A beautiful house can only be so when the windows of the house are right.  All too often today houses that would otherwise be beautiful are not because of choices made in the placement and selection of windows.  While there are many issues of good design that affect the cost of a building, placing and selecting well-designed windows do not.  In the past, while directing the ICAA’s Program in Classical Architecture for Design and Construction Professionals, I have seen a wide range of today’s houses and common window products and have thus been able to see many of the most typical errors in fenestration. For a catalog of windows and their details visit my collection of windows.

From that experience I have become convinced that one of the easiest remedied problems in house design today is window placement and selection.  This article explores five of the most common errors I find in fenestration.  For each error, I offer helpful corrective guidelines.  The scope of this article does not include the many important aspects of window design and performance such as details, design pressures, energy ratings, or materials which do affect the cost of a window; for a designer should always select the best performing and constructed window within their budget. The following guidelines can generally be applied at any price point, but it should be remembered that these are only guidelines meant to establish general rules, which, of course may be broken by those talented enough to do so.

Error #1: The “Here a Window, There a Window” Approach to Window Placement

After the massing of a building is designed, one next determines the placement of the window and door openings. This is the first place where errors are commonly made – the basic horizontal and vertical location of windows.  A quick drive down any suburban American street will reveal houses with windows that are crammed too close to the corners, not aligned with one another, deployed higgledy piggledy across the façade without relationship to other windows as they are related only to the plan of the house.  Instead of this unfortunate visual chaos that assaults us everyday, a successful façade should have windows placed in a manner which reinforces, rather than competes with, the design intent of the building.

To do so, windows should be placed such that a balanced composition is achieved.  This could be thought of as the “just right” factor.  Some houses are simple rectangular forms with a gable or hipped roof and are bilaterally symmetrical such as a Georgian or Federal style house.  Other houses are asymmetrical and composed of discrete masses under different roof forms such as in a Victorian or Spanish Revival house.  In both of these conditions, the windows should be placed to establish a rhythm of openings across the façade and to balance the solid parts of the façade (walls) with the open parts (windows).

In those compositions that are bilaterally symmetrical, windows should be placed one above the other and spread across the façade establishing a three- five- or seven- bay structure. Though more may be possible, it would not generally be desirable to have more than seven bays within the central block of the house as the house will appear too long.  The spacing of each of these bays can be equal or it can be compressed or expanded in places to produce a rhythm, but the bays should be the same about the center of the building.  Side elevations should also have an underlying bay structure that sets where the windows are to be placed; but the side elevations, as they are not as important as the front elevations, can accommodate slight inconsistencies if necessary.

The spacing between these windows should not be less than the width of the window itself, since if it is, shutters would be impossible. Nor should it generally be wider than one and one half times the windows width, otherwise there will appear to be too much wall and not enough window space.  If it is desired to space windows very close together, then they can be joined with mullions to create a one wider window, such as the tripartite windows of Greek Revival style houses.

Many houses, though, are not a simple box, but are compound masses.  In the case of Victorian and Spanish Revival style houses, to name two compound massing types, the strategy for placing windows is different than the bilateral condition described above.  Rather than establish a bay structure that runs across the entire façade, windows are placed such that they create a regular rhythm of openings within each discrete mass, which then balances the entire composition.

In asymmetrical compositions balance is achieved by accenting solid, heavy parts of the composition, such as end gable walls, with small windows of interesting shapes, whereas long stretches of wall running parallel to the ridge beam will likely have windows spaced regularly across the expanse of the wall.  It is generally true that in buildings that are consistent with romantic revival styles, particularly those evoking medieval memories, there will tend to be smaller windows more widely spaced that appear to puncture the façade.

Generally, a traditional house will not have windows placed such that they contradict or infringe upon the apparent or actual structure of the building.  Windows should not be placed closer to the corner of a building than their width, as doing so will appear to weaken the solidity of the corner of the building.  There are exceptions to this, such as found in Lutyens’ work, Wright’s work, or Arts and Crafts style houses, but if one is to infringe upon the corner, careful study of good precedent is recommended.

Window heads should align across the façade at each floor such that a visible line of structure is established and can be a generative force in locating windows.  For example, if an arch is employed within such a line of windows, one should align the spring line of the arch with the head height of the rectangular windows as these both, the spring line and the head, represent a similar line of structural transition.  Setting and maintaining a consistent visual line of structure is one of the ways that windows can be coordinated in an asymmetrical building while other things, such as porches and turrets, create interesting forms.

Vertical location is important as well and one should take care not to locate windows in a manner that interrupts any horizontal lines of structure such as a cornice, stringcourse, water table or base, as this too will appear to contradict the firmness of the building’s construction.  Just because something can be done does not mean that it should be done. As always, there are exceptions to guidelines like these, such as Giulio Romano’s conscious breaking of horizontal lines of structure.

Error #2: Any Style Will Do, Just Pick One

Establishing a structure for the placement of windows is only the first step, for after that one must consider what type of windows will be used.  A designer would be wise to remember that a house’s façade is not a palette for showing off every shape and style in a window catalogue.  Rather, creating a building with character requires all parts, even the windows, of a building to be harmonious with each other.

It may seem obvious, though observation shows me it is not, but the style of a window should be consistent with the style of a building.  For example, broadly proportioned windows with heavy muntins and small lites feel appropriate in a somber Georgian façade, whereas vertically proportioned windows with large lites and knife-thin muntins feel well suited to a delicate attenuated Federal style building, and so on through to the windows slicing through the corner of a Frank Lloyd Wright house; each window adds to and balances the overall composition and spirit of each façade.

One should select the type of window, its materials, number of lites, and muntin profiles depending on the intent of the design of the house for these are all part of the refinements of the design of a house. Generally, earlier colonial style houses tend to use wooden sash double hung windows with paneled, louvered, or plank shutters; whereas later house styles, such as those romantic revival styles like Spanish Revival and Mediterranean tend to use metal casement windows, with wood plank shutters or without any shutters at all, but with features not seen in colonial houses, such as protective metal grilles, or turned wooden spindles forming a screen, or reja, within the open space of the window.  As with all design, the best way to gain knowledge of what will be right for your design is the careful examination of good examples and application of their lessons to your work.

Error #3: The More (Shapes) the Merrier

After selecting the general style of window to be used, one must next select the actual size and shape of the window.  Windows should have a consistent size and shape throughout the building with special window shapes being preserved for special locations, such as an elliptical window over the front door.

Windows should be neither too wide nor too narrow, and while in some instances one might employ square or horizontal windows, windows are generally vertical in orientation.  This relates to the human form and the way that we experience the world from inside a building.

All window sizes and shapes in a building will not be all the same, though they should be related to one another, as if they are all first cousins in the same family.  For example, one would not want to combine pointed arched gothic windows with rounded arched windows in the same building, as these two different arch types have very different visual effects that do not reinforce each other. One should also consider the wall structure in which the window sits. Frame construction lends itself to flat-headed windows, whereas openings in masonry walls may be made with flat or arched heads.

The primary size variation will occur between stories, as the upper storey windows are often smaller than those below due to the upper floors typically lower ceiling height.  This produces a pleasing visual effect from the exterior as windows get smaller as they rise and thus accentuate the apparent height of the building. It also communicates the interior function as these smaller upper level windows typically occur on floors where the functions are more private, such as bedrooms, and where the floor to ceiling space is less.  This dimensional decrease can occur by reducing the window height by one or two lites, or, one can maintain the same number or lites and the same proportion of both the lites and window opening, while reducing the size of the opening and the size of the lites.

A perusal of just about any company’s window catalog will reveal astonishing shapes, most of which one never need use.  Many of the shapes or lite divisions (often called grille patterns by window manufacturers) are simply irrational – too wide, too thin, shapes that one cannot imagine being made, even if they are possible.  One should not use irrational shapes or patterns as they do not contribute to a design grounded in the gravitational reality through which we humans understand the world.  Many of these irrational and bizarre shapes seem to come from a desire, if window manufacturer’s literature is to be believed, to give the designer the most possible options.  Sometimes, though, it is better to consider fewer possibilities by considering better ones.  A façade with a multitude of window shapes is horribly chaotic, confusing and leaves the eye no place to rest.  Stick with basic shapes.  Rectangles and arches, pointed or round, will do for most houses.

Error #4: Dividing the Window

Once one has established a scheme for locating windows on the façade, selected a window style and overall size and shape, the next step is the division of that window into sashes and lites.  Much in the way that window location and shape should reinforce the overall façade composition, so too should the secondary and tertiary divisions of a window reinforce the overall window design.  This step of breaking down the large expanse of a window into smaller pieces, helps to establish the scale of a building, and brings the details of a building into our human scale.  A look at the divisions of a few different window styles will help to illustrate how much variation there is in window design and how different styles are from one another.

In most colonial styles, one finds double hung wooden sash windows with: 6, 9 or 12 small lites per sash depending upon the size of the window, wide muntins about 1 1/8” wide with a quarter round profile on either side of a fillet, or what is commonly referred to today as an ovolo shaped muntin.  In Federal and Greek Revival styles the proportion of the window opening expands to a more vertical proportion and is divided into fewer lites with larger expanses of glass.  One finds double or triple hung wooden sash windows with (often) 6 lites per sash and thin beveled muntins in the range of 7/8” to 5/8” wide.

Victorian style houses extended this double and triple hung trend of tall proportioned windows with a fewer number of lites, such that the windows of flamboyant Victorian houses often have two to four lites per sash, which does produce the odd condition of having a muntin right in front of one’s nose when one stands in the middle of the window, but, nonetheless, this fewer number of lites in each sash provides a quiet balance to the busyness of a Victorian façade.  In some cases of Victorian styles and in Bungalow styles, it is common for only the upper sash to be divided into lites.

The many romantic revival styles in America, such as Spanish Revival, English Tudor, and French Norman, often employ a mix of window types including metal casement windows and leaded glass windows with small diamond shaped panes.  Many of these stylistic traits have their origins in practical purposes. For example, one can imagine that a large tall expanse of window like one might find in a federal house, would like out of place in a thick adobe walled Spanish Revival house designed to keep the sun out in a hot climate!

This brief list of some of the characteristics of different window styles and their compatibility with different building styles could be an article in itself, but, so long as one remembers that one should select a style of window appropriate to the style of the building and stick with it, then the overall resulting design will be a good one.  It is good to always recall that one should consider first the strategy of placement of windows, then the overall proportion of the window, next the division of that window into sashes, and then the division of those sashes into lites, and last how those lites are held together such that the muntin profile, if any, is the last, but certainly not the least, decision in window design.

It seems amazing that something as small as a muntin can affect the appearance of a house, but muntins establish a sense of scale for the building, and, one can see how much it does, when one considers the all to common errors of either using no muntins to subdivide a sash, or placing muntins between the glass of a window.  This incomprehensible strategy in window design, muntins between the glass, means that the muntin casts no shadow and thus the division of the sash into lites cannot be seen at all.

Error #5: Window Openings Don’t Matter

Lastly, each window sits in a wall, and thus the final aspect of window design rests in how the opening itself is finished.  One can alter the appearance of a window and significantly alter the overall façade design with the manner in which a window opening is trimmed out.  Far too often, window surrounds (the moldings) are made too narrow relative to the width of the window opening, or keystones are too small and look as if they will slip out of place, or lintels are made too thin and long so they appear brittle, or bricks are laid in a running bond across a steel lintel rather than creating a jack arch, whether one is needed or not.  These are very typical errors in making the window opening, and it must be pointed out that trimming out of the window can become a cost issue, but, this is an area where it would be wise to allocate money from a project’s budget.

In classical styles such as Georgian, Federal, or Greek Revival clapboard buildings, one can use a general rule of thumb of making the exterior window architraves equal to one sixth of the width of the opening, such that on a three foot wide window, the window architrave (or trim) would be six inches wide.

Likewise in many of the romantic revival styles, like Spanish Revival or Mediterranean, one will find window openings treated with no trim at all, or, often with small colonnettes used at either side, or between mulled units, with round or pointed arches used above the window. Again, the best way to learn is careful study of good examples.

Summary

Windows are the eyes into the soul of a building and each aspect of the design of windows is critical to creating a harmonious building.  From establishing a clear scheme for their location, to selecting the appropriate style of window for your house, to sizing the window properly and selecting the best shapes for your design, all the way down to how the window is broken down into its smallest parts, and, of course, the surrounds that frame all of this.  Each of these aspects of window design is essential.  There are many historical variations, but, not perhaps as many as today’s window catalogs might have you believe.  Recall always to strive for restraint and stylistic compatibility between the house and the windows when placing and selecting windows and you will achieve more beautifully designed houses.

For a catalog of windows and their details visit my collection of windows.

Originally published in Clem Labine’s Period Homes Magazine.