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Doubling up rafters


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have to say dee we wouldn't be allowed that make up, your 4x2 on the flat would need to be 2 x 6x2 on edge up here. why put a lintel in it's not doing anything? either side is going to be carrying the same weight as above the lintel. i see what you mean by the birdsmoth on the wall, seems strange to me, you put a support in then weaken the rafter by cutting a birdsmouth. i would suggest putting a strap hanger around the ends of the rafters when you cut them at birdsmouth and over the wallplate.

 

simon

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On 14/03/2017 at 18:21, Simplysimon said:

have to say dee we wouldn't be allowed that make up, your 4x2 on the flat would need to be 2 x 6x2 on edge up here. why put a lintel in it's not doing anything? either side is going to be carrying the same weight as above the lintel. i see what you mean by the birdsmoth on the wall, seems strange to me, you put a support in then weaken the rafter by cutting a birdsmouth. i would suggest putting a strap hanger around the ends of the rafters when you cut them at birdsmouth and over the wallplate.

 

simon

The top timbers will be doubled up but I've run out and awaiting delivery of more on Thursday so will be 100x100... BI was happy with that. Also he suggested a lintel but I'm with you on that one so I've gone with two 50x175 on edge to keep him happy ?

wWe bought the house with planning already in place by the previous owner. We modified the plans somewhat but as we have yet to have the project signed off I'm going with whatever the BI suggests! 

Excellent idea on the strap hanger... 

Picture please if you have one?

Edited by Dee
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22 hours ago, Dee said:

Quick update with photos..... The old rafters are yet to be cut flush with the wall plate as per BRegs chaps suggestion. 

 

DSC_0620.JPG

DSC_0623.JPG

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DSC_0624.JPG

Discovered a chuffing big steel running exactly under where the front elevation sits so what you see in this picture all the weight will bare on the steel....? 

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10 minutes ago, Dee said:

Discovered a chuffing big steel running exactly under where the front elevation sits so what you see in this picture all the weight will bare on the steel....? 

 

Sometimes a quick design change pays dividends. We have moved our dormers back so they stand on the inner block skin. I may use a thermal block to reduce the thermal bridge (or just a well insulated timber wall) but it meant that the front wall of the dormer became load bearing and the cheek rafters only take half the load from the walls - greatly simplifies the calcs..!

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47 minutes ago, PeterW said:

 

 

Sometimes a quick design change pays dividends. We have moved our dormers back so they stand on the inner block skin. I may use a thermal block to reduce the thermal bridge (or just a well insulated timber wall) but it meant that the front wall of the dormer became load bearing and the cheek rafters only take half the load from the walls - greatly simplifies the calcs..!

Doubling up the joists and cantilevering is another. Need as structural engineer ( SE ) then though.

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On 14/03/2017 at 09:42, Dee said:

Quick update with photos..... The old rafters are yet to be cut flush with the wall plate as per BRegs chaps suggestion. 

 

DSC_0620.JPG

DSC_0623.JPG

DSC_0622.JPG

DSC_0624.JPG

Discovered a chuffing big steel running exactly under where the front elevation sits so what you see in this picture all the weight will bare on the steel....? 

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Brief update...the bones of the roof up in a day.. And not one duff cut! 

It was fun putting the tarps over in gusty wind and rain ?

Any obvious mistakes? 

DSC_0632.JPG

DSC_0634.JPG

Edited by Dee
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