Window coverings address challenges associated with wind. Before we begin, Ron White (an eminent comedian down south) posted a great skit segment to put this into context. When dealing with windows, we must address both “that” the wind is blowing and “what” the wind is blowing.
Damaging winds include several different categories or types of winds, discussed on this site run by insurance adjusters. Once we understand that, then we can look at what constitutes likely damaging winds. For that, we can turn to groups like the National Weather Service, Environment Canada’s description of the Beaufort Scale, or the NOAA National Severe Storms Laboratory. Cutting to the chase, we can look to sites discussing hurricanes at the National Weather Services description of the Saffir-Simpson Hurricane Scale.
What I have found (and this should be verified by people with more experience) is that windows should survive 600 N/m2. What does that mean? For those that are more mathematically inclined, you can find a decent calculator here. Another site you may want to look through is here. For those who don’t like calculators, basically, it’s about 71 miles per hour or about 114 km/h. This is what is called a “SWAG” and you should probably talk to someone who can speak to your specific windows or situations directly.
What are the issues?
Two factors cover most of the issues here. The first involves objects propelled by the wind. These include loose materials, etc. If those items hit the windows, then breakage could occur. Objects “knocked over” by the wind also falls into this category.This includes things like trees and other objects. Instead of the item being “thrown” by the wind, the wind causes something to “hit” the window. In both cases, the question is if the window will shatter.
The second involves the force of the wind. Sustained winds present challenges similar to a constant pressing against the glass. This can cause the glass to deflect and, if the wind is strong enough, shatter. Sustained winds, however, pose less of a challenge that wind gusts. Peak wind speeds for gusts often exceed the sustained wind speeds. Because they are not consistent, they cause the glass flex back and forth that can exacerbate imperfections in the glass and lead to breakage.
Options?
Several options present themselves. Which one you select will likely involve three factors: (1) performance, (2) cost, and (3) availability of the solution. The section below is admittedly incomplete and those reading through it or using it should consult with competent glazing professionals.
We need to remember that a window consists of more than glass. Consider the glass (of course), the frame, and how it attaches to the structure. When you’re dealing with a contractor, make sure they show the whole picture.
Option 1: Materials or the Glass Itself.
Our first option deals with the windows themselves. Different types of glazing offer different advantages. Several groups discuss the different kinds of glass, including glassforum or the National Fenestration Rating Council. What you are looking for is an official mark that can be linked to the windspeed that the glass is designed to withstand. There’s also some guidance (albeit for the UK audience) that deals with glazing in marine environments. Generally, plain glazing may not be enough. Tempered glass may withstand significant winds, but you may want to look at windows that use laminated glazing for higher surface areas. That being said, don’t use this as engineering advice–talk to the professionals about it.
Option 2: Films
Our second option involves film. Film basically prevents the glass part of the window from shattering into fragments that can cause injury (or worse) if the window fails. That being said, if you’re considering this option, ensure that the installer knows what the film is being used for. There may need to be adjustments to ensure that the film attaches to the frame (or something similar).
You will see films advertised for anti-burglary and the like. These may offer some protection against things flying into the glass (like branches, etc). The “Mark 1 baseball bat” isn’t really that different than a tree branch from the window’s perspective. If looking at anti-burglary glazing or films, check to see if it’s been tested against a standard like UL 972 (UL being Underwriters’ Laboratories).
That being said, check with the company to see if their films are rated for use in high wind or in this context.
Option 3: Hasty Coverings
Protecting the windows may involve using something a bit more expedient. Boarding up windows (see our Resources page for videos on this) fall into this category. This option has two parts. The first involves having the materials on hand to protect the window. The second involves leaving yourself enough lead time to put the coverings over the windows safely. Window placement will factor significantly. The last thing you want to try is hanging onto a 2 foot x 4 foot sheet of plywood on top of a 20 foot ladder by yourself as the wind’s picking up. There’s a long list of things that can go wrong with that plan.
For window covers, ensure that you mark down where the cover fits and how it fits (see the top left corner). This will save you considerable time. If using clips to help fit the plywood into the window and hold it in place, remember that the clips should fit the thickness of the plywood (usually 5/8 inch or thicker).
This can be relatively inexpensive in that the plywood should last at least a couple of seasons
Option 4: Shutters
This solution is one of the more trusted but also one of the more expensive solutions. Basically, roll down shutters act as a reinforced barrier between the elements and the window, protecting it. These can be rated for pretty significant wind speeds as well as protecting against things (within reason) flying through the air.
Shutters installed on the second floor. These windows are protected this way because of their exposure to straight winds and the difficulty in protecting them using the expedient covering method (boarding up).
While shutters can be used on the whole home, there may be a case for installing them on “hard to reach” floors where putting the coverings in place would be (frankly) unsafe. In this case, the shutters are only on the second floor as the lower windows are not as exposed and can be protected relatively easily using the coverings.
An installation note: these particular shutters required approximately 7″ of space between the window and the soffit. As a result, some windows (as you see here) can be partially covered. This isn’t a huge issue but be careful to check windows that open outwards as these may become blocked .
This page is just intended as advice and as a way of getting you started to think about this particular challenge. Again, it’s not engineering-level guidance nor is it intended to provide “the answer.” You’ll need to look at your specific situation for that. This will, however, point you towards some resources that you may find useful.
What Guided My Thinking.
I took a look at four different factors. They were the following:
- Would they likely work at preventing damage?
- Would I be able to prepare myself in time?
- Would I be able to prepare very quickly if I got caught off-guard?
- Would I be able to prepare safely?
My end solution basically was this. For those windows that I needed to get on a ladder to cover, I went with shutters. Why? Well, they are engineered to work so no issues there. The last three questions were key. Those second-floor windows or hard-to-reach windows could represent a half day of work. By having the shutters, my preparation time was dropped from that half day to about 30 seconds. At the same time, I could get them ready safely.
I decided to use the plywood approach on the ground level (where the windows are within easy reach). That meant cutting the plywood to the correct size and having the fastening hardware on hand. Those windows are much easier to reach safely, and as I get older, I am increasingly willing to work smarter (versus harder). I can put them in the cart behind the tractor and simply drive around the house and just put them into place. No ladders involved.
My next question involved how much the shutters would cost and would it make sense. Well, the first thing I considered was the cost of damages should one of those windows fail. I figured that those costs would involve damage to stuff, drying and dehumidifying the spaces involved, removal of drywall and other affected materials, probable damage to flooring in terms of water, and so on. The costs ranged from about $15000 for moderate damage to upwards of $50000.
Then came the insurance side. Some of the damage would likely be covered. There were deductibles to consider, and then there was the question of how much rates might increase if I needed to make a claim.
The nine shutters cost me a pretty penny. That said, they have a life expectancy of about 20 years (unless they are damaged beyond repair in a storm). When I looked at the potential for storms in the area, I could find storms that had winds over 115 km/h (Fiona, 2022), Dorian (2019), Arthur (2014), and Earl (2010). I looked at that and thought that those were 4 storms that could (and did, for many) cause this kind of damage over 12 years. That’s about one every three (3) years.
I also saw that most credible sources predicted that the frequency and intensity of storms would likely increase over time. As a result, I considered a storm every three years as my “best case” or “optimistic” scenario. That meant that I was looking at having to face this potential scenario not less than six (6) times over the lifespan of the shutters. In reality, I figure I’m going to face this scenario probably twelve times or so. The shutters’ cost, therefore, was mitigating a total cost of somewhere between $80K to $400K. The shutters looked a bit more reasonable at that point.
So let’s face it. It’s a pretty major purchase. Then there’s the ultimate kicker: peace of mind.