Other than attic ventilation, there is no more misunderstood component to your roof than the ice and water shield. Also known as “ice shield or weather guard”, you’ll see it as IWS when written on an estimate or proposal. Why is IWS so misunderstood? Because depending on the area of the country you live in and your climate zone, it is used differently.
How much snow you get in your area will change where and how much IWS is recommended for your roof. For example, where you put IWS and how much IWS you put on your roof will be different if you live in Omaha versus Minneapolis. Since I am writing this to all of you who live in and around Omaha, I will stick to what IWS means to us:
What is Ice and Water Shield?
It is a self-adhering underlayment that has a release paper to protect the adhesive side of the underlayment. IWS is a secondary waterproofing layer protecting the inside from water infiltration due to ice dams and wind driven rain. It comes in a roll that’s 3’ wide and of different lengths. We use rolls that come in a length of 65’. IWS is installed directly onto the wood roof deck with the sticky side down.
Where is IWS Used On a Roof in Omaha?
You could install IWS on the entire roof but it would not give you any extra benefit. So locally, IWS is mostly beneficial when installed horizontally along the eaves and vertically in the valleys in the place of felt paper. Local building codes reflect that these are the spots most need in our local area. IWS is required by building codes to be installed on every roof in and around Omaha.
How Much IWS is Needed?
Because of our climate zone and the amount of snow we normally get, the code says that IWS needs to be installed 24” or 2’ inside the outside wall at the eaves. Which means since the rolls are 3’ wide, how far the roof hangs over the outside walls of the house will determine how many rows of IWS you will have to install. As an example, if your roof only hangs over the outside wall less 1’, then you only need 1 row. If the roof hangs 2’, then you will need 2 rows. The valleys are easier since you just need 1 row with half of the IWS on each side of the middle of the valley.
What Does IWS Do?
IWS is used in places that are prone to snow, ice buildup, and wind driven rain. The IWS seals around nails and adheres to the roof deck, eliminating voids that allow water to infiltrate the interior and cause damage. A common example is when large amounts of snow sit along the eave and create an ice dam, the snow above then melts into water and builds up behind the ice dam. The maximum amount of water buildup needed to reach nails is 5.5”. If no IWS is present when this happens, that water will start to leak in around those nails and cause interior damage.
Roof-Tech is the Roofing Company in Omaha You Can Depend On: (402) 896-5554
If you’re in need of a new roof and want to be sure that critical factors like the ice and water shield are handled correctly, Roof-Tech is the company you can count on for quality work. Discuss your roofing project with us today by calling us at (402) 896-5554.