I’m planning on building a garage (16×18-with 12/12 pitch roof)–I’m wanting to put shed dormers in the attic but I have not been able to find any detailed explanation on how to best frame them.
As I have it planned right now the face (window side) of the dormer will not be directly above wall of garage below.
My first question is: are there any good resources (pictures are good) that I can access that will help me figure out the best framing method–that will hit code?
Do I need to reinforce the floor joists (below the dormer) – if I remeber correctly I’ll be using 2×10’s on 12″centers to span the 16′ space?
I’m fully aware that my question might not even make sense.
However, any insight would be greatly appreciated.
cje
Take what you want, leave the rest
Replies
I think most basic residential carpentry textbooks have a detail on a shed dormer - have you tried your local library or home center? You don't give sizes on the dormers. I would double the joists below on either side, and double the supporting rafters at either side. Double header between the rafters at the high and low sides of the dormer, with a Simpson hanger at each end of the headers.
not the floor joists.
It is the roof rafters that will carry these small doghouse dormers. You need to double or triple them on either side of it, depending on size, layout, etc.
Then build a dormer like a little doghouse with inverse raked walls on top of those rafters.
BTW, a 1618 garage is not big enough for most cars if pewople wil be walking in there too. Go at least 20 feet deep.
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I meant cj, because you'd have to header them also for the opening, but then I guess there wouldn't be none in a garage!
How far in are the dormers from the outside plate and how wide are they?
The weight of the rafters wont be on the main rafters because it's a shed dormer if it were a gable dormer then the weight of the gable rafters would be on the main rafters but you still want to double those rafters up so that the gable studs have something to sit on.
Since it's a shed and the dormers probably aren't to wide maybe 4' and you just want a window in each one without knowing how far your coming in plus you don't want to come to far in because the further you come in your main roof rises higher and higher which means shorter windows or higher dormers and lower dormer pitch roof.
If your only coming in a foot you can rest the shoe on top of the decking and frame your wall spanning the header the full width of the dormer and posting down on top of the doubles.
You can also just put a header at the bottom of the rafters with hangers whatever your coming in from the outside wall and then frame the dormer wall on top of the header which transfers the load off the floor joists which you said are 2x10's @ 12" o.c.
There's ways to do it but just let us know how wide and how far in the dormer is. Also do you have a set of plans because the plans will show you how it would be framed. On gable dormers with walls underneath some Architects specify doubling up the joists and the rafter walls sit on top some double up the rafters with the walls sitting on top of the rafters.
Are you planning on running the dormer rafters into the main ridge?
Here's a drawing with the dormer rafters going to the main ridge but one side has a header at the bottom and the other side one has the wall going to the deck.
Thanks for all the info--I'm designing and building this myself--hence the questions--I've been working on the plans and will again this weekend--I will post them this weekend sometime and hopefully I can get some further feedback.
Right now the shed dormer is pretty wide about 13ft--trying to increase useable space and light--and I think the way I initially desinged it it would sit about 2 or 3 ft from the outside plate (wall).
So maybe I should redesign that so it's more like 1-2ft as you suggested.
I know that 16x18 is not big enough for a car if you want to be able to walk around--I live in Atlanta close to midtown--so space is somewhat limited--i'm already looking at a variance to build int he setback--this really will be more of a workshop than anything else--I like to build furniture to.
plans will follow.
cjeTake what you want, leave the rest
I suspected you might have setback and space issues re lot size.Framer picked up on what i didn't - that these were to be a shed dormer.Another issue is that with such a wide dormer, the ridge will likely need to be a structural ridge beam, sized to carry the load, though that won't be hard for southern building. If you load the shed rafters on wall to floor as Framer shows without headering, then the floor should carry instead of roof rafters - that's the way to go.I agree you should move that wall out as close to exterior as possible to make best use of space.Looking forward to seeing your drawings
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CJ, good advice from the other guys. For a building that small, I would consider bringing the dormer all the way out to align with the first floor wall. Although on bigger buildings it usually looks better to set the dormer up on the roof, on a building as small as yours it may seem too small.
The only problem is that you might have to keep the top plate lower to the floor so you get a reasonable pitch on the dormer roof.
What is your height requirement on a garage where your from? Around here it's 15' so if your garage ceiling is at least 8' high and your going to use a 12/12 pitch you'll be over your 15' assuming your running the rafters the 16' way. What size rafters are you using?
I'm not an engineer but I've built plenty of dormers coming 1-2' from the outside wall with solid blocking underneath. I would go flush with the outside wall if I were you for the space and if your looking for more shingles in front of the dormer increase your overhang. Like I was saying before the further back you go the higher the rise is on your main roof and that creates smaller widows and a lower front dormer wall.
You have to play with the dimensions so that you have the right pitch for the dormer no lower the a 4/12 - 3/12 depending where your from.
You can start out if you go with a 4/12 pitch that would tell you the front dormer wall from the main ridge would be 2'-8" without counting the size of the rafters and H.A.P. cuts.
Dormers? Someone need some dormers?
blueJust because you can, doesn't mean you should!
Warning! Be cautious when taking any framing advice from me. There are some in here who think I'm a hackmeister...they might be right! Of course, they might be wrong too!
Shed dormers Blue, shed dormers...How do you hook them to the roof? Just nails or wrap a little strapping metal into them?
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Piffin, I really don't know how they hooked those dormers up. I would guess that they nailed them, then added some nailing plates...we seem to use a lot of nailing plates.
blueJust because you can, doesn't mean you should!
Warning! Be cautious when taking any framing advice from me. There are some in here who think I'm a hackmeister...they might be right! Of course, they might be wrong too!
piffin screws?I Love A Hand That Meets My Own,
With A Hold That Causes Some Sensation.
On a building that size, why couldn't you hanger the joist system off LVL's where the front wall of the dormer sits and use that for your bearing?
Are the ones in the 2nd photo the kind where they paint the windows black inside & stick'em on the roof to make it look like a real house?
No, they drywalled the dormers and you can actually get light from them. They aren't accessible though, without a ladder because they are sitting in the middle of the living roof of a sloped ceiling.
blueJust because you can, doesn't mean you should!
Warning! Be cautious when taking any framing advice from me. There are some in here who think I'm a hackmeister...they might be right! Of course, they might be wrong too!
Well I worked on the plans this weekend and my wife pointed out that to her mind having the shed dormers were going to make the building seem really top heavy. <!----><!---->
So that led to whole discussion about aesthetics and space and financial concerns and I think we decided to loose the dormers and go with some skylights instead—which on the surface seems like a pretty big change of plans.<!---->
Right now I see a couple of benefits of not doing dormers-easier, less expensive.<!---->
Obviously the down side is loss of available space.<!---->
I’m still working through what exactly I’m going to do—I think though that if I do decide to go back to the shed dormer I’ll just have both plates rest on top of each other. That seems like the least complicated in terms of framing.<!---->
I’m pretty sure that I can go to 20ft—that’s in the area I’m zoned for—I know that I have some lot percentages that I need to hit and height is one of them—I guess total height of this building will be about 17.5 ft. I’ll have to double check that it will not be too high.<!---->
Good advice thanks<!---->cjeTake what you want, leave the rest
compliments to fine input you're receiving
your concern of top heavy and also the style of your home ( which hasn't been mentioned ) are two topics of import
for me a 12 /12 roof always provides for fine platform for dormers - at those dimensionsmaybe they should only be 5 or 6' wide at which they could be very aesthetically pleasing - is the added headroom sq ft worth it? natural light ( skylights ) is a definite bonus in a garage / workshop - I've put together small dormers like blue shows using old single glaze multi light windows over uninterrupted rafters as an alternative to skylights to provide for natural light to maintain architectural integrity
notes on code: my area the requirements on storage space are more demanding than living space on framing specs - so be forewarned and also one ( where I am ) can put a garage wall on the property line as long as he firewalls ( 2 - 5/8" sheetrock ) the wall on property line and provides gutter and drainage onto his property John
Your Welcome. You think your wife might like two small Gable Dorners?Joe Carola