Precast for cost estimate

[haynewp]

I had a previous project where I had gotten input from a large precast mfr on the size of some load bearing shear walls that were fairly tall with significant shear and axial loads. The precast engineer suggested using 12" walls. Our client on this project, an architect, did not like the size of these walls when a preliminary cost estimate was done because it was going to take away from the funding for his architectural stuff. He told me I needed to find a more economical wall and that the estimate we got was not good enough.

Is it my responsibility to hunt down the most economical precast (or whatever engineered system by others) at the time when I am doing my design? Or is this something that should be left for the bidding phase? I could just have easily have noted on my drawings that the precast wall sizes are preliminary and the precaster (whoever ended up with the job) is allowed to substitute whatever size meets the load requirements I provide for the walls. It is just that the cost estimates could show as higher than needed up to the bidding and award phase.

 

[ztengguy]

Certainly you can get a preliminary design done, and if 12" is the thinnest section they can do, then the architect needs to go back to the drawing board. If you have done your work to get a efficient design, then he needs to live with that.

Whats the panel height, width, etc, and how much load does it pick up? 12" seems to be thick, unless a insulated wall, or 30+ feet clear span.

 

[haynewp]

The project was a while back but we have another coming up soon with the same architect. The walls were 45 ft at roof with a floor support at 20 ft, and they were insulated. Another mfr ended up getting them down to 10" at bidding. I think the answer is I get a preliminary design done and if he wants me to hunt down more manufacturers to get preliminary designs done because he doesn't like the one I got, then I need to be paid for that additional time.

 

[ztengguy]

10" for a 45 foot wall seems iffy, but if done before, why do you need to reinvent the wheel, show 10" and be done, since you know if can be done.

I agree, your job is not to get estimates. Give him the loads, and if he wants to do that, let him go at it.

 

[haynewp]

Those walls won't be part of the upcoming project. It is more of a question of where does my due diligence end when getting an estimate from a third party engineer for a special designed product. I think a single estimate should be sufficient unless it looks way off base and we probably should write in our the contract that a single estimate only will be provided.

 

[ztengguy]

I dont think you should be involved in pricing at all, unless a design build. You have provided a source to the architect that can build/verify your design, he should should be able to go from there to get a order of magnitude for cost, usually thats what they are paid for.

Push back, or tell him it will be additional to get quotes and review the products to make sure they conform to your design.

 

[haynewp]

Sounds good.