Understanding monomur brick and distributed insulation
Monomur brick: principle, composition and common formats
Monomur brick is a thick, hollow fired-clay block, laid as masonry (often with thin joints). Its cells create air pockets that improve thermal resistance. It's commonly found in thicknesses of around 30, 37.5, 42.5, or even 50 cm, depending on the range and the intended use.
Distributed insulation: how the brick limits heat loss
This is called distributed insulation because the insulation isn't an added layer. The performance comes from the brick's own structure, which combines still air and thermal mass. Thin joints and interlocking also reduce certain thermal bridges, provided you take care with tie beams, reveals and floor connections.
When monomur brick replaces an insulation system
It can replace a full insulation system when the chosen thickness and design (thermal bridges, airtightness) allow the target to be reached. In 2026, for higher performance levels, additional insulation (external cladding or internal lining) is often planned, depending on the climate, the glazed surface area and site constraints. A thermal study or an audit settles this quickly, without guesswork.
Thermal performance of the brick: what you can realistically target in 2026
Thermal resistance, thermal mass, thermal bridges: the points that make the difference
With brick, performance is first and foremost about the thermal resistance of the finished wall. Thermal mass smooths out temperature swings, but it doesn't compensate for too low an R-value. The gaps mainly come from thermal bridges at floors, reveals, sills and tie beams. A good detail is often worth more than a "thick" block.
Monomur brick alone or with additional insulation: decisions by climate zone
In climate zone H3, a well-laid monomur wall can already give a correct level, if airtightness and connections are properly treated. In H1 and H2, additional insulation is most often needed to reach the levels expected in renovation projects in 2026. External insulation keeps the thermal mass on the inside. Internal insulation is simpler, but demands more vigilance on thermal bridges.
Summer comfort and hygrothermal behaviour: strengths and limits on site
Brick helps with summer comfort thanks to its thermal lag, provided solar gains are limited and effective ventilation is ensured. On the moisture side, it tolerates variations better than a very sealed façade, but a poorly chosen build-up can trap water. Suitable renders, vapour-barrier continuity and letting the shell dry remain your safeguards.
Installation: getting a monomur brick masonry wall right from the first course to the finishes
Layout, flatness and the first course: securing the base
Before laying the first brick, mark out the axes, check the diagonals and start from a clean, sound support. The first course is laid on a bed of traditional mortar to level out the base. Check flatness with a straightedge and a laser. A defect here carries through the whole height. Also think about reservations and alignment of the block ends.
Thin-bed mortar, thin joints, cuts: avoiding common mistakes
Monomur brick is then built up with thin-bed mortar in thin joints. Respect the water dosage, apply with the right tool, then interlock the bricks without "drowning" them in mortar. For cuts, favour a material saw and remove dust before bonding.
- Do not bond onto a frozen brick.
- Avoid joints that are too thick.
- Protect the courses from rain.
Connections and singular points: floors, reveals, tie beams and lintels
At floors, reveals and tie beams, follow the parts specified by the system and take care over airtightness. Fit compatible lintels, align the sills, and treat thermal bridges with the thermal-bridge breakers or additional insulation provided for. At the end of the job, fill in chases, render or plaster depending on the substrate, then let the masonry dry properly before the finishes.
Site compatibility: joinery, floors, roofing and additional insulation
Fitting joinery: airtightness, sills and jambs suited to brick
Fitting hinges on continuity. Connect the frame and the masonry with sealing tapes, membranes and sealant, not just foam. Check the sills (slope, drip edge, flashing) so water drains away. On a brick wall, choose jambs suited to the thickness of the lining and the reveals, to align the insulation and limit air leaks.
Treating thermal bridges: breakers, load-bearing partitions and junctions
Identify cold zones before closing up. Wall-floor and wall-roof connections, and load-bearing partitions, can short-circuit the insulation. Floor thermal-bridge breakers, insulation returns at the reveals, and careful treatment of junctions (lintels, wall bases, hatches) prevent condensation and discomfort.
When to add insulation: internal/external, renders, linings and compatible cladding
Add insulation if the walls remain inconsistent, or if you're changing the joinery. For internal insulation, favour a lining on a frame with a continuous vapour barrier. For external insulation, check compatibility between the render, base coat and fixings, especially on brick, to keep a consistent, durable envelope. To secure the façade details (sills, reveals, parapets), lean on this guide to treating singular points.
Costs, timelines and points to watch: selling monomur brick without bad surprises
Price per m² and installation time: what makes the budget vary
The cost of a monomur brick wall mainly depends on the thickness, the format (cellular, rectified) and the mortar or adhesive used. Labour also varies with the complexity of the cuts and site access. On site, quote a realistic range and clearly frame what's included. Supplied and installed costs and thermal-bridge treatments often move the total.
Quality, storage and handling: protecting the brick on site
A damaged or waterlogged brick means lost time and dropping performance. Store on stable, wrapped pallets, away from rising damp. Plan for a clean cutting area and limit knocks to the corners. Rain protection and checking batches on delivery avoid bad surprises.
Talking to clients: the "1 step" simplicity, performance and 2026 compliance
With clients, sell the "1 step" idea when the brick delivers structure and insulation in a single stage, while keeping a clear message about the possible additions (renders, thermal-bridge breakers, extra insulation). In 2026, highlight consistency with RE2020, CE marking and compliance with best-practice rules. Compliant and durable, without magic promises.
Key figures
0.08 to 0.12 W/m·K
λ hollow brick
2.5 to 3.5 m²·K/W
R-value, 37 cm monomur
often needed for RE2020
Additional insulation
Frequently asked questions
Depending on the thickness and range, a monomur wall alone is often around R ≈ 1.5 to 3.5 m²·K/W for the wall (excluding renders). For a new RE2020 home in 2026, this level can be enough in climate zone H3 on well-designed projects, but in H1/H2 additional insulation (external or internal) is frequently needed: the thermal study remains the final judge.
Louis Airy
COO of Argile
