Supporting Existing House Wall to build extension

[Contraflexure74]

Hi All,

I have a house extension project where the client wants to open up the entire length of the rear façade of the house and extend outward in the rear of the property.

This involves kneedle propping 6m of the back of the house to get in steel beam supports in place. This beam will be taking a bit of 1st floor, half the roof load and some masonry. I was going to install 2 new UC columns each end of the span with 2 new pad footings. I was going to use 1 UB for the inner leaf and a separate one for the outer leaf. I was going to run these beams over the top of the UC's at each end and bolt them down to a header plate at the top of each column.

I'm just a bit nervous of the rear of the house dropping and cracking as the span to be propped is 6m. Anyone done this before and have any advice?

Thanks.

 

[Tmoose]

I'd want proof of a professionally engineered solution for the insurance company and newspapers in case something unfortunate does happen.

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I'd probably avoid engineering firms with names like Glickman, or any recommended by architects named Wright

https://failures.wikispaces.com/Fallingwater

The main cause behind all the deflection issues was insufficient structural capacity of the cantilevered girders. As one of the first floor cantilevers was being constructed, the reinforced concrete contractor, who was also an engineer, noticed that there were only 8 reinforcing bars in the girder which is a very small amount of reinforcing steel for the particular girder and expressed his concern to Mr. Kaufmann. This contractor ran his own set of calculations and determined that the number of reinforcing bars should at least be doubled to 16. Mr. Kaufmann passed the concern on to Wright who took the correction as a personal attack. An infuriated Wright wrote back to Kaufmann Sr. saying, “I have put so much more into this house than you or any client has a right to expect that if I haven’t your confidence – to hell with the whole thing.” After Kaufmann “smoothed Wright’s ruffled feathers” (Lemley), trust was regained but the extra reinforcing was placed in the girder.

 

[XR250]

I don't really understand your terminology, but in the past if I am taking out a wall like that which includes masonry I do the following:
Cut out vertical sections of the wall at say 4 ft. O.C. and install 3" HSS columns.
Remove the remainder of the wall.
Weld cont. steel channels to the sides of the columns to form the support beam.
Cut out the intermediate columns