Interstitial Spaces Part 2 [Design]

NOTE: THIS IS PART 2 OF THE INTERSTITIAL SPACE SERIES. PART 1 CAN BE SEEN HERE. In Part 1 of this short series I gave a brief overview of what interstitial spaces are and the benefits we found to using them in our projects. In this second part, I'd like to describe the interstitial space in more detail.

Featured Image

Just to recap, in traditional floor assemblies in residential construction, all utilities and services usually run "within" or "inside" the floor. This adds a level of difficulty and challenge, that although common and expected, is truly unnecessary.

Interstitial Construction

As you can see in Fig 1, the first thing that is different about interstitial construction is the void space where are all of the utilities and services are located. This space is created by installing a hung ceiling below the floor joists; we usually make this space 10" - 12" deep. The hung ceiling is comprised of 2x4 joists and 1/2" drywall.

Interstitial Construction

Interstitial Construction

Fig 1 - Interstitial Construction

The benefits of this construction method are immediately apparent.

  1. All utilities can now simply be installed without any additional cutting or boring of structural members. Remember, this takes time and has a financial impact on the project
  2. All structural members are intact. No weak members or over drilled joists to worry about here. The building inspectors love that!
  3. Subcontractors are not in each others way. Without tight and confining spaces, the subs can actually make their runs smaller and more direct from point to point, saving material and time.
  4. Sound between floors is minimized. If you were to add insulation between the floor joists, the sound transmission from space to space, is even smaller.
Interstitial Construction - Close Up

Interstitial Construction - Close Up

Fig 2 - Interstitial Construction - Close up

As you can see in Fig 2, fire sprinklers, recessed lighting, data cabling, plumbing, etc. all fit and work very nicely in the interstitial space. One added benefit of this methodology is an easier repair or expansion process if you ever wanted to add more lighting or increase your data connections, for example.

Here is a picture of the interstitial space we created at our Beethoven Four project:

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I must admit, its not the best picture in the world, but here you can see the 2x4 dropped ceiling (pre-drywall). You can see some recessed can lights going in and electrical cabling as well.

Overall, we love interstitial spaces. Everyone from subcontractor to home buyer wins. What can be better than that?