ᐅ When is it worthwhile to demolish an old building for new construction?

I have a small house (80m² (860 sq ft)) without a basement; the building structure is not particularly good. It was built in the 1950s, and there are no construction documents available. It also seems that there is no concrete slab; I cannot determine whether it has a strip foundation. The walls are thinner than standard, and due to the lack of a proper foundation and the small rooms (two floors of 40m² (430 sq ft) each), the ground floor is prone to mold and moisture.

The plot value, according to the land valuation, is €77,000. Now I am wondering whether a demolition and new build would be economically viable or if it would be better to leave it as is.

cp03525 schrieb:

Now I am wondering whether demolition and rebuilding would be economical or if it’s better to leave it as it is.

What exactly could you build there? How much would renovation cost? Is 80 sqm (860 sq ft) sufficient? What are your requirements?
And so on.

The answer to your question could be either yes or no. A major renovation often costs about as much as a new build. However, the old building may still have the typical issues of older constructions, such as ceiling heights or room layouts that couldn’t be changed.

Basically, it’s acceptable, except for the susceptibility to mold. By the way, only a flat roof with bitumen membranes is used. However, the heating system will need to be replaced soon, and considering the low building value and potential future issues, I wonder whether a complete rebuild with better quality wouldn’t be more cost-effective in the long run. For example, the new heating system could cost 20% of the estimated building value.

Well, let’s look at it from another perspective: you do a full renovation, so what’s left? Ideally, just the shell with all the mentioned issues (unless the structure collapses during demolition). You have to be honest: 70 years old, there probably isn’t much left in good condition. Its expected lifespan has been fulfilled.

Another question
- Do you live in the house yourself or plan to live in it?
- Do you like the floor plan?
- Is the size suitable?
- Are you emotionally attached to the house so much that you definitely want to keep it?

I’ll quote my grandfather: "Kid, tear it down. No matter how much money you put into it, it will remain an old house. I should have torn it down already."
We demolished even though the demolition costs exceeded the land value.
a) The old unsellable house was still there.
b) The house was old, the floor plan didn’t fit, no need to even talk about energy efficiency, half-timbered with 5cm (2 inches) of styrofoam insulation.
c) The location on the property was valuable.
d) We didn’t need a barn, stables, and garages of that size. Definitely not a slurry pit and manure heap.

During demolition, we discovered dry rot even though the exterior still looked good. Old fire damage in the ceiling.
etc.

Whether it was initially the cheapest solution, I don’t know. Ultimately, only a shell with defects would have remained.
For perhaps a bit more investment, we now have a passive house with a floor plan we like, in the position on the lot that we wanted. This means that according to heavy rain management, we are now approximately safe from flooding.

haydee schrieb:

Another question
- Do you live in the house yourself or do you plan to live in it?
- Do you like the floor plan?
- Is the size suitable?
- Are you emotionally attached to the house so that you definitely want to keep it?

… that will remain in the room.