Three common types, and the difference is shadow. Simulated divided lite puts bars on the surface of the glass, where they catch light and throw a line across the pane beside them. Grilles between the glass are sealed flat inside the unit, so they read as a pattern rather than as structure. Bar width changes the character as much as the type does.
Grilles are the part of a window everybody has an opinion about and almost nobody can name.
The bars across the glass. Muntins, if you want the older word.
There are a few ways to build them. They are priced differently, and the reason has almost nothing to do with what they are made of.
It is about shadow.
One kind sits on the surface of the glass and catches light. One kind is sealed flat inside the unit, where nothing can reach the edge of it. From ten feet away, on a gray day, they are the same window. From across the street at seven in the evening, they are not.
Here is what separates them, and where the money is actually going.
What are the kinds of grille?
Four, and the choice usually narrows to two.
True divided lite. Separate panes of glass, each one in its own frame. The original method. Still available on some lines, rarely specified now, and priced like the rarity it is.
Simulated divided lite. Bars permanently applied to the outside and inside surfaces of one sealed unit, usually with a matching spacer inside the airspace so the bar reads as solid all the way through. From any normal distance it looks like the real thing.
Grilles between the glass. A bar sealed inside the insulated unit. Both glass surfaces stay flat. Nothing to clean around, ever.
Applied interior grilles. A bar that clips to the inside face only. The exterior stays flat glass.
There is a practical wrinkle worth folding in early. Grilles between the glass are the only option with nothing to clean around, and that matters more the higher the window sits. A two-story wall of glass over a stair is not something anybody wants to detail-clean twice a year. That is a real argument, and it belongs next to the shadow line rather than underneath it.
What actually makes the difference between them?
Shadow.
A bar sitting on the surface of the glass has an edge. In morning light that edge catches, and it throws a thin line of shade across the pane beside it. That shadow is what your eye reads as structure. It is why the window looks like it was made out of parts.
A grille sealed between the panes has no edge for light to find. The glass is flat on both faces.
On an overcast day it holds up fine. In low sun, raking across the front of the house late in the afternoon, it reads as a pattern printed on a sheet of glass. Which is close to what it is.
That is the whole difference. It is worth understanding before you decide it does not matter to you, because sometimes it does not.
Does bar width matter more than the type?
Often, yes.
Two windows with the same grille type and different bar widths do not look related to each other. A narrow bar reads light and modern, closer to steel. A wide bar reads traditional and heavier, and it takes more of the view with it.
Widths vary by line, and the distance between the narrowest and the widest option on the same window is not subtle. Ask what the line offers before you settle on the type.
There is a common way to get this backwards. Pay up for simulated divided lite, then take the default bar width without looking at it. That is buying the shadow and letting somebody else pick the proportion.
What does the pattern have to answer to?
The architecture, and nothing else.
A grid of equal rectangles belongs on a symmetrical traditional facade. Divide the top sash and leave the bottom clear and you are speaking Craftsman. A band of small panes around the perimeter is Prairie. One or two horizontal bars leans farmhouse.
The failure is rarely picking the wrong style. It is picking a pattern the house cannot support, usually because it looked right on one window in a photograph.
One test before you commit. Look at the pattern across the whole elevation instead of on a single unit. Grilles multiply. A pattern that is charming on one window can turn a wall of five into a grid you have to look through.
Should the back of the house match the front?
This is where the budget conversation usually lands. Grilles on the front, clear glass on the sides and back.
It saves real money, and on a lot of houses nobody ever notices.
The question is whether two elevations are ever seen at the same time.
Stand at the corner of the lot. If you can take in the front and the side in one look, the change shows, and it shows as a decision somebody made about money. If the sides are screened by trees or by a neighbor, it will never come up again.
The rear is its own case. The back of the house is mostly seen from inside it, looking out, where a grille is subtracting from the view you built the room for. Clear glass across the back is often the better design and not only the cheaper one.
When is the right answer no grille at all?
More often than the picture in your head suggests.
If a window is there for the view, a grille takes some of it. That is the trade, said plainly. On a wall of glass facing a backyard you paid to look at, a grid is a strange thing to add.
Contemporary architecture usually wants none. A steel-look window carrying a divided pattern is doing two things at once and neither of them clearly.
On a traditional house, grilles across the front and nowhere else can be a correct reading of where the style is actually doing its work.
Where can you see the difference for yourself?
Not in a catalog. Grilles are a shadow effect, and a photograph has already chosen the light for you.
Lummus Supply has showroom space and full-size display homes in the Atlanta area, with units set in real walls and daylight coming through them. Seeing full-size product and real finish options in person settles this faster than any photograph. Ask to look at the options you are weighing under the same light.
Go late in the day if you can. Low sun is the condition that separates them.
Visits are by appointment, so book ahead.
What should you do next?
Bring a photograph of a house you like. Not a window. A house. The pattern question is architectural, and it is far easier to answer by pointing than by describing.
Then look at your own elevations and count. How many windows sit on the front. Whether the corner is visible from the street. Where the big glass is, and what it is looking at.
Grilles cost real money and change almost nothing about how a window works. That makes them a pure design decision, which is the best kind to take your time over.
Request a Consultation to set up a time.
What is the difference between simulated divided lite and grilles between the glass?
Simulated divided lite puts bars on the outside and inside surfaces of a single sealed unit, usually with a matching spacer in the airspace, so the bar catches light and casts a shadow across the pane beside it. Grilles between the glass are sealed inside the insulated unit, leaving both glass surfaces flat with nothing to clean around. The shadow line is the difference, and it shows most in low sun.
Can you tell grille types apart from the street?
In flat overcast light the difference is hard to read, but in low raking sun it separates quickly. Surface-applied bars have an edge that catches light and throws a line, which the eye reads as structure. A grille sealed between the panes has no edge, so it reads as a pattern on flat glass.
Should every window in a house have the same grille pattern?
The pattern should stay consistent anywhere two elevations can be seen at once, which usually means the front and whichever side is visible from the street. Putting grilles only on the front is a common way to save money and it works when the sides are screened. The rear is a separate decision, since the back of the house is mostly viewed from inside, where a grille subtracts from the view.
