ᐅ House extends above ground level – how much soil can be backfilled (with shallow basement)?
Created on: 15 Oct 2022 19:11
M
Machu Picchu
Hello everyone,
we are now in the final phase of our house construction.
Because the sewage system on our property is not far below ground level and we did not install a sewage lift system, our basement was only excavated to a shallow depth.
The ceiling height of the basement rooms is 2.50m (8 feet 2 inches), as these areas are intended to be living spaces, unlike the neighboring houses, whose basement heights are lower.
As a result, our front door and the two patio doors are positioned much higher than those of the neighboring houses. In the next few days, soil will be filled up to the level of the terrace and front doors.
I do not want this to turn into a discussion about different construction methods; instead, I am looking for advice on how to best handle this somewhat unusual situation.
First, some photos:
Marked in red are the two patio doors. Soil will be filled up to just below these patio doors, except, of course, at light wells and shafts. The terrace will be paved around the corner, following the two indicated patio doors (because we wanted two sunny sides on the terrace for different times of the day). To the left of the single-leaf patio door (where the exterior plaster ends), a retaining wall will be built from the terrace level down to the ground.
This is a front view. On the left, the construction staircase leads up to the entrance door. The front door is at the same level as the two patio doors.
Here is the view from the back.
This is the view from the back toward the front door.
And here is another rear view including the neighboring houses.
As planned, as mentioned, soil will be filled up to the level of the house and terrace doors, and at this level the garden will be designed on the side of the large double patio door as well as behind the house, with steep slopes created just before the property boundary.
On the front door side, soil will also be filled up to front door level.
Toward the "front" (the side with the single patio door), the street level will be reached by terrace-like steps with 2-3 slope terraces supported by walls/granite.
Our concern now is: if we fill soil all around the house at door level on the side with the double patio door, at the back, and on the front door side, our garden height will be so high that, compared to the neighbors, our house will stand out significantly due to the very elevated ground level.
We are now considering ways to soften this.
One idea is to fill soil to door level only at the terrace wrapping the corner and directly at the front door, and to fill soil, for example, 50cm (20 inches) below door level everywhere else.
This way, the garden level would not be so dramatically higher than the neighbors’.
The problem with this is that we would partially expose the "basement" and areas without exterior plaster would become visible. We would likely need to hire a plasterer on our own to plaster additional areas and paint them with gray base paint. Time is tight because the soil will be delivered for filling within the next days/weeks. How long would such plastering take and what would it approximately cost?
Question to the forum: What do you think about this? Do you have other solutions? Or are our concerns unfounded?
Thank you very much in advance for any advice.
we are now in the final phase of our house construction.
Because the sewage system on our property is not far below ground level and we did not install a sewage lift system, our basement was only excavated to a shallow depth.
The ceiling height of the basement rooms is 2.50m (8 feet 2 inches), as these areas are intended to be living spaces, unlike the neighboring houses, whose basement heights are lower.
As a result, our front door and the two patio doors are positioned much higher than those of the neighboring houses. In the next few days, soil will be filled up to the level of the terrace and front doors.
I do not want this to turn into a discussion about different construction methods; instead, I am looking for advice on how to best handle this somewhat unusual situation.
First, some photos:
Marked in red are the two patio doors. Soil will be filled up to just below these patio doors, except, of course, at light wells and shafts. The terrace will be paved around the corner, following the two indicated patio doors (because we wanted two sunny sides on the terrace for different times of the day). To the left of the single-leaf patio door (where the exterior plaster ends), a retaining wall will be built from the terrace level down to the ground.
This is a front view. On the left, the construction staircase leads up to the entrance door. The front door is at the same level as the two patio doors.
Here is the view from the back.
This is the view from the back toward the front door.
And here is another rear view including the neighboring houses.
As planned, as mentioned, soil will be filled up to the level of the house and terrace doors, and at this level the garden will be designed on the side of the large double patio door as well as behind the house, with steep slopes created just before the property boundary.
On the front door side, soil will also be filled up to front door level.
Toward the "front" (the side with the single patio door), the street level will be reached by terrace-like steps with 2-3 slope terraces supported by walls/granite.
Our concern now is: if we fill soil all around the house at door level on the side with the double patio door, at the back, and on the front door side, our garden height will be so high that, compared to the neighbors, our house will stand out significantly due to the very elevated ground level.
We are now considering ways to soften this.
One idea is to fill soil to door level only at the terrace wrapping the corner and directly at the front door, and to fill soil, for example, 50cm (20 inches) below door level everywhere else.
This way, the garden level would not be so dramatically higher than the neighbors’.
The problem with this is that we would partially expose the "basement" and areas without exterior plaster would become visible. We would likely need to hire a plasterer on our own to plaster additional areas and paint them with gray base paint. Time is tight because the soil will be delivered for filling within the next days/weeks. How long would such plastering take and what would it approximately cost?
Question to the forum: What do you think about this? Do you have other solutions? Or are our concerns unfounded?
Thank you very much in advance for any advice.
M
Machu Picchu16 Oct 2022 13:12WilderSueden schrieb:
There are two issues when it comes to water. One is erosion during heavy rain. The other problem is that after a few days of continuous rain, the soil becomes saturated and muddy, which makes it less stable on the slope. How quickly this becomes a problem naturally depends a lot on the type of soil itself. These problems make sense. How can they be prevented? Is there a solution that the landscape gardener needs to implement to avoid any concerns?
A slope of about 1 meter (3 feet) in height is quite common, so this issue must occur frequently?
The soil, which we would get for backfilling as a gift, is clayey. Would clay be beneficial or rather disadvantageous in this case?
When I saw this, my first thought was that this thread should be pinned at the top as a cautionary example for all hillside property owners.
Maybe I missed it or overlooked it: What does the contract say about the exterior work? Does the general contractor handle it completely? Will they carry out the solution as shown in the plans if you don’t say anything? What exactly have you agreed on?
Maybe I missed it or overlooked it: What does the contract say about the exterior work? Does the general contractor handle it completely? Will they carry out the solution as shown in the plans if you don’t say anything? What exactly have you agreed on?
M
Machu Picchu16 Oct 2022 13:16K a t j a schrieb:
When I saw this, my first thought was that this thread should be pinned at the top as a warning example for all hillside property owners.
Maybe I missed it or repressed it: What does the contract say about the exterior landscaping? Does the general contractor handle the entire job? Will they implement the solution as shown in the plans if you don’t speak up? What exactly did you agree on? No, the exterior landscaping is not part of the contract—except for the one retaining wall mentioned for the edge of the terrace on the gable side.
ypg schrieb:
I would try building it all with Lego first. That way you can immediately see where it gets steep, where a wall is needed, or where it just won’t work—the first thought that comes to mind 😉This is meant quite seriously! Not everyone is comfortable with 3D modeling 😉S
Sunshine38716 Oct 2022 13:45Here is a constructive suggestion: build up 1 meter (3.3 feet) of soil and then retain it with L-shaped concrete blocks. This should be quite feasible. Plaster the parts of the house that will then be exposed and create stairs leading from the living room and entrance area down to the garden. A staircase about one meter (3.3 feet) high should not be too intrusive. I also hope you were allowed to build two full stories, because if the zoning plan / building permit only allows a single-story design, you might face restrictions on the basement height. In that case, with such a high basement, you would effectively have two stories.
Machu Picchu schrieb:
No, the exterior landscaping is not part of the contract – except for the one mentioned retaining wall at the terrace edge on the verge side. That was to be expected. So, a major disaster.
Honestly, I see this as a clear case of poor planning and advice. It’s even uncertain whether this can still be considered a basement or if it already counts as a full story, and how this aligns with the building permit / planning permission. The question for me is whether the general contractor can simply be released from responsibility here. In my opinion, fixing this mess will cost between 70,000 and 100,000 (depending on the execution).
Simply “dumping clay” won’t solve the issue. First, drainage must be planned. That manhole cover in the front yard can’t just be buried, right? Clay hardly absorbs water. That means rainwater would run along this “mass” and collect at the lowest point. Depending on the slope, this could quickly cause landslides, washouts, or small streams that might suddenly flood the neighbor’s house, etc. You cannot build anything stable on freshly added natural soil, certainly not terraces—especially not at height. So, to put it bluntly, this looks bad.
To save this mess, I would probably add the 40 to 50cm (16 to 20 inches) that are unproblematic up to just below the window sills. From there, I would work with steps. Around the terrace doors, I would build a narrow continuous balcony wrapping around the corner, as is common in the Alpine region. From there, a staircase would lead down to the actual terrace and the garden. With some luck, that’s just 5 to 6 steps.
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