Which type of look/operation do you prefer? In those openings, you could really go either way, or do a mix of both. That is fairly common as well... The advantages of sliders would be a lower price (less total units), and you would gain additional glass area. On the downside, slider are generally leakier than double hungs, however you will have less lineal feet of sash and weatherstripping with the sliders, meaning less area for potential leakage.

Hi everyone, Thanks for the responses. It's been more than four months since my original query so I thought I'd post an update. After talking with several other contractors and vendors, we decided that going with replacement windows was clearly the wrong choice, so we switched contractors to someone with more large-scale remodeling experience and went with new construction windows. In the end we chose Anderson 400s and used Azek trim on the outside. The old windows came out and we found some damage to the underlying sheathing and framing, but not too much. The new windows were installed and insulated properly and the difference is huge. While we were at it we also replaced most of the edge and corner trim and drip caps on the house as this was rotting off as well. The project is taking a lot longer (we're hopefully wrapping up this week) and is costing a lot more than we thought, but I'm glad we caught this when we did as the damage would have been a lot worse if we had waited. Interestingly, the cost of the new construction windows was actually less than the replacement windows. The labor was more, of course, but we were already being forced to replace the rotting exterior trim so that was all equal. We did have to replace the interior trim, which was not inexpensive, but in the end the project wound up costing the same because the windows were less expensive. The difference in the new trim is amazing- it's nice to have real window sills and stools, with a less generic casing around them. The question of new windows vs. restoration was never an issue- the old windows (only 18 years old) were of poor quality, poorly installed, and leaked cold air to the point that we had to install plastic sheeting over the openings in the winter. Also, many of the window sills, mullions, and jams were rotting, so the amount of work to restore the existing windows would have been huge, We were going with new windows one way or the other. Thanks again for your help, Josh

1) Why have you zero'd in on fiberglass? Not a bad choice at all, but wood or vinyl often have compelling options if your priorities trend more to either looks or performance. 2) Andersen doesn't make fiberglass windows. Additionally, they are generally less expensive than Marvin in their fibrex composite lines which would be the closest competing product that they offer to fiberglass 3) Integrity and Infinity are both well built products. Neither are off the charts when it comes to thermal or structural performance metrics, but both are well made nonetheless. The Integrity has a real wood interior and a fair price point, so that is a pretty nice option if you want a stained interior. The Infinity is nice as well, it is mainly designed to compete in the "replacement window" space, where there is only one exclusive dealer per market, etc. The wood look interior on that product is nice and is stainable, just isn't real wood. 4) In the event that you are looking for an interior that is not real wood, you may want to consider some of the higher end vinyl window options as they will outperform fiberglass in nearly every measureable area (including DP= strength), and typically do so at a lower price point, better warranty, etc. There are some sensational performing fiberglass lines out of Canada, but the stuff here, while again not bad, is more form than function.

The water is coming in around the glass on one window and at the bottom corner of another. The later window doesn't close properly and you can see that it's not level. There is not a tight seal at the bottom when the window closes. With that said, I'm going to have a discussion with the contractor about the installation procedure, specifically how they will be flashing the windows on the sides of the house with vinyl siding. About the Pella Impervia, that thing looked horrible. The one on the showroom floor actually didn't even close properly at the top. Not impressed at all by the look. Who wants to see the fibers in the fiberglass? Thanks for the replies. Have a Happy Thanksgiving!