Hello everyone, this is my first topic here:
We are planning to start building our house this year with a general contractor. The position of the building on the plot is fixed, and we are currently waiting for the building permit / planning permission.
Our plot is approximately 20m by 41m (66 feet by 135 feet) in size, located in a gap between buildings. The shorter side faces the street. The land slopes downward by 3m (10 feet) over the 41m (135 feet) length towards the back, with the steepest slope in the middle of the plot. The neighbors on the left and right have filled their land, which can be seen clearly by the height of the neighbor’s wall on the left side of the photo. The neighbor to the left has built a basement into the slope, the neighbor to the right has not.
According to the soil report, about 50cm (20 inches) of topsoil needs to be removed. Beneath that, the soil is stable. Frost protection material will be used to fill up to the average street level, so that the finished floor level will be about 20cm (8 inches) above the street. Due to the slope in the middle part, the backfill behind the house will be approximately 1.8m (6 feet) above the current ground level. According to the soil report, the fill should be either sloped back at a 45° angle or retained with a retaining wall.
In the rear area of the plot, we want to create vegetable beds and a wildflower meadow. We already established and harvested a small potato patch last year to pass the waiting time.
What do you think would be the most sensible and cost-effective solution in this situation?
I am looking forward to your suggestions and ideas!
We are planning to start building our house this year with a general contractor. The position of the building on the plot is fixed, and we are currently waiting for the building permit / planning permission.
Our plot is approximately 20m by 41m (66 feet by 135 feet) in size, located in a gap between buildings. The shorter side faces the street. The land slopes downward by 3m (10 feet) over the 41m (135 feet) length towards the back, with the steepest slope in the middle of the plot. The neighbors on the left and right have filled their land, which can be seen clearly by the height of the neighbor’s wall on the left side of the photo. The neighbor to the left has built a basement into the slope, the neighbor to the right has not.
According to the soil report, about 50cm (20 inches) of topsoil needs to be removed. Beneath that, the soil is stable. Frost protection material will be used to fill up to the average street level, so that the finished floor level will be about 20cm (8 inches) above the street. Due to the slope in the middle part, the backfill behind the house will be approximately 1.8m (6 feet) above the current ground level. According to the soil report, the fill should be either sloped back at a 45° angle or retained with a retaining wall.
In the rear area of the plot, we want to create vegetable beds and a wildflower meadow. We already established and harvested a small potato patch last year to pass the waiting time.
What do you think would be the most sensible and cost-effective solution in this situation?
- Slope everything back, add stairs and a natural stone wall later
- Build stairs and a wall directly on the right side, slope back the rest
- If building a wall: formwork blocks would be much cheaper than L-shaped blocks; regarding the earth pressure, a structural engineer would probably need to be consulted.
I am looking forward to your suggestions and ideas!
H
hanghaus20238 Feb 2023 01:13May I assume that the planning for the building permit / planning permission was handled by the company carrying out the construction?
E
Eifelbau20238 Feb 2023 07:27WilderSueden schrieb:
14,000€ for gravel. Or 14% of the basement cost. Installation is additional, and you will definitely need larger equipment for that 😉
I just did some calculations for our site, and we have a 5.5% slope diagonally across the entire property. You can build without a basement, even though we initially expected a much smaller gradient (the survey came after the contract and financing were already finalized...). However, that is not exactly straightforward. For a true hillside house, that slope is a bit too low. The sweet spot for this gradient would probably be a daylight basement room, for example, a study or hobby room, which can be realized without a light well. Yep, a mini-excavator won’t cut it (or would be very slow) 😀
We actually only got the survey results after the house was fully planned, the first sample selections were done, and the building permit application was ready. As for the basement situation, we saw that with our neighbors—the outside access to their basement is below the natural ground level. To have it at ground level, the entire house would need to be set higher, which would make it too tall.
hanghaus2023 schrieb:
May I assume that the planning for the building permit application was done by the company that is carrying out the construction? The building permit planning was completed by the architect of the general contractor. What makes you suspect otherwise?
Very few general contractors plan with a split-level design or a living basement. The standard options are slab foundation, basement (if not needed, often added underneath), or retaining wall with about 1 meter (3 feet) of space for a slab-on-grade house. Six years ago, I encountered only three general contractors who deviated from these approaches.
If you disregard the garden issues and look at the house only from the street, and consider it with limited barriers, it sits well. As I mentioned before, I would balance the height relatively close to the house, and that compensates for the worst of it. The only drawback is that if there are small children, their play area is out of sight. However, that usually resolves quickly.
And be careful with what you use for backfilling. Trees and plants prefer soil.
If you disregard the garden issues and look at the house only from the street, and consider it with limited barriers, it sits well. As I mentioned before, I would balance the height relatively close to the house, and that compensates for the worst of it. The only drawback is that if there are small children, their play area is out of sight. However, that usually resolves quickly.
And be careful with what you use for backfilling. Trees and plants prefer soil.
E
Eifelbau20238 Feb 2023 08:43haydee schrieb:
Most general contractors (GCs) don’t plan for split-level designs or walk-out basements. The standard options are slab-on-grade, a basement (even if it’s not needed) tucked in, or a retaining wall creating about 1 meter (3 feet 3 inches) of space for a slab-on-grade house. About six years ago, I came across three GCs who deviated from these typical approaches.
Ignoring the garden challenges and looking at the house just from the street side, it fits well and is barrier-free. As I already mentioned, I would balance the height fairly close to the house, which levels out the worst issues. The only downside is that if there are small children, their play area won’t be visible. However, that usually improves quickly over time.
And be careful what you use to fill in—trees and similar plants prefer actual soil. The GC didn’t plan much more because we mainly provided the floor plan; we spent quite a long time working on it. The architect later improved some detailed solutions, so it’s not the GC’s fault that nothing “more” was made of it. 😀
The children’s play area will only partly be on our property anyway. There is a large playground just across the street. That saves us from having to install some slides or climbing walls on our plot. 🙂
Regarding the terrain slope, we have now agreed on a relatively high embankment of 1.7 meters (5 feet 7 inches) behind the house, which will later be beautified with natural stones and plants or terraced with small retaining walls. But this is easier to decide once you see it in person. For now, apart from the lava and installation work, it’s an affordable solution that will avoid major earthworks later on.
The subsoil will consist of lava rock, and for the lower level behind the house, a layer of topsoil/excavated material will be applied on top for planting. I’ve read that 25 centimeters (10 inches) should be sufficient for most plants.
W
WilderSueden8 Feb 2023 08:47For the material alone, it could work as long as the delivery distance isn’t too far. I paid €15 (about $16) net per ton of gravel in September. It was a three-axle truck; with a tractor-trailer it costs about one euro less. But as I said, you still have to place it, and a mini excavator and a vibrating plate from a hardware store are far too small for that kind of work.
Turn the 1.7m (5.6 ft) slope into two small terraces and plan them properly. Cutting back a 1.7m (5.6 ft) slope correctly can easily consume 3m (10 ft) of space. Also, 1m (3.3 ft) is the height from which retaining walls require precise construction to avoid major errors.
25cm (10 inches) of topsoil over subsoil is sufficient. But 25cm (10 inches) over gravel is not enough for most plants, as the water drains downward. For trees, it’s definitely insufficient.
Turn the 1.7m (5.6 ft) slope into two small terraces and plan them properly. Cutting back a 1.7m (5.6 ft) slope correctly can easily consume 3m (10 ft) of space. Also, 1m (3.3 ft) is the height from which retaining walls require precise construction to avoid major errors.
Eifelbau2023 schrieb:
The subsoil will be lava; for the lowered area behind the house, a layer of topsoil/excavated soil will be placed on top for planting. I read that 25cm (10 inches) should be sufficient for most plants.
25cm (10 inches) of topsoil over subsoil is sufficient. But 25cm (10 inches) over gravel is not enough for most plants, as the water drains downward. For trees, it’s definitely insufficient.
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