Adding a 5th Floor
Adding a 5th Floor
(OP)
I've got an owner who wants to put a 5th floor on a 115 year old 4 storey masonry load-bearing wall (4 wythes of brick) building. It has wood-framed floors & flat roof. He has a prospective tenant who wants to run a rooftop restaurant, mostly glass-enclosed. The building is only 28' wide, but 150' long. I think I can drop a steel structure on top of the walls consisting of basically a pre-eng frame with floor beam/tie at the column base that will carry joists between the frames. If the frames are close together (15-16') & the baseplates big enough, the brick can carry the gravity loads and there is minimal lateral load on the masonry. The brick walls extend 2' above the wood roof joists so the roof can remain in place. I have not done any calcs yet, it has all come up very quickly. Am I crazy?






RE: Adding a 5th Floor
Also have to consider wind, which 115 years ago, was not per our specs today. Snow?
Mike McCann
MMC Engineering
http://mmcengineering.tripod.com
RE: Adding a 5th Floor
RE: Adding a 5th Floor
The adjacent buildings can always be demolished, exposing the structure to wind. Remember that you cannot control the land that you do not own.
Mike McCann
MMC Engineering
http://mmcengineering.tripod.com
RE: Adding a 5th Floor
Thinking really simply for a moment, if you are adding a story to a 4 story building you are going to be increasing the demand/capacity ratio of the existing building by at least 25%. This doesn't mean that the existing building in inadequate, it just means that a more complex/detailed analysis may need to be run.
Good Luck.
RE: Adding a 5th Floor
RE: Adding a 5th Floor
RE: Adding a 5th Floor
RE: Adding a 5th Floor
The link may not work from here.
RE: Adding a 5th Floor
Of course, I'll probably have to drill small holes in the columns to get thicknesses.
RE: Adding a 5th Floor
The addition of a restaurant may require a 100 psf LL and may be difficult to accommodate.
In addition, any change in the loading regime that the building has been exposed to for the last decades? may have other effects, differential settlement, etc. Also old buildings derived their longevity by natural ventilation, air leakage, etc. Change in use may increase humidity substantially... and the addition of an added vapour barrier may have adverse effects on the old 4 wythe walls...
Dik
RE: Adding a 5th Floor
RE: Adding a 5th Floor
Dik
RE: Adding a 5th Floor
RE: Adding a 5th Floor
How close are the adjacent buildings?
Mike McCann
MMC Engineering
http://mmcengineering.tripod.com
RE: Adding a 5th Floor
Dik
RE: Adding a 5th Floor
RE: Adding a 5th Floor
Designation includes the exterior facade on 2 street fronts, not including the grade level storefronts which were changed in the 1960s. Specifically the masonry walls (brick with sandstone trims & embellishments), windows, and sheet metal ornamentation. The owner is a little tough to keep a leash on but we have got heritage approval for the facade restoration as of last week (he had already scaffolded & cleaned it without permission) and the interior is not listed in the designation. The Heritage Board is reviewing the proposed 5th floor addition, & the owner assumes he'll get their blessing & wants to be ready to go when it comes.
RE: Adding a 5th Floor
Has either architect addressed the vapour barrier issues? Do either have experience with historic masonry?
RE: Adding a 5th Floor
Had a job like this in Everett once where we had only about a foot between the buildings. We found a special insert that had a folding section that would spring out when it cleared the wall.
How much distance is there between the buildings?
Mike McCann
MMC Engineering
http://mmcengineering.tripod.com
RE: Adding a 5th Floor
MM: There is 0 distance between the buildings; in fact they have a common wall in one area. There is a sign painted on the former exterior of the neighbouring building that was uncovered when the plaster was removed.
RE: Adding a 5th Floor
Dik
RE: Adding a 5th Floor
Also for some ideas I'd recommend checking out FEMA 547 it's a good reference for retrofitting existing buildings.
RE: Adding a 5th Floor
I am in NYC and we do this type of thing all the time. The code here is extremely forgiving with alterations to existing buildings including adding stories and increasing load while not forcing you to upgrade. Whether or not that is good practice is a separate issue but it is done very frequently.
As for cast iron columns - you can find a lot of literature that will give you the original design strength equations (look at a book called 'Historical Building Construction', it has a lot of good references). I would not trust those at all though. If you follow the history of those equations you will find that the design capacity was successively reduced as we learned more about cast iron columns until eventually we stopped using them. One of the biggest problems is the connections. They are truly close to a pin, they basically just stack the columns and add some very wimpy connection plates. I would not increase the load at all on existing cast iron, it is unpredictable. You should span outer brick wall to wall, and add posts/reinforce as required at those areas.
RE: Adding a 5th Floor
whenever an alteration is done to a building here, we have to bring it up to code requirements (seismic).
RE: Adding a 5th Floor
Michael.
Timing has a lot to do with the outcome of a rain dance.
RE: Adding a 5th Floor
RE: Adding a 5th Floor
Dik
RE: Adding a 5th Floor