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 are the issues?
Two factors cover most of the issues here. The first involves objects propelled by the wind. The first subcategory involves loose items picked up and propelled by the wind. These include loose materials, etc. If those items hit the windows, then breakage could occur. The second subcategory involves things knocked over by the the wind. 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.
Our second factor 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).
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 covering method.
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.