- Can someone objectively explain to me why, for example, aerated concrete is to be preferred over formwork blocks?
For example, because aerated concrete plan blocks also have a high degree of DIY suitability when it comes to the "masonry" itself, but without raising such questions as
- If sockets are now to be placed on the exterior walls of the room. How is that done? Is it enough just to cut the polystyrene to the concrete, or is that even allowed? Is the depth sufficient and how do you secure this box?
(In the formwork block systems, they work with integrated boxes, empty conduits, and sometimes even integrated downpipes).
Simply put, a formwork block system is a concrete wall that also has a (only finger-thick there) quasi external thermal insulation composite system (ETICS) "on it" on the interior side of the room. With all the consequences for fastening-related issues.
If you, as a typical building client, want to have a contractor do the masonry for you, they will surely be happy to deliver the blocks to you, but you are not actually the target group. Among other things, because of questions like
- To properly distribute the concrete inside, you have to use a vibrating poker. That is quite a robust process. Do the blocks withstand this? How do you avoid honeycombs?
(the answer to which I unfortunately have to withhold), formwork block systems are extremely rare in the portfolio of commercial processors. Such systems are found almost exclusively in the (usually also spatial) environment of the respective inventors. Elsewhere, they are thinly spread, and an inexperienced contractor with this system will do you the greater favor of convincing you to use another building material. Your joy if he said yes out of a willingness to experiment would be short-lived: you would then be his guinea pig, and for example, the mentioned honeycombs or core drillings for every socket would be the consequence(s).
- or what are the disadvantages of the ICF system?
I do not know all formwork block systems nor the differences between them. Each inventor has their own modular dimension and special blocks (for octagonal bay windows, etc.), but the principles are largely the same: formwork block either made of polystyrene or cement-bonded chipboards or similar, symmetrical or thicker on the outside, not much more variation than that. The basic principle is always that anyone who knows "Lego" should be able to handle it; and the filling should be provided by any concrete supplier.
My mantra that block and processor should be seen as a system applies accordingly also within the category "formwork block systems": since the differences lie precisely in the details, I would strongly advise against commissioning a processor experienced with formwork block system XY to build a house with system ABC. And take one who builds entire houses with it, otherwise you will have the problem again at the interface of shell construction/interior finishing to find suitable follow-up workers (or risk that they have to improvise at detail connections).