Here’s a picture of the exterior.
Could you be more specific?
I imagine Peter is referring to you swinging the roof section up, where in actuallity, as you know, it will have to be removed rafter by rafter, a new outer wall section built, then install new rafters, new decking for flat roof.
The area of major concern is at the peak. You are removing the support for the ridge all along one side, then loading the ridge with a flat roof in snow country. There may need to be a beam added under the ridge or some other means to transfer the weight, where that was not an issue for the steep pitched roof.
The other issue is looks. It’s a fine looking house at this point. How will it look with a flat roofed dormer?:neutral:
There is a central wall that runs “North-South” on every floor of the house. My understanding is that you can build a temporary wall or support under the ridge, and that the weight of the roof is then transferred down the temporary wall through the walls underneath.
Now there is still the horizontal force of the roof as well. I assume that is braced somehow. We’re also not removing the entire roof, just a section of it, so the pieces at the ends should help hold the ridge in place, especially if they are beefed up with sistered rafters and new collar ties.
As for the look, about 25% - 30% of the houses on my street have shed dormers. I’m sure they don’t make it onto the front pages of the architectural magazines, but I don’t think they look too bad 
No offence intended Nathan but you would really benefit from a professional design.
We can’t do what needs to be done by looking at a couple of pictures and talking on a message board.
Nathan, you need to find an architect who does residential additions and alterations as a specialty. To charge 18% for something like you describe is an outrage, even considering that it would include full construction observation. If all architects charged that much, then no one would ever use them, and things would not be done right. All you need is a detailed floor plan (not the sketch floor plan that you posted), a cross-section, about an hour’s worth of structural engineering, and three elevations, plus a decent set of specifications. Even at $100/hour, if that can’t be done in 20 hours or less, something is wrong somewhere. If the architect does his job right, you don’t need construction observation. Many of my jobs are built without so much as a phone call to me after plans are drawn.
Nathan:
In larger firms, an architectural CET (certified engineering technician) does much of the basic work for the architects. You may be able to find a CET who runs a small house plans firm who will do the work cheaper. Just make sure they’ve been in business for a while, have extensive experience in renos and not just new homes, and have E&O insurance
PM me and I will send you my home # if you wish to call sometime.
John, my thought exactly, I hope he keeps us posted, I for one like to see how the contractor is going to push that roof up like it’s hinged, not to mention, what happens to the plumb cuts on the rafter tails, totally different pitch.
Now that I see the exterior of the house there is only one way to do this job, or the only way I would do this job and that is to hire a structural engineer to come up with a framing plan. This needs to be documented by a engineer, at least in my area it would and should be a matter of public record, not to mention the documentation should be in place so in the event of a future real estate transaction proof can be produced that it was done correctly.
In my area I would expect to pay somewhere are 1500.00- 2000.00 for this plan, the rest is easy.
While there is nothing wrong with using a structural engineer, there is nothing about this project that any good architect would be incapable of doing. An engineer could well be overkill. For the same price one should be able to get architectural advice PLUS engineering. There isn’t but about an hour of engineering required.
The idea of “hinging” the roof is, of course, preposterous. If that is what the writer is expecting to do, I see a good dose, unfortunately, of doom in his future, especially if the rest of the project is equally misguided.
Richard, I use a engineering firm on a regular basis, the reason is I have never had a problem pulling a permit, executing their plan and getting the CO.
Architects on the other hand I have not had the same results.
This is based solely on my own experience in my area based on the kind of jobs I do on a regular basis, which by the way is similar to Nathans job.
I should also add that I never build anything to a minimum standard, everyone of my projects are done exceeding minimum codes or standards and add value to the property. This may be why I have four projects in three states currently in progress.
I think we can all agree on one thing though, he needs professional help!
Here are some measurements and drawings. I’m still waiting to hear back from the structural engineer on what he’d recommend.
Nathan, I’m glad you have sought out an engineers advise and I hope you will have them do the framing plan for you, this is money well spent.
When the engineer give you the framing plan it will be more detailed than what you show here and I assume you realise this. It will also show the load points. One thing I noticed in your plan is the height of the shed roof. In my area we need to have a 7’ 6" floor to ceiling height and that is from the finished floor to the Sheetrock on the ceiling, this is why I stated earlier that many times this results in a flat roof.
Glad to see you are still posting and please continue to do so.
Let’s see if Nathan’s engineer suggests making that new wall a load-bearing wall, which would eliminate the need for the collar ties / ceiling joists, since they’re too high to do any good anyway. Also, the new rafters should nearly as possible match the bottom of the existing rafters in order to maximize the slope on the dormer roof, and that roof should have full coverage of waterproofing shingle underlayment to help mitigate leaks from ice dams, if Nathan’s home is in a cold region.
My understanding is that collar ties actually NEED to be high. If they are too LOW, they don’t do any good. What holds the two sides of the roof spreading apart are the floor joists, not the collar ties. I believe the collar ties are there to hold the top of the roof together.
The rule of thumb I was taught by a structural engineer is that collar ties should be no higher than the bottom of the upper third of the disance between ridge and floor. Everything I have seen published about them seems to agree. What would be the point of having collar ties directly under the ridge? The only book I can find with any reference to height is the AF6PA Wood Frame Construction Manual, which says they should be in the upper third.
Richard is correct, the 1/3 rule is a good rule of reference in the US.
You also need to take into consideration that in cold climates you need to achieve a 70 pound live load on the roof, that being said that live load combined with the new wall will carry the weight downward through the structure to the foundation wall. If the existing floor in the attic is 20" OC than more than likely the 70lb load of the roof combined with a 60lb live load for the floor will not sufficiently carry the load to the foundation on the existing 20"OC attic floor.
Now all that being said, this house was built in the early 1900s, if so it more than likely is balloon framed and to add all that extra load to a ballooned frame wall has to be calculated, you can’t say I have X amount of money and want this done to my house house and except the opinion of the contractor who will tell you what you want to hear.
Live load for a floor containing bedrooms needs only to be 30 PSF, certainly not 60. The attic floor was already contributing 20 PSF, so the net increase is only 10 PSF, plus the roof load. Half the roof load will be taken off the outside walls and on to the center bearing wall if that is done. I don’t know what lies below; the load paths would have to be examined.
Steel straps over the top of the peak of the rafters can be used in place of collar ties as well.
So there are some choices.
Sorry , you are correct, 30 lb live load for living space.