If your house is more than 75 years old and you are considering installing impact windows, there are a few important things to understand. Older houses, like yours, were usually built with balloon framing. This type of structural framing presents several problems when it comes to making home improvements like installing new windows. And, impact window installation in a balloon framed house is even more challenging. Here's what you need to know before you get started on your home renovation project.
How to tell if your house has a balloon frame
A house with a balloon frame will have wall studs running from the top of the foundation sill to the bottom of the roof. The wall studs are in one length, with no interruptions. With modern timber frame construction, the wall framing is interrupted by the floor joists.
Inside your attic, look for an opening at the top of an exterior wall that has no obstructions, such as windows and electrical outlets. Tie a washer (or other small, weighted object) to a string that is long enough to reach the ground outside. Slowly drop the washer through the opening until it hits the bottom.
Make a mark on the string at the top of the wall opening to show the length of the drop. Slowly pull the washer back out of the opening and measure the string. If the string measures the length of the height of your house, then your house has a balloon frame.
Window openings may not be properly framed for your new windows
With balloon framing, window openings are typically not framed up to today's standards. Since the wall studs run the entire height of the house, window frames generally consists of short lengths of lumber nailed perpendicular to the vertical wall studs. This type of framing is not strong enough to support impact windows.
The glass and construction of impact windows is what gives the windows the ability to resist strong winds and hard impact from objects. However, impact windows need to be securely and properly framed into the wall in order to provide the protection they were designed to give. The frames will need to be beefed up. To do this, the wall studs will need to be cut so better framing can be installed for the impact windows.
Temporary structural supports need to be installed so windows can be properly framed
Given that wall studs in balloon framing goes the entire height of the structure, it is crucial to support the walls with temporary structural supports. To accomplish this, contractors will attach strong joists to help carry the load of the wall when the wall studs are cut for the window framing improvements. In order for the contractors to know exactly where to attach the temporary structural supports, you will need to hire a structural engineer.
Once the wall studs are cut and the window openings are beefed up, your new impact windows can then be installed. It's a good idea to have the structural engineer check the new framing work before the contractors start removing the temporary structural supports. Don't be alarmed when the contractors or structural engineer informs you that you may need to remove a portion of the wall coverings in order to properly attach the temporary structural supports and improve the window openings.
Impact resistant windows are designed to withstand strong winds and impacts from objects that may get tossed around by a hurricane or tornado. In order to do this, however, the windows need to be properly framed into the structure of the house. For a house with balloon framing, this means making significant adjustments to the exterior wall studs of the house.