With most things in life, it’s important to start with a solid foundation. This even applies to roofing insulation, and it is especially true for those designing a low-slope foundation that would combine low-slope roofing insulation and flat roof crickets. This tapered roof insulation and roof cricket design combination provide much needed water drainage and long-term protection from the elements.
Architects and specifiers struggling with their tapered roof insulation system for a low-slope rooftop will learn the basics about tapered insulation in this article, starting with what tapered insulation is.
Please note that this article is intended to provide general information only about tapered roofing insulation and commercial roofing systems, and is not a substitute for professional advice from a roofing contractor, architect or other specifier with respect to any particular roofing project.
What is Tapered Insulation?
Tapered insulation has a geometric sloped profile that acts as part of a roofing system along with the deck, vapor barrier, membrane, and surfacing/accessories. It is designed in such a way that it tapers off to allow for adequate water drainage to avoid damage from pooling on flat commercial rooftops. There are a variety of different styles and thicknesses of tapered insulation that can be grouped together to direct water that would otherwise pool to the proper drains.
When is Tapered Insulation Used?
The main aim of a tapered insulation system is to deter water from pooling. Therefore, it is typically used on low-sloped roofs that do not have adequate drainage built into the structure (would otherwise not provide adequate slope) to achieve water drainage. There are many different thicknesses, slopes, profiles, and sizes of tapered insulation, so the layout will largely depend on the roof design and insulation requirements.
What Are the Pros and Cons of Tapered Roof Insulation?
To begin with, these are some of the benefits of installing a tapered roof insulation system.
Pros
- Protects the roof from ponding water
- Contributes to energy efficiency
- Great design flexibility
Ponding, or pooling water can become a significant issue with roofs over time. Commercial roofs can be specifically affected because of the HVAC and plumbing components located on the top of their buildings. These components can cause water not to flow properly and not allow excess water to be drained correctly. Standing water can be a home to insects which may spread viruses like the West Nile virus. Tapered roof insulation can be used to create unique pathways for water to drain around these components allowing for proper water flow.
Any exterior surface of a building will allow for heat to escape in cold temperatures and cold air to escape during hot weather. This can be especially true for environments that experience extreme weather. Insulation, including tapered roof insulation, creates an added layer of protection or barrier between those elements inside and outside of a building. The benefits of this include allowing for a comfortable, even temperature and potentially less energy being needed to cool/heat a space.
In comparison to other techniques, tapered insulation is better suited for complex designs. Even in the most complicated roof shapes or locations for rainwater, outlets can be easily accommodated using insulating boards that can be easily cut on-site. To make this operation even simpler, hips and valleys can be factory-cut and pre-mitered.
Cons
While there are many great benefits to gain from a tapered insulation system, there are also some challenges to consider.
- Can be costly in certain situations
- Challenging to adapt to some roofs
The primary downside of a tapered insulation system may be the cost. As a specialty product, it tends to be more expensive than commodity flat insulation panels. Tapered roof insulation panels also have an added installation cost because the panels must be installed in a specific “blueprint” sequence for them to be effective. The maximum thickness required to achieve the proper taper or slope may also impact the cost.
Unlike other forms of roof insulation, tapered roof insulation can be challenging to adapt to some roofs that have limitations for insulation thickness. This can occur on roofs that have HVAC equipment or other roof curbs and parapets. For example, tapered roof insulation might need a thick edge of 8”, but if the roof has a curb that starts at just 4”, it will be impossible to make the tapered roof insulation fit properly.
What Are the Functions of Tapered Insulation?
As much as 40% of all building issues* are due to some form of water intrusion, the source of which is usually on the roof. Therefore, many commercial buildings employ a low-slope roofing system to reduce the chance of standing water occurring. However, a low-slope roof doesn’t always account for collecting water around walls, curbs, and HVAC components. The main goal of tapered roof insulation is to help redirect pooling water from low-slope roofs that do not have an adequate slope and adding additional drains is not a solution.
Tapered Insulation Design Considerations
When designing a tapered insulation system, there are many things to consider. If the roof has skylights, drains, expansion joints, or HVAC, those elements need to be accounted for in the design. As a solution to this issue, several layouts can incorporate more than one of these design considerations. Here are some of the most common terms and explanations.
- Shed Roof Design
- Two-Way Slope
- Three-Way Slope
- Four-Way Slope
In a simple layout, tapered insulation forms a high point, causing the water to travel down to the edges of the building into scuppers and roof drains or gutters.
In this layout, the roof is split into two parts, each with its own slope. The slopes can direct water towards the building’s outer edges or inwards towards a center drain.
This layout is typically reserved for smaller buildings attached to larger ones as it slopes to a point that lies on the side of a drained area rather than sinking to the middle.
The four-way slope is widely considered the most effective method for proper drainage and uses inverted slopes to eliminate the water within the drainage area. Eliminating a lot of water through a small drain in this fashion can also cause pooling. That is why it is crucial to use tapered products, like crickets, to ensure that doesn’t happen.
The Impact of Roof Crickets
Crickets are V-shaped applications used in tapered insulation installations to divert water from valleys and rooftop curbs to low points like drains and scuppers. Roof crickets are very economical and are incorporated in the design and are typically combined with two and four-way tapered roof system design to achieve maximum drainage, even in challenging spaces. In a commercial setting, you can use crickets up against walls, HVAC, skylights, and drains to prevent pooling.
Benefits of Using Roof Crickets
There are many benefits to incorporating a roof cricket design into a tapered roof insulation plan.
- Roof Crickets are a cost-effective and straightforward way to help reduce the risk of leaks. Without the assistance of the roof cricket slope, water can pool around exit points like drains, causing leaks.
- Investing in roof crickets will help minimize or eliminate further damage down the line, potentially saving thousands on roof repair and replacement services. Not to mention the extended lifespan the roof will gain as a result.
There are many awkward areas of a roof where water can pool without the proper use of roof crickets. On commercial roofs, areas around HVAC components, walls, curbs, and drains are susceptible to pooling water. Roof crickets allow contractors more flexibility in designing a tapered, low-slope roof for a commercial application with more than adequate drainage. Therefore, roof crickets are essential to any successful tapered roof insulation system.
R-Value
R-value for insulation depends on the type of insulation, its thickness, and its density, and is expressed as a value per inch of material thickness. An insulation with a greater R-value will be more effective at retaining conditioned air, whether it is heated in the winter or cool air in the summer. Tapered insulation will vary from a low R-value at the low point and a higher R-value at the thickest point.
How to Determine a Roof’s Required R-Value
- Location
- What heating and cooling infrastructure are in place?
The building’s location, its intended use, and the local building and energy code requirements will determine what R-value should be specified for the building’s roof system. For example, warehouses and industrial buildings in temperate climates may need little or no insulation. Buildings used for cold storage or other specific conditions will require a lot of insulation. Higher R-values will also be required in office buildings located in extremely hot or cold climates so that worker comfort can be economically maintained throughout all seasons.
Tapered insulation can be used to meet a building’s specific R-value needs. The areas where the tapered insulation is thicker may have a higher R-value. Where the tapered insulation is thinner (such as where the roof will be draining) the R-value will likely be lower. That is why it is important that whatever the minimum R-value requirements are, they are met by the thinnest part of the tapered insulation.
Try IKOTherm™ III Tapered Commercial Roof Insulation for your next commercial roofing project. Available in a wide range of thicknesses, this durable and lightweight Polyiso Foam Insulation is designed to be part of a hot or cold-applied modified bitumen or built-up roof system.
Get everything necessary to complete a tapered insulation system, from roof crickets to iso board for flat roofs and more, from IKO Industries.
Additionally, IKO is proud to provide online informational and supporting documents for lines of commercial roofing, building, and waterproofing products.
With facilities across Canada, IKO offers everything from modified bitumen systems to insulation. As global leaders in manufacturing and the supply of commercial roofing supplies, IKO Industries continues to innovate and grow.
*Architect Magazine, When it Leaks it Pours Article, June, 2011
