Saturday, March 21, 2009

Composite Model Strategy p.1

I recently was asked how to use architects models if they're "trash". While it seems like a good question and easy to ask if you aren't an architect, I have been asked the same from engineers and fabricators by contractors and heard from the architects, what kind of model is the contractor looking for?? Basically everybody is asking why they can't use each other's models. Here's the deal (generally speaking).

- Engineers (mechanical) are using general architecture models to run CFD and daylighting analysis. Here's what's important to have right in the architecture model. First, floors align with the exterior walls, no gaps and if the floor bears on the exterior wall verify it aligns with the internal structure of the wall and doesn't penetrate or overlap the exterior wall finish, go. Next the roof needs to align with the parapet wall, same rules on the exterior finish.

- Contractors are using models for just about everything depending on who you're working with. This means more things than I can probably include in a blog but here is my best shot.

1) Model it right. If the interior walls are 9'-6" high and then diagonally braced to structure above. Model the walls at 9'-6" not to structure. It helps on estimates, clash detection and just about everything else. Accuracy is the first step to a good model.

2) There is no generic modeling. And architects and engineers everywhere say "but what if?" and "won't the contractor lock me into my material selection?"

There are a couple of answers to this and why I say there isn't any generic modeling. First the relationship between the architect and the contractor needs to change. Desgn-build and IPD are great starts to a reformed process, I think that we are probably going to see even more integrated forms of delivery soon. This of course means that a brick wall, can turn into a rainscreen, which can turn into metal panel. This is the very nature of design and construction... things change. So model as the design is being envisioned. The estimating contractor will be making assumptions on construction type and materials anyways, might as well better inform the assuptions being made. If you're wondering why contractors are calling models "worthless" this would be one of those reasons.

3) Design models don't work. BIM isn't CAD. If you're building a BIM to provide a construction tool that helps better coordinate the project than build the model to a level of constructable detail that a GC can use and build from start the dialog with the contractor to find out what they need as well. Construction is a team sport. Otherwise use CAD or use BIM to just generate your CD's, but don't sell it as "doing BIM."

4.) More detailed models replace less detailed models. For example, structural models supercede intial architect structural models. Detailed structural models/fab models supercede structural models.

Well this is a start.... I'll continue this when my daughter isn't needing to go to bed..turns out she's not as into ESPN as daddy...what's up with that?!