Contributed by Liz O'Sullivan
Recently, I was preparing a masonry architectural specification section for a remodel project. The project has an existing CMU wall which is to receive a small area of new CMU infill. It’s an exterior structural wall, and the architectural drawings indicate that the infill CMU is to be grouted solid.
I asked the structural engineer if we need reinforcing bars (rebar) in the cores of the CMU. I told him that I would delete rebar from the spec section if we don’t need rebar, so that the Contractor knows he doesn’t need to provide it.
The engineer said, “You can just leave it in the specs. If the rebar isn’t on the Drawings, they’ll know they don’t need it.”
Drawings and Specifications are complementary and what is called for by one shall be as binding as if called for by both.”
This is according to the General Conditions of the Contract for this project. This is a typical provision in construction contracts. (1)
So, if rebar isn’t required for that wall, there should be no rebar in the spec or on the drawings. If rebar is in the specs, even if it’s not on the drawings, rebar is required by the contract. If rebar is on the drawings, even if it’s not in the specs, rebar is required by the contract.
Design professionals need to completely comprehend this concept, and for some unknown reason, many don’t. Contractors need to completely comprehend this requirement, and for an understandable reason (it’s not in their best interest at times) they don’t always seem to grasp this.
The lead design professional on the project, the entity who is performing construction contract administration, is the party who must enforce the contract documents, including the specifications. This party has to understand the relationships among contract documents before he or she can properly enforce them. If the specifications and drawings have been prepared to be complementary, and are clear, concise, correct, and complete, they will be easy to understand (for all parties) and easy to enforce.
Contributed by Chris Maskell
The flooring industry is constantly challenged by the same repeating issues. Installing too early, wet concrete, non-flat sub-floors, sub-floor surface not prepared, heat not on, windows not in and lack of installer training and certification. In fact, as construction speeds up to meet demands for faster build times and with the threat of an increase in the cost of borrowing money lurking in the economic wings, the provision of acceptable conditions for the flooring contractor is becoming less likely.
This raises the importance of supporting those in the construction team (Building Owner, Construction Manager, General Contractor, Design Authority, and Flooring Contractor) with good, timely information that helps all involved plan ahead for the floor covering installation. As one of the last significant trades onsite, the flooring contractor needs certain conditions, that if not planned for in advance, will be next to impossible for the Construction Manager/General Contractor to provide without extra time and/or extra money: two things in short supply at the end of a build or renovation.
Change is possible, but requires a few things to be understood and acted on in advance.
There is a generic Canadian floor covering industry reference manual available for specification, which supports all construction parties, and when included in the Division 09 section of the construction documents, means correct flooring processes and supportive language is available to guide the floor installation and all the points listed below.
Contributed by Laverne Dalgleish and Roy Schauffele
In the last few years, a lot of attention has been placed on the proper installation of continuous insulation in buildings (editor: As per EnergyCodes.gov, continuous insulation is defined as insulation that runs continuously over structural members and is free of significant thermal bridging; such as rigid foam insulation above the ceiling deck. It is installed on the interior, exterior, or is integral to any opaque surface of the building envelope). The purported reason for this has been to stop the thermal bridging that occurs when you put thermal insulation between steel studs.
Years ago, we started out insulating our buildings by requiring a certain R-Value insulation to be installed in the cavities. In those days, wood framing was very common. As we moved to steel studs in commercial buildings, we realized that the building assembly was performing less than the R-Value of the insulation. From that, we started requiring an “effective thermal insulating value”.
Today some building codes simply require a maximum U-Value for the building envelope, which is supposed to reflect the thermal performance of the building assembly. But does it? In most cases, the answer is “not really”.
When we look at the requirements in the International Building Code and in ASHRAE 90.1, the basic principal of overall building assembly U-Value is there, but the only requirement is that you take into consideration the primary framing members (in a lot of cases, simply the studs). This is a good first step.
If we want to get to truly energy efficient buildings, we need to look at all thermal bridging materials that are incorporated into the building assembly. Not only should the main structural beams be calculated and the steel studs, but we need to look at all thermal bridges. This includes Z channels, fasteners, brick ledges, hat channels, masonry ties, balconies, parapets and anything else that will transfer heat. But the codes are not yet there.
Peering in to the future, there are some manufacturers that are starting to develop thermal break materials, and designers are starting to incorporate thermal breaks into their building envelope design. This is a desire by forward-thinking architects.
Today, the International Building Code and ASHRAE 90.1 do not require you to take all of the thermal breaks into consideration and you do not have to include them in your modeling. The Z channel is a common method used to be able to structurally support the cladding system. Is it a thermal break? Yes. For code purposes, do you need to consider it? No. That is a disconnect between code requirements and good building practice.
We want to reduce the energy use by our buildings and the building envelope provides the biggest opportunity. We need to bridge the thermal gap between what is required by the codes and what is good building practice. Having requirements for continuous insulation was a good step forward. We need to keep going.
This article was originally published by the Air Barrier Association of America under the title 'How Continuous is Continuous? And what about Z channels?' and a PDF may be downloaded here.
Contributed by Elias Saltz
Getting this out of the way first, lest anyone accuse this article of being in the denial camp: Anthropogenic global warming is almost certainly real and will very likely have significant long-term societal, economic, and ecological consequences. Studying the processes that contribute to AGW, predicting the effects with a high degree of certainty, and finding technological solutions to reduce climate change’s impact should be a high priority of the world’s governments at all levels, as should incentivizing reducing carbon output from all industrial and business sectors.
However, some industries are more ready than others to make impactful changes, by dint of embedded scientific expertise and economic feasibility. The energy sector has low- (and zero) carbon options, for example, and the transportation industry is developing feasible technologies for reducing emissions as well. The building sector, for all of architects’ good intentions, is still a significant contributor of carbon emissions and architects, by dint of their lack of rigorous scientific and technical training, do not have the necessary expertise to contribute meaningful innovation.
In his recent column in Architect magazine, AIA President Carl Elefante writes that the newest design imperative is reducing and eventually eliminating carbon output from buildings. “A zero net carbon building sector is the architectural design imperative of our time,” he argues. In his article, he makes a number of problematic arguments.
First, Elefante invokes the changes made to make buildings more fire- and earthquake-resistant: “In 1871, the need for fire-safe buildings rose from the ashes of the Great Chicago Fire. In 1906, from the rubble of San Francisco came understanding that earthquake risk is a design imperative.” Elefante acknowledges that fires and earthquakes are singular catastrophic events that cause immediate death and destruction; specific deadly events shocked the public into demanding safety reforms that were rapidly baked into building codes. This is still a false equivalency. Climate change is acknowledged by the code writers and the International Energy Conservation Code, and requires incrementally improved energy efficiency in envelope design, mechanical and lighting systems. But since neither architects nor anyone else really knows how to make a building fully zero-carbon, let alone do it for a reasonable cost, there’s no true mandate for architects to follow.
Contributed by Jason Spangler
For years now, the in situ relative humidity (RH) test for measuring the moisture condition of concrete has been shown to be the most reliable, accurate test available.
As far back as the 1960s, laboratories at the Portland Cement Association conducted controlled tests that verified the accuracy of RH testing. This research was followed by years of additional testing at Lund University in Sweden and elsewhere. In 2002, ASTM International first established the F2170 standard for conducting RH tests on concrete slabs.
The research confirmed two key discoveries:
Other methods typically involve taking measurements only at the surface of the slab. As the research has found, a surface-based moisture test can’t provide an accurate measure of a slab’s true moisture condition. That’s because it doesn’t account for the moisture conditions deeper within the slab, and those conditions are typically quite different than conditions at the surface.
The Standard Evolves as the Science Tells Us More
The initial ASTM F2170 for in situ RH testing was established in 2002, after continuing research at Scandinavian universities in the 1990s identified the exact specifications for conducting a reliably accurate RH test—placing the test probe at 40 percent depth for slabs poured on grade or 20 percent for slabs drying from both sides. After these scientifically-validated specifications were firmly established, ASTM International published a usable standard.
Until now, the ASTM F2170 standard has required a 72-hour waiting period between drilling the test holes where the RH probes are placed and taking official RH measurements. In practice, readings are often taken before the 72 hours has passed, so contractors have an idea of how things are trending. But because the official readings couldn’t be taken before 72 hours, that meant all decisions and work were basically on hold for those three days. Full stop.
Yet we’ve seen how the research on the RH test method has helped to refine our understanding of how best to use it. This trend continues. In 2014, a Precision and Bias (P&B) study, commissioned by the ASTM committee, tested for differences in RH readings at various intervals within the 72-hour period. In part, the idea was to assess if it is actually necessary to wait the full 72 hours for an accurate, actionable moisture readings.
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