Do I need a permit to add a skylight?
Usually needs a permit
Cutting an opening in a roof is structural work on the framing plus a new penetration in the weather layer, which is why this is typically permitted even though the unit itself arrives ready to install.
What changes the answer
- A new opening in the roof — typically a permit: rafters or trusses are being cut and headed off
- Replacing an existing skylight in the same opening — often ordinary repair, and much more likely to need nothing
- Cutting an engineered truss — a structural change that generally requires the truss manufacturer's or an engineer's sign-off
- Glazing in a roof has safety glazing requirements the same unit would not face in a wall
- Tubular daylight devices are smaller and often fit between rafters without cutting any, which changes the answer
These thresholds come from the model code and are commonly amended locally, which is usually where people get caught.
Why it matters
Skylights leak more than any other roof penetration, and almost always at the flashing rather than through the unit. The structural half is less forgiving: cutting a truss without engineering removes a member that was carrying calculated load, and a truss is not a rafter you can simply header around.
Confirm the requirement with the authority that would issue the permit before deciding.
The version of this people actually ask
Do I need a permit to replace an existing skylight?
Replacing a unit in an opening that is not changing is much closer to ordinary repair and frequently needs nothing. What makes it worth confirming is that a replacement usually means re-flashing, and the roofing has to be opened and reintegrated — so the work that follows a straight swap is exactly the work most likely to cause a leak if done casually.
Do I need a permit for a solar tube or sun tunnel?
Often the lightest case in this category. A tubular daylight device is small enough to pass between rafters at standard spacing without cutting any structure, so there is no framing alteration — leaving a roof penetration and its flashing, which some jurisdictions permit and many do not. If installing it requires cutting a rafter, it stops being the easy case.
Can I cut a truss to fit a skylight?
Not without engineering. A truss is a designed assembly where every member is carrying a calculated force, and cutting one is not comparable to heading off a rafter. Modification generally requires a repair detail from the truss manufacturer or an engineer, and that is exactly what an inspector will ask to see. This is the most common way a skylight project becomes a structural one.
This is the typical rule, not your answer
This is the typical rule in the United States and not a decision about your property — permitting is run by more than 22,000 separate authorities and any of them can amend the code it adopts, so confirm with your local building department before you start. Put a ZIP in to see what applies in that state, and how to reach the office that decides.
Not in the IRC R105.2 exemptions where the roof structure is altered. Requirements come from IRC Chapter 8 for the framing, R308.6 for skylight glazing and screening, and R903 for roof flashing and drainage.
Other projects
- Build a deckA permit is usually required once a deck is more than 200 square feet, more than 30 inches above grade, serves an exit door, or is attached to the house.
- Put up a fenceFences under 7 feet are typically exempt from a building permit — but height limits, corner-visibility rules and pool-barrier requirements are set locally and catch people constantly.
- Add a shed or small outbuildingOne-story detached sheds are typically exempt up to 200 square feet under the residential code — but the number people quote is 120, and both are right depending on which code your jurisdiction adopted.
- Replace a water heaterReplacing a water heater almost always requires a permit, even though it is routinely done without one.
- Remove or open up an interior wallIf the wall is load-bearing, a permit and engineered drawings are required. If you are not certain whether it is load-bearing, assume it is.
- Upgrade or replace an electrical panelPanel and service work always requires a permit, and in most places must be done by a licensed electrician.