# Forum More Stuff Owner Builders Forum  Timber Extension to Double Brick House WA - Engineering HELP

## Opalsecurity

Hi, 
I'm looking for some advice on lintels for these plans and anything else that you can see is not drawn right.
Any advice on the best way to position the beams as the Engineering/Overlays are in some conflict from my view. 
 I want to do as much as I can myself, and need to order timber soon to get started. Slab is down.  
The Engineering done seems to be a bit vague or overdone in places and I want to approach them again to confirm all the structural RB sizing and suggest some options.
I have had to home study to understand the Engineering and AS1684 and although I like to know what I/m doing there is just too much to take in with no background in structural timber framing.
The Timber supplier has done the most part, but the Lintels are my main issue with them.  
So I have used the DesignIT software to calculate some sizes, and span tables for Smart LVL15 etc: 
RB1        -              200x35 2.4m  Hyspan Lintel supporting Strutting beam. 
RB2        -              240x63 3.6m  Hyspan used as Strutting beam and replace middle hanger
RB3        -              240x45 3.6m  Hyspan used as strutting supporting hangers
RB4        -              200x63 3.9m  Hyspan Strutting/Counter beam? 
Lintels on Overlays are mostly shown as 140x45.  The rear windows are both supporting struts, one a strutting beam so?
The others I expect might be fine.   
I also plan to use H2 120x35mm studs/plates on all external walls.  Any issues with this?  
My reasons are that the replacement wall along the Patio has a door frame 130mm wide so it needs to be done here.  
Also, the benefits of using RFL paper with a 30mm gap to the bat insulation is recommended from my reading.   
Does anyone have any span tables for LSB for replacing the 250PFC Lintel as engineered?   
Cheers     Attachment 105743Attachment 105742

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