4D BIM for Construction

Clarifying Details and Scope Using the Power of a 4D Schedule

Posted by James Norris- Beck Group on Feb 18, 2015 4:00:00 PM

Often times when we create our initial construction schedules, we don’t know some of the specific details that will determine how the building can actually go together. We all have ideas on what we “want” to happen in order to meet our promised end date to the owner. But, do we ask all the right questions needed to build our buildings in the way we logistically formed our schedule for the project?


We should but sometimes we just don’t have the details needed from the documents or feel we can’t conceptualize what has been placed on a 2 dimensional set of drawings. However, those documents most likely came from a 3D model, especially with today’s architects working more and more with 3D authoring tools. 


By using the 3D model, we can track down some of those open questions we just don’t know yet or cannot conceptualize. We are a team with the architects and although details must be created, the onus is also on us to help fill in the gaps if we have the capability. And, if we can help fill in those gaps early, we can work out better details with the architects that look good for them, and work well for us, from a constructability point of view.

When we build a schedule from a 3D model, many new questions arise that we would normally not think about early on in the project.

Here are some examples of questions we may have missed if not for the project team taking the initiative to build the schedule in 4D.

  1.  We are trying to build the masonry walls on the North side of the building while concurrently building the curtain wall on the south side. However, after looking at the 4D schedule model it seems we need clarification on the details of how these two systems tie into each other.Beck_Blog_2_3
  2. We want to start on this storefront system early, as this area drives our schedule. However, we noticed while building the 4D schedule in this area that there is some confusion on what is existing storefront and what is new. See the highlighted area in question. We also noticed that if this highlighted area is an existing system, the new storefront’s mullions on the left do not match the elevations of what may be existing mullions in the highlighted pink region. Beck_blog_2_4
  3. We will begin erecting the structure fairly soon and want to build the retaining walls first. In the 4D schedule we noticed that the retaining walls going up to the new and existing elevated decks hug the structure and we need detail clarifications on how this condition should be built.                                         Beck_BLog_25
  4. We noticed that in this new area, the existing slab is actually modeled higher than the new slab but there are no details on how these two slabs connect to one another and if needed, where a ramp or steps will be located. 


It’s not that we do not ask good questions, but having access to a 3D model while building our schedule helps all of us see things that we would normally never see in a set of 2D documents. So, if you do have access to your designer’s 3D model, open it up and put it into Synchro. Then, dive into building your schedule with the 3D model right in front of you. I guarantee you will have a ton of logistics questions.

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