Planning single-family house - construction of exterior wall

Thank you for the hints. That already helps me a lot with understanding. No, we are in Phase 2. Everything is still in the preliminary planning. If I understood correctly, with the wall construction including the appropriate insulation, it will not fit into the modular grid or I will have loopholes.

In that case, the construction in random bond will probably be the preferred option. I also don’t want to do the masonry myself...

What concerns me right now is whether an alternative wall construction (2-layer) is basically possible if it costs 40% less in material alone. I already understand that the architect’s fee is based on the construction sum. Therefore, I can somehow "comprehend" his explanations. I do not want to exhaust my budget to the limit and also want to have a buffer for myself, not for the architect. I think that is understandable.

No, we are in phase 2. Everything is still in the preliminary planning stage.

This is a good time to "change horses" (if it seems appropriate). But does that fit with the contract with the current architect? – ideally, you should now explain where else the problem lies.

If I understood correctly, the wall structure with the corresponding insulation will not fit the module dimension or I will have loopholes.

I cannot follow you at all regarding the loopholes *completely clueless*

My concern right now is whether an alternative wall structure (2-layered) is basically possible if it alone costs 40% less in material costs.

I consider the two mentioned as essentially equivalent alternatives, but I put a question mark behind the 40%.

I am aware that the architect’s fee is based on the construction sum. Therefore, I can somehow "understand" his statements.

Which statements do you mean here? – the fee linkage to the construction sum is not "form-locked," so it is not proportional to the actual construction costs. This small cost item "alternative wall structure" does not have to change the fee scale allocation at all.

The masonry in a random bond will probably be the preferred variant. I don’t want to do the masonry myself either...

I wasn’t thinking of doing it myself either, but rather of subcontractors without commitment – see:

- He recommended a partial cellar/storage cellar and a fixed garage. That would supposedly save costs. Since we need the space (3 children), we want a full cellar and a carport.
- However, the first proposal included a hipped roof!? The plot is oriented north-south. We can install a larger photovoltaic system on the gable roof and it is significantly cheaper in construction.

Somehow I have the feeling that an already existing design with slight modifications is being made attractive to us. We have another appointment next week. Then I can report.

I can't follow you at all regarding the loopholes *at a loss*

It was just an idea. If you use larger bricks and adjust the insulation, you could create a 60cm exterior wall. But who wants that anyway?

I consider the two mentioned to be essentially similar alternatives, but I put a question mark behind the 40%.

The builder only roughly sketched the example for the exterior wall. For a T9-30 Poroton, the costs per sqm are about €65. For the T14-24 it's about €35 / sqm (pure material costs). The insulation on the 24 is larger. But the price difference is about €4-5 / sqm.
I think that’s already a significant amount. Whether the mason installs a 30 or 24 brick probably makes no difference.

- He recommended a partial basement/storage cellar and a fixed garage. That would supposedly save costs. Since we need the space (3 children), we want a full basement and a carport. - In the first proposal, there was a hip roof!? The plot is oriented north-south. We can accommodate a larger photovoltaic system on the gable roof and it is significantly cheaper in construction.

Partial basements are always relatively more expensive. Whether your plot even suggests having a basement, we do not know – so far you have neither shown your plot nor the preliminary design. A garage is one of the most dispensable things at all (except as a basement replacement room). Hip roofs tend to be costly. However, a hip roof can of course be cheaper for photovoltaics than a gable roof with an unfavorable orientation. In combination with KfW40 and a granny flat, I suspect you are on a funding-romance trip. Purchase price additions of bricks and insulation lead to naive calculations of varying quality, but hardly to decisive insights. Exterior walls are strongly overrated because of their large contribution to the shaping of the building body, but are mainly to be classified in the peanuts category concerning price levers when building. How you came up with loopholes, I still cannot follow. I understand that as narrow windows, but what are they supposed to have to do with wall thickness or even specially with the octameter grid???