I guess so, never thought much about it before, but it does seem that for dealing with the compressive forces timber is probably a better option, although obviously more difficult and time consuming to fit.
What to make herringbone strutting between joists from
- Thread starter garyo
- Start date
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Problem with timber strutting is it's not that easy a job for the average DIY to get it right. OK it's not difficult if your used to it but fiddly if not. I've seen plenty of ill fitting struts with split ends that are doing nothing at all. You can't go wrong with metal straps. And I've never had any squeaking or really any issues with them at all. But that comes down to fixing boards properly and correct screw centres.
Ronny; they act in tension so shouldn't buckle.
Ronny; they act in tension so shouldn't buckle.
From what I can work out, timber struts have to act in compression due to the nature of the connection...the joint wouldn't work for tensile forces.
Steel members under load will act in tension like cross bracing in a building...if they are not capable of acting in compression...
If the above is correct then they are not struts at all...but ties...
If they do as Tony suggests - and I have no doubt that they do - then both members will be in compression until vertical load acts on them...
That's what I think anyway!
Just been reading up on this...
http://learning.covcollege.ac.uk/co.../CnJ/materials/CJ13_Tools_Partitions/M133.pdf
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http://learning.covcollege.ac.uk/co.../CnJ/materials/CJ13_Tools_Partitions/M133.pdf
No, they act in compression...
They are capable of acting in compression
They're struts
They will still be in compression with vertical load on them
Well...wasn't a million miles out...always good to learn moreThat's what I think anyway!
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Given their thin profile, the ends would lift away from the joists top and bottom - constrained only by the boards above, and the plasterboard below. And we know that both the floorboards and plasterboard are both structurally stronger than the joists ... err, something wrong there
The fundamental difference is that unless the diagonal struts are fixed together where they cross, if you push down on one joist, then it can move and will twist itself and it's neighbours - again only constrained by the boarding above and below (and the nailed on plasterboard isn't going to offer much resistance). Solid noggins can do the same, but only if the joists physically spread to allow the noggin to rotate.
I suspect that the effect is minimal in both cases - and both methods will prevent the whole floor of joists falling over like a line of dominoes.
Depends on whether or not they are capable of acting in compression...if they weren't capable of acting in compression - due to buckling - then they would only ever be tensile members...
However, as I said above, I don't believe that the connection of a timber strut would be sufficient to allow it to transmit tensile forces, therefore they can only be compressive members (clue is in the word "strut").
Basically, one of the cross members takes all of the force while the other does practically nothing...
I guess the steel members with positive connection to the top and bottom of the joists will be capable of acting together...
Assuming we're not all bored with strutting, attached is an extract fom McKay.
Sorry its a bit small - you might need to zoom - but it makes the case for herringbone as against solid.
It also points out that the struts tighten up (ie are in compression), the more so when the joists shrink.
Sorry its a bit small - you might need to zoom - but it makes the case for herringbone as against solid.
It also points out that the struts tighten up (ie are in compression), the more so when the joists shrink.
Thanks for all the posts guys. All things being equal I think I'd be on the fence with what to use, but the timber I've ordered for the joists are 50cm too long so the noggins will be free, so that's the way I'm going.
Cheers
Gary
Cheers
Gary
Perfect.
Don't forget to use the tips i've given in an earlier post, i.e. don't just measure the joists in the centre and assume they are all correctly spaced.
FWIW: In the USA, the home, of course, of timber framing, studies have shown that blocking or strutting is not necessary in joisting for sway, squeaking or structural integrity - it's claimed that 3/4" or 1" sub-floor will do the trick.
Framing contractors know this but it's a rare site where blocking is eliminated - i'd say it's a split between solid blocking and Simpson metal.
Another consideration in platform framing is that the rough-in plumbers and HVAC guys will come along tight behind the framers and often blow the blocking away.
The blocking is typically staggered for speed of installation, altho some contractors in custom homes will screw the blocking rather than shoot it in.
Framing contractors know this but it's a rare site where blocking is eliminated - i'd say it's a split between solid blocking and Simpson metal.
Another consideration in platform framing is that the rough-in plumbers and HVAC guys will come along tight behind the framers and often blow the blocking away.
The blocking is typically staggered for speed of installation, altho some contractors in custom homes will screw the blocking rather than shoot it in.
I don't know who did that study, but if you have ever walked on a floor with and without joist strutting, you will immediately see what a massive difference it makes
And I think that we were doing timber framing long before the yanks
The strutting also helps with load sharing, and a sub floor isn't going to help much with that.
As i i indicated by using the plural "studies" there's been more than one study - several over a period, by different institutions.
In recent years, Fine Homebuilding and Journal of Light Construction both had articles discussing such studies. The claim referred to is not mine as any competent reader would have seen.
I've walked on many a floor with and without strutting, and i've built many floors into Uk masonry structures and USA framed structures. I dont recall a "massive difference" with or without.
I'm afraid that you "think" wrong. The timber framing that i'm referring to, as i specifically mentioned and is commonly understood by people experienced in the building trades, is platform framing, which was developed from balloon framing - both specifically US inventions. Pegged, mortice and tenon timber framing is not the same.
RonnieRaygun,
"loadsharing" in platform framing is typically taken up with double joisting or framing below. The sub-floor referred to, is glued and screwed 4FT x 8ft T&G ply sheeting.
In recent years, Fine Homebuilding and Journal of Light Construction both had articles discussing such studies. The claim referred to is not mine as any competent reader would have seen.
I've walked on many a floor with and without strutting, and i've built many floors into Uk masonry structures and USA framed structures. I dont recall a "massive difference" with or without.
I'm afraid that you "think" wrong. The timber framing that i'm referring to, as i specifically mentioned and is commonly understood by people experienced in the building trades, is platform framing, which was developed from balloon framing - both specifically US inventions. Pegged, mortice and tenon timber framing is not the same.
RonnieRaygun,
"loadsharing" in platform framing is typically taken up with double joisting or framing below. The sub-floor referred to, is glued and screwed 4FT x 8ft T&G ply sheeting.
You must float across them like Jesus then
I'd rely on the published works of TRADA, the BRE or the BS/Eurocodes more than any yank study or magazine
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