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There can be a lot of unknowns between your spark of inspiration and its realized splendor. Wisconsin Solar Design would like to share some of the insight that we’ve gained over more than 40 years of experience.

Click the icons above for design & cost considerations along the way, or click the links at right for answers to some common and more specific questions.

Or, browse below and explore the possibilies.

We think you’ll find the information you’re looking for, whether it’s an initial question of feasibility, choosing one option over another, or clarifying LEED reporting.

If we haven’t answered your question, then just email us!

You can always ask for a quote, too.

The Basics

Often, one of the earliest design decisions is what configuration or style is appropriate. Sometimes, the design – whether by vision or constraints – is very specific. The rest of the time, multiple options will be possible and must be assessed by performance, cost, etc.

For instance, a skylight over a rectangular space could be configured as a gable, a hip, a vault, a ridge, or a single slope (if narrow enough). A skylight over a square space is likely a standard pyramid, but could be a many-sided polygonal pyramid or even a segmented dome. Complexity increases cost. A single slope is simplest and cheapest, a ridge skylight adds another pitched half, a gable adds end walls, a true or segmented vault requires either bent materials or many additional joints, and a dome compounds that with another radius, each getting increasingly complex and expensive.

On a more granular level, 4-sided orthogonal profiles are cheaper than multi-sided and/or curved ones, 90° angles are cheaper than others, planar profiles are cheaper than curved/segmented ones, etc.

Larger is obviously more expensive than smaller. Less obviously, it’s not a linear relationship – though a 4’-0” square pyramid requires less material than an 8’-0” square pyramid, the manufacturing process and time is the same.

Speaking of size, an attached greenhouse or solarium eliminates one or more glazed walls and will be less expensive than a freestanding one.

Choice of glazing greatly impacts both cost and performance. Plastic dome/pyramid unit skylights are the cheapest option for small openings (up to 8’x8’), but have the lowest performance and product life. Glass is available with many options affecting performance, appearance, and cost. It has the highest upfront cost, but has a very long lifespan. Translucent, structured polycarbonate panel glazing can be used in lieu of glass – it tends to have better insulating properties than glass and costs less upfront, but has a shorter lifespan. (See “Glazing” below for more details).

Beyond what you design, how you design it can have a big effect on final cost. It’s important to have clear project documents, require an appropriate level of quality, and to invite competitive bidding. If drawings/specs conflict or are vague, manufacturers/installers have to put a cost on the uncertainties, usually “worst-case”. You want enough specificity/detailing/testing to ensure quality, but excessively-picky/demanding standards, testing, etc. can inflate costs with little or no additional benefit. This ties into competitive bidding, as many proprietary product specifications will impose “features”, extreme standards, or unnecessary requirements specifically to exclude competing products. If you start with a proprietary spec, spending a little time to identify and eliminate this and “open the spec up” will likely lead to savings from the competition inherent in having multiple options.


Well-detailed drawings save money and time, from “apples-to-apples” bids to fewer surprises during construction.

Ensure that all necessary dimensions are provided. If skylight, greenhouse, or solarium will sit atop a curb or knee wall, provide dimensions to outside finished face of that curb. If skylight includes integral curbs, provide desired clear roof opening dimensions. (Either way, ensure sufficient information is shown to understand curb construction/depth). For glazed canopies, provide overall dimensions for supporting structure (steel, wood, etc.) and centerline dimensions of members. For translucent wall assemblies, provide rough opening dimensions and ensure there’s sufficient information to understand depth of surrounding construction. Ensure pitch is indicated for sloped construction (or eave and ridge heights, if more critical). Provide height of any vertical walls (top of curb-to-eave, top of slab-to-eave, etc.). If spacing of elements is not equal and calculable, provide desired dimensions. Lastly, indicate any required clearance to adjacent construction.

Depict all general aspects of the configuration. Clearly indicate if a skylight includes glazed walls (end, front, and/or back). If there is a design intent regarding number of bays / division of glazing, clearly show this. Same thing for any intended relationships to other systems, such as aligning rafters with adjacent curtain wall or ceiling joists. For non-square single slope skylights, clarify direction of slope. Locate any operable vents, windows, etc. and depict direction/manner of operability.

Provide detail(s) of each condition (sill, jamb, ridge, eave, etc.), including how the system joins adjacent construction. If the same condition varies (for example, part of a jamb butts into a masonry wall and the rest has a glazed end wall), provide multiple details as needed.

Show enough detail to clearly indicate desired system and construction, but be careful of proprietary detailing that can limit competitive bidding. If unclear of exact detailing, indicate design intent without unnecessary guesswork.

Be careful that the system you’ve drawn and detailed is consistent with the associated specifications – especially if either one has been altered/revised.

Be certain to choose a system that’s designed for sloped, overhead applications. For instance, most of WSD’s systems are wet-sealed (continuous beads of weather sealant at all joints, instead of relying on gaskets) and utilize our special, tested lapped glass detail at horizontal joints (provides positive drainage similar to lapped shingles, in addition to the joint sealant). Structural silicone glazing (SSG) horizontal and/or vertical joints are also available, featuring a flush appearance (but relying solely on the sealant for weathertightness). Both horizontal flush joints and WSD’s lapped horizontal joints can employ exterior, (concealed) mechanically fastened bar cap at vertical joints. Translucent, structured polycarbonate panel glazed canopies and skylights come without horizontal joints (up to 39’ lengths) and are also offered with standing seam and batten vertical joints. (See “Detail Manuals, Example Shop Drawings, & Specifications” page for more information).

Although Wisconsin Solar Design’s high-performance systems minimize the potential, overhead glazing in climate-controlled spaces can experience condensation when there is high humidity and a large interior/exterior temperature differential. It’s important that a condensation collection system is noted and/or part of the specification. (WSD’s systems include extruded gutters, drip pans, weeps, etc.).


Well-written specifications save money and time, from more competitive bidding to clearer scopes, and ensure a quality product/installation.

First, define a specific scope, by product type and application; do not lump related but distinct products or applications together. Some examples: put sloped glazing assemblies in a separate spec instead of in the curtain wall spec; plastic unit skylights and metal-framed skylights in different specs; tubular daylighting devices and skylights in different specs; etc. That said, keep all components of a system or assembly together in one spec. For example, greenhouse windows are an integral component of a greenhouse system and should be in the greenhouse spec rather than in the windows spec; items in a greenhouse space but not integral to the greenhouse system itself, and which can be provided by other trades, such a sinks, trench drains, general non-grow lighting, etc. should be in other spec sections. Doing so delineates logical, separate scopes that can be bid individually (or together), without confusing entanglements.

Once you’ve made your large scope decisions, make sure they (and any smaller items) are clearly delineated in each specification, i.e. what is in that spec and what is in a related spec section. For example, are skylight curbs site-built and in a related general carpentry specification or are they prefabricated and to be provided as part of the skylight specification? If shading, burglar bars, laylites, etc. are to be provided, is the skylight contractor responsible or will other trades be providing them under related specification sections? Will gutters and downspouts for a glass canopy be provided as part of the glass canopy spec or under a related specification?

There are three basic types of specifications: prescriptive, performance, and proprietary. Prescriptive specs enable you to provide specifics of the type of materials and system; they are open to all manufacturers who can provide such a system. Similarly, performance specs allow you to list specific performance standards and/or criteria for a system; they are also open to all manufacturers of systems that meet these. On the other hand, proprietary specs tend to narrowly describe a particular manufacturer’s system and restrict the bidders, often to a single manufacturer. Occasionally, you may truly want a particular product only; many times, proprietary specs are simply chosen as a starting point, and it’s important you edit them to list only the substantive criteria, eliminate irrelevant / unnecessarily-restrictive language, and solicit as many qualified bidders as possible.

Some proprietary spec language to watch out for includes: product approval requirements that are more restrictive than the general 016000 (or similar) section; overly-demanding quality assurance requirements for years in business, similar projects, etc.; unnecessarily exhaustive / restrictive test report requirements under submittals; burdensome and unnecessary submittal requirements (for example, bid time Daylight Autonomy Reports are redundant to the design process and unnecessary for products that comply with the project drawings and specified light transmittance); explicit exclusion of similar but competing products (e.g. “Thermoplastic (e.g. polycarbonate, acrylic) faces are not acceptable.”); construction/performance requirements that are much more stringent than the project’s code requirements (for example, Class A Burning Brand Testing when a Class A roof classification is not required by code); nitpicky numbers for items that are not central to the product’s performance; special “technology” features that are not central to the product’s performance; etc. There are cases where such language may be warranted, but it should be a conscious decision, weighed against the diminishment of competitive bidding.

On a related note, some items that belong in a specification need to strike a balance between cost and utility. Warranties are important for glazed structures; a 2-5 year system warranty will provide protection against defects and abnormal performance and is generally a built-in cost. An extended warranty, 10 years of more, may provide some peace-of-mind (especially for large installations), but is likely to add significant cost – whether or not a bidder will end up with a warranty claim, they must cover the potential cost in their bid. Also, any big problems are most likely to have arisen during the standard warranty period. Testing is another area that provides valuable quality assurance, but can quickly pass from money well spent to money wasted. (See our “Testing” page for details). Mockups (for WSD’s product types) can add significant cost and are rarely warranted.

Finally, be careful that the system you’ve specified is consistent with the associated drawings and details. If you started with a template spec, make sure that all unused options have been eliminated from your final specification.


There is a plethora of glazing options available, and Wisconsin Solar Design provides many.

Insulated glass is a sandwich of two or more glass lites, separated by interspaces, and with sealed perimeter spacer assemblies. Monolithic glass is either a single glass pane or multiple panes laminated together, without insulating interspaces. Structured polycarbonate panel glazing is a translucent thermoplastic, extruded at various thicknesses with many layers of insulating air pockets. Plastic domes are solid sheets of acrylic of polycarbonate, formed into a dome or pyramid profile, and often paired together with an insulating air space between.

WSD’s metal-framed skylights, sloped glazing, solariums, and greenhouses - enclosing climate-controlled interior spaces - use either insulated glass or structured polycarbonate panel glazing. This is usually captured within a rafter and bar cap system, but glass can also employ structural silicone glazing adhesive and structured polycarbonate can have standing seam and batten joints at overhead, sloped locations.

Our canopies – over outdoor spaces – typically employ either monolithic laminated glass or structured polycarbonate panel glazing, in one of several different systems. Since glazed canopies are usually supported by a structure of steel or wood, they can use standard rafters or a more minimal extrusion beneath them. Topside, bar cap can be used at joints, in the direction of the canopy’s pitch, or glass joints can utilize structural silicone glazing adhesive. Alternatively, structured polycarbonate panel glazing can be provided with standing seam and batten joints (aligning with canopy pitch), and the whole system is clipped directly to the steel/wood structure. Another option is point-supported-glass (PSG): metal “spider” fittings are mounted to the steel/wood structure and fit through coordinated holes in the laminated monolithic glass, clamping it in place; the flush joints in the glass are then filled with sealant. Point-supported-glass fittings are typically mounted beneath the glass, but can also be placed above the canopy, suspending the glass.

Pre-assembled and glazed unit skylights, available for smaller openings (8’ x 8’ or smaller), can either be smaller versions of our metal-framed skylights, or be plastic dome unit skylights. Our metal-framed unit skylights use glass or structured polycarbonate panel glazing (standard, no standing seams) in our standard framing, as detailed above. Plastic unit skylights utilize domes of solid acrylic or polycarbonate, captured in an aluminum retaining ring at the perimeter. Plastic unit skylights almost always are double dome, as the air space between the two domes provides additional insulation for interior spaces.

WSD recommends glass for most applications. Glass offers standard-to-high light/thermal/visual performance, long product life, and a high-grade appearance. There are almost endless options for glass (discussed below) to produce just the performance and aesthetic your project.

When a project budget is tighter, or thermal performance needs to be extremely high, structured polycarbonate panels are a good choice. Structured polycarbonate panel glazing is lower per square foot than glass, yielding a lower upfront cost. Structured polycarbonate panel glazing has an intermediate product life. While there is a lot of overlap with glass in terms of thermal performance, the thickest of WSD’s structured polycarbonate panel glazing has better U-factor numbers than glass.

Projects with a lower budget, or with a large quantity of small openings, might consider unit skylights with solid acrylic or polycarbonate domes. These are on the low end of the spectrum in terms of thermal performance and product life, but are quite cost effective.
Glass options include colored tints, low-iron glass, silk-screened ceramic frits, low emissivity (low-e) coatings, gasses for the interspace, different spacers, translucent/specialty interlayers for laminated glass, etc.

Low-e coatings are the most commonly used option. They can substantially improve the thermal performance of your glass. This is accomplished by reducing conduction between the glass and the adjacent air volume; often, the low-e also reflects much of the infrared light from the sun, reducing radiant heat gain. Depending on your project’s climate and dominant heating/cooling needs, you should start by looking at low-e’s that either minimize (reflect) radiant energy or admit it. From this point, compare low-e options based on U-factor (conduction), SHGC (radiant heat gain), VLT and reflectance (clarity), appearance (some produce a slight coloration, similar to tints), and LSG (light-to-solar gain; a measure of performance). Low-e’s work best on insulated glass, on a surface facing the interspace (usually #2 or #3). Sputtered low-e’s offer better performance, but harder pyrolytic low-e’s are available to exposed interior or exterior surfaces. While some high-performance low-e’s can be a bit costly, most are a small – moderate price increase and provide a lot of bang for your buck.

Glass tints are usually produced by adding small amounts of metal oxides to the glass, producing a slight, integral color with low reflectance. This yields a range of green, blue, bronze, or gray colors. Glass coatings can also provide tints with stronger colors and higher reflectance. Glass tints are more than just aesthetics, though – they can be a very useful tool for controlling solar heat gain. Some tints are commonly stocked, adding a small cost, while others are special order and can add significantly to both cost and lead time.

Standard clear glass is well-suited for most projects, but does have a very slight green coloration (most visible when viewed edge-on). In some applications, such as laminated glass with a translucent white interlayer, the green becomes more pronounced. Sometimes you may want that little bit of extra clarity. Low-iron glass (including brand names like Starphire, UltraClear, etc.) can be used in these situations. It does cost a little more.

Ceramic frits can be applied to glass to produce a pattern, a design, or reduce light transmittance or heat gain. They are available in white, gray, black, or a variety of muted or bright colors. The frit is a mixture of tiny glass particles and pigment that is heated and fused to the glass, creating an extremely durable coating. There are many standard patterns (dots, lines, etc.) with multiple levels of coverage (percentage of glass remaining transparent) – or custom designs can be silk-screened onto the glass. A standard color and pattern/coverage will add a small cost, while custom colors and silk-screen designs can add significant cost.

Insulated glass usually comes with an air-filled interspace, but inert gasses like argon are available, resulting in a small cost and performance increase. There is debate over whether/when inert gasses escape the interspace and the performance boost is lost.

Laminated glass typically comes with a clear PVB (polyvinyl butyral) interlayer. Base colors are available and can be built up to produce different colors/levels of translucency. A single white base interlayer is often used; there are several (differing translucency) to choose from. Other options provide enhanced acoustics, small or large missile / hurricane resistance, blast mitigation, etc. Color and specialty interlayers increase the cost a little.

Insulated glass typically includes a mill/natural finish aluminum perimeter spacer between the glass lites; a black finish color is also available. “Warm edge” spacers increase edge-of-glass and overall thermal performance, along with some additional cost. Stainless steel is less conductive than aluminum. Spacers made of biopolymers or thermoplastics provide even better thermal performance.

Sizing your glazing properly is important; performance and cost implications should be taken into consideration as part of the design. For glass, large units will require thicker glass in order to meet increased loads. Thicker glass costs more in terms of materials, but also because large glass units are heavy enough that they cannot be safely installed by hand. As a very rough rule-of-thumb, insulated glass units over 16 square feet may require a crane and vacuum lifter, with associated cost. Bay widths of 3 – 4 feet are a good starting point for glass. Translucent structured polycarbonate panel glazing is much lighter, and the main consideration is waste. These panels come in 4 foot standard widths (sometimes 6 foot); designing bay widths at or just under these dimensions result in less waste and thus less overall material cost. The panels come in lengths up to 39 feet; take advantage of this to eliminate horizontal joints. Standing seam structured polycarbonate panels have standard widths of 2 feet or 4 feet, with 39 foot lengths.

Lastly, the price of glass is based on a rectangular footprint that captures a unit’s particular shape. Thus, square and rectangular glass units are the most cost efficient. With triangles, polygons, etc., you still pay for the glass that was cut away. Curved edges are a bit more expensive to cut and insulate than straight edges.


Skylight systems are typically constructed with aluminum framing, as it is strong, lightweight, and easy to work with.

Aluminum also has the benefit of being less susceptible to weathering/corrosion than many metals, as it naturally forms an invisible, hard oxide “skin”, which reforms if scratched or worn away. When aluminum does corrode, it develops localized pits; aluminum does not discolor and stain when it corrodes (like rust on steel), but a natural (mill) finish will darken slightly over time. This mill finish offers decent durability if not exposed to harsh (highly alkaline or acidic) environments.

In practice, many environmental pollutants can be corrosive to aluminum: salt in coastal/marine locations or from de-icing roads/sidewalks, excrement from birds and other animals, acid rain, industrial pollution, automobile emissions, fertilizers, etc.

Aluminum is often given an anodized or painted finish, for additional protection and longevity, as well as for aesthetics.

Anodizing is a controlled electrochemical process that creates a thicker version of the natural aluminum oxide skin. While a mill finish will naturally form a skin that’s .004 microns thick, a Class II anodized finish is at least 10 microns (0.4 mil) thick and a Class I anodized finish is at least 18 microns (0.7 mil) thick. This extremely hard and durable aluminum oxide layer is integral to the aluminum below it (as opposed to an applied finish), so it will not chip or peal.

Standard anodized colors range from ‘clear’ (natural color) through a range of bronze tones, from very light ‘champagne’ to ‘black’. These integral colors are inorganic and will not fade or chalk. Premium palette options are also available, from the appearance of other metals (copper, brass, etc.) to bright, bold colors, via additives and dyes during the anodizing process. (It’s worth noting that white anodized is not available).

There are too many options for painted aluminum finishes to cover here. Broadly, we recommend powder coating over liquid painting for higher performance and lack of volatile organic compounds (VOCs). Specifically, we recommend thermoset (vs. thermoplastic) powder coatings using fluoropolymer resins (PVDF, vs. epoxy, acrylic, or polyester) as these finishes best suited for exterior architectural applications: they yield the best weatherability and UV-stability available. (Brand names include Kynar, Hylar, Fluropon, Duranar, etc.). We recommend painted finishes with at least 70% PVDF by weight; 50% is cheaper, but comes with a big performance drop. A 2-coat application (primer + color coat) is typical, but 3-coat (primer + color coat + clear coat / effect coat) is available at additional cost. You can specify either AAMA 2604 or 2605 as a standard for exterior painted finishes. 2604 is a typical, intermediate standard and will ensure good wear-resistance plus color and gloss retention for at least 5 years of exposure. 2605 is a more expensive, high performance standard for longer term protective and cosmetic performance.

Painted aluminum is available in a rainbow of standard colors (including various shades of white). You can also get custom/matched colors, extra bright colors, pearlescent or metallic effects, etc. or for a moderate upcharge.

In terms of cost, standard anodized and painted aluminum finish costs are usually fairly comparable. Anodized finishes are more durable and longer lasting, but have a more limited selection of colors/effects. Anodized finishes allow the aluminum’s natural appearance to show through – more for lighter colors, less for darker; the effect is beautiful, but requires care by the manufacturer and installer as damage, die lines, welds, etc. will show through. On projects that require bent/stretch formed components, component dimensions may preclude an anodized finish. Components cannot be formed post-anodizing as the hard aluminum oxide skin will crack and craze; components can be anodized after forming, as long as they fit in the anodizing tank!

WSD can provide separate interior and exterior finishes. WSD has even provided a different material, like copper, at the exterior in lieu of aluminum. (Care has to be taken to prevent galvanic corrosion from dissimilar metals).