Any help with this greatly appreciated.
Part of the construction of my house includes a 4′ wide x 32′ long deck(walkway) that runs along the south side of the house about 5-6′ off the ground. (connecting inside and outside living areas) I asked the builder if we can avoid using posts so as not to obscure the view from the windows below the deck. I was hoping to accomplish supporting the deck with brackets that would angle back down to the wall. I drew a mock up which basically looks very much like a miniature post and beam roof truss (on it’s side)
If it were a straightforward right triangle we’d be on our way but here’s the catch…
I want the long part of the bracket, the part that angles back toward the wall (the hypotenuse of the triangle) to have a slight arch in it. (to match some other arches throughout the house). The builder is not sure how to accomplish this so it will be structural. The ledger board is 2 x 12, the deck floor joists are 2 x 8’s, no roof, live in NE Pennsylvania. There is no way to cantilever the deck out from the inside of the existing house, so it’s either ugly posts instead of the view or some kind of brackets.
Wish I could send a picture…any ideas or suggestions? Anyone done this before?
Thanks for your replies,
kb
Replies
Here ya go. A little outside the box but it will preserve the view from under.
I interpret your drawing such that you are suggesting I support the deck from above. It did cross my mind but it would obstruct one's ability to walk across the deck without having to duck under the supports (I think). Is that what you meant?
Thanks for the reply
KB
It's a suspension bridge. The cable supports are on either side of the roadway or deck walkway, in your case, and there is nothing over the walkway to duck under.
With your deck/walkway being attached on one side to the house framing, all that would be required on the outboard side should be the cable looped over two verticle supports toward each end and then anchored into the ground. The vertical pylons, being firmly anchored to a footing in the ground and firmly attached outboard of the walkway framing would only receive a balanced tension along the path of the main suspension cable. The attachment of the deck to the house framing would then be only in shear and not subject to cantilever stresses. The pylons would probably not be just 4x4 but could start fat and taper upward.
The loop of the cable, dropping in the center of the span to about 3 feet, and the vertical cables, spaced according to code, would provide the railing/balusters for the outboard edge of the walkway. Since you probably don't need verticle cables on 4" centers to support such a small structure, I'm thinking that the main verticles could be 4-6 or so feet apart, attached to the suspension cable, while the verticals that comprise the spaced balusters could be attached at the code spacing to another horizontal cable at the 3 foot height of the loop of the suspension cable which would then be equivalent to the top rail of a normal deck.
That arangement preserves the unobstructed view from the windows below because the pylons are spaced so far apart, and there are only two of them, and the walkway view is also preserved because of the thin vertical cable arrangements.
It's different and a figment of my imagination and I can't say that I've ever seen it done in real life but you asked for ideas... think it over.
I understand now, thanks. That is quite "out of the box" thinking....but stimulates the imagination. Not sure how that might look as you're looking out of the windows and doors that lead out onto the deck/walkway. The 32' wall is mostly sliding doors and windows facing south and with the best view. I'll let you know what comes up,
thanks,kb
Understanding what you want to do is the easy part, the hard part is that what you want to do whether it be with a triangle or with the arched leg, is that the bottom point of the vertical leg that is against the house ends up becoming a fulcrum or pivot point and the top of the triangle where you would be anchoring into the ledger board wants to pull away from the house. The further out on the deck the load is the more the outward pull. Not good when the whole party is satnding on the deck at the railing. The 2 x 12 may be great in supporting a load in shear if it is sitting on the foundation wall but if it is just nailed into the ends of the floor joists it isn't going to last or be safe when being pulled outward.
I have seen way too many roof overhangs and bay windows that were supported just like you want to do and they sag seriously while basically just supporting only their own weight.
I see an engineer in your future.
My dad was an engineer. He said "once an engineer always an engineer"...wish he were here to give some help. Any engineers out there that want to weigh in on the subject?
I was in an old church two days ago and noticed the entire building appeared to be held up by massive arched brackets....maybe a post and beam builder could offer some advice? If I find out anything worth pursuing I'll post it. Thanks for the reply
kb
Google Corbels. That is what you are asking for
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I spent most of yesterday looking on line before I posted. Found lots of decorative ones, just no structural ones large enough to do the job. The architect on this job didn't have any answers, nor did he have any ideas where I might find an answer. Lot's of dead ends so far, but I'll keep looking and let you know if I find out anything.
Thanks for the reply,
kb
Are you SURE this is what you want? I wouldn't even breathe on it - how are the joits attached to the ledger, how's that att'd to the wall? What holds up the outer edge, how is the guard rail att'd?
If you're worried about blocking the view, there must be quite a span between brackets - then there's going to be inadequate support, or one h*lluva lot of weight on thise brackets
The hypotenuse is simple - straightforward straight piece of stock, with 1x cut to the arch, planted on each side. I'd send you a pic if I could get 'attachments' to work for me
I like challenges...but I'd walk away from this one.
cheers
***I'm a contractor - but I'm trying to go straight!***
Edited 6/30/2005 2:20 am ET by piko
All questions I'm thinking about. I can tell you that the joists are attached to the ledger boards with joist hangers. The ledger board is tacked up with nails but will be bolted to the house girt. Not sure of the spacing of the bolts yet. I like a challenge but I'm not crazy, I want it to be safe...
I'll let you know what I come up with, thanks for the reply..
kb
"the joists are attached to the ledger boards with joist hangers. " JH's aren't designed for that - they'll be in tension too. Don't rely opon the deck joists to hold the thing together
"The ledger board is tacked up with nails but will be bolted to the house girt" The rim joist neither. I'd go thru the wall to every 3rd joist with a new deck joist. Alternatively, make your kneebraces so strong that you can run the deck joists PARALLEL to the house. (Heck you're using 2x8s)cheers
***I'm a contractor - but I'm trying to go straight!***
I'm thinking you are thinking of something more like this:
View Image
The "trick" of the arch is knowing what the minimum depth of the diagonal is. If it needs to be a 2x8, for example, then you could take a 2x10 or 2x12 or whatever, and arch it as much as you wanted, as long as it is not less than the required 7 1/4" depth of a 2x8.
Capn, that's a nice looking knee brace there !
Tell me, what would all the connections be, saying that top member was 36" long, and this was going to hold up a narrow 4' wide walkway (with other braces spaced say 5' apart).
I'm especially interested in hearing how it would attach to the buildings' wall.
Joe wood,
I do those all of the time on my timberframe, While one side remains flat the other side gets the bandsaw approach.. You could use a sawsall but then you'd need that curved base Makita powerplane to clean up the inside radius.. (if you are near here come on over and borrow mine)
I use normal timberframe connections only I counterbore a hidden lag bolt into mine. Since it's not inside a building where it could be exposed to prolonged fire I suspect you could be perfectly happy with just wooden trenails.
If you want, get a timberframer to do the work for you, Or stop over here and I'll show you how myself. I might even have enough timbers on hand to get the job done..
that's a nice looking knee brace there
Well, it's actually a decorative brace going on a bank that's to look like a railroad station.
Since those are decorative, they are getting fastened through the "flat" back board behind the "meat" of the bracket. I've not seen the shop drawings to see how the millwork sub is jointing the brackets together (we drew them with a sort of half-lap, just to have one way to draw them).
Now, spacing and fastening for your proposed use probably needs an engineer (if only because you are in seismic country). If I were just sketching, I know I'd oversize the things no small amount, just out of reflex (think timber-frame scantling dimensions, 4 & 6 x 10 and 14 and the like). That's likely to be overkill for SD.
What might not be, would be some welded steel brackets. A local welding shop could cobble up a jig, and turn out nice, strong, visually "light" brackets you could then have epoxy powder-coated making them near maintenence free, even right down by the beach.
How big would those be? Dunno, back to needing an engineer. Might only take, say a pair of 2x2 angles back to back for a vertical, with maybe a 2x4 pair for the horizontal, with the diagonal sandwitched between. A bit of bent filligree to dress the space between would be nice, too. Or not.
The metal brackets also simplify the attaching to building question, as the flanges would be a logical place for the bolts/lags/whatever that are needed.Occupational hazard of my occupation not being around (sorry Bubba)
Just got back and whipped out this Sketch of your beautiful brace. I'd really like to design one that was structual though, enough so that it could hold up at least a 4' wide walkway. I bet that if I had the right connections, this one might do, but your comment about having one welded made me think , maybe I could have a slim one welded up, then face it with wood so that it looked right. Think I'll work on that.
Capn, do you have any pics of structual knee braces you've made ?
have any pics of structual knee braces you've made
Nope, and it's a great pity that nags at me (particularly the compass timber knee braces I whittled for the one very-exclusive customer down south of here. Those were trunn'led (treenailed, i.e., using tapered wooden dowels) into the timber frame at direction and with the concurrance of the timber frame boss.Occupational hazard of my occupation not being around (sorry Bubba)
Callem up! and go take some pics !
That sounds a little scary, what with all the colapsing decks the past few years.
That being said, I disagree with whoever said roof brackets always fail. Poorly designed brackets fail, for sure. But I use applied brackets a lot. Here are a couple examples. Both of these extend 4' from the face of the wall(s) and they're not gonna sag. The cedar one in the first photo is built with tightknot WRC 4x4s. The second has full dimension 2x4 vertical and diagonal members and...I THINK...4x6 horizontal member.
Nothing like some strategically placed lags, through bolts, rafters nailed to the side of the building with sheething tieing the entire thing together. If you couldn't build solid roof brackets out here in the Pacific Northwet, you'd have a hard time making a living remodelling.
Anyways, I stake my good name on these things, and I sleep just fine. In fact, the second one is a photo of a house I intend to live in.
thanks for the pics, I also have a 3' overhang on the screened porch that I want to use brackets like these to support.
I'm hoping on visually tying all these brackets (roof overhang, deck supports, and an entry porch) together. If I had my druthers, I would somehow work an arch into the design, if I can't get good support that way, I guess I'll have to settle for a simple right triangle type bracket.
nice work, good looking brackets!
kb
Sketch of your beautiful brace
It's actually the boss' purdy brace, and the arched diagonal is a solid 4x; the GC is still working on how it's going to be actually built.Occupational hazard of my occupation not being around (sorry Bubba)
That's really close to the bracket I sketched for my builder. Only question that remains is how to calculate it's dimensions so it is structural and can support the load...an answer I have not yet found. The code inspector suggested an engineering group I might try.
Thanks for the pics!!
kb
Kb,
Run this one by your archy.
View ImageThe 4x4x14 1/2" is backed by blocks glued and bolted to the floor joists. The bolts are in shear = Load x W/H. The threaded rod runs down the center of the horizontal member of the corbel. It is in tension = Load x W/H.
The bottom of the corbel at Load Point pushes in on the doubled studs, also = Load x W/H.
For sizing, treat the doubled studs a a floor joist for deflection and applying joist hangers. 1/2 of Load x W/H will be pushing inwards at the top and the bottom of the doubled studs.
Edit: The doubled studs will also be bearing Load. This bearing plus the sideways force of Load x W/H will adversely effect deflection.
Don't forget good flashing details.
SamT
Edited 6/30/2005 3:54 pm ET by SamT
That's a complicated detail Sam, but you know, it doesn't look over engineered at all.
looks good, I'll run it by him and see what he says, thanks
kb
I have used that threaded rod too, after learning it by taking apart a couple on a house during renovation. Of the four I rebuilt, only one showed any signs of failure and that because they had not made sure to have a stud ( this house had 4x4 studs from way back when...) backing up the vertical element. The wall had bowed in about three inchesand the two story bay above it had settled to where the double hung windows didn't close so well anymore, which was the only symptom the owners noticed in spite of the fact you could trip over the rise in the floorleading to the bay bumpout
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Sam, that is one heck of a good design! good thinking - you've covered everything.cheers
***I'm a contractor - but I'm trying to go straight!***
SAM - Where did you get the design training? Are you an archy or engineer or self taught? Just curious. Don
God's gift. She granted me the ability to "See" forces and stresses at work.
SamT
where are you in pa ?
carpenter in transition
I'm in North Central PA, 60 miles East of State College, 90 miles North of Harrisburg
A little town called Williamsport, home of Little League Baseball.
kb
Sure thing. My cousin Mike Hufnagel lives there. Know him ? I think he is involved in city or county planning.
Anyway, if you were closer to the Lehigh Valley, I could have given you some contacts.
carpenter in transition
His name sounds familiar, but can't say I know him. I'm waiting on a proposal from Timber-fab, currently. They advertise in FHB. I'll post my findings. Thanks,
kb