We are working to add shed dormers to each side of our 1.5 story cottage build around 1860. Currently my head touches the ceiling a majority of the second floor hence the need for the dormers.
Current suggestions are leaning towards adding a ridge beam to span the 34′ ridge, divided with a column in the mid-span. The roof is a 10/12 pitch, framed with no ridge beam or board, original rafters 3″x6″ 30″ oc (fun right?). The idea is that we would be able to ‘cathedral’ one half of the roof iwo the master suite, at least up to a collar tie because the ceilings are only 6’5″ max with the ceiling rafters.
This is our current plan of attack:
-Support and stabilized rafters and ceiling joists
-Add ridge beam with midspan lally column to basement footing, and gable end support collumns.
-Cut and add rafters to subdivide bays, along with headers and framing for the dormers.
-Pad exisitng rafters to allow insulation in cathedral space and re-sheathe entire roof.
Crazy? Probably. Worth it? That’s the question: Worth adding the beam and saving the existing structure or do we cut the roof off and re-frame entirely.
edit: we are working with a structural engineer. I am one as well but work with boats, not houses. Just curious for ideas and recommendations from our plan
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Pictues? Historical implications? City/Township restrictions?
No historical implications or restrictions, other than we don’t want to totally deviate from the ethos of the house.
Here is the house from a few months ago (mid residing).
I assume you're considering a shed dormer rather than a couple of 'dog house' dormers.
If you add a ridge beam (NOT board) and the additional support column, you should be able to achieve a full cathedral ceiling beyond the dormer(s). However, adding a ridge beam is a challenge because you'll have to determine how to tie the rafters on either side together (to maintain the 'tie' from one wall to the opposite wall) so you can trim their ends to properly fit against the ridge beam. Getting the ridge beam into place without disrupting the 'tie' previously mentioned presents a bit of a conundrum.
Inserting intermediate additional rafters after the ridge beam is secure is possible, although sistering on either side of the existing rafters could be less 'fussy' with respect to proper cutting of each end.
It's good Winter work as long as the roof stays intact. I would not want to be doing this work in the Summer.
Thanks for the feedback. Yes, shed dormers, essentially half-length on the left side and the right. Would have loved a "Nantucket" dormer, but the inboard faces of the doghouses would land in difficult places for the interior, might fake them in with some extra eaves.
Ridge beam (yes definitely not a board) will be fed in from the backyard via crane, not a tricky task but powerlines make that difficult on the front. Currently, the ceiling rafters are flush with the tops of the second-story windows, so temporary bracing and collar ties should stabilize enough until we can slit the rafters at the ridge, load the beam and bracket the rafters to the beam. The 30" span makes me think intermediates are the solution over sistering but good insight. Too much rain and snow for a winter project, hoping for early summer as not to melt in the attic.
Since you're going to create dormers on both sides of the ridge over half the length of the house (front to rear), are you planning to frame them in while leaving the existing rafters in place, then cut the existing rafters above the ceiling in that portion?
OR
Are you going to remove the existing roof completely before framing in the dormers?
How are you going to frame the taller exterior walls along the dormer - from 2nd floor to eave or extend the existing walls to the new eave height?
It's beginning to seem like it might be more expeditious to totally remove everything from the 2nd floor up and reframe it in its entirety. More exposure to weather for sure, but much less time time futzing around existing framing, and no wrestling with a ridge beam (and all that's involved in getting into place).
JMNTBHO
I'm not a professional builder but I have to agree. If you are already replacing most of the roof, just do the whole thing. It will probably go much faster. Working around 1860s framing sounds like a nightmare.
The intention is to from the new dormers with existing rafters in place for as long as possible/feasible, just a belt and suspenders to keep movement to a minimum.
We are considering cleaving the house off on the second floor, there is a significant cost leap at that point. The structural engineer says he would prefer to retrofit, not sure if that's just a play to get a few more billable hours. The ridge beam doesn't scare me as much, I play with cranes all day and have a pretty good rigging team lined up but may not be the most efficient route.
I vote for the tear the whole roof off solution, but I don’t have to pay for it. At that point I’d just raise the height of the side and gable walls and reframe a simple easy to frame and air seal gable roof just like you have now out of 2x12’s to give lots of room for insulation. If you want more light and floor space add a gable dormer on one or both sides with matching proportions to the front.
Picture is inside a bedroom with a cross shaped double gable dormer. Don’t forget the built in on the sides.