Masonry basement or concrete basement?

Hello,

we are currently planning a single-family house on a south-facing slope plot. A living basement is planned, which is located entirely below ground level on the north side and completely above ground on the south side.

However, we are very uncertain whether to choose a masonry basement (brick + bitumen thick-layer membrane) or a concrete basement.

A soil report is not yet available, but for plots in the immediate vicinity, the load case temporarily accumulating seepage water has been determined.

For bricks, the lower price, better thermal insulation, and possibly better indoor climate speak in favor. For concrete, primarily the more reliable waterproofness. We have also been suggested a compromise solution – concrete in the north, bricks in the south. However, I have concerns about different settlement behavior. Are these justified?

The garage is directly adjacent to the house. We might also cellar the garage. The garage basement would then serve as a pellet storage and tool shed. Garage and garage basement should be outside the thermal envelope of the house. What is the general opinion about this? Can thermal bridges be avoided at all?

I would be very grateful for some suggestions.

The house we now live in was built in 1979. Set on a slope, the basement is underground on the north side, at ground level on the south side. Clayey soil. Well drained. Made of calcium silicate bricks. Plastered inside, outside a kind of asphalt on it. Dry, tight. Until today.

We have also already been proposed a compromise solution - concrete in the north, bricks in the south. However, I have concerns regarding different settlement behavior. Are these justified?

Since concrete would then presumably be chosen for all (also partially) buried walls, it would therefore be east and west in concrete as well, and only south in bricks. I find this questionable in the overall extent of the possible difference. For reasons of wall connections, I would rather see calcium silicate bricks than bricks. I share the concerns regarding settling.

The garage is directly adjacent to the house. We might possibly cellar it as well. The garage cellar would then serve as a pellet storage and tool shed.

The garage cellar would be without connection to the house, only accessible from outside? – What kind of garage are we talking about: a double garage? – In the case of a single garage, the ratio of walls and excavation effort to usable space is unfavorable, which raises a pricing question behind the cellar.

The garage and garage cellar should lie outside the thermal envelope of the house. What is the general opinion on this? Can thermal bridges be avoided at all?

This separation consistently also means: no "shared" wall between house and garage. The garage is mostly kept closed, so it is windstill and only ventilated briefly when entering and exiting, which limits heat loss. I consider it a myth that many heat thieves dwell there. I’d say the garage is basically an air layer with parking spaces.

Yes, it is a double garage with approx. 40m². We have not planned an access from the house basement to the garage basement.

The interior basement walls could be built from bricks, and for the shared wall, you could use perlite-filled bricks. Then there would still be the thermal bridge over the shared exterior wall and floor slab.

The basement interior walls could be built from bricks,

Walls made of sand-lime bricks may butt together directly, those made of bricks as far as I know may not. Besides, masonry is more labor-intensive than concreting - are you sure this was taken into account in the calculation?

and just use perlite-filled bricks for the common wall.

Solid bricks have not been common for quite some time now, and bricks with hollow chambers are standard in that regard. There are different scholarly opinions on whether leaving the (air) chambers hollow or filling or foaming them is the best solution. At the moment, the issue of heating energy stinginess is a bit overhyped. You can also overdo everything.

However, we are very uncertain whether we should choose a masonry cellar (brick + bitumen thick-layer membrane) or a concrete cellar.

Ask an architect and he will tell you that only the masonry option can be reliably constructed as a waterproof cellar. Ask a general contractor and he will claim exactly the opposite.

Since part of your cellar is intended to be used as living space, I would always vote in favor of masonry.

Garage and garage cellar should be located outside the thermal envelope of the house. What is the general opinion on this? Is it even possible to avoid thermal bridges?

As long as no walls are "shared," this is not a problem. Your planner must consider sufficient ventilation.