Hey everyone-
I used to hang here a LOT a few years ago. Haven’t been around for awhile.
I’m about to launch into a shed-dormer project .. looks like it’ll be about 26′ wide .. the whole back of the house. It’s my own place so I’m not on a rigid time-line or anything. Wondering where there may be info — with diagrams, hopefully — hiding here at FHB or somewhere else on the web that any of you could recommend.
A side note: Could do two separate side by sides each about 12 feet wide .. and wondering if there would be any advantage to this. I’ve added on ground level additions before and built/outfitted complete apt. conversions (garage to apt.) but have never attempted a dormer of any kind.
Thanks!
Terry
Replies
terry... sounds like 26' is the total width of the house.. so i would probably shoot for 22' for the dormer.
the easiest way to frame the ridge intersection is to turn the old ridge into a structural ridge..
and try to maintain a minimum of 3/12 pitch for the dormer roof.. and keep the lower bearing wall within say a foot of the main wall below..
two 12' dormers would tend to be very awkward two 6' gable dormers might be pleasing .. in any case try to integrate the architectural style of the dormer with the style of the house
keep your insulation envelope in mind with your framing details
and have fun.. dormers really open up underutilized space
Mike Smith Rhode Island : Design / Build / Repair / Restore
What Mike said...
especially about keeping the dormer a few feet short of the whole house width.
Also.....one long front wall is easier/quicker to build.....just takes more hands to stand......or rent some wall jacks.
again...like Mike said...work off the existing ridge if possible.
Have a big tarp on site before ya cut anything!
and plan the drywall stocking before you button things up.
JeffBuck Construction Pittsburgh,PA
Fine Carpentery.....While U Waite
I was reading your post and you talked about a "ridge intersection"? Alls he'll be doing is nailing the new dormer rafters to the existing ridge. Is that what you mean by the intersection? Also, why would you make the ridge structural? How would you go about that? Just a little confused. Thanks!
draw a force diagram.. he's removing the balance from a conventionally framed roof.. that roof relies on the rafters of one side pushing against the rafters of the other side.. and the floor joists holding the walls from spreading...
a rafter from a shed dormer changes the direction of force and is not the equivelent of the gable rafter it is replacing
cutting a 22' section out of the roof leaves nothing for the remaining rafters on the other side of the roof to push against.. so instead of pushing, they now have to hang.. design a structural ridge in and carry it down thru the main bearing wall below
there are other ways of framing it.... but most don't do it correctly...Mike Smith Rhode Island : Design / Build / Repair / Restore
ah. excellent! thanks for the explanation Mike.
Terry,
Are you planning on keeping the dormer ceilings cathedral or putting a ceiling back in at 8'?
To maintain a 3/12 pitch the dormer wall usually winds up being around 7'- 7'6" high minimun.
This all depends on the height of your existing ridge.
Some cases you just nail the new rafters right to the existing ridge and then nail all your ceiling beams along side your existing rafteres and new rafters at 8' and that will give you a small clipped ceiling because of your 7' - 7'6" heght wall.
Some cases once the old rafters are removed we've nailed 2x10 or 2x12 against the old ridge and then nail the new rafters to that with the same procedure for the ceiling beams.
Some cases the existing ridge height was to low so we extend the ridge by adding new raftyers to the existing ridge and add a new ridge. That will give you a nice comfortable pitch and nail your ceiling beams up against your existing ridge and use that as the height of your dormer walls, which will give you at least 8'.
If you want a cathedral ceiling then you can put a structural ridge in and nail all your rafters on top. No collar ties.
I wouldn't do two seperate side by sides at 12' feet each being that your house is on 26'.
It would look alot better one dormer stepped in minimum 1' on each end in your case.
We've done alot of dormers where you have two seperat ones but they were small like 8' -10' each. One in each bedroom.
On Capes you usually have the bathroom in the middle and the two bedrooms on each side, we just do the whole thing in on shot.
Joe Carola
Good points Joe, the ceiling joists can act as ties. It could be tricky for a 22' long shed though. Hard to say from here.
I's even possible that there is a way to carry load to foundation via interior walls. Again - can't see it all from here.
You would need a really skinny roofer to flash and shingle between two shed roofs in that space, wouldn't you? I've been there - don't like it!.
Excellence is its own reward!
Maybe if you stopped eating those doughnuts, you'd fit between the dang dormers. <G>
OH, I get it, you hold Krispy Kreme stock in your portfolio!
Piffin,
I don't think that his shed is 22' from front to back, it's side to side, unless I missunderstood his post but if it were to be 22' then you would defintely have to extend the ridge to get some kind of a decent pitch because you would wind up with a flat roof.
Did you have fun roofing those two dormers that were close together, or was that back in the day with the 29" waist and befor the Krispy Kremes Panama said you like. ;-)
Joe Carola
I'll let you in on a secret - I hate sweets!
;)
.
Excellence is its own reward!
Hey Folks,
Very much appreciate all of the replies. Wish some of you with past experience in this area were in Seattle and could drop by for a look-see.
A few points:
This house sits far enough back on the lot and is hidden enough by the two structures on either side that I really dont care that much about the aesthetics of this upcoming project. That may sound 'insensitive' .. but as I said .. it's my place and I really want to take advantage of every possible indoor sq. ft. that I can. If I could go end to end -- a full 26 ft. -- as one big monolithic span .. I'd likely do it.. and may.
This house is a little odd as it is 26 by 40 ft. -- the footprint -- but the ridge runs the short way right smack-dab in the middle (at 20 feet). It's billed as a 1 1/2 story .. meaning that the first floor is filled out, of course, and then the second floor is only used at the middle .. for one large room and one very small room. This leaves quite a bit of unused side space .. which I'm hoping to capture some of on one end. So .. from the wall of the larger upstairs bedroom to the end of the house is a full 13.5 ft. That's space that you can get into and walk around in (over the kitchen) .. and it's a perfect set-up for the dormer. At the point where this wall of the bdrm meets the rafters the rafters are at just under 8 feet from the 2nd flr joists. The Ridge is dead-center over the middle of this bedroom at exactly 12 ft. high from the flr. joists. ((Wish I could somehow transfer my drawing of it to here but haven't the computer saavy)). Hopefully I'm communicating the picture. What I'm working with, then, is the narrower end of a 40 by 26 ft structure .. and I have all 26 feet wide and from the outside 26 foot wide wall back towards the center some 13.5 ft where one meets with the wall of two bedrooms. Big, dead, usable space .. just sittin there. I believe that it may be possible to use these bedroom walls -- which rest on bearing walls below -- to 'bring the load down' from the new rafters. I'm not an expert in this sort of thing and will ultimately have to hire a few hours (expensive!) from an engineer .. but it certainly looks invitingly doable to me.
When I bought this house in '94 the inspector told me that it was a Sears Craftsman Bungalow and that they were purchased through the Sears catalogue in the '20's. You could either just buy the plans .. or the plans and a cargo-hold full of all of the needed boards and wood all cut to size and marked like a giant puzzle. Or .. the drawings, the wood, and a Sears crew of builders to frame it up. He said that he'd been through the identicle house on several occassions over his years as an inspector. Somewhere there are still the house plans available .. just as they were drawn in 1926. I haven't looked nearly enough yet but to give SOME idea of something similar try this link: http://architecture.about.com/library/bl-bungalowplan-s-3051-dundee.htm but my house has the front porch extending all the way across the front (much cooler!). But from the pic you can see that the whole back side of the house is wide open for dormer .. while the front is 'gabled out' sort of uselessly .. capturing only what could be possibly used as storage over living room and ourside porch area.
Part of the reason for the consideration of the two side by sides as opposed to one giant dormer was that in my county the max width for a project enjoying a vastly simplified permitting hassle is 14 ft. But also .. I thought that leaving that middle two rafters or so extending down to the outside wall along with the end rafters might really help in the major off-setting of structural forces that this sort of really large re-arrangement of things will entail.
Also .. no one has any links to any sort of online sites that offer reliable drawings/plans for shed dormers? Certainly FHB must! Anyway .. thanks and any further details much appreciated also!
Terry
this picture is even closer to the structure I'm talking about:
notice that the ridge runs the short way across the house and that the back of the house at the second floor is wide open .. empty .. crying to be used! :)
http://architecture.about.com/library/nbungalowplan-s-3049-vallonia.htm
T.
Couple of response comments without much point
Given the choice between an extra ten or twelve hours of permit work Vs. maybe another thirty hours to frame and trim two separate dormers containing less space than otherwise...
It's a no-brainer for me.
The second set of plans you linked is close to what I imagined you to have based on your text.
Do you actually have rafters?
I have worked on a couple of these and I see it reminding me in the picture, that some of these have no rafters. They have purloins and the decking is run vertically across them. That fact could complicate your plans.
I think you do need a good framer or an engineer..
Excellence is its own reward!
Piffin,
Yes .. how right you are. I think another thing was that part of me wants to break up the work .. do one and then the other as easier chunks to bite off. But I basically agree with you. The difference here, though, is between having a guy come out and say "wha did ya wanna do?" .. "oh .. ok .. yeah .. go ahead" And a very long formal process with drawings and computer this an that and checking and rechecking everything. But again, .. your point is very well taken.
I'm sorry ... I dont really know what 'purloins' are. But I do believe that I have rafters. Loooooooong 2X4's that are spaced 21" (oddly) on center. Stretching the full 20 ft. to the ridge-line AND up 12 ft. as well! But they appear to be supported at the line of the upstairs bedroom walls .. which, as I stated, are bearing-walls .. which hit them at about half way up their stretch.
Yes .. again .. I agree that I'm going to have to 'seek outside counsel' before proceeding. Wish I didn't.
Terry
Terry,
This is how I framed many dormers in your situation. Hopefully it's close to what your saying.
Joe Carola
First drawing a little to big.
Framer ..
If yu drew a line down from the point at the left in your drawing where the 2X8 ceiling joists meet with the rafters .. then that triangular space which resulted at the extreme left end of the drawing .. under the rafters and to the left of the central bedroom box .. would be the space I'm working with .. 13.5 feet from 'left' end of house (where rafters meet support wall) to bedroom wall. (( unfortunately, perhaps it's too difficult/awkward to do by drawing ... good attempt though!))
T.
Terry,
What your saying is, is that your dormer is going on the front of the house and your second floor is layed out like your second floor plan in your picture?
If so reverse my drawing and make the right side of my drawing the front of the house.
Joe Carola
We have an odd little glitch here.
Ummm .. the right side of your drawing is cut-off in what comes up for me from the url. But it looks to me like if you extended it out then, yes, that is what I'm working with. In other words .. the space to the right of the vertical bedroom wall that you have there that meets the rafters at 8 feet. And it runs the full width of the house.
Again .. hope I'm making sense!
T.
Terry,
I shrunk the picture and drew a dotted line in where your roof is now. The rest is drawn in after the new dormer is built (side view).
Can you at least see where the 40' line stops and where it says 5+/12 pitch (a little triangle) ?
Joe Carola
Joe ..
VERY cool -- I love it! From your drawing I see that I DID finally get what you were suggesting. As I said .. that is something that I never would have thought of and I like the looks of it alot! You see? .. this is your field and not mine! :]
Now .. there is one other weird thing that I didn't mention (only one.. really!) that slightly detracts from the appeal of this unless it can be 'elegently' addressed in construction approach. I dont know if I can communicate it with words but I'll try. OK .. the bedroom wall that extends across the back of the house at 13.5 feet from the back wall of the house only goes about half way. Then .. it jogs just short of 4 feet over towards the back and then continues on parallel to it's first line .. on to the opposite outside wall. So it's not a straight shot all the way across as the new ridge would be .. it goes half way .. they jogs out .. then continues on to the end. And the second half of the wall is ALSO over a bearing wall on the first floor. ((But actually ... the real 'bearing' wall in the basement runs the perpendicular to these sideways first and second floor walls. In other words .. the main support beam and posts in the basement run the LENGTH of the house right down the center from back to front .. so maybe what I'm calling 'load-bearing' aint. )). Anyway .. any sense of how to approach the fact of the jog in the second floor wall-system? (Hope this aint too confusing!)
Terry
Terry,
Is this something like your talking about?
Joe Carola
dayam! .. how do yu do that? is that with a scanner?
No .. the wall extends from one point on the 40 foot side across towards the other 40 foot wall at 13.5 feet back from the 26 foot end wall. Then .. at 13 feet along, it jogs TOWARDS the 26 foot end wall .. then turns again BACK to a line that now PARALLELS it's original direction and continues on to the opposite wall at a distance of 9.5 feet from the 26 foot back wall. So .. it runs along at 13.5 feet .. then jogs over 4 feet .. then continues on at 9.5 feet all the way to the opposite wall. Moves along .. jogs over a few feet .. continues on. So .. it aint a nice tidy straight line.
Are my words drawing the picture?
T.
Joe -
Just figured out what you're trying to do there I think. Sorry .. not as 'versed' in all this as I once was .. rusty, I guess. So .. looks to me like what you're suggesting is an extension of the front of the house up beyond it's existing ridge to create a new ridge several feet on up. Then .. to bring the load from that ridge .. which is now directly over the existing 2nd flr bedroom wall and first flr bearing wall, down. Huh! .. this is an arrangement that I never would have thought of! Is this what you're proposing? I would have thought more of simply coming off of what was already there .. but this is reeeeeeally interesting!
T.
Terry,
So .. looks to me like what you're suggesting is an extension of the front of the house up beyond it's existing ridge to create a new ridge several feet on up. Then .. to bring the load from that ridge .. which is now directly over the existing 2nd flr bedroom wall and first flr bearing wall, down. Huh! .. this is an arrangement that I never would have thought of! Is this what you're proposing? I would have thought more of simply coming off of what was already there ..
Yes, I am suggesting you extend the ridge only if you can't maintain a 3/12 pitch minimum and I don't really like that but we do it. Another thing is that 20' is such a long span, you might have to have 7' or 7'6" max with your new wall. That's ok also.
Only frame it like my drawing if your ridge isn't high enough and you can't maintain a 3/12 minimum and your walls can't be less than 7'.
At 7', we've done it but I don't like it because it limits what size headers you can put in. For example if you put a large picture window in that requires a 2x12 header, the top of your window would be around 5'10". that's the problem with short walls.
The way I drew it you don't need a structural ridge.
Hope this helps.
Joe Carola
Joe ..
Thanks for your time and expertise on this.
I dont mind at all if the outside walls are down to 7 or even 6.5 .. which is ok here by code. And a builder friend recommended 'torch-down' for the less than steeply angled roof. He's a builder of some repute (even has a local radio show answering 'house-problems') who, when doing his own dormers years ago had the 'minimal slope' problem and ended up being VERY happy with torch down materials. (Gone 12 years so far no leaks.) I love your suggestion though for it's image of OPENING everything up so much! But if I could just come off of what's already there .. well .. a lot less work I suppose. My only (well .. not 'only') question is what'll be needed to bring down the load and how to handle the jog in the wall. One of the reasons I'd thought of two different dormers .. one for each side.
Your input is greatly appreciated!
Terry
Terry,
This is what it will look like if you don't extend the ridge and use the existing.
Joe Carola
yes .. I believe so.
I dont know if there's even a ridge beam there now. May simply be rafters meeting at ends .. or at just a thin little 1X4.
Thanks-
Terry,
Is this close?
Joe Carola
Terry,
I shrunk the picture.
Joe Carola
Joe
if that upper line continued STRAIGHT after the middle four foot jog it would appear exactly right. In other words .. no little square-box side-step along that wall that's 9.5 feet in. Just 13.5 feet .. then jog over .. then 9.5 feet to the end.
Terry
Terry,
I don't know if your layout is like your picture for the second floor but I didn't put this in my drawing. You can also post down from your existing ridge down to a bearing wall.
Does your house have those big Fly Rafters on the gable end like your picture?
Joe Carola
If 'Fly Rafters' are those rafter overhangs that stick out and have those big 'braces' .. more for show than anything, I think .. then yes .. my house has got 'em.
Of course .. I'd like to avoid bringing the load all the way down .. floor by floor. thought I could make use of the existant bedroom walls which are allready on main-floor bearing walls and which my new rafters will likely need to extend up over.
Does that make any sense?
T.