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.

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Energy Efficient Metal Building

In another post, I commented on thermal bridging and how metal is super conductive. It takes 10′ of steel to have the same r-value of 1″ of rigid insulation. So do the math…without a thermal break metal buildings perform quite poorly.

 

However, it doesn’t have to be this way. If you are building a pre-engineered metal structure you are not limited to fiberglass insulation, or “bag and sag” as it is commonly referred to. Why is it called that? Well, once its installed, the material is generally compressed between the purlins and the girts (wall or ceiling) and at that area, the advertised r 19 (minimum) is performing at maybe a 2 or 3. That is not a sufficient thermal break, so we get condensation inside that material. It collects, weighs down the rolls, and it sags. Using 2″ of rigid insulation in the roof and wall assembly may only be a r 13, but will out perform the higher advertised fiberglass  all day due to the lack of thermal bridging. Dow Chemical offers a fire resistant iso rated for interior exposure without a thermal barrier called Thermax. Within the Thermax family, there are several prefinished options that are aesthetically pleasing, so once installed you can call the interior finished.Thermax HD

 

OK…so you are NOT building a pole barn or ag structure and are offended that I would even suggest that.  Keep reading please:

Architectural metal roofs and walls are really gaining momentum for several reasons. Aluminum, steel, zinc, and copper are very green products. They are recyclable, made from recyclable materials, and have a long in service life when the right metal is used for an application.

We get calls all the time for steel panels to be used in roofing applications. And that’s fine. We ask a few questions before we get to work though, and I encourage you to do the same:

-Climate: Where is the project located? If this is going in an area of the country that is coastal or there is corrosive airborne materials, aluminum may be the best bet. If for some reason the Kynar finish is compromised and goes undetected for an extended period of time, the material will not be phased. Steel will eventually start to rust.

-Use: If this is going in a high abuse area, steel might be a better way to go. As much as I love aluminum, you can actually work at it with an exacto blade and make a hole. Not so much with steel. However, if you are looking at a panel profile that lends itself to standing water, we are back to aluminum.

-Roofs: Some of the oldest metal roofs in the world are not copper as some might think, but zinc. Zinc has an amazing capacity to maintain its integrity through wet/dry cycles. When designing with zinc, make sure the application allows for adequate drainage. Weather its positive slope on a roof, or a wall panel profile that allows for the rain to run off.

This list can go on forever, but I wanted to just give a little insight as to material selection. Phone calls and emails are free, so you are more than welcome to reach out.

 

So we have recognized that not all metals are equal, and there is not one type that is better than the other, They are all different. Know we get into finishes. Over the last ten years or so, whats known as “cool pigments”. Coatings colored with conventional pigments tend to absorb infrared radiation. Replacing conventional pigments with “cool” pigments (absorb less infrared radiation) can yield similarly colored coatings with higher solar reflectances. Mainly, cool coatings lower roof surface temperatures, reducing the need for cooling energy in conditioned buildings and making unconditioned buildings more comfortable. 

 

Pigments provide color by absorbing and reflecting different parts of the sun’s wavelength spectrum based on their chemistry. Color pigments selectively absorb visible light, and what light it reflects appears to the human eye as color. Pigments also have IR characteristics. While nearly 40% of the sun’s energy occurs in the visible light range (400 to 700 nm), more than 50% of the sun’s energy is in the non-visible infrared region (700-2500nm). It’s infrared (IR) that is largely responsible for heat build-up.

There are two types of pigments used in coatings: organic and inorganic. Organic pigments offer very vivid and bright colors but are generally not as lightfast and opaque as inorganic pigments. It is the inorganic pigments that are used for applications that are warranted against color change from sunlight and the elements. For the most demanding applications, like metal roofing, a special group of inorganic pigments known as Complex Inorganic Color Pigments (CICP) are used. Certain pigments within this group exhibit high IR-reflectivity for a given visible color.

Reflecting pigments have been designed to reflect infrared light while still absorbing the same amount of visible light. If the pigment has low infrared absorption, then it’s “cool”. Conversely, a pigment with high infrared absorption is “hot.” 
*Courtesy of The Metal Roofing Alliance
After all that, we determined that A) metal roof and wall panels can be “cool” in many respects and B) we still need to separate the metal from actually contacting the structure to minimize or eliminate heat transfer.
Traditional design has built the wall out like so:
-Interior gyp
-steel stud w/fiberglass in the cavity
-exterior gyp w/WRB/Air Barrier assembly
-Horizontal furring or hats
-Rigid insulation friction fit between the furring or hats
-Metal or metal composite panel
On paper this looks “ok”. But every contact that furring has with the stud is an energy super highway of conduction.  I went into this in my last post, so I wont belabor the point here again.
If you want your architectural metal facade to perform, incorporate a continuous thermal break and adequate back ventilation behind the panel. You have now created an aesthetically pleasing, energy efficient, and highly sustainable envelope.

A Systems Approach

Best practices looking at the building as a “system”. Specifying components to get the job done is a recipe for disaster. Is their any way to make sure they work together? Look for tested assemblies. Many manufacturers have gone through a lot of trouble and expense to do the heavy lifting for the design community. What if you could get the four basic control layers up in two trips around the building? What of you had some built in redundancies to make sure the envelope technology remained effective even in the event of damage gone un treated before the cladding goes on?    Thermax Total Wall System 1  Pager

 

Is this perfect? No. Nothing is perfect. But I will say that to date this is the closest thing to a silver bullet we have seen to control air, water,vapor,and temperature with as few trips around the building as possible.

Less trips around the building=Faster you dry in the building

Faster you dry in the building=Faster you finish

 

At the end of the day, the quicker the facility is turned over to the owner, the quicker everyone gets paid. And the bonus here is that you have created a better envelope in the process.

201300458177__4_07000 IMAG1267

 

IMAG1279

Project: Lawrence Public Library, Lawrence, KS

Architect: Gould Evans, Lawrence, KS

Installer: Drewco Construction, KC, KS

Assembly: Dow-Knight Ci System, Terreal Terra Cotta

The Building Envelope

Currently, this seems to be a hot topic. All sorts of manufacturers from asphalt to zinc are planting their flag in this new found piece of land, claiming efficiency, ease of use, and how they are the epitome of carbon neutrality. Yawn. From my timeline in this business, it goes a little something like this:

2002: The Invention of Mold and Mildew

If you were to look in any trade publications, they would make it seem that mold spores never existed before then. All over the industry material suppliers were laying claim to eradicate mold from the face of the earth.  Litigation happened….mitigation companies popped up left and right to clean up sick buildings. Was it a real or perceived problem? Who knows. At the end of the day, sticking kids in sick buildings is a bad idea. Working in an office with poor indoor air quality is not better.  I can say this-through all the hype some positive did come of it all. It begged the question from designers, “how do we control this?” and those with solid science prevailed.

2006: Green/Reflective Roofing

Vegetated roof systems have been around forever, but not clearly defined in the US until the mid 2000’s. Certain forward thinking companies saw this as a fantastic way to utilize the roof space on their structure for more than equipment storage. The benefits of a vegetated roof systems are many….too many to ramble on about in this space, so look for a whole entry on Garden Roof Assemblies in the near future. That being said, not every facility can handle such a beast so enter reflective roofing, stage left. The industry went nuts with SRI values, “cool roofing technology”, and more options than you could shake a stick at. But wait for it……here is the ONE THING no one ever talked about. And it seems so simple, its no wonder why it was swept under the rug. White roofs only reflect when they remain white. How many owners/facility managers work a cleaning contract into their quote request? How long will that tight, bright, and white roof remain well……bright and white? Not long usually before the project is completed the roof is pretty well trashed. So before you have the facility up and running with all the mechanical equipment, its performing poorly.

2006-Present:Green Washing

This one needs little explanation. Around that time it was so hip to be environmentally friendly you were seeing “green” on the most ridiculous labels, from building products to inconsequential consumer items. And most of it was a complete scam. I still get a small chuckle when I see a manufacturer of anything PVC related tie their product to “green”, “sustainable”, and “eco friendly”. If you have ever seen that stuff made you would understand why in plumbing it can only be used for waste service.

2007-LEED

It hit the scene prior to that, but around then in the Kansas City area, it was all a buzz. 1/2 of the contractor base and supply portion of the industry had absolutely no clue what this was. We would get phone calls for “leeds products”. The conversations would go like this: “Matt, this is Joe at XYZ Masonry. I need some of your LEEDS Styrofoam.” Wow. I feel the USGBC and the design community did the overall industry a disservice by setting new standards and imposing them on a world that fights change tooth and nail.  Are the LEED fundamentals sound? You better believe it. I think the intent is the most responsible thing to to happen to the construction industry in quite some time. Too band some of the criteria is completely whacked. And getting LEED accredited before achieving the basics like the CDT exam offered by the Construction Specifications Institute seems a little backwards.

2009-The Building Envelope

Yes, its been a long road of my rambling to get to this point. Thank you for sticking around, I hope you have found this a worthwhile conversation so far. As I mentioned before, all sorts of manufacturers have been claiming they have “superior building envelope technology”. But what does that even mean? What is the envelope, and how does it work? That is where the huge disconnect is. Warning to any A/E entities reading this: If anyone tells you they have a single solution for the project you are working on, and the next three (without knowing any details) run. Run fast, and in the opposite direction. There is to date no single solution for any project coming out of the ground. Hold these people to task. Ask them exactly what they are trying to accomplish and provide. It seems that every project we have worked on, one of these “solutions” type companies is no where to be found when it comes to interfacing with another component on the envelope. They generally turn tail and run since their product is already bought and paid for. Don’t be that guy. Push back and demand answers. Another hanging offence is ignoring the codes in favor of a slick presentation.  Recently I attended a presentation where a gentlemen was promoting a rainscreen system that he claimed was thermally broken, and adhered to the 2012 IECC. Last I checked, aluminum brackets attached to exterior gyp board fastened back to the studs is far from thermally broken, When confronted, he said, “well, its almost compliant”. Now, how do you start off your presentation with Thermally broken, code compliant, etc, and end with “almost compliant”?

 

Anyway…do your homework. Check it twice, and make sure you call someone with a well stocked tool box. Check this space, and check it often for tech bulletins, project profiles, and general industry related information. Please share with your peers and comment.  I encourage dialogue, and look forward to others with sound opinions and logic to either agree or challenge the science we are promoting.

-Matt