Common Mistakes People Make Installing Windows Themselves April 28, 2016 Keep this in mind: many window manufacturers today may not honor a warranty if the windows they produce are not installed by somebody who understands all of the specifics and features of those windows. In other words, unless the windows are installed by an actual certified installer, if there is anything wrong with the window itself, the homeowner who purchased them could be out of luck. Here are some of the most common mistakes people make when installing windows themselves. Common Mistake one: The window is not level. If the old window used a shim to be level within the frame, it’s important to make sure the new window goes in level as well. This does not mean flush to the bottom of the frame, since the house could have settled or the frame itself wasn’t built properly in the first place. If the window is not level, it can cause drainage problems, leading to water getting trapped in the walls, leading to rot, mold, and other serious issues. Common Mistake two: The window is not flush properly. The window should be flush on the inside and outside portion of the wall. If it’s not, it can create unsightly issues and problems installing molding and other finishing touches around it. Common Mistake three: Broken glass. If a person is trying to install a larger window by themselves, accidents can happen. Cracking the glass or even breaking a panel out can not only break the seal, it can also make it virtually impossible to have it repaired on the spot. It’s best to rely on an experienced and certified installer when making an investment in new, replacement windows.