Fixed vs vented skylights comes down to one trade: a fixed skylight gives you the most daylight per opening at the lowest price, while a vented skylight costs more and admits less light but lets heat and humidity escape through the roof. On VELUX’s own published data, a venting unit in the same rough opening shows 14 to 27 percent less glass than the fixed version, and at Home Depot a like-for-like VELUX C06 runs about $665 fixed versus about $1,044 manual-venting and about $1,811 solar-venting. Both pass the same lab water test. Below are the numbers, the code rules, and which one fits each room.
By The Roofing Brief Team ยท Last reviewed: October 2026
Key numbers at a glance: fixed vs vented skylights
These are the figures that decide most fixed vs vented skylight purchases. Prices are retail listings and change often, and the performance figures are VELUX America published test values for its deck-mounted FS (fixed) and VS/VSE/VSS (venting) lines with standard 04 laminated glass, so treat them as a reference point rather than a quote for every brand.
| Question | Fixed skylight | Vented skylight | Source |
|---|---|---|---|
| Retail price, VELUX C06 (21 x 45 3/4 in) with solar shade | About $665 (FS C06 2004S) | About $1,044 manual (VS C06 2004S); about $1,811 solar (VSS C06 2004S) | Home Depot listings, October 2026 |
| Daylight (visible glass) area, same rough opening | 4.56 sq ft (C06) | 3.66 sq ft (C06), 19.7% less | VELUX Skylight Measurement Guide, 2026 |
| Water resistance, lab test with no leakage | 720 Pa (15 lb/sq ft) | 720 Pa (15 lb/sq ft) | VELUX Residential Skylight Tested Performance Information |
| Air leakage at 75 Pa | 0.01 cfm/sq ft | 0.03 cfm/sq ft | VELUX Tested Performance Information |
| Whole-unit U-factor / SHGC / visible transmittance | 0.44 / 0.26 / 0.60 | 0.43 / 0.23 / 0.53 | VELUX Tested Performance Information (NFRC-certified values) |
| Warranty on motors, rain sensors and controls | Not applicable (no powered parts) | 5 years (vs 10 years on the skylight itself) | VELUX USA product pages |
What is the difference between a fixed and a vented skylight?
A fixed skylight is a sealed glazed unit that never opens, so it delivers light and a view of the sky with no moving parts. A vented (venting or ventilating) skylight has an operable sash that tilts open by hand crank, control rod, wired motor, or solar motor, so it can exhaust hot, humid air from the top of a room. Most makers sell both in the same sizes.
That shared platform matters when you shop. VELUX builds its deck-mounted FS (fixed), VS (manual venting), VSE (electric venting) and VSS (solar venting) to the same rough openings, so choosing fixed or vented does not change the framing; our VELUX skylight size chart lists which size codes come in which versions. Not every size is offered both ways: the A06, C12, D26 and D06 are fixed-only in the VELUX deck-mounted line, per the 2026 VELUX Skylight Measurement Guide.
| Factor | Fixed skylight | Vented skylight | Source |
|---|---|---|---|
| Opens for air | No | Yes, sash tilts open | VELUX USA product pages |
| Moving parts | None | Hinge, sash seals, operator (crank, chain or motor) | VELUX USA product pages |
| Insect screen | Not needed | Included on VELUX VS | VELUX VS product page |
| Automatic rain closing | Not needed | Standard on VELUX VSE and VSS; none on manual VS | VELUX VSE and VSS product pages |
| Wiring | None | None for manual or solar; 20 ft hardwire to a junction box for electric VSE | VELUX VSE product page |
| Deck-mount roof pitch range (VELUX) | 14 to 85 degrees | 14 to 85 degrees | VELUX FS, VS, VSE product pages |
For how fixed and vented units sit alongside tubular and custom skylights, see our overview of types of skylights. This page stays on the head-to-head decision.
How much more does a vented skylight cost?
A vented skylight typically costs about 1.5 to 3 times as much as the same-size fixed unit, depending on how it opens. In like-for-like VELUX C06 listings at Home Depot (October 2026), the manual VS costs about $379 more than the fixed FS, and the solar VSS about $1,146 more. Fixr’s 2025 cost guide puts ventilating units at $574 to $1,044 against $295 to $537 for fixed.
| Model (VELUX deck-mount, C06 size) | How it opens | Retail price | Premium over fixed | Source |
|---|---|---|---|---|
| FS C06 2004S | Does not open | About $665 | Baseline | Home Depot listing, Oct 2026 |
| VS C06 2004S | Manual crank or control rod | About $1,044 | About +$379 (+57%) | Home Depot listing, Oct 2026 |
| VSS C06 2004S | Solar motor, remote, rain sensor | About $1,811 | About +$1,146 (2.7x) | Home Depot listing, Oct 2026 |
| VSE C06 2004 (sold without shade) | Wired motor, remote, rain sensor | About $1,414 | About +$961 vs FS C06 2004 at about $453 (3.1x) | Home Depot listings, Oct 2026 |
The unit price is only part of the gap. An electric VSE needs a circuit run to the roof opening, and Fixr estimates that hiring an electrician can add $435 to $793 to a skylight job; a solar VSS skips that line, which is why it often lands close to the electric version once installed. Labor for setting the unit, flashing and finishing the shaft is broadly similar for fixed and vented units of the same size. This Old House (March 2026) puts typical material cost at $200 to $1,200 for fixed and $400 to $2,000 for vented skylights, with whole projects commonly $1,000 to $3,000. For the full labor and finishing breakdown, see our skylight installation cost guide.
One tax note: solar venting skylights were long sold with a 30 percent federal credit, but that Section 25D credit does not apply to expenditures after December 31, 2025, so a 2026 installation should not be priced as if it does. Our solar skylight guide covers the details.
Do vented skylights let in less light than fixed ones?
Yes. A vented skylight admits measurably less daylight than a fixed skylight in the same rough opening, because the operable sash adds a second frame inside the outer frame. VELUX’s 2026 measurement guide lists the visible daylight area of every deck-mounted size, and the venting version shows 14 to 27 percent less glass, with the smallest sizes losing the most. No competing guide we reviewed quantifies this.
| VELUX size code | Rough opening (in) | Daylight area, fixed FS (sq ft) | Daylight area, venting VS/VSE/VSS (sq ft) | Light lost by choosing vented |
|---|---|---|---|---|
| C01 | 21 x 26 7/8 | 2.40 | 1.76 | 26.7% |
| C04 | 21 x 37 7/8 | 3.67 | 2.86 | 22.1% |
| S01 | 44 1/4 x 26 7/8 | 5.80 | 4.57 | 21.2% |
| C06 | 21 x 45 3/4 | 4.56 | 3.66 | 19.7% |
| C08 | 21 x 54 7/16 | 5.55 | 4.53 | 18.4% |
| M04 | 30 1/16 x 37 7/8 | 5.69 | 4.65 | 18.3% |
| M06 | 30 1/16 x 45 3/4 | 7.08 | 5.94 | 16.1% |
| M08 | 30 1/16 x 54 7/16 | 8.61 | 7.36 | 14.5% |
| M02 | 30 1/16 x 30 | 4.29 | 3.69 | 14.0% |
| S06 | 44 1/4 x 45 3/4 | 11.02 | 9.51 | 13.7% |
Source: VELUX America Skylight Measurement Guide (VUSA5859-0326, 2026) for daylight area and rough openings; percentages are The Roofing Brief’s calculation from those published figures.
The whole-unit ratings point the same way. VELUX lists a visible transmittance (VT) of 0.60 for the fixed FS with 04 glass and 0.53 for the VS, VSE and VSS, about 12 percent lower. VT is an NFRC whole-product rating that already counts the frame, so it overlaps with the daylight-area gap rather than adding to it. The practical takeaway: if a room needs a set amount of light and also needs venting, size the vented unit up one step (for example M06 instead of C06), and check the rafter spacing first.
Do vented skylights leak more than fixed skylights?
In lab testing, no. VELUX’s tested performance sheet shows its fixed FS and its venting VS, VSE and VSS all resisting water penetration up to 720 Pa (15 lb/sq ft) with no leakage. In service, a vented unit adds two leak paths a fixed unit does not have: sash seals that wear with use, and the open sash itself if it is left open in a storm.
Air leakage does differ. The same VELUX data lists 0.01 cfm per square foot at 75 Pa for the fixed FS against 0.03 cfm for the venting models, three times higher but still far under the 0.3 cfm per square foot limit the IECC (Section R402.4.3) sets for windows and skylights. In most homes that gap is too small to show on an energy bill; U-factor (0.44 fixed vs 0.43 venting) is essentially a tie.
The bigger leak risk on both types sits in the flashing, not the glass or the sash. Most skylight leaks trace to failed or improvised flashing, step-flashing errors, or condensation mistaken for a leak, which our skylight leak diagnosis guide walks through. VELUX’s 10-year installation warranty applies to its deck-mounted FS, VS, VSE and VSS only when installed with a VELUX flashing kit, per VELUX USA, and that condition applies equally to fixed and vented units.
How do skylight rain sensors work?
A rain sensor is a small detector on the skylight frame that tells the motor to close the sash when it senses rain. VELUX fits one as standard on its electric VSE and solar VSS venting skylights and describes the VSS sensor as acoustic, closing the unit at the first sign of rain. Manual VS units have no sensor, so they stay open until someone closes them.
The sensor is the main reason powered venting units are the safer choice for skylights that will be opened often or left open while nobody is home. It is also a part with a shorter warranty: VELUX covers motors, controls and rain sensors for 5 years, against 10 years for the skylight product and 20 years for the glass.
Manual, electric, or solar: which vented skylight operator fits?
Pick the operator by reach and by wiring. A manual venting skylight suits units you can reach or a rod can reach and that you will remember to close. An electric unit suits new construction or remodels where a circuit is easy to run. A solar unit suits retrofits on finished ceilings, because it needs no wiring and still gets a rain sensor and remote.
| Operator (VELUX deck-mount model) | Power | Rain sensor | Electrician | Best fit | Source |
|---|---|---|---|---|---|
| Manual (VS) | Hand crank within reach; control rod out of reach | No | No | Bathroom or kitchen skylights within reach, tight budgets | VELUX VS product page |
| Electric (VSE) | 20 ft hardwire to a standard junction box | Yes, standard | Yes, often $435 to $793 extra (Fixr) | New builds and open framing where wiring is easy | VELUX VSE product page; Fixr |
| Solar (VSS) | Solar panel charging a battery | Yes, standard (acoustic) | No | Retrofits, high vaulted ceilings, finished drywall | VELUX VSS product page |
Curb-mounted equivalents exist for low-slope roofs: VELUX sells the VCM (manual), VCE (electric) and VCS (solar) venting units alongside the fixed FCM. For a brand-by-brand view of venting lineups beyond VELUX, see our best skylight brands comparison, and for VELUX model codes and pricing, our VELUX skylights guide.
What do building codes say about fixed and vented skylights?
Under the International Residential Code (IRC), a fixed skylight counts toward required natural light but not ventilation, while a vented skylight can count toward both. Most bathrooms meet the ventilation rule with an exhaust fan instead, and a typical venting skylight does not open wide enough to serve as an emergency escape opening. Local amendments vary, so confirm with your building department.
- Habitable rooms (IRC R303.1): glazing of at least 8 percent of floor area and openable area to the outdoors of at least 4 percent. The section lists skylights among approved ventilation openings and requires them to have ready access or be readily controllable by occupants, which favors a control rod or motor on out-of-reach venting units.
- Bathrooms (IRC R303.3): at least 3 square feet of glazing, half of it openable, unless artificial light and a local exhaust system are provided. IRC Table M1505.4.4 sets that exhaust at 50 cfm intermittent or 20 cfm continuous, so a vented skylight usually supplements a bath fan rather than replacing it.
- Kitchens: the same table sets local kitchen exhaust at 100 cfm intermittent or 5 air changes per hour continuous. A venting skylight helps clear heat but is not a substitute for a range hood; our kitchen skylight guide covers placement.
- Low-slope roofs (IRC R308.6.8): unit skylights on roofs flatter than 3:12 generally go on a curb at least 4 inches above the roof plane unless the manufacturer’s instructions say otherwise. That applies to fixed and vented units alike.
- Emergency escape (IRC R310): sleeping rooms and habitable attics need an opening with at least 5.7 sq ft net clear area, 24 inches clear height and 20 inches clear width. The North Carolina Office of State Fire Marshal (2014 interpretation) confirms a skylight can qualify only if it provides those dimensions in the open position, which ordinary venting skylights do not. Egress-rated roof windows, such as larger VELUX GPU top-hinged units per VELUX’s installation guide, are the product for that job; see our skylight vs roof window guide.
Which one should you pick, room by room?
Choose a vented skylight where the room makes heat or moisture and a fixed skylight everywhere light is the only goal. Bathrooms, kitchens, laundry rooms and hot upper-floor rooms benefit from venting. Stairwells, hallways, vaulted living rooms and any skylight nobody will open are better served by a fixed unit, which costs less and passes more light.
| Situation | Pick | Why |
|---|---|---|
| Bathroom with shower or tub | Vented (solar or electric if out of reach) | Releases steam that otherwise condenses on cold glass; still keep the code-required exhaust fan. See our bathroom skylight guide. |
| Kitchen | Vented | Lets cooking heat escape at the ceiling; does not replace a hood |
| Hot top-floor room or loft | Vented, ideally powered | Opens to dump heat that stratifies at the ceiling |
| Stairwell or hallway | Fixed | Light only; up to about 27% more glass and a lower price |
| Vaulted living room, nobody will reach it | Fixed, or solar vented if you want air | A manual unit out of reach tends to stay shut |
| Bedroom or attic needing egress | Egress-rated roof window | Neither a standard fixed nor a standard vented skylight meets IRC R310 dimensions |
| Low-slope or flat roof | Either type, curb-mounted | Code curb rules apply to both; see our flat roof skylights guide |
| Home often empty, frequent storms | Fixed, or powered vented with rain sensor | A manual vented unit left open in a storm lets rain straight in; a sensor closes powered units |
How to choose between a fixed and vented skylight
Work through these six checks in order before you buy. Each one either rules out a vented unit or tells you which venting operator to specify, and together they take about the same time as getting a single installer quote.
- Name the room’s job. If the room produces steam, cooking heat or trapped summer heat, start from vented. If it only needs light, start from fixed.
- Check reach. Measure from the floor to the skylight. Within reach, a manual crank works; beyond it, budget for a control rod, or for a solar or electric operator.
- Check for wiring. Open framing or a planned electrician visit favors electric; a finished ceiling favors solar, which needs no wire run.
- Size for light. Compare daylight areas, not rough openings. A vented unit may need one size step larger to match the light of a fixed one, and the opening must still fit your rafter or truss spacing.
- Check code triggers. Confirm whether the room needs egress (IRC R310), whether your roof is under 3:12 (curb required), and whether the bathroom has a code-compliant exhaust fan.
- Price it like for like. Ask for quotes on the same brand, size code, glass and flashing kit for both versions, so the only variable is fixed versus vented.
Frequently asked questions
Are vented skylights worth the extra cost?
Vented skylights are usually worth the extra cost in bathrooms, kitchens and hot upper rooms, where releasing heat and moisture at the ceiling has a daily payoff. In stairwells, hallways and rooms nobody will open the skylight in, the premium (about $379 for a manual VELUX C06 at Home Depot in October 2026) buys less light and more parts, so a fixed unit is the better value.
Do vented skylights leak more than fixed skylights?
Not in lab testing: VELUX rates its fixed FS and venting VS, VSE and VSS for the same 720 Pa (15 lb/sq ft) water resistance with no leakage. In real use, vented units add sash seals that wear and the risk of being left open in rain, which rain sensors on electric and solar models address. Most skylight leaks on either type start at the flashing.
Do fixed skylights let in more light than vented skylights?
Yes. In the same rough opening, VELUX’s 2026 measurement guide lists 14 to 27 percent more visible glass for the fixed FS than for its venting models, because the operable sash adds framing. A fixed C06 shows 4.56 square feet of daylight against 3.66 for a venting C06. Fixed units also carry a higher visible transmittance rating, 0.60 versus 0.53.
Do I need a vented skylight in a bathroom?
Not always. IRC R303.3 requires bathroom glazing with half of it openable unless artificial light and a local exhaust fan are provided, and most modern bathrooms use the fan route (50 cfm intermittent or 20 cfm continuous). A vented skylight is still the better pick over a shower because it clears steam that would otherwise condense on the glass, but it supplements the fan.
What happens if it rains while a vented skylight is open?
On a powered model with a rain sensor, such as the VELUX VSE or VSS, the sensor detects rain and the motor closes the sash automatically. A manual vented skylight has no sensor, so it stays open and lets water in until someone closes it. That difference is the strongest argument for a powered unit on skylights left open while the house is empty.
Can a vented skylight be used as an egress window?
Usually not. IRC R310 requires an emergency escape opening with at least 5.7 square feet net clear area, 24 inches clear height and 20 inches clear width with the unit open, and standard venting skylights tilt open only partway. Some egress-rated roof windows, such as larger VELUX GPU top-hinged sizes, are designed to meet those dimensions; confirm with your local building official.