I see builders demo a whole house and leave one wall up. Then tear that wall down and build a whole new house. However it is still considered a renovation rather than a new build. Can you explain why and how this process works?
When a builder demolishes a building in the manner that you described he is technically completing a renovation. That’s what the permit will read that they were granted.
In a lot of places there are restrictions on building and renovating homes and building’s because of certain criteria. Those criteria are as follows;
• Age of the building.
• Historical significance of the building.
• The design, shape and style of the building.
• They importance of the building as a potential land mark.
• The cultural significance of the building and what it can represent.
When you are working with a building that falls under any of the above criteria then you are working with special rules that you have to agree to follow before you can be granted a permit to do any kind of work on the structure.
A building that falls under the above criteria is not allowed to be completely demolished and removed leaving nothing of the old building behind.
Sometimes in an area that can cover several city blocks you can have homes that are deemed historical but have no historical value other than their age and their location. Some of these buildings might be in such disrepair that it would cost more to try and salvage the building then it would to demolish it and build a newer one. These are the buildings that you described seeing under construction.
The builder and the client will produce a plan that removes much of the above grade structure leaving one or two walls standing. They leave most or all of the existing foundation in place untouched. They then work with the building department to meet the requirements to call the project a renovation and not a new build. To qualify for this you have to leave a certain percentage of the building standing including at least one exterior wall. By leaving the entire basement intact you raise the percentage of the building that you are leaving to qualify it as a renovation.
After they have demolished most of the building, the foundation intact and one wall still standing you then add any additional footings and re-enforcements to the foundation that you might require to hold up the new building above it. You then proceed to frame the building while leaving the front wall standing. Once most of the building is framed you remove the wall you left standing. The reason that you can do this are several, actually you can select from several options from the wall is a safety issue, the wall is damaged beyond repair, there is rot in the wood or the wall can no way meet code.
At the end of the process you have basically a brand new, safe and properly built home. The only part of the existing building that is left is the concrete walls and footings in the basement.