Working with Existing survey model in Proposed

[pthornborough]

Good Morning,

We do a lot of work with existing buildings and as such have surveys commissioned providing us with a Revit Building.

Now, in quite a lot of instances we need to demolish aspects of the existing building in the proposed works and wanted to know if there was a best practice way of doing this. 

Usually, the existing revit building is linked in to our proposed scheme so we don't have ownership of it per se. We also have a company template from which all our new projects are set up, so simply building a proposed model from the existing survey model obviously doesn't contain most of that template info (even with a transfer of project standards).

Can anyone out there share their thoughts on this please?

Thanks in advance!!!

[andybrack]

I think this needs to be approached by understanding the project scope and timing.  If you want the existing building to serve simply as a background then your current workflow is fine. But not having ownership of the Existing Conditions model elements is problematic. Demolition / New Construction projects can be very extensive so you need to be able to edit the objects. 

At my firm we use the typical Revit workflow and do all the work in the same model.  Setup plan views for Existing Conditions, Demolition, and New Construction by using Phases. Model the existing building, then demolish items in the New Construction phase.

You stated that you don't often have ownership of the existing building model. Why not?  Even if another firm such is modeling the existing building, I wouldn't approach it any other way.  We have hired outside firms to do point cloud scanning, which are then converted to an existing bldg. model. Once we receive the EB model, the new design starts moving forward. This is a linear process in terms of timing, but works well and is easily understood by my team members.

If the new design work needs to start prior to receipt of the EB model, I would do some project setup and give the scanning company a base file to work from which has Shared Coordinates established and includes your firms standard template items (families, titleblocks, etc). Then you can work in a new design model in the interim and copy objects back in to the composite model. Refrain from doing a lot of sheet work and annotation until you receive the EB model to make the transfer smoother.

If you want to maintain the setup you have now, you could keep the existing building as a linked model, but you still have to have ownership of it to adjust the 'Phase Demolished' parameter to create your Demo plans.  I would be interested to hear how you have been documenting demolition so far without ownership of the model. Can you explain?

Sincerely,

Andy Brack

BIM Manager

[pthornborough]

Hi Andy,

Thank you for your response. I agree that the project scope and timing drives this.

We actual do have the physical model(s) from a surveyor so there is no problem manipulating / altering that where necessary. By ownership I guess my concern was more to do with accidental alteration of elements by in-experienced users.

So, going forward - when your company have received the survey model do you then link this in to a new project, set-up with your companies' template and then bind so the geometry transfers? That is the only way we have been successful maintaining our standards.

Thanks again for your time!

Best Regards,

Paul

[andybrack · Accepted solution]

Yes, that is a good way to do it if you are concerned about maintaining integrity of the original data from the surveyor.  I would probably review the model first, prior to binding it in your new project file, to make sure the model content meets your requirements (elements model as the correct categories, tolerances, level of detail, etc.). I've never had a problem, but I do this type of integrity check even with CAD files.  Like in construction, measure twice, cut once.

The other option is to send a copy of your template file to the survey company and ask them to use it. After all, they work for you, right?

At my firm, we infrequently use outside survey companies to create the existing conditions files and normally build them ourselves based on the original building drawings. This way we can ensure assemblies are right, such as in a project where we re-skin a building. We use a survey crew if the original drawings can't be obtained, if the building is extremely complicated, or if it is cheaper / faster than doing it in-house.

Sincerely,

Andy