Constructability

Its been quite a while since we had an update here, and I apologize. But we are back and you can expect regular updates regarding technical issues and building science practice and theories.

Since the last update, my team has consulted on dozens of projects from concept to completion and in my 13 years, 7 months, and 14 days in this field, I have seen quite a bit. Some good, some bad, and some really ugly. This is your chance to get some free advice on what not to do. Going through life, we learn that learning the wrong way to do something can be just as important as learning the right way.

In this instance I will tell you a story about a relationship between an architect, a builder, and a subcontractor. Now if you are a professional in this industry, you know contractual rolls and relationships and proper process to get things done.

Three years ago, a well meaning architect designed a really nice (dare I say exquisite) hotel for a high end brand, to be built in a college town with a lot of money. Naturally, I will not name names. This hotel was to feature a roof top bar with an open joint paver pedestal system. This type of assembly is good idea (if not a best practice) for traffic areas, as it allows water to freely drain from the surface eliminating ponding water. Who wants to get all dressed up and wade through puddles after a rain storm when you are trying to enjoy a $15 beer?

The paver system was well thought out. The architect went through a lot of effort to research a durable surface, a broad color palette to choose from, and a sub structure to compensate for the structural slope in the deck. The roof system itself, not so much. An commodity single ply system was specified for the primary waterproofing to go under the pavers.

On paper, this all works out just fine. The plans clearly outline and detail the membrane, flashings, and terminations. Also, the section details were meticulously outlined showing the pavers elevated 23″ up from the roofing, with the pedestals set directly on top of the roofing.

To any designers that read this, you are probably thinking, “whats wrong here? This guy is obviously out of his mind.”

Setting the pedestals that high is just fine. But when you have site conditions that dictate that they need to be 36″ high to accommodate for the after thought of additional duct work and plumbing stacks you need to be flexible.

So, normal people would contact a professional and ask for design assistance, and then run the proposed changes up the chain of command for approval before proceeding. Once all the proposed changes are approved, you move forward.

In this case, the information was submitted to the GC, and the GC gave the go ahead to make the additional changes and issued a change order. Additional materials were purchased, to the tune of around $85,000 and the labor to install.

Fast forward about thirty days and the architect and owners rep show up for a site visit. Neither one had any idea these changes were made, as the GC never kicked the changes up to the designer for review. None of these changes were run by the warranting entity for the membrane system as either. Who was left holding the bag? Right, wrong, or otherwise the subcontractor is still waiting for his final pay out on this.

Fast forward to this week, and the roof is leaking like a sieve. The warranting entity has not released the warranty to the owner because the roof system that was installed is not approved for the designed application. All the deflection on the roof deck (when occupied) has the flashing being pulled off the walls, and the seams in the field splitting. Now the GC is trying to find creative solutions to fix this so they can finally close the job out.

When this was in the design phase, a system was proposed to handle this application. After the project was awarded, the successful sub contractor submitted an assembly to replace the one specified that would have eliminated these issues. And of course now everyone has amnesia since it was documented that this was a bad idea.

The moral of the story here, is just because it can be built doesn’t mean that it should be built in such a way. Do more research, and perhaps look at real value and long term performance and not what appears to be low on bid day. Read your construction documents. Follow the rules for submitting information. Do not take it upon yourself to make changes unless approved. Join your local CSI Chapter and get your CDT.