Tom Shafer

Comparing Atrium 8600 and Pella Pro-Star replacement windows

September 19, 2011

Both Pella and Atrium are well-known names in doors and windows. Located in Dallas and with manufacturing plants across the country, Atrium is the larger company, selling products under its own name and several private labels.

In the vinyl frame category, Pella and Atrium both make a 3 1/4-inch-thick replacement window. The window comparison chart below shows some of the similarities and differences between the 8600 and the Pro-Star.

Atrium Vs Pella

Frames in focus

Both are fusion-welded, a process that heats the cut corners of the window frame until very soft, then pushes the two pieces together to allow for cooling and fusing. The resultant corner is welded together to form a very strong bond. The biggest difference here is that Pella has a more detailed sash profile.

Pella sash profile

The sill is one area where significant differences exist: The Atrium 8600 has a sloped sill, causing water to run downhill, which drains the sill slopes and pushes water outside the window. Pella Pro-Stars have a hollow sill and small holes known as weep holes to drain the water from the sill into a chamber. The water exits the window from additional small holes in the front of the sill.

The concern about pocket sills are the many opportunities for weep holes to become clogged or plugged. A sloped sill that allows the water to run downhill tends to be less prone to debris and water damage.

Atrium sloped sill
Pella sloped sill with weep hole

Good balance for easy movement

A window balance is used to equalize the weight of the sash, so it can be lifted easily. This is another area where the two products differ.

The Pella Pro-Star comes with what is called a block and tackle balance. It has a string attached to the top of the windows and sash. A hidden, galvanized-steel channel holds a spring that equals the weight of the sash. In contrast, the Atrium 8600 uses a coil spring. Similar to the way a measuring tape operates, a coil of steel creates tension equal to the weight of the sash. The coil spring is concealed behind the sash.

One upside of coil spring balance is that it is not visible in an assembled, installed window.

Finally, the two windows' glazing beads differ. Pella has a vinyl strip surrounding the glass. It is thinner and not tight to the glass. Atrium's vinyl window offers a glazing bead with a dual barometer--vinyl with two different harnesses--that adheres tightly to the glass.

Atrium glazing bead

Pella Glazing Bead

Making sense of the differences

Both are equipped with the same glass package and insulating values. Each tests similarly for energy efficiency. Both windows are double hung, and designed to be used as a replacement.

The Pro-Star and 8600 windows make excellent choices for climates in the Central and Northern United States. The Atrium window may be more suitable for coastal climates and areas prone to very fast winds.

The major differences between these two windows are their balances, sills and glass breakage warranties.Whether you are considering the Atrium 8600, Pella Pro-Star or another high-quality, vinyl-frame replacement window, understanding features beyond the glass can help you make a clear purchasing decision.

About the Author

Tom Shafer has decades of experience in window sales, marketing and product development. He's worked closely with window design engineers in testing, design, and building code interpretation. Past employers include United Windows and Doors and Norandex, MI Windows. He currently works at a home improvement retailer.

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