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Bearer size - 1st post to group
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Author:  matthewm [ Feb 02, 2009 2:26 pm ]
Post subject:  Bearer size - 1st post to group

Hi everyone, I have a quick question about the bearer size which I am after some advice. I have noticed some DIY areas on the net suggest using 2 bearers each side of the post and some only 1.

I am building a 5 mtr long x 4 mtr wide deck and using 140mm x 45mm bearers. The bearers will sit on a post span of 1mtr

Joists will be 140mm x 45mm as well as I have these from an previous project. Joist will sit across the bearer span of 1.6mtrs

Is it ok to use a 140mm x 45 mm single piece for the bearer or should it be doubled up.

Kind regards Matt

Author:  Dukekamaya [ Feb 03, 2009 8:52 pm ]
Post subject: 

140mmx45mm will span 1.6m fine as a bearer and 2.3m-2.6m as a joist depending on whether a single or continuous span.

Author:  rldragon2003 [ Sep 02, 2009 4:24 pm ]
Post subject:  Re: Bearer size - 1st post to group

I am just come across this post, and have the same question.

I am planning a 9m (long) x 2.6(width)m deck off ground 280mm and using 140x45mm TP as bearer and joist, the bearer direct sit on the stirrup,
and the joist will butt joint with the bearer using joist hanger.

The joist will single span 2.6m, and the bear will continues span at 1.8m.

As I understand, the two bearers are end only and only support half of the span (2.6).


Does the bearer need to be two 140x45 TP or only a single 140x450mm TP?

Author:  Dukekamaya [ Sep 02, 2009 7:31 pm ]
Post subject:  Re: Bearer size - 1st post to group

2.6m is too far for a 140x45 F7 treated pine joist to span - 2.4 would be maximum.
The 140x45 will continuous span 1.8m though a span table will not show it as they only show bearers as being doubled up. In you case it would probably show 2/140x35mm.
I have used 140x45mm a couple of times on its own as a bearer spanning 1.8 continuous and it was rock solid.

Author:  rldragon2003 [ Sep 03, 2009 10:40 am ]
Post subject:  Re: Bearer size - 1st post to group

Quote:
I have used 140x45mm a couple of times on its own as a bearer spanning 1.8 continuous and it was rock solid.


Are they middle bearer or side bear?


If I am using 190x45 TP for the bearer and joist, does the Joist can single span 2.6m and single bearer continuous span at 2.8m?

I have read Allan's span table, it shows double up the bearer as 2 x190x45. Would it be for middle bearer only which has full FLW (2.6m). I have only two bearers both only has half FLW (2.6/2).

The reason I go for the large size of the joist and bearer, it needs less posts and may be less work( 2 row of bearer for 190x45)

If I am using 90x45 for joist continues span at 1.3, I need three row of bearers continues span at 1.8; one 2x90x45 for middle bearer, two 90x45 side bearers. In this solution, the joist can sit either on top of the bearer or butt joint the bear with the joist hanger (if there is a joist hanger for 90x45).

So what is the best size of the joist and bearer for this size of the desk?

Author:  nomad [ Sep 03, 2009 12:15 pm ]
Post subject:  Re: Bearer size - 1st post to group

190x45 F7 as a joist spans 2.6 easily but as a bearer spanning 2.8m 190x45 isn't sufficient. A single 140x45 F7 wont span 1.8m either.

Author:  Dukekamaya [ Sep 03, 2009 9:33 pm ]
Post subject:  Re: Bearer size - 1st post to group

nomad nomad
190x45 F7 as a joist spans 2.6 easily but as a bearer spanning 2.8m 190x45 isn't sufficient. A single 140x45 F7 wont span 1.8m either.

As a joist 190x45 will span 3.6m continuous and 3.3m single.
A 140x45 will do a 1.8 continuos bearer span easily, have used and seen it many times. A friend of mine used 190x45 as a continuous span bearer spanning 3.0 metres with a FLW of 1.2m and they are rock solid - it was also passed by buiding inspectors. My own front verandah I have 190x45 bearers spanning 2.7 continuous, also certified.

Another thing which creates variables albeit slight, is that rougher header treated pine is cuurently available as F5, F7 ans MGP10 which all have slightly different spans

Author:  nomad [ Sep 04, 2009 10:10 am ]
Post subject:  Re: Bearer size - 1st post to group

Dukekamaya Dukekamaya
nomad nomad
190x45 F7 as a joist spans 2.6 easily but as a bearer spanning 2.8m 190x45 isn't sufficient. A single 140x45 F7 wont span 1.8m either.

As a joist 190x45 will span 3.6m continuous and 3.3m single.
A 140x45 will do a 1.8 continuos bearer span easily, have used and seen it many times. A friend of mine used 190x45 as a continuous span bearer spanning 3.0 metres with a FLW of 1.2m and they are rock solid - it was also passed by buiding inspectors. My own front verandah I have 190x45 bearers spanning 2.7 continuous, also certified.

Another thing which creates variables albeit slight, is that rougher header treated pine is cuurently available as F5, F7 ans MGP10 which all have slightly different spans

umm I have 1 table that shows it just does it and 2 that shows it fails (140x45) so I'd rather have a bit of safety factor in telling someone over the internet if it does it or not. "As a joist 190x45 will span 3.6m continuous and 3.3m single" That's strange because at the minimum FLW I have it showing 2.6 single and 3.0m continuous maybe your reading the F17 table and that is under the FLW required by the rldragon. But if your willing to sign of on all of this go ahead.

Author:  rldragon2003 [ Sep 04, 2009 12:07 pm ]
Post subject:  Re: Bearer size - 1st post to group

Quote:
My own front verandah I have 190x45 bearers spanning 2.7 continuous, also certified.


Is that a single 190x45 and double up 2 x190x45?

Author:  rldragon2003 [ Sep 04, 2009 12:08 pm ]
Post subject:  Re: Bearer size - 1st post to group

Quote:
"As a joist 190x45 will span 3.6m continuous and 3.3m single" That's strange because at the minimum FLW I have it showing 2.6 single and 3.0m continuous maybe your reading the F17 table and that is under the FLW required by the rldragon.


Would the FLW only be related to the bearer span?

In Allan stanely book, it shows 140x45 seasoned F7 treaded softwood as joist spacing 450mm will span maxium 2600 mm,
and 190 x 45 will span maxium 3600mm. In the timber solution sofware it caculate as 2500mm for 140x45, and 3600mm for 190x45.

Author:  nomad [ Sep 04, 2009 12:49 pm ]
Post subject:  Re: Bearer size - 1st post to group

Yes your right I meant to say bearer, got confused with duke referencing 190X45 as joist and bearer in his post my mistake.

Author:  Dukekamaya [ Sep 04, 2009 7:16 pm ]
Post subject:  Re: Bearer size - 1st post to group

I'm not looking at F17, I use these things nearly every day.

You will find slight variations between differnet programs/tables of 100mm or so.

The 190x45mm bearers in use I was referring to are single, not laminated. I have no problem recommending that size for those spans with that FLW, builders use it every day of the week in that application.
You need to keep in mind deck spans are over-engineered for maximum large amounts of people on a concentated spot.
Whilst span tables wil always show a double-up member for a bearer, they are often not stocked are very expensive and there are issues with nail or glue laminating 2 separate members on site. This is why the majority of the time larger single members are used.

Author:  nomad [ Sep 07, 2009 12:21 pm ]
Post subject:  Re: Bearer size - 1st post to group

Balcony's are designed with additional loading but decks aren't unless the user adjusts the loads accordingly but even AS 1684'S deck tables don't have additional loading factored in. The user needs to know to adjust the loading to 3kpa.

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