Home > Windows > Window Installation Guide: How to Install or Replace a Window

Window Installation Guide: How to Install or Replace a Window

Updated Nov 22, 2022

Updated Nov 22, 2022

Home > Windows > Window Installation Guide: How to Install or Replace a Window

DIY home renovations can save you a good deal of money in a pinch. If you have the right tools at your disposal, and enough patience, then doing your own window replacement could be a valuable use of time and resources. We highly recommend having a trusted friend to help, for both safety and efficiency. Whether you decide to get such assistance or not, a do-it-yourself window replacement can lower your energy costs and lead to a more energy-efficient home overall.

Window Replacement Basics:

Estimated Time Per WindowEstimated Cost Per WindowRecommended AssistanceSkill Level
3 to 7 hours$300 to $800One helperIntermediate

Please note that the above time estimate assumes that no structural alterations to exterior siding or frame have to be conducted. The estimated costs include the cost of a new window, as well as associated materials, but can be higher, depending on the kind of window you install.

How to Remove a Window for Replacement 

For our purposes — and yours — we’ll be detailing the process for inserting replacement windows instead of new construction models. New construction windows fit best within total remodel projects, and will often require the removal of sections of siding or outer case moldings in order to properly fit them to your home.

Replacement windows are far easier for the average DIYer to install. Though any remodeling project will require a fair amount of know-how and baseline technical skill, we think that this guide will help you on your way.

If a DIY window replacement seems out of your reach after reading this, then we recommend reviewing our top window contractors here:

How to Install a Replacement Window: DIY Guide

Follow this step-by-step guide for a smooth home improvement project. We recommend hiring a licensed professional if your window project requires working on a second story, but the following steps should make for an overall positive experience when installing a replacement window.

Measure the Window Opening

Thoroughly measuring your window frame opening is the first step in any window replacement project. Getting precise opening measurements will ensure that you purchase the right-sized window for your needs.

For all measurements, be precise. Record all figures to the 1/16th of an inch, and use the shortest measurement for height and width. This will ensure that the replacement window you order will fit into your existing window frame.

How to Measure Your Window

You’ll need to take a few different measurements of your window opening before proceeding further.

Across

Measure your window frame width from the inside, from jamb to jamb. Do this at the top, middle, and bottom for a fully accurate measurement.

Top to Bottom

Measure your window frame height from the sill to the top jamb at the far left, middle, and far right.

Diagonal

To ensure that your frame is fully squared, take diagonal measurements from the corners of your window (bottom-left to top-right and vice-versa). If your measurements differ by 1/4 inch or more, you’ll have to correct the squareness of your frame with shims later on in the installation process.

Choose a New Window

A common reason homeowners cite for replacing old windows is to increase energy efficiency within their homes. Double-hung windows are the norm now, due to their insulative properties. They make outer storm windows unnecessary, as their double panes and argon gas insulation provide all of the shielding you’ll need from the elements. Be sure to choose a window model that comes in your desired size.

Options

  • Full-frame replacement: This type of window will be a necessity if your entire existing window and frame are rotted or deteriorated to a point where leveling with caulk and shims is impossible. These windows include a sill, as well as jambs on all sides.
  • Pocket windows: Pocket windows fit into the existing jambs and frame, and are fastened to them with caulk and nails.
  • Sash kits: Sash kits involve replacing all existing moving parts of your window, including both lower and upper sashes and jamb liners, a head parting stop, and sill liners.

Gather Tools and Materials

Your next step will be to assemble your tools and materials. Aside from your ready-made window replacements, you’ll need the following:

  • Tape measure
  • Level
  • Hammer
  • Caulking gun
  • Silicon caulk
  • Expanding foam (canned polyurethane foam works well for DIY applications)
  • Power drill
  • Screwdriver
  • Pry bar
  • Putty knife
  • Utility knife
  • Pair of pliers

Once you’ve gathered all of the necessary tools, and have your replacement window in hand, you can begin the process of removing your existing window and replacing it.

Infographic showing the tools and materials needed for a DIY window replacement
Image Source: Elisabeth Beauchamp

Remove Your Existing Window

Follow the steps below to safely and efficiently remove your old window.

Score and Remove the Inside Vertical Strips

Using a utility knife, score the paint between the sash stop and the inside casement. Do so on both sides of the window you’re replacing. Your aim here is to simply cut the paint without pressing your blade into the wood.

Next, use a putty knife or similar wide, flat tool to separate the stop from the casement. Do so carefully, so as to avoid breaking the sash stops. They’re secured with finishing nails, which should come out with your sash stops. You’re going to reuse these pieces to finish your window installation, so set them aside once you’re finished.

Remove Parting Bead

Next, you’ll have to remove all parting beads – sometimes called parting stops – from your window. These are strips of wood or vinyl which are about 1/2-inch square and run along the top and bottom of your window frame. Use pliers to pull them away from the frame. Since you won’t be re-using these, you needn’t worry about damaging them. These features are labeled in the window diagram above.

Remove the Existing Window

If your window has sash weights, use your utility knife to cut the ropes attaching them to the sides of the window. Do so as close to the window as you can, so you can use the remaining rope to easily remove your weights.

If your window is sitting on any tracks which are adhered to the inside casement, use your putty knife to separate the tracks from the casement. These will either be secured by wood staples or nails, so you’ll need to be firm when removing them.

Once these are free from the frame, bring the top sash and lower sash together around the middle of the window frame. Grip them together, and tip the top of the window assembly back toward you. Once it is halfway out of the window frame, grip it by the sides and firmly lift it away from the frame.

Prepare for Window Replacement

Thoroughly inspect the interior and exterior of your window frame. Before installing your new windows, clean up any defects that you find. Sand, repaint, and level your window frame to prepare it for your new windows.

Bear in mind that vinyl replacement windows can be ordered to match almost any color scheme, and will not require any painting. Aside from offering efficiency, these can be weatherproofed on the outside, while giving the appearance of a wood window on the interior.

Apply Sill Pan Flashing Tape and Caulk

Once your window sill is clean, apply a bead of caulk to each corner of the sill pan. Roll your weatherproofing tape over this, so that it covers the bottom of the sill and six inches up each side. Be sure to firmly press the tape against the sill to ensure that there aren’t any gaps.

Test-Fit Your New Window

From the inside of your home, lower your new window into the existing frame, bottom first, and slowly press it fully into the frame. Use your level to ensure that your new window is sitting evenly within the frame, against the exterior stops.

Once you’ve done this, remove the window and re-seal your window frame. Apply a bead of caulk around where both the inner and outer edges of your new window will sit within the frame.

You’ll want to try this test fit before applying any caulk around the window opening. Doing so will help you to see how many shims you need around each side of the window to level it, if any.

Install Your New Window

Once again, lift and place the front bottom edge of your window into the frame, and gradually press the top of the window into place. Once your window is in position, measure the gaps on each side to ensure uniformity. This gap should be no wider than a 1/2 inch. Once you’ve ensured that your window is plumb and level, you can move on to the next step.

Install Shims and Secure the Window with Screws

Your window kit may come with plastic shims to ensure proper spacing around its edges. If not, you can purchase cedar shims to ensure proper spacing between the window and frame. Once you know the window is level, use shims to hold the window in place at the screw points.

Once your shims are in place, drive mounting screws through the marked holes in the side jambs, as well as the underlying shims. Score your shims with your utility blade and break each off around the edge of the window.

Caulk the Interior Side of the Window

Once your screws are fully in place, you’ll want to caulk around the edges of your window frame. A thin bead should adequately seal your window from the outside elements. Ensure that there are no gaps around this newly-caulked edge.

If any excess caulk has gotten on the surrounding wood, you can wipe it off with a moist paper towel before it dries.

Re-Install all Inside Stops

The small strips of wood that you removed at the beginning of your window installation are going to go back on your window as a finishing touch, over the new caulking. Once your inside stops have been placed flush against the caulk, secure them by hammering in finishing nails every six inches.

Install Backer Rods or Spray Foam

Now, you’ll move to the exterior of your home. You may notice some gaps between your new window and the surrounding frame. You can either install a layer of spray foam or foam backing rods to seal this gap.

With either, you’ll want to achieve at least 1/4-inch of actual insulation within a given gap. Spray foam is a popular choice due to its malleability and usefulness in oddly-shaped spaces. However, if you have a home with more recent construction, foam backer rods are a viable choice. These come in numerous sizes to suit many small insulation needs.

Use your putty knife to push the backer rods to at least 1/4-inch into the gap in question. After your foam backer roads or spray foam insulation are in place, apply a bead of caulk around the exterior. Use your putty knife to make it level and flush with the surrounding window and wall.

Install Exterior Trim and Paint

If you had to remove any further exterior fixtures in order to install your windows, re-install them to the outside of your home once your window is in place.

Once this is done, paint any disturbed or scraped outside fixtures to match their former appearance and your new window.

Tips for Window Installation

Here are a few tips you can follow to help your window installation project go according to plan.

  1. Protect your interior floors before beginning installation. Laying down a tarp or protective cloth inside the windows you’ll be replacing can go a long way toward protecting your floors from outside or construction debris that could find its way inside during the process.
  2. Protect your belongings in any exposed rooms. Removing your windows and screens could potentially allow dust, bugs, or debris to get into your home during the installation process. Prepare any upholstered furniture or rugs accordingly.
  3. Clean your windows before removal. This will help to prevent excess dirt and debris from making its way into your home during removal.
  4. Make your windows easily accessible. Trim any outside hedges that could partially or fully block your windows, and move any interior furniture away to create a clean and open workspace.

Cost of Window Installation

Window installation costs will vary by the type and number of windows you ultimately install. On average, labor will cost between $35 and $50 per hour for most window installation projects, which will equate to around $100 to $120 total per window.

We’ve outlined the overall costs of simple window replacements here, but extra labor and materials for drywall or siding could also cost you between $200 and $1,500 extra. This will largely depend on the age of your home, the condition of your existing window frames, and the number of windows you need to install.

Generally speaking, your windows will fall into the following categories:

  • Single-pane: These windows will provide the least amount of overall insulation and energy efficiency, but will be best for those on a tighter budget. Expect to pay between $100 and $450 for such windows.
  • Double-hung windows: Double-pane windows with gas insulation and a solid Energy Star rating will cost between $200 and $650 per window, on average. This is the most common choice for most homeowners.
  • Triple-pane windows: These are better suited for more extreme climates with drastic temperature fluctuations between seasons, and will cost between $500 and $1,500 per window, in most cases.

According to an EPA survey, the average residence has around 22 windows, which can make a full-scale remodel with window replacements fairly costly.

Before deciding whether to go the DIY route or to pay for professional window installation, we recommend taking a look at these leading window installers we’ve listed. Each is thoroughly vetted for quality and cost and could be an excellent alternative for your home renovation needs.

Conclusion: Professional Window Installation vs. DIY

We always recommend going with a local contractor when planning any home renovation project in an area where you don’t have direct expertise. That said, a single window replacement on a ground floor is a fairly common project for homeowners to undertake. You’ll save a fair amount of money, but will only be left with the manufacturer warranty on the window and associated parts. You’d be without the protection that many window contractors’ labor warranties provide for faulty installation.

Frequently Asked Questions

Is replacing a window difficult to do yourself?

Window replacement is a manageable project for the average home DIY enthusiast, especially if you’re using replacement windows rather than new construction windows. It will be difficult without a set of helping hands, but very accessible when compared to many home renovations.

Is it cheaper to install windows yourself?

If you do the job properly, a DIY window replacement should be cheaper than hiring a contractor. Material costs will be lower if you purchase them through a retailer, and labor costs will be nonexistent. Since most windows come with warranties of around 20 years, you’ll be able to be ensured of quality for the entire life of your chosen replacement.

However, a poor window installation could result in unexpected costs down the road. These can include higher energy bills or water damage due to an incomplete seal on your windows, or eventual professional repairs for poor workmanship.

Do you replace a window from the inside or the outside?

The short answer is “both.” The main window assembly can be removed and installed from the inside, while any storm windows or screens will require exterior removal.

Do you need to remove the trim to replace a window?

Yes, you will have to remove the trim and replace it along with your window. Re-using the same trim for your replacement windows will lead to excess nail holes and overall degradation of the material.

Can you replace a window without removing siding?

If you’re not using a new construction window when replacing your windows, then you won’t have to remove any vinyl or other siding materials. This makes replacement windows the go-to option for DIYers.

Other Window Resources