Category Archives: Single Ply Roofing

Flat Roof Ponding

Is It Acceptable to Have Ponding On My Flat Roof?

By Allen Sensel

Moderate Water Ponding

Introduction

There is a lot of speculation with older building designs and how their flat roofs have a tendency to collect pools of standing water referred to as ponding. The purpose of this report is to provide clarity for a commonly misunderstood notion that a flat roof, whether it’s asphaltic built-up, modified bitumen, or any kind of single-ply membrane, should not bear any kind of collection of rain water. I will provide brief examples from the IBC, U.S. Department of Housing and Urban Development, and Factory Mutual, all of whom mandate construction and renovation standards to comply with regional climates,weather patterns, and safety.

Definition

Ponding water, as described by the IBC and recognized by the U.S. Department of Housing and Urban Development, is water that remains on a roof surface longer than 48 hours after the termination of the most recent rain event.

Standing Water

This explanation from the IBC can also point out that directly following persistent rainfall, water is not considered standing until after 48 hours of dry weather, after which, can evaporate efficiently at temperatures above 45 degrees Fahrenheit. Only when the same volume of water exists after this period can there be a concern for potential leaks, providing that the roof system was properly installed.  The U.S. Department of Housing and Urban Development elaborates on how building inspectors approach ponding after an installation:

“48 hours before conducting a physical inspection, check the local weather forecast to see if precipitation is expected. If there has been precipitation within 48 hours prior to your inspection, use your judgement in deciding if observable ponding is due to the recent precipitation or because of an ongoing problem. Keep in mind that some flat roofs are designed to allow ponding.”

Concurrent with the size of the roof, Factory Mutual Global explains rain load on a dead flat roof:

“2.1.1.1.7 Roofs should be designed with positive drainage: however, dead-flat roofs consistent with this guideline are acceptable.”

An older building will lack modern specifications for framing slopes a minimum of  1/4” rise per 12” run. The solution to controlling water flow on a dead flat roof, if ponding is still a noticeable concern after following the aforementioned provisions, is designing a framed slope for positive drainage to scuppers and/or bowl drains.

Resources

“Definitions Supplement.” U.S Department of Housing and Urban Development Real Estate Assessment, October, 2001: 3

“Roof Loads for New Construction.” FM Global Property Loss Prevention Data Sheets, September 2006: 3-5

International Code Council. 2009 International Building Code. 2009

 

 

Cover-Boards: Purpose & Application

by Allen Sensel

Glass-Matt Roof Protection

When putting a low-slope roof together it’s important, as a building owner or engineer, to understand how to control moisture, combat mold, and provide fire protection. Cover-boards offer sufficient roof deck protection that meet these requirement for installing a roof. They can also serve as a purpose for re-covering your roof. These boards provide a clean, smooth surface to attach your next roof system to.

Glass-Mat Roof BoardUSG manufactures Securock, a glass-mat board that can be used on a flat roof for dimensional stability, surface protection, and overall increased lifespan of a structure. When installed correctly, Securock acts as vapor and fire barrier, keeping the roof membrane from developing mold and succeeding in fire standard ratings (rated at the maximum ’10’ with Factory Mutual [FM] Class 1 and a Class A Fire rating with Underwriters Laboratories [UL]). This is a great way to qualify for lower insurance rates as your building is less prone to fire damage.

One of the other benefits to using Securock is its ease of installation. The packaging is efficient and the board utilizes a high-quality, mat-to-core tensile bond, making each piece easy to cut and hand-break. This creates a faster labor work-flow and less of a mess to clean off of the roof surface, which helps to cut cost and keep workers focused on installing a quality roof as a whole.

As a local certified Seattle roofing contractor, we’re all about installing a quality commercial flat roof and so we recommend using USG Securock for our installations. We also specialize in single-ply residential roof systems. Give us a call at 253-445-8950 for a free estimate or drop by our website, http://www.chasenw.com.

What is single ply roofing membrane, is it right for my home in Seattle?

Single Ply Roofing For Seattle, Washington

Single Ply Roofing For Seattle, Washington

Chase NW specializes in single ply and commercial roofing!

When it comes to roofing in Seattle we all want to know what is the best type of roofing for our home or business. Low slope roofing systems (a roof with less than 3” of rise per lineal ft) can get even more technical with commercial and architectural specifications required by the city building codes. Its important that you use the best material for your roof design. As a commercial roofing contractor in Seattle we have seen a huge spike in the popularity of single ply roofing systems.

What is single ply roofing membrane

Single ply flat roofing membranes are sheets of strong, flexible material made of synthetic polymer. You will often hear the terms of different types of single ply like “TPO”, “PVC” or EPDM. Single ply comes in different thicknesses that determine the roof life and the length of warranty that a flat roofing contractor in Seattle can offer. The most common thickness or millage are .45, .60, .80 and now EPDM comes in a .90 mil. The membranes come most commonly in white, black and gray, but is also available in custom colors like green, red, tan and other colors.

Sustainable roofing with single ply membranes

Single ply membranes in white have a high solar reflectivity rating. This helps to reduce Single ply systemover heating in a given structure and lowers energy bills. This type of Sustainable roofing often qualifies for special building deductions in Seattle and or the Energy Star federal tax credit.

Application

Single ply membrane comes in rolls ranging most commonly from 4’ to 10’. There are fire rated slip sheets and cover boards that can be used to attain the necessary fire rating you need to insure your building and meet codes. Typically you will run your membrane in the direction of the slope which is either framed in or built using a ridged insulation. The membrane can either be mechanically attached with screws and plates or fully adhered. The mechanically attached application requires welding at the seams. It is commonly stated that the tear strength of the seam weld is stronger than the material itself.

Warranties

Seattle Single Ply Roofing

Chase NW Roofing is a certified contractor with Versico!

The standard material warranty for single ply membranes such as Versico is 20 years. With special application procedures we are able to offer “complete system warranties” with “no dollar limit” coverage. These no dollar limit warranties are 100% manufacturer backed coverage on material and workmanship from 10-30 years.

Chase Construction North West, Inc is your qualified commercial and flat roofing contractor. We have a wealth of experience installing single ply on commercial and residential structures. For a free quote and consultation please visit our quick estimate form or call us at 253-445-8950.

Thank you for reading our roof life blog. Best wishes from our family to yours!