hvacinsulationroofskylightweatherstripping
I have 2 skylights in my master bedroom and they cause the room to get much hotter than the rest of the house in warmer months. Today it is in the 90s outside. My IR thermometer shows the area just under the skylight glass is 134 degrees! My central AC is struggling to keep the house cool. What can I do about this? I would prefer to do something about the cause (skylight), instead of something like putting a window A/C in there.
Go to any big box store and get some 6" flexible insulated duct (this pic shows black sheathing on the outside, but it's often made of shiny reflective mylar):
And a couple of 6" boots, one for each end:
Use aluminum HVAC tape or a large band clamp or zip tie to connect the inner sleeve of the duct to the boots, then use another layer of tape to seal up the insulated layer and prevent it from sliding around. Cut holes in the ceiling to match the rectangular boot opening, keeping one long edge of each hole flush to a ceiling joist. Then take your duct assembly up into the attic and insert the boots into each hole. You can just leave the flexible duct lying on top of the ceiling joists. Back downstairs, use small nails (with heads, not finish nails) to nail through the inside of the boot opening into the side of the adjacent ceiling joist. Then install a couple of register grilles and you're done!
For Q#1, no. It is typical, indeed expected, that they will only insulate the parts of a wall that border the outside of the home. Insulation isn't that cheap.
For Q#2, get an IR/no contact thermometer, frequently selling for $20 online for the lower end models. Check all the walls in the room and compare to other walls on the same side of the house. This will give you an idea of whether the problem is real or imagined.
The reason I suggest the issue could be imagined is that people, lights, and electronic equipment put off a lot of heat, possibly more than you are seeing transmitted through the walls. Just by working in the room, you will likely see a large spike in temperature.
The easy fixes for this problem are more weather stripping around leaking windows, outlets, etc and adding insulation to places you can reach, such as the attic. And finally, make sure your air vents are properly adjusted to send more air to the rooms you use. You may consider placing a fan on the floor at the door blowing cool air into the room (effectively pushing hot air out the top of the doorway).
Best Answer
Where I live (southern Arizona) skylights allow too much brightness and too much heat into the house. The solution is to install a sun blocking screen that lets in lots of light but very little heat. Big savings in cooling costs! The screen is stretched over an aluminum frame.