5 Reasons Your New Windows Are Drafty (#1 Might Sting a Bit)

Written by Eric Gans - I have completed over 1000 comprehensive home energy audits with homeowners like you trying to figure out why their windows are so leaky - you may be surprised by what we usually find.

If you spent a good sum of money in the spring to replace old drafty windows and you find yourself this winter season with drafty new windows - you are not the only one!

It is not uncommon for homeowners that have purchased new replacement windows to be disappointed the next cold season because the new windows still seem drafty after installation. 

But don't feel bad or lose hope that you can actually have a cozy home. You just might have to take a few more steps to get there.

As a former window contractor turned home energy auditor, I come across this all of the time and homeowners are always amazed at what I have to show them. 

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

Why are my new windows drafty?

1. The Windows Were Not the Draft Source to Begin With

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

 A misconception for most homeowners is the idea that simply because a window can be replaced (put in/ taken out/ put back in) it is the only location in your home's "shell" that air can get in. 

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

One commonly overlooked example:

If your home is stubbornly drafty you may want to take a look around and see if your bathroom exhaust fans have a properly functioning damper. 

A damper is essentially a small flap that stays closed when the fan is off and opens when the fan is turned on.

If the damper is not working, non-existent or improperly installed - your bath fan could be a source of drafts.

FACT: Most Window Salesman Talk About U-Factor and Solar Heat Gain Coefficient

Guess what...neither measure for air leakage!

?Have you ever heard of the National Fenestration Rating Council or seen this label? The NFRC "governs" what windows are rated for and it is broken down into five categories. 

If you purchased windows recently, you likely have heard of the big two:

A. U-Factor

B. Solar Heat Gain Coefficient (SHGC)

The three other categories are:

C. Visible Transmittance

D. Air Leakage

E. Condensation Resistance

 The two main ways a window is "judged" is by how well it insulates (U-Factor) and how well the glass blocks heat from the sun (SHGC).  

Air leakage, a measurement window companies do not even talk about, is indicated by a rating, expressed as the equivalent cubic feet of air passing through a square foot of window area. 

To be clear, this tests the window unit itself independent of how it is secured and sealed to the framing of a building.

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

Everyone should learn about the stack effect when they go to purchase a home. 

Understanding how it can play a big part in the drafts you feel around your home could go a really long way towards better comfort and 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, comfort and drafts.

When the warm air rises in your house and it escapes through all of the holes in your ceiling (holes that you can't necessarily see, but do exist!) it flies into the attic.

This problem causes a "viscous cycle" because when the air goes out at the top new cold air gets drawn in down low - like in the basement or crawl space.

This is why recessed lights are invisible gateways to the attic and should receive way more blame than windows. If the warm air is flowing right out then you feel the wave of cool air being drawn in from lower points in the home.

These are the drafts that you feel and need to disrupt to feel more cozy.

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 do 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 if you have them and you had your windows replaced and your draft problem did not go away - consider it as a possible source of your issue. 

Recessed lights in ceilings on the top floors are usually very leaky and should be covered and sealed at the attic floor.

4. Improperly Treated Crawl Space/ Basement

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 foundation area from the room above, then drafts will surely occur through the floor.

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.

5. Improperly Installed 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.

Drafty Window Solutions: What will Actually Work?

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. 

A great energy auditor will take you around so you can check the windows for leakage as well as other common sources of home air leakage and which plays into home drafts and poor comfort.

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!

Do It Yourself Tips

It an energy audit is not an option and you are looking for effective ways to reduce drafts, you can try these things:

-Seal can lights (recessed lights) from inside. Watch how: