How To Weatherstrip Windows

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In some cases, improper use and installation may result in a breach of insurance. Even worse, you could be putting yourself or your family at risk as an incorrectly installed electrical device could start a fire. So, don’t risk it - seek the services of a fully licensed electrician instead.

Our heating/cooling systems work incredibly hard to stabilize ambient temperatures during the frosts of winter and the scorching heat of summer, and even a few small gaps in our window fixtures can send them into overdrive and our energy bills into the stratosphere.

How To Weatherstrip Window

But a bit of well installed weatherstripping can completely seal off our homes from the outside world, thereby taking the load off our thermal systems and cutting our scary energy bills down to size.

The only problem is that typical double hung windows have a lot of moving sections, which can make the weatherstripping process quite confusing, but don’t sweat it!

I’ve composed this comprehensive window weatherstripping guide so you can transform your home into an energy efficient eco hub!

What Will I Need To Weatherstrip My Windows?

Tools

Materials

Weatherstripping Windows: A Step-By-Step Guide

Step 1 — External Inspection

Before you get the ball rolling on the installation, take the time to inspect the frame of your window outside of your home.

Take a look at the trim and the mating point between the trim and the siding.

Make a note of any structural issues in these areas, as they’ll need to be caulked before you head inside and continue the weatherstripping process. 

Step 2 — Snipping & Loading Your Caulk

Slice the tip of your caulk tube with a utility knife, paying mind to the flow rate you need.

For instance, cutting the very tip at a 45-degree angle will give you a very steady and precise flow, while making a flat incision lower down the tip will increase flow rate for larger projects.

You may also need to lower a needle down through the incision to pierce an internal seal.

Once the caulk is flowing, load it into your caulk gun by pulling the rod all the way back, positioning the base of the tube into the “chamber”, and pushing the rod all the way back forward.

Step 3 — Applying Caulk

How To Weatherstrip Window (1)

Now’s the time to fill in any structural defects you discovered around the trim and siding of the window during your inspection.

I’d recommend practicing on a piece of paper before applying the caulk directly to your  window, just so you can get used to the flow rate of your caulk gun. 

Step 4 — Inspecting The Interior Of Your Window

Just like you did outside, inspect the inside of your window.

If there are any cracks or gaps where the trim meets the wall, fill them in with invisible caulk. You can paint this later so it matches the wall color. 

Step 5 — Washing The Area

Since you’ll most likely be using weatherstripping with an adhesive back, it’s crucial that you give the sections of the window that need stripping a thorough washing with soapy water.

Once complete, dry what you can with a cloth and leave the rest to air dry. 

Step 6 — Measure Your Window & Cut The Weatherstripping

Next up, you need to measure the seams of your window.

Once you’ve got the measurements noted, you can cut your weatherstripping into appropriate lengths.

To fully seal the window, you’ll need to cut lengths of weatherstripping for…

  • The side of the inner sash
  • The side of the outer sash
  • The bottom of the inner sash
  • The top of the outer sash
  • The outer meeting rail

Step 7 — Raise The Inner Sash

Raise the inner sash as far as it will go then grab the appropriate lengths of weatherstripping.

These are the lengths that will line the sides of the inner sash when it’s closed.

Peel away the backing of the strip, revealing the adhesive surface, but stop when you get to the last inch or so.

You’ll need to press this end bit between the jamb and sash once the rest of the strip is already secured, and it’s a much easier process if you leave the backing on.

Now simply press the strip into place along the side jamb, running your fingers over it a few times to ensure optimal adhesion. 

To finish this stage off, repeat the process on the other side jamb, then remove the backing you left on the upper tabs of the weatherstripping and secure them in place.

Step 8 — Lower The Inner Sash

With the lower sash fully closed, you can repeat the exact same process on both side jambs of the outer sash, but this time, you can forget about leaving a section of the backing on the strip. Just remove it all and stick the strips down in one go.

Step 9 — The Bottom Of The Inner Sash

Once more with feeling, raise the inner sash as far as it will go, then apply a length of weatherstripping across the underside edge. 

Step 10 — The Top Of The Outer Sash

Next up, lower the outer sash and apply a length of weatherstripping across the top edge. Be sure to run your fingers over it a few times to encourage total adhesion and get rid of any possible leak points. 

Step 11 — The Outer Meeting Rail (Inside Face)

Bring down the outer sash some more and you’ll see the outer meeting rail, otherwise known as the inside face.

Simply secure one more length of weatherstripping along this surface, and voilà; job done!!! 

Final Thoughts

That’s how it works, folks. Figuring out how to weatherstrip complex window fittings can be a real head scratcher, but you really just have to use a bit of common sense. 

Inspect the window and note down all possible entry points.

This usually means any edges of moveable sections. Line each of them with a length of weatherstripping, and that’s that!

Some double hung windows may already have some metal stripping across the top of middle sections that simply isn’t working anymore, but you don’t necessarily have to replace it.

Simply bend it back a bit to “re-spring” it, and it should form a secure seal against neighboring surfaces.