Skillion roof for Garage

[JohnSmith]

Hi all,

Happy New Year.

I have a question about a Skillion roof for a garage.

The rafters rest on the top plate. If the angle of slope is 10°, is it a requirement to 'birdsmouth' the rafter onto the top plate, even though it is minor?

Regards,
John

[Stuckster]

Hi John,

No, not a requirement.

Standard AS1684 2021

7.3.13.3 Birdsmouthed and non-birdsmouthed rafters
Where rafters are not birdsmouthed over top plates... Rafters shallbe supported by means of wedges or other alternative support systems, such as framinganchors that provide equivalent bearing support.

Nominal fixings for rafters to top plates of Non-coupled roofs are 2 x 75mm skew nails. That's the bare minimum. Multigrips or triplegrips (framing anchors) with connector nails will be much stronger. Structural screws down through the top edge of the rafter into the top plate should also be acceptable. A birdsmouth will create a more stable connection, but not mandatory.

[JohnSmith]

Hi Again,

I cannot believe it has been over a year since I posted the original message.

In regards to the walls, if my pitch is about 5°, what is the best option for the walls on the slope sides?
i. Slope the top plate the same as the roof slope and change stud lengths as required
ii. Build a square wall whose height is the same as the lowest height of the roof and use jack studs from the top plate to another 'top plate' directly under the roof rafter

If I am not clear enough, please let me know.

[r3nov8or]

i. Slope the top plate. This site will have a calculator for all your stud lengths based on your wall heights and stud spacings.
https://www.blocklayer.com/

This one
https://www.blocklayer.com/gable-studseng

[JohnSmith]

Thank you. That is what my preferred option was, but wanted to clarify what was common practice.

Thanks for the website. It is excellent value.

[Neil]

Need a few more like you John.