Roof Decks

ISE Logik can make the difference in your roof decks, too.

ISE Logik knows that moisture within roof assemblies can be a major focus of discussion for the design/build community due to project schedule delays and disruptions to businesses and institutions. Despite the disruption to projects this issue causes, there remains significant misunderstandings across the industry regarding product warranties, field moisture tests, and just how long it takes concrete ‘to dry.’

To help you understand the major issues associated with moisture mitigation in roofing systems, let’s start with some
basics: Curing and Drying

Building

ISE Logik MVRA 900 admixture used in this Minneapolis condominium tower

The Purpose of Curing

To prevent the loss of moisture from the slab and, when needed, supply additional moisture to maintain favorable conditions for the concrete to mature. It occurs after the concrete has been placed. When properly cured, the concrete is given the right temperature and amount of time, and sufficient moisture, to develop its performance properties: strength, durability, stability, and resistance to abrasion, scaling, and freeze/thaw. Water is needed for hydration to continue to ensure the concrete is strong and the surface of the slab performs as intended.

Drying is the “Evaporative” Process

A mass transfer process to remove water from a material; in this case the concrete. Compare that with one of the fundamental goals of “curing” which is to keep the water in the concrete so it can gain strength.

The drying process occurs due to the evaporation of moisture from the slab, and the location’s environmental conditions will determine how long the process takes.

You Should Also Consider Dew Point

How many days of the year do you have dew form in areas where you have projects? Each dew cycle likely re-saturates the concrete slab surface, potentially up to and including the planned date of roofing installation.

 

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Remember …

  • The drying of a concrete roof deck is not determined by a set number of days (28 days for example) or the amount of water in the mix. 
  • Roofing projects are commonly delayed because of long drying times and drying/wetting cycles due to inclement weather events. 
  • A typical specification may state what the compressive strength of the concrete should be at an age of 28 days or such earlier age as the concrete is to receive its full-service load or maximum stress. “28 days” is not related to “curing”.
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A Word About Moisture Sources …

There are several main sources of roof system moisture – vapor diffusion, air leakage, air intrusion, and concrete moisture vapor emissions. Moisture can enter a roof system from the atmosphere, the installation of wet materials, and leaks. Moisture can also enter into a roof system due to the “movement” of moisture from an area of high concentration to an area of low concentration.
Roofing

ISE Logik for Roofing Solutions

So, how does a roofing contractor go about achieving the best roof assembly design and install for a project? First, it’s important to be mindful of all the potential sources of moisture in a roof assembly—and all potential sources should be proactively addressed. A vapor retarder for vapor diffusion, air barriers for air leakage and air intrusion, and MVRA 900 for concrete moisture vapor emissions. For examples of ISE Logik work in roofing systems, see our Project Profiles.

Dean CraftAs an associate member of SPRI (Singe Ply Roofing Industry), Principal of ISE Logik, Dean Craft, spearheads our interaction with the leading authority on single-ply roofing, and is a leading member of the ASTM D08 committee on Roofing and Waterproofing.