Are you building old brick or stone with cement? Cement is harder than the wall and traps moisture. The old structure cracks around it. The solution is pure NHL 3.5 lime. It breathes and works with the wall. For bedding brick, tuff, stone, and mixed masonry. This is Kerakoll Biocalce Muratura.
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Cement mortar cracks old walls: breathable, flexible lime bedding — works together with brick and stone walls
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Building a breathable house: the wall dries freely — high vapor permeability (μ ≥ 15 ≤ 35), only natural raw materials
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Load-bearing masonry required: M5 class, 50 kg/cm² compressive strength — stable, durable bedding for all masonry
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Old and new bricks mixed: long workable mass — you have time to adjust the elements
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Mixed, irregular masonry: coarse, 0–2.5 mm grain — fills gaps, also suitable for rubble filling
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Monument, old house: traditional material, cement-free — lime, Carrara marble, dolomite limestone
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Exterior and interior: A1 fire resistance class, non-combustible mineral mass — suitable for both facade and interior
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Healthy, eco-friendly construction: antibacterial and antifungal, low VOC (EC1 plus) — GreenBuilding Rating 5
| Binder |
NHL 3.5 pure natural hydraulic lime |
| Strength class |
M5 (50 kg/cm²) |
| Grain size |
0 – 2.5 mm |
| Water vapor diffusion (μ) |
≥ 15 ≤ 35 |
| Material requirement |
≈ 1.7 kg/dm³ |
| Packaging |
25 kg bag |
What is it suitable for?
Substrates / masonry elements: Hollow and solid brick, tuff, natural stone and mixed masonry — both load-bearing and infill masonry. Monument and historic building restoration.
Functions: Bedding for breathable masonry, rubble filling and replacement of masonry (rebuilding missing wall parts), indoors and outdoors.
Spaces: Exterior and interior masonry — facades, internal load-bearing and partition walls where a healthy, breathable structure is the goal (Edilizia del Benessere).
Not suitable for:
- For dirty, loose, dusty substrates — clean first
- For interstitial (within the wall) salt content, salt efflorescence surfaces — first remove the salt
- For reinforced plaster (strengthening) — the finer M10 Biocalce Muratura Fino is the right choice
- For visible masonry jointing alone — for finer joints use Biocalce Pietra
The Biocalce masonry and restoration system
Biocalce Muratura is the layer for building the wall. A fully breathable wall construction from the structure to the finished surface:
| Layer |
Product |
Role |
| 1. Masonry |
Biocalce Muratura (this product) |
breathable lime bedding, wall construction and filling |
| 2. Base plaster |
Biocalce Rinzaffo |
adhesion promoter under the plaster |
| 3. Base coat |
Biocalce Intonaco |
breathable plaster layer |
| 4. Fine plaster |
Intonachino Fino / Granello
|
smooth or grainy, paintable surface |
| 5. Surface |
breathable paint or fine plaster |
final, breathable, colored surface |
Which Biocalce mortar do I need?
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General masonry, bedding, rubble filling (M5): Biocalce Muratura — coarse grain (0–2.5 mm), Rating 5 — this product
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Load-bearing masonry + structural reinforcement (M10): Biocalce Muratura Fino — stronger, also for reinforced plaster (ARV 100 mesh)
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Pointing + visible masonry (M5): Biocalce Pietra — fine grain (0–1.4 mm), low water absorption, can be colored with local fillers
Frequently asked questions
Why do old walls crack from cement mortar?
Cement is harder and denser than old walls and traps moisture. It does not move with the wall, causing cracks. Breathable lime mortar is more flexible and lets moisture escape.
What is breathable (lime) mortar?
Breathable mortar is made from lime and allows water vapor to pass through. This lets the wall dry out and prevents moisture from being trapped. Pure NHL 3.5 lime, high vapor permeability (μ ≥ 15 ≤ 35), without cement.
What kind of masonry is lime mortar good for?
For brick, tuff, natural stone, and mixed masonry — both load-bearing and filling. Suitable for interior and exterior, bedding, and rubble filling. For pointing, Biocalce Pietra is better.
What does M5 class and 0–2.5 mm grain size mean?
M5 is the strength class — 50 kg/cm² compressive strength, stable masonry. The 0–2.5 mm grain size: coarse mix, fills joints well. For stronger masonry, the M10 Biocalce Muratura Fino is suitable.
Muratura or Muratura Fino — which one do I need?
Muratura M5 — for general bedding, wall building, and filling. Muratura Fino M10 is stronger and can also be used for reinforced plaster. Fino is needed for repairing damaged or weakened walls.
Is lime mortar good for historic restoration?
Yes. It consists of traditional, natural ingredients — lime, Carrara marble, dolomite limestone. It suits old, breathable structures and preserves the original material.
How many bags do I need? What is the yield?
From a 25 kg bag, approximately 14.7 liters of fresh mortar is made (≈ 1.7 kg/dm³). The required amount depends on the joint size and masonry unit dimensions. We are happy to assist with calculations for larger projects.
When should I NOT use it?
Do not use on dirty, dusty, loose, or salt efflorescence-covered substrates — clean first. For reinforced plaster strengthening, Muratura Fino is suitable, and for pointing, Pietra is appropriate.
Can I build walls with it myself?
Yes — it works like a traditional mortar with a mason's trowel. However, load-bearing and historic masonry require expertise — we also execute the complete system.
