The plan was to start with the bricklaying yesterday. However, the contractor had brought the wrong thermoblocks that need to come underneath the inner brick wall. So that’s been postponed until Monday.

Those thermoblocks are meant to prevent a thermal bridge. I explained how walls are typically constructed here earlier. The problem is that where the wall meets the floor, you often end up with a thermal bridge aka a leak in the insulation. The insulation is placed on the outside against the inner wall. The floor insulation is placed on top of the concrete floor. So where the inner wall meets the concrete, there’s no insulation. Thermal bridges are to be avoided because of the extra heat loss, but also because of the risk of condensation (and mold) on those spots because they’re colder than the rest of the walls.

To avoid this thermal bridge, they’ll put an insulating block underneath the inner brick wall. Most common materials used for this are cellular glass or cellular concrete. The problem with the first, which is what the contractor had actually brought, is that the load bearing capacity of the block is rather limited. I’ll have a 4 story house, the cellular glass cannot support that. Cellular concrete is a bit stronger, but still not strong enough, I fear. And you have to be careful that the block doesn’t get wet.

What I am going to use is a brand new product called Marmox thermoblock. It consists of little concrete cilinders that are poured into insulation. The concrete makes the block very strong and the insulation value is pretty good too. But as it’s a new product, contractors aren’t yet familiar with it, which is how my contractor ended up getting the wrong product. You can see in the image below, which is a cross section of the detail of where the wall meets the floor, that the block comes underneath the inner brick wall and as a result the insulation is uninterrupted.