Provisions for future vertical expansion
Provisions for future vertical expansion
(OP)
I am designing a 4-story steel building (100'x100'). The first phase of the construction will only build the first 3 stories. What type of provisions should I make for the future story? It is unknown how far in the future the 4th story will be added. Thanks.






RE: Provisions for future vertical expansion
At the tops of the columns, make provisions for a future splice. Usually, the detail involves extending the columns above the roof approximately 3 to 4 feet (to allow a future welder good access to the splice). This can be worked in with the architect (hopefully) with perimeter parapet walls. Interior columns would extend above the roof, and would already be flashed and waterproofed with the roofing. So when the future construction occurs, the splicing and framing can proceed without digging into the existing roofing materials and compromise the user spaces below.
The 3rd floor roof/future floor would most likely be concrete so you would satisfy safety issues for occupants below during construction of the fourth level.
After the upper, final roof is in place, the existing 3rd level roofing can be removed and finish work could proceed.
RE: Provisions for future vertical expansion
Carl Bauer
www.bauerconsultbotswana.com
RE: Provisions for future vertical expansion
RE: Provisions for future vertical expansion
With steel structures, I generally provide for an opening at the location where the columns are to be added if a deck is cast. Often don't include for the the concrete deck to be added at the time of construction (many proposed additions never happen).
Use tapered insulation to achieve the roof slopes.
Taro's comment with respect to documentation is of particular note and I usually provide a good outline on the drawing itself for methodology and design loads assumed, not the project design note file. In addition to including info on the additional design loads, also include information on lateral loading.
For horizontal expansion, and sometimes for vertical expansion provide detail of connection. I've encountered many projects where the only provision for future expansion is an increased load capacity for columns and footings.
RE: Provisions for future vertical expansion