In a previous life I used to be a carpenter but haven’t done it for a long time so I don’t trust my own judgment here; would like some feedback.
Scenario 1:
In framing plans/diagrams for skylight framing I’ve seen the typical detail where the outside of the skylight is defined by two sets of doubled rafters (typically shown as continuous from plate to ridge). Then, 2 headers (doubled 2x each) are installed that define the upper and lower part of the rough opening where rafters that are in the way can be headed off. I’ve done it this way in the past.
Scenario 2:
I have a location in my house where I want to install a skylight and it is to be centered over a stairway. What I want to do is to double up two existing rafters that are outside the skylight location by adding a 2x to each one. I’ll install the 2 doubled headers which will define the rough opening low point and high point. There will one rafter to head off. However, in this scenario, I’ll need two sets of doubled 2xs to define the width of the skylight. For these I want to hang them off of the headers, and this is the main difference between this scenario and Scenario 1. I’m essentially ‘infilling’ the entire skylight rough opening by hanging it from the two doubled up continuous rafters. Is this scenario considered OK? I’m planning on using joist hangers with screws for all hanging connections (as I would do in Scenario 1 as well).
Thanks for any info.
Replies
Skylights
Are you installing these in an existing house? What size are they?
Hi finefinish,
Thanks for the reply. Let me give you more info; my situation is a bit different from what you are assuming:
- It is an old house; I have skip sheathing so there is no continuous plywood sheathing to cut away.
- I'm doing this work from the 'semi-finished' attic; there is no ceiling to remove or issues with working in my living space. I'm lucky in that regard for this skylight. From a demo and logistical standpoint it's fairly simple.
- Don't laugh: Existing roof rafters are 2x4 (old full size 2" x 4"), 30" on center.
- The skylight is 30" wide. It is a Velux deck mounted unit.
I was planning on using 2x6 framing to go along with the existing old 2x4 rafters. SInce I'm cutting out one rafter and heading it off, the headers will be spanning ~ 5'. That's why I was thinking of having to double them.
Question: When you say it's not necessary to double the rafters, you are referring to the full length existing rafters that I was planning on adding to by face nailing a new rafter to each on (in order to double)? Or are you referring to the infill 'partial rafters' that define the width and location of the skylight that I'm planning on hanging from the headers? I'm pretty sure you are referring to the full size common rafters, but not 100% sure.
I sort of like the idea of using doubled up lumber around the rough opening due to the fact that this is a deck mounted unit. I'm pretty sure that Velux's configuration with their nailing flange and the size of the unit with regards to the R.O. will still allow nails to hit a single 2x around the R.O. but just in case I'd like to have more 'meat' there for the nails to hit. I'm pretty sure that the nails that they provide are long enough to want to go into framing rather than just nail into the sheathing.
Oh, I should add: I'm getting a new roof soon...complete re-roof with new 1/2" plywood sheathing.
Thanks, again!