Installing skylight, no ridge board?

LizMovingNorth · #1 10/09/04, 01:11 PM

Hi all,
We're installing a skylight and just discovered this old house doesn't have a ridge board. Now what? We need to cut one rafter to put the skylight in, so we were going to double (sister) the rafters on either side. But there is nothing for the top end of the doubled rafter to sit against. If it wasn't the weekend we'd call the building inspector, but we were hoping to finish this weekend.

Has anyone else dealt with cutting a rafter and doubling with no ridge board?
Thanks,
Liz

Beeman · #2 10/09/04, 01:18 PM

First I ASSume this is a standard peaked roof. Is this roof over an attic or is a vaulted ceiling? What actually supports the roof? If there is no ridge board how are the rafters attached at the top? Are they butted to each other? How far apart are the rafters and how big a hole do you need? What is the sheathing and roofing materials?

LizMovingNorth · #3 10/09/04, 01:36 PM

Yes, it is a standard gable (peaked) roof. There is living space until partway up the roof (about a four feet high vertical wall in the bedroom, non load bearing, then sloped area, then flat ceiling). There are collar ties on the rafters a few feet down from the top. The ends of the rafters are just butted up against each other (and nailed) but not attached to any of the other rafter pairs. The rafters are about 24 inches on center, and are 2inch by 6inch (actual measurement) boards. The hole needs to be about 30 or 32 inches wide, so I only need to cut one rafter. The roof sheathing is random width (1 inch thick) boards, with asphalt composition shingles on top.

moopups · #4 10/09/04, 06:08 PM

Normally I would cut out the rough opening and place a cross member to the top and bottom of the horizonal plane exstending to the next rafter on each side of the opening. Then cut a short rafter to place back up to the ridge line. It would not hurt to double the top horizonal member. Also keep in mind that a skylight that is mounted on a 'curb' is much easier to replace if it gets damaged or broken.

LizMovingNorth · #5 10/14/04, 05:05 PM

Hi all, thanks for the replies. The final word from the building inspector was that if you are cutting a rafter, you have to double (a.k.a. sister) the rafters on either side before putting in the header and footer, and if there is no ridge board or ridge pole, you have to sister the rafter on the opposite side of the house as well so that it has something to butt against at the top.

Final verdit: Skylight has been returned, narrower skylight that fits between rafters has been purchased.

Thanks again,
Liz

3girls · #6 10/15/04, 09:05 AM

Liz,

I hope I am not too late. There is a product, one brand of which is Solartube, that would really fit the bill. It is literally a tube of some kind of super shiny material that joins a round "window" at each end of the tube. The tube is maneuverable so the holes do not have to exactly line up. I am greatly simplifying here. I have seen these installed in several places and they are dynamite. My sister has one in her guest bath, and I was always trying to turn out the light! We are building an addition for me, and I am going to try to get several for my space. I have not seen that they open if ventilation is your goal. If additional light is your goal, these work just great. They come in sizes up to 16" so there is no need to mess with the rafters at all, and installing them is very simple.

Sandi