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Product Guide

The FORTIFIED Roof System

An introduction to a roof assembly and certification program from the Insurance Institute for Business and Home Safety

A FORTIFIED Home–certified roof installation is designed and built to withstand high winds and severe weather.

In 2013, a thunderstorm with high winds took a large section of shingles off the roof of the home I owned at the time, leaving the roof deck exposed to heavy rainfall that followed. For over a half hour I stood by helplessly watching rainwater enter the house, soaking the attic insulation and seeping down through every light fixture. Fortunately, the shingles and a couple pieces of siding were all that were impacted by the winds. (The public forest behind the home was not so lucky, thousands of trees were uprooted.) Cleaning up and making repairs to the roof, along with dealing with the insurance company took weeks, but eventually the house was made whole again.

Wind damage on roof
Roof damage after high winds; missing shingles led to interior moisture issues.

An issue to consider

My experience with roof damage during a storm is not unique; every year, thousands of people experience the damage that can occur when winds tear off sections of their shingles. According to the Insurance Institute for Business and Home Safety (IBHS), roof-related damage is responsible for an estimated 70-90% of the total insured residential catastrophic losses.

Recently, I was asked to consult on a new home in my area. The homeowner wants to build above code and asked if I would help the builder and designer with ideas and products that would best fit the homeowner’s budget and goals. One of the conversations we had was about durability. (In the back of my mind was my experience with wind damage.) The house is being constructed on the northeast corner of Minnesota’s fourth largest lake, 67,000-acre Lake Winnibigoshish. The home faces southwest and an 11-mile expanse of open water. As you can imagine, the wind can blow quite hard at times.

It so happened that I had been…

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  1. GBA Editor
    MIKE GUERTIN | | #1

    Great profile of the Fortified program Randy. The simple upgrades and small changes to standard installation practice can make a big difference. There are two related resources on the Fine Homebuilding website. One is a webinar on roofing in high wind zones focusing primarilly on asphalt shingle installation ( ) and the other an article

    1. Randy_Williams | | #2

      Thanks for the additional information Mike!

  2. owen_p | | #3

    Hi Randy,

    Thank you for the article.

    Could you expand on this statement:
    "The first is to use a self-adhering membrane over the entire roof. Depending on your climate, type of self-adhered membrane, and choice of finished roofing material, this may or may not be a good idea. "

    Specifically in my case, Ottawa, Ontario, a solar contractor who started in roofing but now does less of that than solar PV is proposing 100% roof coverage with ice and water shield (vented 4/12 pitch roof, well air sealed and insulated attic) - before installing new higher end shingles. The thinking is that this approach minimises the risk of leaks from solar PV racking mounts.

    During the roof install we will be removing the first row of roof sheathing to allow the proper installation of SmartBaffles from above (followed by cellulose top-up to R-60).

    The current decking is 3/8ths and soft in spots so we plan to add a second layer of 1/2" on top and this is what the ice & water shield would be applied to. Assuming that there is already 3' of ice and water shield on the perimeter we may end up with a sandwich assembly here...

    Does this sound like a dumb idea to make the roof "fully impervious" from the top side? The soffits are continuously vented and we are putting a 2" airspace in to 4" vertically above the cellulose with good ridge vents that stand above the snow.

    I am also implementing aspects of the Fortified system and in fact had their high wind checklist out when I met with the roofer. I've reinforced our single gable end-wall and plan to add Simpson Strong-tie screws to secure the trusses to the double top plate from the exterior during a future exterior continuous insulation project, or if I can get them through the nailing plates on the trusses to the double top-plates from the top I will try that when doing the baffles.



    1. Expert Member
      MALCOLM TAYLOR | | #4


      I don't want to put words in Randy's mouth, but here is my take on what he meant:

      Some unvented roofs have no drying capacity to the underside, and some roofs are designed with a gap between the sheathing and roofing material. Both of these would benefit from a permeable underlayment, rather than being covered with a self-adhered membrane like I&WS.

      Conversely, in some very wet climates like the PNW, or where there is very good drying capacity on the underside of the sheathing, impermeable underpayments which provide a stronger defence against roof leaks may make more sense. I would put your situation in this category.

      I can't think of a situation where the underlayment being self-adhered, as opposed to mechanically fastened, is not an advantage.

  3. michaelcatz | | #5

    I'm interested in a FORTIFIED roof assembly with exterior insulation. A raised heel truss is out of the question as this is a retrofit, so unfortunately I need the more complicated assembly if I want FORTIFIED and to have a highly insulated conditioned attic in zone 2A. I find plenty of diagrams for FORTIFIED roof assemblies and diagrams for exterior roof insulation, but I have yet to come across a diagram depicting the combination. It would be great if this resource was available to bring in to form a plan or even start the conversation with a structural engineer and a roofing contractor.

    1. Expert Member
      MALCOLM TAYLOR | | #6


      It should be fairly easy to include all the Fortified details for a more conventional roof on one with exterior insulation. The only difference I can see is the attachment of the upper sheathing or strapping, which would benefit from a fastener schedule designed by a structural engineer.

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