ᐅ Planning a Building Extension (Foundation/Load-Bearing Capacity/Alternatives)
Created on: 26 Sep 2019 13:09
P
pmuenteHello,
I’m Peter and new here.
At the moment, I’m dealing with my eight-family house.
The house was built in 1957. Actually, it consists of two adjacent four-family houses, each with two apartments side by side and two stacked above. All the apartments are about 57m² (600 sq ft) each.
The previous owners renovated a lot over the decades, but not the roof, and it is now beyond repair.
Since the stairwell leads up to the attic, the idea came up to add another floor with four more apartments (side by side).
The city building authority approved this. Unfortunately, there are no original plans, not even in the city archives. Because of this, the structural engineer instructed to expose the foundation of the load-bearing exterior walls and the central wall in one continuous section.
And here things stand now. All the foundations are only as wide as the load-bearing walls (30cm (12 inches)) and the structural integrity is, by today’s standards, insufficient even for the existing building.
To add the additional floor, all load-bearing walls and foundations would have to be strengthened.
However, for a building of this length, the foundation reinforcement alone would reportedly cost no less than €100,000.
I don’t want to put such a strain on the old house.
Currently, neither architect nor structural engineer can offer a solution.
One idea I had was to build the apartments almost independently, using steel columns and beams above the existing structure at a height of 5.5m (18 feet). Visually, I find steel beams running along the existing building appealing, and it would decouple the weight of the new apartments from the old structure. Everyone still looks at me skeptically, but I’m searching for solutions and both the architect and structural engineer seem somewhat conservative at the moment.
I hope to find national and many other suggestions in this forum.
Thank you very much.
Peter
I’m Peter and new here.
At the moment, I’m dealing with my eight-family house.
The house was built in 1957. Actually, it consists of two adjacent four-family houses, each with two apartments side by side and two stacked above. All the apartments are about 57m² (600 sq ft) each.
The previous owners renovated a lot over the decades, but not the roof, and it is now beyond repair.
Since the stairwell leads up to the attic, the idea came up to add another floor with four more apartments (side by side).
The city building authority approved this. Unfortunately, there are no original plans, not even in the city archives. Because of this, the structural engineer instructed to expose the foundation of the load-bearing exterior walls and the central wall in one continuous section.
And here things stand now. All the foundations are only as wide as the load-bearing walls (30cm (12 inches)) and the structural integrity is, by today’s standards, insufficient even for the existing building.
To add the additional floor, all load-bearing walls and foundations would have to be strengthened.
However, for a building of this length, the foundation reinforcement alone would reportedly cost no less than €100,000.
I don’t want to put such a strain on the old house.
Currently, neither architect nor structural engineer can offer a solution.
One idea I had was to build the apartments almost independently, using steel columns and beams above the existing structure at a height of 5.5m (18 feet). Visually, I find steel beams running along the existing building appealing, and it would decouple the weight of the new apartments from the old structure. Everyone still looks at me skeptically, but I’m searching for solutions and both the architect and structural engineer seem somewhat conservative at the moment.
I hope to find national and many other suggestions in this forum.
Thank you very much.
Peter
pmuente schrieb:
Everyone still looks at me incredulously, but I am searching for solutions, and both the architect and structural engineer seem a bit conservative at the moment.I’m certainly conservative as well, and I wholeheartedly share those incredulous looks. With a building of this age and apartments all of the same size (= a homogeneous tenant mix), you have very different challenges than adding a penthouse floor on stilts above. Thirty-centimeter (12-inch) exterior walls, even if made of pumice, are no longer considered top quality on today’s market. If there are no existing plans for the building, good luck with the renovation of the plumbing system—likely still made from lead, if not cast iron—and upgrading the heating system upwards. Also, expect to have to retrofit additional chimneys. In the Voreifel / North Rhine-Westphalia region, you’ll find @wpic here on the forum as the nearest expert, although for realistic renovations and modernizations.https://www.instagram.com/11antgmxde/
https://www.linkedin.com/company/bauen-jetzt/
@11ant
The issues you described are well known and not the main problem. The real challenge remains finding an alternative due to the structural stability. A new roof only costs money and doesn’t generate income, which is why so many houses are extended upward to offset the high costs with rental income. Installations and related aspects have been considered. If the structural design had fit as the architect expected, everything would already be economically viable.
Now the question is whether, given the limited living space, it is still profitable to build upward, and here I only see a load transfer that either does not affect the building or only exerts forces comparable to those of the original roof.
Why should I retrofit chimneys? I already have enough unused chimneys, as renovations have taken place over the past decades.
I almost feel I would be better off with a system hall manufacturer.
I can only create profitable affordable housing if I can add something to the existing property.
The issues you described are well known and not the main problem. The real challenge remains finding an alternative due to the structural stability. A new roof only costs money and doesn’t generate income, which is why so many houses are extended upward to offset the high costs with rental income. Installations and related aspects have been considered. If the structural design had fit as the architect expected, everything would already be economically viable.
Now the question is whether, given the limited living space, it is still profitable to build upward, and here I only see a load transfer that either does not affect the building or only exerts forces comparable to those of the original roof.
Why should I retrofit chimneys? I already have enough unused chimneys, as renovations have taken place over the past decades.
I almost feel I would be better off with a system hall manufacturer.
I can only create profitable affordable housing if I can add something to the existing property.
pmuente schrieb:
Now the question is whether adding an extra floor is still profitable when living space is limited [...]
I almost think I’d be better off with a modular building system manufacturer. I hadn’t heard that joke before—but I’m definitely familiar with their prices.
https://www.instagram.com/11antgmxde/
https://www.linkedin.com/company/bauen-jetzt/
pmuente schrieb:
OK, then I don’t get your joke. The joke was yours and consists of wishing for a special solution to be more economical than a traditional one.
pmuente schrieb:
but you also don’t seem to know any alternative to classic foundation reinforcement. Putting the house inside a wall-less industrial hall wouldn’t really count as an alternative here—at least not economically—compared to simply renovating the roof without gaining any living space.
https://www.instagram.com/11antgmxde/
https://www.linkedin.com/company/bauen-jetzt/
Similar topics