Well, here I am again.. :)
I'm in a situation where I need to hang my 2x6 floor joists from a ledger and (hopefully) without hangers. Being that we are using rough-cut lumber and trying to keep expenses down, I'd like to frame the the floor without joist hangers, if possible. One idea I had was to screw all the joists to the ledger from behind, before securing the ledger itself (picture a rim joist). I'm just not sure if a few screws through the ledger into the ends of the joists is going to be strong enough, though. I'm just not really sure what to expect as far as shear strength from a few deck screws..
I could also go with a larger ledger (2x8) and put a 2x2 supporting strip underneath the joists. Do you guys think that would cut it, or would a 2x10 and a 2x4 support be more what I'd need?
It's not possible to place the joists on the ledger, rather than having to resort to hangers or purely mechanical means of fastening?? :-\ That would be the ideal. Is that ledger set in to the studs?
Also you say 'screws'. What type do you have in mind? deck type screws are not up to this job. Too brittle, they'll snap off rather than give any at all. Lag screws are better suited to this.
Rather than relying on fasteners from behind as you describe I'd think the addition of another 'ledger' would likely be more secure. Lags thru the add-on ledger, thru the main ledger and into the studs would be superior to any fastener into the end grain of the joists.
If I understand your concept, ...it is very risky. Screws into the end of the joists, parallel to the grain, would not be good at all. Ledgers must be set-in to the studs, or otherwise securely supported ... or they themselves become very risky.
Set-in ledgers combined with brackets is the way to go with ledgers. But if you're using lumber that has not been sufficiently dried, you are faced with unusual shrinkage problems. The joists will attempt to shrink away from the ledgers.
Resting the joists atop a set-in ledger, as Mountain Don suggests, definitely would work well. Let the joists protrude into the walls past the ledgers a bit ... allowing for full bearing on the ledgers even if there is extra shrinkage.
If the studs line up from one side wall to the other side wall, perhaps you should look at extending the joists into the wall and attaching joists to the side of the studs. This approach does not use a ledger but allows adding a full-height jack-post-stud to be placed under each joist end ... would make me feel pretty secure.
It's not a conventional system we're using.. We are building a vertical log cabin on piers, and the floor hangs from the 8x8 sill beams. We could put the floor joists over the beam, but we'd have to add solid blocking between every joist to bear the weight of the log walls. Here's a quick sketch:
(https://img.photobucket.com/albums/v667/AirsoftAndy/Floor-Joist-Details-2.jpg)
I'm thinking the the "add-on" ledger beneath the joists is the way to go, but how big does it need to be? 2x2, or 2x4?
Not too good a setup. Andrew. If the ledger board splits even with the added one under it, your floor goes to the ground.
How about the reasonably cheap joist hangers to hold the boards to the main ledger.
If it is lagged to the beam, each 1/2 inch lag screw - pre-drilled around 3/8 or 7/16 dia to prevent splitting, will hold around 500 lbs rule of thumb off the top of my head. Weight would be around 45 lbs per foot for 1/2 your span across the room x one space between joists. Rough numbers only.
Say a 14' wide building - 2' spacing -- 2x7=14 sf - round 45 to 50 for ease of calc -- =700 lbs each end of the joist so 2 lags would support it.
Alternatively -- bolt an angle iron to the beam? OK for no insp -- reqs engineer if inspected.
Just ideas -- others may think different. You be the judge.
How about joist hangers right off the beam? No ledger.
Or as Glenn suggested angle iron lag screwed direct to the beam. Something with a one inch arm at least should do the trick.
I'm thinking the 2x2 ledger under the joists would work like you showed in the sketch so long as it's continuously supported. I'd go so far as to glue it to the 2x8 behind it as well as put lag screws under every joist. The 2x8 would need to be lagged or bolted to the sill beams.
Approx. how much would joist hangers made for rough-cut lumber cost? I was under the impression that they might be pricey, being a special order item and all.. I could attach right to the sill like Don said and save on less lumber, unless I wanted the edge support for a diagonal 2x sub floor/finish floor.
Good point about the splitting, Glenn.. What if I bolted through the ledger, AND added the 2x2/4 support underneath? Though, I'm probably not saving anything over hangers at that point..
Thinking outside the box ??? Could you plane down the end of the rough cut to fit a standard joist hanger, might be more work, but it wouldn't cost as much as custom hangers?
Yeah, that thought has crossed my mind too... Couldn't think of an easy way to do it, though. Plus, I like taking advantage of the extra strength that rough-cut has to offer. I don't know how much you would weaken the joists by doing that..
One thing most are missing is the floor only has the live load to hold , IF I'm seeing this right . The walls and roof ALL will be picked up by the beam. So all you have is the stuff people , etc on the floor?? Yes ??
So IF I have that right I'd say the 2x2 under the joist might make it , I'd say a wider ledger and a full 2x4 would be better , I'd even say , IF it's possible to fasten thru both the ledger and the 2x4 cleat right into I'd guess a concrete foundation?? Maybe it's a post and pier foundation I don't recall.
If there is nothing behind that hanging down ledger I'd thru bolt the 2x4 cleat and ledger together every 24 " or so with a 1/2 x 4" bolt. Or what ever lenght it would take to get thru the rought sawn stock.
Does that make sense Ernie?
Yup it does, PEG. And you are right, the floor is only holding itself + the live load. Yes, it is a pier foundation. I'll have to look into the bolts.. Like I said, it may be cheaper just to buy hangers. :-\
Well, rough-cut 2x6 joist hangers would be nearly $4 + shipping special-ordered from our local building supply. :o I couldn't find any sources online, soooo... The bolts are about $0.80 apiece, and I could probably find half of what we need lying around the shop, so we'll probably go that route.
Thanks for the help, guys!