Not all houses built in 1910 are of the same historic style. Need to see the house.

@RES, architect

Link to similar house in text above.

Can’t see it on my phone

These windows are in a Colonial Revival house built in 1915. That was the most popular style in the first half of the century.

Even less of the OPs original post is visible on my iPad. Post the link again.

Here is the link, RES,

http://www.architecture.org/learn/resources/buildings-of-chicago/building/two-and-three-flats/

Is the building in an historic district where modifications would be subject to design review? Early single pane windows were more expensive so multi pane windows were used on the sides and rear.

The building does have “landmark” status and our permits have already been approved. The plans showed double hung windows. I was told no one would probably check if I did change them.

So what you’re saying is single pane in front and multi in back could actually be historically accurate then?

Here is the house

Landmark status often only means its on the National Register of Historic Places and cannot be demolished without permission. You need to ask the building dept if the building is in a historic district. If it is, you would need to propose the window design for approval before applying for a building permit.

If someone complains you might be forced to remove the sash. That would be easy if they are removable "grilles" instead of simulated divided lites.

I take it there is no professional designer involved.

No I am doing it all myself. Besides permits and all, what is your opinion on mixing grilles and no grilles?

I don’t see a problem adding mullions in the back and keeping the front like the rest of the units. It’s been done for centuries.

Thank you for your help! So do you think it would be best to do the sides and the back? This would mean that the living/dining room would have a mixture within the same room.

2x3 is the way some window companies (like Andersen) designate the “grilles” In an individual sash. The more common way is to describe the lites or panes. For a double-hung it would be 6 over 1. Whatever you buy check the written order carefully and make the contractor do it too. The drawing that usually accompanies the description is the safest way to verify the pattern. Make sure the glass is tempered and there are fall prevention devices where required. Check the direction of the operable panel of sliding doors. Also inside and outside finishes and hardware. Places like Home Depot are notoriously bad at ordering properly.

Yes we have been working with a windows and door place to order Marvin windows. We will triple check. So you think the combo of grilles and non grilles in the same room
Would be ok?

I have SDL's (6 over 1) on the front of our house and none on the back, our floor plan is open and you can see them both; it looks fine. Over time you won't even notice the difference unless you are thinking about it. I'm sure glad we only did the sdl's on the top sash, it is so nice not to see grids when you look out the windows when you are seated. They gave our house charm both inside and out!