Many people are unaware or unsure what their decision entails. And hopefully with some good guidance from your contractor, he will explore your needs and explain them to you in detail. If not, here are some points to consider. Whether your current windows do not function properly or as you would like or you are concerned about the efficiency of them, or even both.
Once you have decided to explore your need to upgrade, most window remodeling jobs are in the thousands of dollar range, given the usual high quantity of units installed, so many choose to have a Thermal Infrared inspection performed to see where the issues are and the best remodeling method to use. The inspection is basically a thermal x-ray of your house, showing where air infiltrates and temperature differences on the surfaces of walls and ceilings, indicating insulation or moisture related issues.
There are significant differences between replacement or new construction style windows from both a cost and requirement perspective, lets take a look at both styles.
A popular option is the replacement window style, the window unit from a price perspective is similar to, or slightly lower than a new construction style unit, and the Installation costs is less because less labor / time and less materials are used in this installation method.
The window sash units themselves differ little if Double Glazing Sash Windows Kent any, from the new construction style units.
A basic replacement window installation consists of a measurement of the existing window opening, width and height, “accuracy counts” for a proper size replacement unit to be made. Once your windows arrive the first step is removing the existing window sashes and the tracks or guides they operate on. A general cleaning of the opening is completed, and then the replacement unit is “dry fit” to check for any obstructions or other issues.
Once this has been done we are ready to do the install, an application of sealant is applied to the exterior stops, insulation is installed in the adjustable / expandable top and or lower portions of the window unit, the unit is then put in place, shimmed and adjustments for plumb and level are made, then the window is secured with screws in the manufactures supplied holes. If the original sizing was performed correctly there now is a requirement for minimal amount of insulation to be installed in between the unit and the opening, then reinstall any interior stop trim and any needed touch up. And your window is in.