irun, Zarautz), in 50 x 20 cm (Hondarribia, Eibar) or a large-format clay partition (Mutriku). The choice depends on the thickness, the weight of the piece and how fast you want to work.

How many bricks are needed per m² of partition?

It depends on the piece: about 20 for Irun and for the Eibar machetón in format 33, ≈33 for Zarautz “a tabicón”, 10 for the 50 cm formats and 2.77 for the Mutriku partition. Add a margin for cuts and breakage.

What partition thickness should I choose?

For a single partition, 7 and 10 cm are the usual thicknesses in Mutriku and Hondarribia, and 4.5 cm in Irun when you want to save space. For double-leaf partitions and wall linings, 5 and 4 cm.

Can you hang weight on a hollow brick partition?

You can hang light loads using anchors made for hollow brick, and on thin partitions such as Irun you should reinforce the area for kitchen units or radiators. For heavier loads, consult the project engineer.

What are the advantages of a large-format clay partition?

It covers more surface with fewer pieces: 2.77 per m² in Mutriku. That means fewer joints and less mortar, and its regular surface makes finishing easier. On the other hand, the pieces weigh between 12.5 and 20 kg, so it is best to lay them as a two-person job.

Find every piece in the clay bricks and blocks collection and the rest of the range under building ceramics. You can also read the guide to clay bricks: types and how to choose, the one on the thermal clay block for single-leaf walls and the one on concrete blocks.