Do you have a link for the two types?
Contact the manufacturer yourselves to find out if his advice will void the warranty.

Here is the link for the grilles; these are vinyl windows: http://www.plygemwindows.com/prod_grilles.aspx?product_id=33.

We are considering replacing just a few of the sashes, where we really wanted a view. These face the back, but we aren't sure about mixing styles.

A URL is an internet address that must be copied and pasted into a browser.

A "link" is hypertext that when clicked takes you to that address.

Putting a URL into the "Optional Link URL" at the bottom of the message windows turns it into a "link". Don't forget to give it a name.

Here is my opinion:
Full perimeter double hung window mullions are not a common characteristic of historic Prairie Style houses. Typically the perimeter mullions would be on the upper sash only. Putting mullions on the lower sash is an embellishment that I think clutters up the window and detracts from the strong design principles of the style. Full decorative treatment is more common in featured fixed lights.

Therefore, I would ask the contractor to replace all of the lower sash with mullionless units and call it a compromise. That will make a hero out of you and improve the authenticity of your house. Don't tell him it's an improvement or he'll charge you for it.

Here is a link that might be useful: This is a LINK

It should not be a problem to substitute new lower sash units if they are of the tilt-out type.

However, the windows to which you linked only mention "grilles" not "between-the-glass", "simulated", or "applied" mullions. "Grilles" are normally interior snap-in mullions that can be easily removed. Unfortunately the manufacturer does not offer much information about their windows on the internet but if they have already been delivered take a good look at them and ask the builder if the "grilles" can be removed. If so, see what they look like with the lower grille removed.

I am pretty sure that the Windows are of the between the glass variety. Unfortunately, I think this means the grilles cannot be removed without damaging the window. But thanks for the suggestions about the lower pane. We are also thinking of asking him to just replace the sashes in our big living room with the nice views.

PlyGem sells many different kinds of vinyl, vinyl clad and aluminum windows because it is the result of a NY private equity company, CI Capital Partners, taking over many different struggling window companies in 2004. They bought Nortek, MW Windows, CertainTeed Windows, Patriot Windows, Great Lakes Windows and Alenco Windows.

Typical of this kind of leveraged buyout, costs were slashed by combining operations, closing facilities, eliminating about half of the work force and amassing a lot of debt.

So, when you link to an all vinyl Pro Series Double-Hung Classic Double-Hung window once made by NW Windows, that's all I know about the window. These windows are sold primarily to builders so it is virtually impossible, even for an architect, to find out much about them.

The fact that you don't know what kind of mullions are used means the builder has not been very forthcoming with you about the design of the house. It's time to get more information from your builder and ask him to let you participate more in the design.

For instance, all window and door mullions should be drawn on the elevations and those drawings should be used by the builder, the local supplier, and the owner or an independent representative of the owner (like me) to check the order. I've never checked a window and door order that was entirely correct. I love that moment of silence when I tell a builder a sliding door opens the wrong way.

Good luck.

I second the suggestion to replace only the lower panes on all your windows. Are your view windows double hungs as well, or some other style that you are trying to figure out how it'd look?

First, thank you to everyone, especially to Renovator 8 for the lesson in architecture. I'm a little embarrassed to admit we aren't familiar with that, we just liked the look out of the grille options that were available.

Before we could offer some suggestions, our builder wrote to us tonight and offered to replace all the lower sashes without any grille pattern at all. He noted that that would be architecturally more accurate! Or we could get a refund for the amount of the upgrade. As I said, we like our builder and this reaffirmed that feeling. We actually love the compromise even more than the original choice, so despite a somewhat stressful few days, this has worked out much better than we hoped. Again, thanks for all the information, that was so helpful as we worked things out.

Maybe your builder is member here and you don't even know it ;-)

What is in the contract?