I have an office in my workshop with no roof & need to add a roof/ floor for extra storage & better winter warmth/ summer cooling control It's approx 2.8m at the shortest width & approx 4.2 long I have a few lengths of rough sawn 5x2 beams spare here & need to know if they will do the job ok & at what spacing
martin11,
Jun 1, 10:49am
125mm x 50mm will not do 2.8m as a floor joist or a ceiling joist unless you can put a runner in above for the ceiling joists .
mrfxit,
Jun 1, 11:02am
Thanks, it's true measurement is 50mm x 150mm rough sawn
pdc1,
Jun 2, 7:57pm
I reckon if you could put two doubled across the middle of the 4.2 span, so the 5 X 2’s sit on top and are only spanning 2.1 metres, you will be getting close, depending on how much weight you are putting up there and what you are using it for. Depends on the flooring, etc but 300 apart will make it quite strong, however you may be able to stretch out to 450 or more depending on what you are doing up there and how thick your floor is.
oldfrt,
Jun 3, 5:58am
The formula I used to use was half the span plus two So span= 3m ( 10ft) half = 1.5 m ( 5ft ) plus 2 = 174mm x 50mm (7x2) not available so use 200x50 (8x2) your timber is not big enough
boar,
Jun 3, 8:18am
You want some advice? My advice would be get someone that is qualified to give this advice such as an architect or take the risk that your advice may be incorrect, as most of the advice given so far has been off the mark or out dated.
budgel,
Jun 3, 8:44am
Do you know the dimensions of your wall frames? It is possible that they are ex70x50, so wont be up to carrying the floor load.
mrfxit,
Jun 3, 8:54am
Having a few ideas of what to do, can help prevent being charge far more for the same job then would be normally expected. It can also help prevent the job being far too weak just to keep within a cheaper price. When the majority of advice is to do it a specific way, then theres probably a good reason for staying within similar systems.
The old adage of "If you have to ask, then you probably shouldn't do it" is a big incentive for not learning & for opening ppl up to getting ripped off big time
mrfxit,
Jun 3, 8:57am
Also, how the heck do you think the "professionals" get qualified for their chosen job if not by asking questions.
Outdated advice generally only applies to regulations. Regulations are well known to be riddled with lots of non physical advice & a tiny bit of practical knowledge
mrfxit,
Jun 3, 9:02am
Yep probably is with it being std dressed 4x2 Was thinking of a 5x2 on edge on top of the wall around the outside & 5x2 bolted end butted to that rail. Just to keep the height down a bit. It's a leased building so don't want to spend a lot of cash that I may not be able to recover gear for the next place. The 5x2 rough sawn (150x50) is really cheap where I get my timber.
martin11,
Jun 3, 9:19am
Get someone that knows what they are doing 5x2 is not 150x50 !
fast4motion,
Jun 3, 1:16pm
I did something similar about 10 years ago, above a 6x3m area. The floor was to be walked on regularly and have stuff stored on it. I was told to use 8x2" joists for a 3m span, which corresponds to post #5 above. I used 200x50mm (rough sawn), and glued and screwed sheets of Kopine flooring down to it as well, and it hasn't sagged at all in that time, despite heavy use.
Sounds like you just want a ceiling which you can store items on, not an actual floor to walk on. If so, I think 150x50 would be fine provided you have some decent bracing and flooring material to spread the load. I'd be more worried about the strength of the walls, and would check them for stud spacing, dwangs and diagonal bracing. But it all depends on the weight of the items you want to store.
Also, I think you're getting confused with terminology of timber sizes. 6x2" rough sawn is approx 150x50mm. 6x2" dressed is 140x45mm. 4x2" rough sawn is approx 100x50mm. 4x2" dressed is 90x45mm. So I think you have 6x2" rough sawn.
dastedly,
Jun 3, 1:53pm
A old rule of things was foot per ins , 10ft span the 10ins high ,3m 250 high . It is in nzs timber framing book but that be out of date now
johotech,
Jun 3, 2:41pm
But your not planning on becoming a professional are you. You just want to second guess them.
Unless your timber has a SG grading, it can't be used for the job.
I can tell you off the top of my head even without being a builder, that your 50x150 won't be suitable for the "2.8m minimum span". What is the maximum span?
Why don't you just download a copy of NZS3604 and check it yourself? It's not that hard to follow.
zak410,
Jun 3, 3:47pm
1 strong central beam, long way, and Triboard floor ?
stevo2,
Jun 4, 1:22pm
My copy of NZS3604 is at work so I cant look it up for you but what ^^ he said ^^ is a general rule of thumb
budgel,
Jun 4, 6:23pm
That's interesting, the rule of thumb that I learned for 2" timber was: take the depth of the joist in inches and add two, then call it feet. So a 6" joist would span 8'. I noticed a few years ago that more recent versions of the code had reduced the allowed span for pine timber joists. I have a 1984 version of the code stored away somewhere.
mrfxit,
Jun 4, 10:28pm
Sorry, yes turns out you are correct. 6x2 rough sawn is what I have. Never bothered to convert it as don't have an imperial tape here & when I brought it, was told 5x2. Hey it was cheap & I wasn't going to argue the point, far too busy in the last 12 months to worry about that as at the time, all I needed it for was high shelving. It's not going to be a workspace or for heavy gear as getting up there as access will be via a decent ladder. Basic floor plan https://trademe.tmcdn.co.nz/photoserver/full/805599600.jpg Will probably be using somewhere between 15mm or 19mm custom/ chipboard (1.2x2.4) wood sheets depending on whats available at the right price.
mrfxit,
Jun 4, 10:31pm
Interesting, on that basis the 6x2 rough, would be only slightly over for 2.8m. Did it have any allowance for sheet flooring, tho most likely it was tongue & groove back then.
mrfxit,
Jun 4, 10:35pm
Not second guessing at all, it's a matter of being better informed for guidance. Options information is what I am after, not another bleeding heart nag about getting a pro for the whole job if you aren't trained your self.
tegretol,
Jun 6, 6:28am
Be vastly cheaper to put in three times as much timber as your best guess is. You ever employed an architect to design a roof in an office?
boar,
Jun 6, 6:47am
Who would take responsibility of the design if it fails and injures someone? I'm sure none of the non-professionals that give advice on this post here would. The timber that is being talked about is RS150x50, this would not span the 2.8 required. as per the code would need to be 190x50 SG8 (stress graded) with a floor load rating of 2kpa. It doesn't take much to look in the code. My advice is to get advice from a professional as there are risks.
boar,
Jun 6, 4:33pm
Opps, I ment 190x45 SG8.
pdc1,
Nov 2, 10:00pm
may as well cut that timber up for firewood mrfixit, curl up and ready yourself for your leaky rest home that the professions have designed and built. Yes there is serious risks you need to consider, and consequences of unauthorised building work, but you can build something safe and strong with the timber you have despite the professional advice that you can’t. I do get a bit worried though as it sounds like this is a work place, and that throws a big bunch of termites into the equation with the Health and safety, and Work Safe. Technically boar is right and I totally agree with what he is saying, but I’d be the first to just do it. Your call!
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