ᐅ Concrete blocks behind external thermal insulation composite systems (ETICS), block type or joint masonry, costs

Hello!
We are about to build our house using 30cm (12 inches) LIAPOR Super-K-Plus blocks, with a 14cm (5.5 inches) external thermal insulation composite system (ETICS) using polystyrene on top.

Now my question:
Our general contractor says that it might not really be worthwhile to bond the Liapor blocks as formwork blocks, and that it would be sufficient to lay them normally with a 12mm (0.5 inch) mortar joint.

Is this something you would agree with, and how much more expensive would the formwork blocks be? Would that be practical behind an ETICS?

Thank you!

Hello,

Behaim schrieb:
..Our general contractor thinks it’s not really worth it to bond the Liapor blocks as plan blocks but that it would be sufficient to lay them normally with a 12mm (0.5 inch) joint.

Who exactly is supposed to benefit from that? He definitely saves on adhesive and possibly one row of blocks 😉
When combining materials, you should also check the vapor diffusion calculation / condensation formation and accumulation!

Best regards

€uro schrieb:
Hello,
Who is this supposed to benefit? It definitely saves on adhesive and possibly a course of blocks 😉
When combining materials, you should also consider the vapor diffusion balance / condensation formation or prevention!

Best regards.

What do you mean?
Well, benefit... the plan blocks are more expensive and are usually used when you apply plaster directly on them, which is not the case with an external thermal insulation composite system (ETICS). So, you would have a "neat" masonry that is probably somewhat more expensive overall than standard masonry, but then it’s “hidden” behind an ETICS.
I’m just curious if it makes any sense energetically or for some other reason to choose plan blocks after all!
Do the interior walls also need to be made with plan blocks and glued, or does that even make sense?

Hello,

I would recommend sticking with adhesive bricks / precision bricks. The mortar joint is the weak point in the wall and, from an energy efficiency perspective, is generally worse than adhesive bonding. As a trained bricklayer, I suggest using precision bricks. The mortar joint contains more moisture, which then needs to dry out. If the external insulation composite system (ETICS) is already applied, this drying must happen through window ventilation and heating. With adhesive bonding, the butt joints also need to be done carefully, and no mortar should be squeezed in between.

It should not be more expensive, or the costs should roughly balance out, as this has been standard practice for many years.

Regards

NorbertKoch schrieb:
Hello,

I would recommend sticking with adhesive bricks/plan bricks. The mortar joint is the weak point of the wall and, from an energy efficiency perspective, is actually worse than adhesive bonding. As a trained bricklayer, I suggest plan bricks. The mortar joint contains more moisture, which then needs to dry out. If the external thermal insulation composite system (ETICS) is already installed, drying has to happen through window ventilation and heating. And with the adhesive method, special care must also be taken with the butt joints to avoid any mortar being squeezed in.

It shouldn’t be more expensive or, in fact, the costs should balance out since this has been the standard technology for many years.

Regards

Thanks for the opinion!
I hope my general contractor (GC) is as enthusiastic about this as I am. After all, I also have to somewhat align with what their construction company can, wants to, or recommends.
I see it similarly to you; I think it’s the state of the art, so I will probably insist on it... it shouldn’t be the first time something like this is requested, ETICS or not.
Should this approach also be followed for the interior walls? We are building with eco-friendly limestone blocks from Meier (look them up). They are quite heavy and absorb sound, and hopefully, I can get used to the difficulties of hammering nails and hanging pictures. Allegedly, it’s not easier with bricks...

Behaim schrieb:

I hope my general contractor (GC) is as enthusiastic about this as I am. After all, I have to partly align with what their construction company can/wants to/do recommends...

I believe you are completely mistaken there. The GC has to align with what you want. Where would we be otherwise.........?

Regards