roof truss detail for extension

[climber101]

Big thanks all for more comments – some good stuff for me to think about , plus I couldn’t help notice the entertaining diversion !! I’ll see if I can’t try and sketch out some more detail of how the ceiling joists and other joists might look/tie together for more comments from the pros here. That could take me a while seeing as how I’m still trying to work it out..

I didn’t say before but it does say in my plan to ‘build ends of the hips into the existing wall’ – I’m guessing I chisel out some slots and then how am I ‘fixing it into’ existing wall? Should I also extend top wall plate and birdsmouth it onto same as well don't think so not sure?

Another query please – I’ve been looking for how to connect the rafters to the timber frame headbinder where the sloping ceilings will meet same at the 3 exterior walls. I have seen plenty details in books etc. how it is done for the more ‘normal trussed ceiling’ (which has a horizontal rafter within the truss as well at this point as per attached diagram) but not for my type. I’m believing for my sloping ceiling I would use angled truss clips but would like to see a picture or some confirmation as I’m finding it curious I cant seem to find this detail in books/internet etc. (My plans show some detail of how to join to a lengthy RSJ over back sliding doors with truss clip but I am wanting to see an example for rafters meeting headbinder where no RSJ like new end walls) Sorry if I make it sound confusing. Again thanks in advance for any comments!!

Untitled

• climber101
• 8 Jan 2009
• 1

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[Shytalkz]

Hi Climber, you must stop going back on topic, after we hijack the thread

Your rafter will be birdbeaked over the plate as per normal; a couple of nails into the plate will suffice, you don't need any clips.

If you build the hips into the wall, that's ok. Make a slot, form a birdsmouth on the hip rafter and slip it into position. The main thing is that it must be birdmouthed on the wall support and over the plate.

 

[climber101]

thanks Shytalkz,

whilst i'm going to build the ends into the wall any thoughts as to what this actually 'gives me' in terms of strength or ? for my education. I'm guessing if you had some bizarre failure of your wall plate then if the hip is buried a bit in the wall then the hip is lless likely to fall down completely...just curious

 

[noseall]

the powers that be have asked for the upprmost part of the hip blade to be built-in, yes?

 

[climber101]

unfortunately not that specific - all i have on my plans is "Ends of hip rafters built into outer wall" if i were to go just on the detail that the plans show then it would be as if the only rafters going to wall plates are the two roof common rafters between the hips and the horizontal ones below same AND the hip rafters are 'built into the wall' as if not connected to a wall plate at all. (as a n aside In my plans this "ends of hip rafters built into outer wall is in a different text colour, but so are a number of other comments - in short i don't know if it was an architect revision or something architect added after building control reviewed)

 

[Shytalkz]

thanks Shytalkz,

whilst i'm going to build the ends into the wall any thoughts as to what this actually 'gives me' in terms of strength or ? for my education. I'm guessing if you had some bizarre failure of your wall plate then if the hip is buried a bit in the wall then the hip is lless likely to fall down completely...just curious

Sorry about the delay in replying, was forced out for a meal!

An inclined member, be it a rafter or hip will always want to move outwards at the lower end, if both ends do not have a horizontal seat onto their support; the same is also true where the member is birdsmouthed only over the wallplate, but not at its top end. Ceiling joists usually do the job of tying the foot back, but you've only got these at high level, so they won't be doing anything useful in this regard.

 

[climber101]

Thanks noseall, Shytalkz, woody, it’s making more sense to me (I think!)

Couple more questions I’m afraid

This ‘building into wall’ - might it be a case of a) using a grinder and chisel to carefully cut out as least brick as possible, put the hip end in and cement back in some carefully contoured bricks around the hip end. or b) is there a bit more to it than that like inserting some form of angled metal wall hanger as well into the opening to nail hip end onto as well, as well as birdmouthing onto a wall plate below. Perhaps don’t need it to birdsmouth onto a wall plate at all but just birdsmouth into wall?

Also when noseall said “uppermost” part of the hip blade I’m thinking once I put the end into the wall I will have ended up rebuilding all around it so am I missing something

Thanks again

 

[noseall]

there are more economical and sturdier ways of restraining a hip blade than building it into the masonry. i find building it in mildly amusing. when the timber shrinks you will be able to pull it out if you wanted to.

it would make more sense to bolt something below the hip to the wall then mechanically connect the hip to this.