Roof Structure. Raised Ceiling Joist


Hi Everyone,
I am re-roofing my home in Ireland. I'm a DIYer, not a pro!
My span is 20ft, Wall plates are anchor bolted at 48" centres.
The pitch is a weird 36 deg (Had to run to meet the chimeny flashing!!)
I worked out the rafter length (148" 5/16 :)) and put up 4 master rafters(2" x 6" C18 grade) along with ridge board.
All goin well so far!
I am putting in a purlin flush with rafter at rafter mid point.
The problem is I want to raise my ceiling joist about 18" up offf the wall plate.
Should I collar tie 18" down from ridge?
Should I still use a hanger from purlin to joist?
What about strut from purlin to celing joist? Do I need to have a supported runner to carry the struts along the ridge line at celing joist level?
The next part of my roof hips into this roof, its span is 15 1/2 ft. My plan is to valley rafter to the 20 span roof ridge and use a shortened valley rafter on the other side.

using a purlin on this one. rafters are 2" x 6" C24, good'n strong ;)
Again here I presume collar tie below the ridge?
And the same raised ceiling joist happens here also! Will I need to strut for this? Will 4 10d nails do, or should I bolt or use some special ties?
any info appreicated.
Kind Regards Pat!
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, snipped-for-privacy@skynet.ie writes

Sorry, no answer for you but you may catch more replies on uk.d-i-y , more traffic there and quite a few who have done roofy type stuff.
HTH
--
fred
Plusnet - I hope you like vanilla
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thanks Fred --ph
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