Wood Guys - This a Problem?
Wood Guys - This a Problem?
(OP)
***I'm wholly unaffiliated with this project***
Driving home over the weekend and saw these condos under construction. Thought the framing was interesting so I stopped for a look.
Any concern with the checks/splits in those cantilevered 4x8s? Or is this already considered in the lumber grading?



Driving home over the weekend and saw these condos under construction. Thought the framing was interesting so I stopped for a look.
Any concern with the checks/splits in those cantilevered 4x8s? Or is this already considered in the lumber grading?




RE: Wood Guys - This a Problem?
1) Pretty much every beam and column in every ski lodge in all of Canada has this.
2) Some massive glulam columns at the university of British Columbia have this.
3) When I've looked into it myself in the past, the answer seamed to be that if it was truly partial thickness checking rather than actual shear failure, it was okay. Sadly, I failed to file my hard won research and am unable to produce it here.
4) Part of me feels as though this is just something that woodies choose to turn a blind eye to because their woodies.
RE: Wood Guys - This a Problem?
RE: Wood Guys - This a Problem?
RE: Wood Guys - This a Problem?
Remember - More details = better answers
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RE: Wood Guys - This a Problem?
RE: Wood Guys - This a Problem?
What’s up with the ground floor lateral stability here?
RE: Wood Guys - This a Problem?
I'm not saying it's inherently dangerous. Things like this can be optical illusions, after all. And, the wood had to be rated in that condition. Presumably, that means it would still satisfy stress requirements.
Lastly, I actually kind of like the long back-span detail for the cantilever. That bodes well for the future safety of the balcony. Someone else mentioned decay. But, we don't know what architectural detail there will be to prevent that. I don't do enough of these types of decks to say that they shouldn't be done out of wood. Especially if they're a one-off family home. For condos and apartments with a balcony like this repeated 100 times, it might be worth it to use some other material. But, tough to justify another material for a single family home.
RE: Wood Guys - This a Problem?
That's almost always the way of it with these row house looking things over here. One hopes for an interior shear wall hidden away in there. There was a fun LinkedIn video a while back where somebody tapped the side of one of these with a backhoe and it pancake racked just like you'd be afraid it would. Of course, that changes nothing.
RE: Wood Guys - This a Problem?
RE: Wood Guys - This a Problem?
1) The guard rails on the sides of the balcony will be sturdier than usual but;
2) Not so much with the guard rails on the front of the balcony unless the rail's meant to span to the sides maybe.
RE: Wood Guys - This a Problem?
RE: Wood Guys - This a Problem?
The fact that there are only two beams is what causes me the issue and the fact non one will know they are a bit dodgy until the balcony gets rather "spongy" or just plain collapses one day when a bunch of people lean on the rail admiring the view.
Putting the drain right by the joist could be very bad if the detailing and sealing of the drain isn't perfect.
Remind me never to sit on a a balcony where you can't see the beams or attachments to the building....
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Wood Guys - This a Problem?
RE: Wood Guys - This a Problem?
> what holds the joists onto the beams? are they just toe-nailed in place?
> is the gap between the bottom of the joist and the left side beam supposed to be there?
> is the slope of the deck typical?
TTFN (ta ta for now)
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RE: Wood Guys - This a Problem?
RE: Wood Guys - This a Problem?
The following two pictures show splits/checks that are obviously not straight, which would be required for two 4x4's
The end of this beam isn't split at all, indicating it is one piece:
Go to a typical lumber yard and tell them you need lumber to build a condo and they will order it all for you from their suppliers, it won't come from their stock.
RE: Wood Guys - This a Problem?
Some of the photos showing the end grains makes me think they are single 4x8's, but then the side elevations make me think that maybe it's two 4x4's with beat up edges.
I think AzCAT needs to go back into to the field and get us better photos.
RE: Wood Guys - This a Problem?
Gap is supposed to be there as it seems the two beams are at different heights. Interestingly it shows on the RH beam that the cantilever is about 1/3: 2/3 You assume the LH beam des the same thing
Slope looks a little steep but pooling water is a big issue on decks so maybe they go for a 1: 20 or something
The other thing about stucco is to the uninitiated it makes it look like the frame is brick or concrete not timber, ditto the important bits holding the balcony up.
I'm sure one of the balcony collapses recently looked like that.
this one I think https://www.eng-tips.com/viewthread.cfm?qid=389494
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Wood Guys - This a Problem?
RE: Wood Guys - This a Problem?
RE: Wood Guys - This a Problem?
The balconies pitch heavily to one side. It may just be that we're seeing the other side in the photo with the stucco.
RE: Wood Guys - This a Problem?
RE: Wood Guys - This a Problem?
Thanks for the link to that previous thread.... For those of us who don't deal with this issue often, it's helpful to have links like that in this thread. :)
RE: Wood Guys - This a Problem?
RE: Wood Guys - This a Problem?
RE: Wood Guys - This a Problem?
RE: Wood Guys - This a Problem?
BA
RE: Wood Guys - This a Problem?
I've been involved in a few wood/cfm projects where precast balconies were substituted for durability and that institutional feel. Anybody who's had a look a the fragile connections back to the stud walls in those setups is likely to feel safer on cantilevered wood, even with the rot potential.
RE: Wood Guys - This a Problem?
RE: Wood Guys - This a Problem?
RE: Wood Guys - This a Problem?
RE: Wood Guys - This a Problem?
RE: Wood Guys - This a Problem?
Steel / CFM: buckling, buckling everywhere.
Concrete / Masonry: can't really ever figure out your loads or deflections with any certainty & minor detailing errors are catastrophic.
Wood: Tension perpendicular to grain and checking.
I'm holding my breath for structures built from monolithically site cast, 36 ksi steel rectangular sections.
RE: Wood Guys - This a Problem?
Not sure anyone in this forum does from the sounds of it!
RE: Wood Guys - This a Problem?
Repeated row houses like this are typically done as cheap as possible in some instances that means if its a big developer like Pulte, etc. pay a little up front premium to get some performance based design to side step some code criteria and satisfy the AHJ (Authority Having Jurisdiction) if it will net them material and labor savings. Part of the penny pinching is also the grade of lumber I wouldn't be surprised if they were using stud or standard grade lumber which would explain the checks and some of what looks like twist also.
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RE: Wood Guys - This a Problem?
One more PDF: Link
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RE: Wood Guys - This a Problem?
RE: Wood Guys - This a Problem?
But, based on this picture below the wood is checked, not split, as the crack does not go all the way through the timber, it terminates at the center of the timber (probably the center of the tree) and does not go all the way through.
Here is a decent blog post on the subject of splits/checks http://www.woodscienceconsulting.com/wood-science-...
RE: Wood Guys - This a Problem?
RE: Wood Guys - This a Problem?
2) No limit at all for #2 or lesser.
3) In my opinion a more reasonable limit for #1 and better.
4) One would think that "ends" would really be the high shear location at the start of the back span for a cantilever.
RE: Wood Guys - This a Problem?
From KtooK's latest excerpt, can this 4x8 graded as No.1 lumber, with the checks near/at ends less than 1/4 of the thickness? Seems the check outside of the end region does not count towards grading.
RE: Wood Guys - This a Problem?
RE: Wood Guys - This a Problem?
RE: Wood Guys - This a Problem?
RE: Wood Guys - This a Problem?
Yes, that's the type of weep to which I was referring.
RE: Wood Guys - This a Problem?
Moving to USA because you have more documents explaining code provisions, TFEC Tech Bulletin 2018-10 says "the tabulated allowable shear stresses [in the NDS] are based on the conservative assumption of the most severe checks, shake or splits possible, as if the timber were split through its full thickness for its full length." It also says there are limits on the depth of check for the higher grades which is more encouraging than the Aust requirements.
What I don't get is the reasoning behind only reducing the allowable shear stress because of the hypothetical full-length full-width check. That could halve the bending strength if located at mid-depth, whereas I picture two parabolic shear stress distributions that sum to the same as the single full-depth distribution. More than happy to be set straight here.
RE: Wood Guys - This a Problem?
RE: Wood Guys - This a Problem?
Why's that?
RE: Wood Guys - This a Problem?
RE: Wood Guys - This a Problem?
They reduced the allowable shear stress, means there is some shear stress passing through the checks (not completely lost). By limiting the shear stress, the span length and intensity of loading will be reduced as well, which in turn reduces its effects - moment and normal stresses.
I shall have highlight the word "halve". Thinking 2 4x4 stack together, what is the moment capacity - with limit set on loading, and without?
RE: Wood Guys - This a Problem?
RE: Wood Guys - This a Problem?
A 4x8 is rated to carry the shear due to 100 plf uniform load. Due to the presence of the seam (in mid height), the allowable shear is reduced to effect a 50 plf uniform load (by code). Does the code needs to further stating limit on the bending strength of the 4x8? No. My point is through "reduction" in shear capacity, the code has already reduced the moment capacity without the need to limit the consequent flexural stresses.
RE: Wood Guys - This a Problem?
RE: Wood Guys - This a Problem?
RE: Wood Guys - This a Problem?
In your last sketch (boards bonded together), the end slope should not be vertical.
BA
RE: Wood Guys - This a Problem?
RE: Wood Guys - This a Problem?
Framing residential housing with a wood truss system gets complicated quickly. The rim board (or rim truss or whatever they would call it in this case) highlights the extra complexity. The balcony framing still looks a little convoluted none the less. If the ceiling is the same height as U/S of balcony they could have simply cantilevered the floor framing out at least until the exterior wall over. The house on the left has the floor system cantilevering out but I think it has a different balcony. If the slope (for drainage) ends up being lower than the inside floor height they can still make a truss that accommodates for that without much additional cost (it's shop fab'd anyways). Maybe I'd understand their approach better if I saw the drawings; perhaps they didn't want a beam getting 'squished' by that corner post but there's not much load there anyways. If it were my house I would have really preferred to see a 3rd cantilever for some much needed redundancy. I don't quite get why the truss attachment at the bottom-right looks so flush/square and the bottom left looks so out of wack - it looks like somethings off there. They would have had to do something their prior to closing and installing the exterior finish (stucco?). The trusses look like there is no positive connection to the cantilever beams (maybe I missed something but hopefully it's not toe nails). Quite honestly I think they could have framed the balcony without trusses but I'd have to see the bigger picture. The cantilevers need a strap or some sort of hold down at the interior. Maybe it exists but is hidden by their temporary guard rail. Hopefully this is a very favorable climate. It would have been much wiser to go with an engineered product, or at least a pressure treated product (I forget how much weaker PT'ing makes wood though). A lot of the issues we're seeing on the wood could be due to weathering. Maybe it was really wet followed by a dry period.
My best guess is that the engineer came to site, saw this, and made them fix it up before they closed the building in. Unless that exterior finish is something special I think it's going to crack.
Just my disorganized thoughts...
RE: Wood Guys - This a Problem?
I spent a couple years around the old parts of town on the west coast doing alterations on existing timber framed buildings. They dont build them like they used to, thank god for that. I have seen timber do some pretty impressive things for an impressive amount of time.
Have seen more than a few sets of 18' long 2x4 roof rafters at 24"OC, on low slope roofs that have seen a century of winters.
2x4 stud walls balloon framed that have supported 3 levels of occupants - where the floor framing was notched 2" into the 4" depth of the stud. that have served as boarding houses/brothels/gambling dens since the 1800s.
Seen plenty of old houses where 3 levels of significant tributary area of framing will be bearing down on a single 4x4 post. resting on a 10" round rock as a footing.
None of these applications come close to meeting modern building code. But they demonstrated proof of performance.
This framing attached, even if it doesnt meet code, will survive. So long as the end of that cantilever is strapped down (which i didnt see).
And it doesnt matter how grunty your framing is, it will eventually rot out with a face sealed cladding like that shown, unless you are in the desert.