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Whats my attic truss load capability?

SLYDIT

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Mar 28, 2014
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having a new house drawn up and and am having some storage above the garage. as per the drawing below what sort of load would the storage space handle. the bottom plates of the trusses are 190mmx45mm floor joists so about 8"x2". the span accross the garage is 7.2 meters. i wasnt planning on putting V8 blocks up there but am after some sort of square foot loading..(the roof is 25 degree pitch).
The "depth of te storage is 3.6 meters and has 5 trusses covering the load so 900mm spacing...

any ideas?
 
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SLYDIT

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Thanks... its just a snippet of the working drawings that go to council for permit signoff. Hopefully they will be happy with whatever the Truss manufacturer comes up with and not make us get it engineered.

Just trying to get an idea of what sort of loading figure i should expect with the above setup. roof tiles are concrete tiles.
 

laser3kw

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Your question would be best answered by the truss manufacturer.
what he said^^^^
after you receive your trusses, you will get a report stating all the specifications. I have a 30ft (9.1m) x 40 ft (12.2m) with about the same amount of open storage area as yours. Mine listed 20 lb per sqft (9kg) I believe.
 

Kevin54

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Thanks... its just a snippet of the working drawings that go to council for permit signoff. Hopefully they will be happy with whatever the Truss manufacturer comes up with and not make us get it engineered.

Just trying to get an idea of what sort of loading figure i should expect with the above setup. roof tiles are concrete tiles.

What you get from the truss manufacturer WILL be an engineered truss. The truss company has to make each truss design by engineering it for the requirements of the area it is going. You get with your builder, or if you are building it yourself, you go to your lumber yard, you tell them what you are wanting, they in turn get with the truss manufacturer, and they will look at the size, and either go with a stock plan that has already been done before, or they will design it up for the proper snow loads, plus it looks like you have a tile roof, so that will be factored in. The lumber yard calls you, you write a check, pay for the trusses, and bingo-bango, all you have to do is wait for them.

Believe me, as many trusses as the truss manufacturers make over the years, yours won't be unique. Oh and when you get your trusses, you will also get the engineered drawing along with them
 
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SLYDIT

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my concern is that the permit issuer will deny the permit and make us over engineer it with steel RSJ's for instance "just because they can".I wanted an independant estimate so I am fore armed so to speak. the building company are building to an agreed price so its in thier interests to build it as cheaply as possible at "minimum spec" so i need to get an idea if what i asked for is what i am getting.
 

bczygan

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DETROIT! Arsenal of Scrappers
Either YOU need to specify what they are to be, or you need to find out from the builder or designer, what he specified, and ask what that will accommodate. Sounds like this is not in the US.

Structure design follows the function. What is it going to be used for? It could be designed for anything from very light storage (And no human habitation), to heavy storage with human access.
 

chamoisfive

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You may not be intending to put the V8 blocks up there but the next owner might. There's only so much MX5 stuff you can jam up there too. Contact the supplier of the trusses to get the info you need, their experts will have it, but you have to ask for it. In my experience, the information you're seeking does not get delivered on site with the trusses other paperwork. I strongly suggest you're proactive and get it first before committing further
 
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DekeT

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my concern is that the permit issuer will deny the permit and make us over engineer it with steel RSJ's for instance "just because they can".I wanted an independant estimate so I am fore armed so to speak. the building company are building to an agreed price so its in thier interests to build it as cheaply as possible at "minimum spec" so i need to get an idea if what i asked for is what i am getting.

Why don't you have a conversation with the permit issuer beforehand? That way you can alleviate your unsubstantiated fears about the "just because they can".
 
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SLYDIT

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Why don't you have a conversation with the permit issuer beforehand? That way you can alleviate your unsubstantiated fears about the "just because they can".
By law our council has to process an application in 20 days. But if they can query something or come up with a demand the 20 days starts again. At the moment they are behind in thier work so are happy to make you in off and get thousands of dollars in engineering done just so they get more time.
 

tomroblee

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As others have said, only the truss manufacturer will be able to answer your question. A lot depends on the species and grade of lumber used, how the truss members will be attached, the dead load, and the maximum deflection.

For some kind of very wild guess you might look at a floor joist span table for the size of your intermediate joists (190 x 45 x2,310 or roughly 2" x 8" x 8') with spacing of 900 mm (about 36"). I've never seen such a table for joist or truss spacing greater than 24". I would guess that 36" truss spacing would require a rather heavy dead load for whatever ceiling covering you are intending to use and for flooring in the attic storage area.
 

Kevin54

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my concern is that the permit issuer will deny the permit and make us over engineer it with steel RSJ's for instance "just because they can".I wanted an independant estimate so I am fore armed so to speak. the building company are building to an agreed price so its in thier interests to build it as cheaply as possible at "minimum spec" so i need to get an idea if what i asked for is what i am getting.

You can still get drawings from the truss company. Go to Lowes Construction area in the back of the lumber departments, go to Home Depot, or go to any lumber company, and have them give you the phone number where the trusses get ordered from. Here in Ohio there are only a few truss companies that supply the whole state. Anyone that works in the engineering department of the truss company can supply the information that you need. They had all better been to college to learn structural engineering :lol:

When you tell the truss company what you are looking for, you can send them a copy of your drawing and they can give you an estimate from that, or they will tell you that to have that space and span, you will have to change this and that.

ANd like I said before, or at least I think I said.....you will not be unique. Any truss company that has been in business for any length of time will have stock drawings most likely. They don't just sit around doodling with nothing to do. I would guess they have drawings of almost any length, with any pitch, and with and without upper storage. For your state, or area, and calculated loads.
 

Kevin54

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SLYDIT.....if you would, could you put your state in your profile? I was going to do a search for truss manufacturers in your area and help you out, but I don't even know what part of the world you are in. If you are living in Siberia, I seriously doubt that you are going to have a truss manufacturer anywhere close.
 

LB-1911

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SLYDIT.....if you would, could you put your state in your profile? I was going to do a search for truss manufacturers in your area and help you out, but I don't even know what part of the world you are in. If you are living in Siberia, I seriously doubt that you are going to have a truss manufacturer anywhere close.

He is in New Zealand

New Zealand 20'x24' build.
http://www.garagejournal.com/forum/showthread.php?p=3885949#post3885949

Edit to add:
Pryda has been an integral part of the building industry in New Zealand for almost 50 years, particularly in timber truss and frame solutions with the development of a diverse range of timber connectors and structural brackets. Today Pryda remains a trusted New Zealand brand on building sites, in trade stores and in offices of architects, engineers and designers.
http://www.pryda.co.nz/about-us
 
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DekeT

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By law our council has to process an application in 20 days. But if they can query something or come up with a demand the 20 days starts again. At the moment they are behind in thier work so are happy to make you in off and get thousands of dollars in engineering done just so they get more time.

You should just move. WTF would want to live there?
 

johninct

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I think a better way of looking at is what do you want to put up there? Will it be all in one spot or spread out then design the truss for it.
 
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SLYDIT

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its the same all over the country. they come up with all sorts of stupid reasons to knock back an application, just so they make the 20 day rule. they can say "we have processed 99% of applications in under 20 days" but that doesnt allow for all the ones they knock back due to "questions" they ask. i know of one case where a build was knocked back to get a geotech report done, even though the two houses built either side did not require one, so that cost the owner $2000 just because the council were behind on consent issuing.
 
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