Serving Salt Lake City, UT & Nearby Areas
(385) 438-3591
Serving Salt Lake City, UT & Nearby Areas
(385) 438-3591
A skylight cannot go wherever the light looks best. Valleys and furnace flues rule out whole sections of a roof, and if your house is framed with trusses rather than rafters the framing decides for you. Go up in the attic and look before anyone cuts a hole.
Have a roofer check your attic and pick the location before anyone commits to a spot from below.
Valleys, flues, and truss framing rule out large areas of a roof that look perfectly fine from below.
Go up in the attic and see whether you have rafters or trusses.
A skylight is a hole cut in the one surface of your house whose whole job is not having holes in it. A Utah winter will find it if the spot was wrong.
Mattie Tueller, Master Roofing
Because a valley is where two roof planes meet and hand all their water to one channel. That line carries far more water than any other part of the roof, especially in a heavy Utah spring rain or a fast melt. Putting a skylight beside it means cutting an opening directly into the path of everything the roof is draining.
Skylights set too close to valleys are one of the more common placement mistakes we find. The valley runs its water straight past a curb and a flashing joint that were never designed to take that volume. It only has to get past once. A skylight installed anywhere else on the same roof might never see a problem.
Distance is the fix, and it is not negotiable by sealant. No amount of caulk turns a bad location into a good one. This is separate from the question of how skylights fail generally. That's covered in whether a skylight is worth it or just asking for leaks.
Flues, mostly. Furnace and water heater flues come through the roof at a fixed point set by the appliance below them. They generally cannot be moved to suit a skylight. The area around a flue is also crowded with its own flashing. So there is rarely room to work a second penetration in cleanly.
Most of that list is invisible from inside the house. It is why the honest answer to "can I put one here" is often "let me go up and look first," and why an installer who answers instantly from the living room has not actually checked.
It matters more than anything else on the list. Rafters can be cut and headed off to make a skylight opening. That is routine framing work. Truss members cannot. Under the residential code, truss members may not be cut, notched, drilled, or altered in any way without the approval of a registered design professional.
A truss is an engineered assembly where every member carries a calculated share of the load. So removing part of one is not a framing decision, it is an engineering one. In practice that means a skylight on a truss roof either fits between the existing trusses or it does not happen. That's because engineering a truss alteration for a window is rarely worth what it costs.
The good news is that this is knowable in an afternoon. Trusses look like triangulated webs of smaller lumber. Rafters look like single larger boards running from ridge to wall. Ten minutes in the attic tells you which house you own. It tells you before anyone has quoted you a skylight that cannot be installed.
The roof should choose it. An interior contractor can cut the opening, frame it neatly. Finish the drywall so it looks like it was always there. None of that work stops water. The location has to clear the valleys, the flues, and the framing first.
Only someone looking at the roof and the attic can confirm that. That's why the order of these conversations matters more than anyone expects.
Worth knowing for planning: lead times vary a lot by unit. Some skylights we can get in about a week, and larger ones can take two months. So the location conversation is worth having early rather than the week the roof work starts.
The part of this that costs people money is that a bad location looks exactly like a good one from inside the house. You stand in the room, you point at the ceiling. Nothing about that view tells you there is a valley six feet away dumping half the roof's water past that spot.
So at Master Roofing we go up in the attic before we agree to anywhere. Sometimes we come back down and tell someone the place they picked will not work. That is a really disappointing conversation to have. That's because they have usually been imagining it there for a while. A company that has not looked will just say yes. That is a much nicer meeting and a much worse roof.
A skylight is a hole you cut in the one surface of your house whose whole job is not having holes in it. So the roof gets to pick the spot. You choose the room and roughly where you want the light. Let the roof rule out what it needs to rule out. You will get the window you wanted without buying a leak to go with it.
This article is general information about Utah roofs, not an assessment of yours. Every roof is different, and no article can tell you what is actually happening on your specific house. Have a licensed roofing contractor look at it in person before you act on anything here.
No. Every skylight model has a permitted pitch range published by its manufacturer. Installing outside that range voids the warranty and invites leaks later. Low-slope roofs usually need a curb-mounted unit rather than a deck-mounted one. Very steep roofs carry their own limits. Ask which unit is rated for your actual roof pitch before anybody measures an opening for it.
There is no single number that covers every roof. That's because it depends on how much area drains into that valley and how steep the roof is. The practical answer is that the skylight needs to sit clearly outside the water's path with room to flash it properly on all four sides. A roofer looking at your actual roof can give you the distance for your house.
Often yes, and vaulted or cathedral ceilings are a common place for skylights because the roof deck is right above the room. What changes is that there is no attic to inspect from. So the framing has to be confirmed another way. The light shaft is shorter. The valley, flue, and pitch constraints all still apply exactly the same.
Usually, yes. The roof is already open, the crew is already there. The flashing integrates into new material rather than being woven into an existing roof. It also means the placement gets decided while the whole roof is visible. If a skylight is on your list for the next few years, the reroof is the moment to do it.
They have more flexibility, not none. A tubular unit is small and its reflective tube can route around some obstacles. So it fits places a full skylight cannot. It still cannot sit in a valley's drainage path or on top of a flue. It still needs its own dedicated flashing kit for the roof type. Smaller opening, same rules about water.
We're here to see what's going on with your roof. A real assessment starts with your history and your attic, not a number from the driveway. You'll get a straight answer about what's up there, what it needs, and what it costs. Sometimes the honest answer is: your roof looks great.