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Energy Auditor


Eric Gans
Certified Energy Auditor


Residential Comfort & Energy Efficiency

Tuesday, December 22 2020
5 Reasons Your New Windows Are Drafty (#1 Might Hurt)

Energy auditor and window specials

Written by Eric Gans

I have completed over 1500 home air leakage tests using a blower door system.
-6 min. estimated read time

Table of Contents

Intro: What Makes Me the Expert?

#1 Places Most Drafts Originate

#2 Home Drafts & Simple Physics

#3 Biggest Home Draft Sources

#4 Basements & Sealing Drafts

#5 Proper Window Installation

Conclusion: Find Your "Real" Issue

If you spent a good sum of money to replace old drafty windows and you find yourself still dealing with drafty new windows - you are not the only one!

So don't feel bad or lose hope that you can actually have a cozy home. You just might have to look in a few other places to get to the real problem.

As a former window contractor turned certified home energy auditor I have been on both sides of the coin.  Early on I was convincing people (with the right intentions and wrong information) to replace windows to solve draft issues.

Now, I am on the other side getting called out to do an energy audit to check windows because the new windows still seem drafty after installation. 

It took me years to figure it all out, but when you stop and think about it all for a moment - it really makes a lot of sense.  So, with the right fixes and new windows, you can move much closer to complete comfort.  

Here are five reasons why your new window replacement investment might leave you asking: 

Why are my new windows drafty?

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1. The Windows Were Not the Draft Source to Begin WithA draft from a window may not be from a window

FACT:  Windows Account for Only 10% of Total Air Leakage in a Typical Home

A misconception for most homeowners is that windows are the only location in your home's "shell" that air can get in and out. 

But, there are many other places around your house that might be much more connected to the outside than windows.

And, a lot of these gateways are hiding in plain sight!

If your home is stubbornly drafty you need to think about the issue in three-dimensional ways.  This does not mean that you wasted money on windows or that you need special glasses.  It just means that you need to shift your hunt for the drafts by starting to look up and down instead of only through the sides.

FACT:  Air needs some help to get through cracks and crevices around your home and the pressure inside your home is greatest at the top (attic) and at the bottom (basement/ crawlspace).


Read on to learn about the stack effect and how getting the basics from this physics phenomenon can help you begin to think in three dimensional ways about drafts.

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2. Understanding Stack Effect & How it Can Solve Your Draft Issue

In the book Rich Dad Poor Dad by Robert T. Kiyosaki, he talks about how as school children we are never really taught the vital lessons of personal finance and how to stay out of debt and save for the future. A drafty window may not the issue due to stack effect

Similarly, I say everyone should learn about the stack effect when ready to purchase a home. 

Understanding how it can play a big part in drafts around the house can really help with better comfort and overall energy efficiency.

The stack effect can be simply understood by taking one concept we all learn as young children:  Hot Air Rises

Here is the part they don't tell you when it comes to your home.

When the warm air rises in your house it escapes through all of the holes in your ceiling right up into the attic - especially if there is no air-barrier in place or if the air-barrier is mis-aligned. 

Many of the holes where this is happening you cannot see, but they do exist!

This problem causes a conveyor belt in a sense. When the warm air goes out at the top new cold air gets drawn in down low - from the leaky parts of the basement or an open crawl space.

The stack effect is why recessed lights in the top ceiling and rim joists down around the foundation should receive way more attention than windows. A slotted recessed light is no match for the warm air pressure and it drags cold air in down low.  As a result - your comfort and money go right into the attic.

drafts from windows may be caused by recessed lights

Slot filled recessed light with light bulb removed.

Leaky recessed lights may be one example of why you feel drafts despite thinking things were sealed up once the windows were installed.

A do it yourself solution is to remove your existing bulb and install a retro fitted LED kit that sits flush to the ceiling. As a result, a better seal is created to reduce drafts.

Not convinced your basement is leaky? 

Watch this!

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3. Fireplace Flue & Recessed Lights - Sealing Up "Gateways" to the Outside

If you just put brand new windows in and you still feel drafts, then look around a bit.  One easy way to find drafts is to look for the "gateways" to the outside. 

For example, one out of every five customers that I do an energy audit for does not have the flue shut on their fireplace chimney which is a huge gateway to the outside.  

Recessed lights are also gateways to the attic (outside) and it is a good practice to check the dampers on any exhaust fans you have venting to the outside. A mis-aligned, damaged or non-existent damper can be a real draft maker.

Solutions include covering and sealing can lights at the attic floor, improving exhaust terminations and using chimney "balloons" to seal faulty flue dampers.

Recessed lights are the source of home drafts

Check out these unsealed recessed lights.
Watch the blower door test reveal air leakage through a recessed light fixture

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4. Improperly Treated Crawl Space/ Basement

why windows are drafty

If the construction style of your home is on a crawl space that is open, then you might experience high drafts. 

An open crawl space will allow unconditioned air into the the crawl space and unless there is a proper pressure boundary separating the crawl space from the room above, then drafts will surely occur.

Open crawl spaces traditionally have vents in the foundation wall.  The theory is to allow fresh air into the space and keep it dry, but in actuality the complete opposite happens in summer.  Crawl spaces become breeding grounds for insects, moisture and both want into your house!  In winter it is a constant source of cold air into your home.

If you have a full basement it is very likely that the rim joist in any finished or unfinished area has not been properly air sealed and this will allow air infiltration in the basement area that will cause drafts through walls and floors into the living space above.



How to Seal Up an Unfinished Basement Rim Joist

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5. Improperly Installed or Misaligned Windows


Another possibility for drafty new windows, however the least likely, is that the windows were installed improperly or worse yet, not caulked and sealed. 

Even if this is the case, it would still be difficult to make a draft problem worse with new windows even if the windows are incorrectly installed due to pressure dynamics in a house. 

It is important to note however, that basement windows and windows on the second floor could be susceptible to leakage if not properly installed and sealed due to higher pressure.

Make sure your windows are fully closed and locked!
Another common issue that homeowners with new replacement windows have problems with is making sure that top sash in double hung windows (most common type) are pushed all the way up in the u-shaped header.

When new window users are not accustomed to both sashes of the windows being operable, the thought that the upper sash dropping down does not come to mind and the notion that the windows are leaky is the typical conclusion.  Operable windows have several parts that all work together for peak performance.  If one thing is slightly off track, the rest of the system can suffer.

Watch this typical replacement window installation to get more perspective on your building's shell. 

Only replacing windows is not likely to change whether air is infiltrating into your home.


Watch how a window should be foam sealed once set in the structural framing. 

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Drafty Window Solutions: What will actually work?

air leakage testing new windows
Get a Comprehensive Home Energy Audit

A great way to deal with the issue of drafty new windows is to have a comprehensive home energy audit performed

An energy audit includes a blower door test.  A blower door test is an air leakage test on your house.  It is a large fan that pulls air out of the house.  When the air leaves at the front door new air replaces it from the holes and cracks around the house due to the negative pressure it creates.  

A great energy auditor will take you around so you can check the windows as well as other common sources of home air leakage so you can judge for yourself which is worse.

If you decide not to have an audit then you can follow additional guidance about how to seal up your home and do some things yourself.

Then, you can target the areas of the home that are leaking the most.  Soon you will be on the path to a more comfortable and less drafty home!


Join a Helpful Group on Facebook

Learn from energy auditors and other homeowners about all of the comfort problems that we all experience, root out and solve daily.  Many of the issues are hiding in plain sight! This group's sole purpose is to illuminate them so we can all live more comfortably and efficiently.

Join today (costs nothing!)

Share any stories or ask any questions.  You will be glad that you did!


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I would like to hear your comments about this article.  Feel free to post something below...

We recently renovated an old farm house and put a new addition on. We replaced all the windows with new windows. The new windows howl when the wind blows and you can see the curtains move. The manufacturer has been out several times and suggested fixes but none have worked. You can feel cold air on either side of the channel. Any suggestions?
Posted by erica on 03/01/2021 - 10:04 PM
Hi Erica-thanks for your question. I am sorry you are going through this and I don't have any great answer, but I can share with you the first questions that pop in my mind. Location of the windows that are problematic? What age is the farmhouse? Has the attic been air sealed and insulated? Is the home exposed to abnormal winds due to where it is situated? Where are you located? A seasoned energy auditor can help you with your problem. Eric
Posted by Eric Gans on 03/07/2021 - 07:00 AM
Thanks for this article. I own and can't tell you how many times we get customers blaming their drafts on their windows. I'm saving this for reference to share when I suspect that's their real issue.
Posted by Pete on 03/16/2021 - 04:32 PM

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