Planning extension (foundation/load-bearing capacity/alternatives)

  • Erstellt am 2019-09-26 13:09:47

pmuente

2019-09-26 13:09:47
  • #1
Hello,
I am Peter and new here.
Currently, my 8-family house is troubling me.
The house was built in 1957. Actually, it is 2 adjacent 4-family houses with 2 apartments next to each other and 2 above each other in each. All apartments are about 57 sqm each.
The previous owners renovated quite a bit over the decades, but not the roof, and it is worn out.
Since the stairwell leads up to the attic, the idea came up to add another floor with 4 more apartments (side by side).
The city building authority has also approved it. Unfortunately, there are no old plans, not even in the city archive, so the structural engineer instructed to expose the foundations of the load-bearing exterior walls and the central wall in one piece.
And here it ends. All foundations are only as wide as the load-bearing walls (30 cm) and the statics are not sufficient according to today’s standards, even for the existing structure.
For an additional floor, all load-bearing walls/foundations would have to be reinforced.
However, for the building length, the reinforcement would allegedly cost no less than €100,000 just for the foundation strengthening.
I also do not want to impose this intervention on the old house.
Currently, neither the architect nor the structural engineer offers a solution.
For example, the idea occurred to me to build the apartments almost self-supporting with steel columns/steel beams over the existing building at a height of 5.5 m. Visually, I find steel beams along the existing structure appealing and thus would decouple the new apartments from the weight. Everyone still looks at me incredulously, but I am looking for solutions and the architect as well as the structural engineer seem somewhat conservative to me at the moment.

In this forum, I hope for national and many suggestions.

Thank you very much.

Peter
 

11ant

2019-09-26 13:53:24
  • #2
I am certainly conservative as well, and I wholeheartedly share the incredulous looks. With a property of this age with apartments all of the same size (= homogeneous tenant mix), you have completely different problems than placing a penthouse floor on stilts above it. 30 cm exterior walls, even if made of pumice, are no longer a big deal on the market. If there are no plans left from the house, good luck with the renovation of the risers of the (probably still lead, if not even cast iron) water pipes, and the extension of the heating system upwards. Also expect additional chimneys to be retrofitted. In Voreifel / NRW, you will find here in the forum the nearest expert (however for realistic renovations / modernizations) in Münstereifel.
 

pmuente

2019-09-26 15:46:14
  • #3
The problems you described are known and not the issue. The problem remains an alternative due to the statics. A new roof only costs money but does not bring in income, which is why so many houses are simply extended upwards to compensate for the high costs with rental income. Installations, etc. have been considered. If the statics had been as the architect suspected, everything would already be profitable. Now the question arises whether it can still be profitable to extend upwards given the tight housing situation, and here I only see a load transfer that either does not act or only acts to the extent of the old roof on the building. Why should I retrofit chimneys? I have enough dead chimneys since renovations have already taken place in the last decades. I almost believe I am better off with a system hall builder. I can only create profitable affordable housing if I can still add something on the existing plot.
 

11ant

2019-09-26 16:44:04
  • #4
I didn’t know that joke yet – but I did know their prices
 

pmuente

2019-09-26 17:00:24
  • #5
OK, then I don't understand your joke. I am seriously looking for a solution, but you also seem to know no alternative to the classic foundation reinforcement. Maybe others will still respond.
 

11ant

2019-09-26 17:15:21
  • #6
The joke was yours and consists in wishing for a special solution to be more economical than a traditional one. Putting the house into a system hall without walls would not be called an alternative here – at least not economically to simply renovate the roof without any gain in living space.
 

Similar topics
18.02.2011Architect totally messed up - experiences?17
25.05.2015Extractor hood / roof or wall14
24.05.2015KfW 55 with wooden house - U-values: Wall 0.18 - Roof 0.1617
05.05.2016Insulate the roof: flakes, panels or wool17
17.11.2016Sell apartments or keep them?36
15.08.2016Civil engineer contradicts structural engineer27
20.10.2017Roof with photovoltaic or other investment, any experiences?19
25.03.2019Ceiling suddenly too small for controlled residential ventilation!54
02.12.2019Single-family house (2 floors + residential basement + developed attic) approximately 200 sqm - changes162
07.12.2019Bank guarantee from the roofer due to defects in the roof16
27.02.2020Is the vapor barrier in the roof vapor-permeable? Yes? No!16
10.04.2020Rainwater from the roof - drainage in the soil for discharge?12
03.09.2020Modern single-family house with architect in southern Germany25
11.02.2021Structural engineer needed for rough assessment of load-bearing capacity25
05.12.2021Cost of structural engineer single-family house23
30.03.2022Developer New Build: Buy two apartments and then combine them18
01.01.2023Structural engineer according to HOAI or flat rate offer?13
27.07.2023Cross-ventilation - is it mandatory in apartments?28
12.01.2025Comprehension question: Gable roof - load-bearing walls - floor plan11

Oben