ᐅ Concrete slab flush with the top or bottom edge? Who has experience?
Created on: 29 May 2018 11:58
P
Peter L
Hello everyone,
We are planning to buy a plot of land and build our house on a slab foundation instead of a basement. So far, we are considering an insulated slab foundation.
Yesterday, I noticed that the roads are almost finished, and they seem to be about 1 meter (3 feet) above the actual plots of land. This raises the question of whether this is a good or bad situation. Of course, it also depends on how the slab foundation is constructed—whether the bottom edge is level with the top of the road or the top edge is level with the top of the road. We are trying to answer some questions ourselves but are having difficulty and hope you can help us.
1. What are the advantages, disadvantages, and costs of building with the bottom edge level with the top of the road?
2. What are the advantages, disadvantages, and costs of building with the top edge level with the top of the road?
3. Which method is recommended when the road is about 1 meter (3 feet) higher than the plot?
4. In this case, would it be worthwhile to consider a basement after all?
We imagine that having the top edge level with the road might be best. This way, the ground wouldn’t need to be filled beforehand, and it would also save the cost of stairs leading to the door. But perhaps we are overlooking something?
We also wonder if having a basement might actually make sense, since you wouldn’t have to dig as deep, and the excavation could be used for the rest of the fill. Whether a basement is worthwhile is always subjective, but could you roughly estimate how much money it might save?
We understand that everything needs to be carefully planned, but we would like to have an independent opinion beforehand and get a rough idea of the pros and cons as well as the cost implications.
Thanks for your help!
We are planning to buy a plot of land and build our house on a slab foundation instead of a basement. So far, we are considering an insulated slab foundation.
Yesterday, I noticed that the roads are almost finished, and they seem to be about 1 meter (3 feet) above the actual plots of land. This raises the question of whether this is a good or bad situation. Of course, it also depends on how the slab foundation is constructed—whether the bottom edge is level with the top of the road or the top edge is level with the top of the road. We are trying to answer some questions ourselves but are having difficulty and hope you can help us.
1. What are the advantages, disadvantages, and costs of building with the bottom edge level with the top of the road?
2. What are the advantages, disadvantages, and costs of building with the top edge level with the top of the road?
3. Which method is recommended when the road is about 1 meter (3 feet) higher than the plot?
4. In this case, would it be worthwhile to consider a basement after all?
We imagine that having the top edge level with the road might be best. This way, the ground wouldn’t need to be filled beforehand, and it would also save the cost of stairs leading to the door. But perhaps we are overlooking something?
We also wonder if having a basement might actually make sense, since you wouldn’t have to dig as deep, and the excavation could be used for the rest of the fill. Whether a basement is worthwhile is always subjective, but could you roughly estimate how much money it might save?
We understand that everything needs to be carefully planned, but we would like to have an independent opinion beforehand and get a rough idea of the pros and cons as well as the cost implications.
Thanks for your help!
It depends...
For excavation here, for example, the worst material imaginable (clay, silt, sandstone chunks, etc.), so it’s only suitable as a base fill at the very bottom. Because of this, you’ll need to bring in good quality soil.
As a rough reference (in rural areas with short transport distances): screened topsoil costs about 25€/ton officially. Through a direct channel, about 300€ for a tandem truckload (22 tons). But that only covers the material delivered to the site, not installed. So your backfill can potentially become quite expensive. In any case, consider comparing this cost to building a basement. Then it also depends on the quality of your soil. Do you need larger amounts of good soil anyway, or do you have excess material?
If you want to calculate, simply take the expected area you want to fill, multiply it by the average height of the fill to get the volume (m³ (cubic meters)), then multiply by 1.8. That will give you the required tons for a compacted fill...
In the end, it also depends on your plans for the property. Do you want a flat, level area like a baking sheet, or are you more the garden type who would terracing the land, maybe with small steps and a dry stone wall to plant on?
For excavation here, for example, the worst material imaginable (clay, silt, sandstone chunks, etc.), so it’s only suitable as a base fill at the very bottom. Because of this, you’ll need to bring in good quality soil.
As a rough reference (in rural areas with short transport distances): screened topsoil costs about 25€/ton officially. Through a direct channel, about 300€ for a tandem truckload (22 tons). But that only covers the material delivered to the site, not installed. So your backfill can potentially become quite expensive. In any case, consider comparing this cost to building a basement. Then it also depends on the quality of your soil. Do you need larger amounts of good soil anyway, or do you have excess material?
If you want to calculate, simply take the expected area you want to fill, multiply it by the average height of the fill to get the volume (m³ (cubic meters)), then multiply by 1.8. That will give you the required tons for a compacted fill...
In the end, it also depends on your plans for the property. Do you want a flat, level area like a baking sheet, or are you more the garden type who would terracing the land, maybe with small steps and a dry stone wall to plant on?
However, having a basement does not change the fact that the area around the building must be backfilled, and if the excavated soil from the construction site is unsuitable, it must be disposed of and replacement fill material purchased. In that case, the basement does not save any costs.
I see the slope mainly as an embankment on the opposite street... are there two rows of lots in the middle, or just one? From which side is the property accessed? I can’t tell if the depth is 30 or 60 meters (100 or 200 feet).
The embankment at the back could also become public land...
There’s a lot of guessing and assumptions… the seller probably has quite a bit of information on hand.
The embankment at the back could also become public land...
There’s a lot of guessing and assumptions… the seller probably has quite a bit of information on hand.
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