G’Day and welcome back to Buildsum and in this video I just want to take you through
the main components of a typical roof in this case we are going to have a Broken Hip and
Valley roof.
I’m just going to take you through and show you all the members.
So at the moment you can see everything
so we will take it back to the top plates and then we will build it up from there, so
the first thing you are going to have is the
ridge so the ridge is always level and it should always be parallel to our external
walls
So you can see there that this runs parallel to our external walls.
In this case this is the ridge for our major span section of this roof and we will also
have to have a ridge for the minor span section of the roof
so there's the minor span ridge there, ok so you can see that the ridge is the highest
member at the apex of the roof and as i said it’s level and runs parallel to our external
walls,
So the ridge is basically held up then by our common rafters as the name suggests they
are pretty common they are all the same and again we are going to have common rafters
for our major span and common rafters for our minor span section of the roof.
As you can see we have sort of made up most of the roof with those so rafters always run
at 90 degrees to our external walls up to our ridge, they make contact with our ridge
We are then going to have our crown end rafters, they are very similar to our common rafters
except they are a fraction shorter just because of the shortening associated with the intersection
at the ridge, you can see more information on that in other videos, and again we have
a crown end rafter for the major span and a crown end rafter for the minor span sections
of the roofs.
So we than have our hips, so our hips bisect our external corners at 45 degrees on plan,
with a 90 degree corner they always bisect our external angle here and they run up to
where the common rafters and the crown end rafters intersect
So they are our Hips and again a Hip for our major span and a Hip for our Minor span
We also have valleys, so valleys are fairly similar to our hips except they run up from
any internal corner of our wall plates we get a valley instead of a Hip.
We then have our creeper rafters or jack rafters so just like our common rafters our creeper
rafters run at 90 degrees to our plate but in this case they intersect with our hip instead
of our ridge and they are cut with a creeper cut so they fit into the Hip nicely.
So that is a Jack rafter or a creeper and you can see them on all four corners or every
hip is going to have a set of creepers intersecting with it
We then in our, in this area because we’ve got two different spans we have a Broken Hip,
so you can see here our Broken Hip if you were to extend that line all the way through
it would line up with where this wall plate would extend to, it’’s part of the Major
Span but because it’s intersecting with this minor span area it doesn't need to go
all the way so this is a Broken Hip
And then we have to infill this area so we end up with Valley Creepers, so you can see
these, these are cut in to our ridge and down into our valley so they are Valley Creepers
and we have Cripple Creepers because they are cut, this one is cut into our Hip up here
and into our Valley down here.
So they are Cripple Creepers because they are cut with plumb and bevel cuts on both
ends.
Then on the larger part off the roof we have a Purlin now this may be necessary on our
minor span area of the roof but in this case it’s not.
Now the Purlin what it does is because our rafters are spanning such a large distance
they may need extra support so you may end up with several rows of purlins but generally
at the midspan of the roof you will have a Purlin supporting your rafters where it’s
deemed necessary
and obviously that just doesn't float there in mid air it’s got to be supported down
on to our wall frames with Struts.
As you can see this set of Fan Struts are sitting onto our wall plate here and the other
alternative other than a Fan Strut is a Straight Strut, so it just comes down, it transfers
the load of the Purlin and the roof onto our wall plate.
Now in the case where we don’t have a wall plate in an appropriate spot we have to put
in Strutting Beams and these can be incorporated into your ceiling design, and there is another
video of mine on Ceilings, but they then take the load from the Struts and they transfer
that to the external walls.
Ok so there we go that's all the main components of a Broken Hip and Valley roof and you know
90% of those components are used in just about every roof that you would construct.
G’Day again, I’m back, just to let you know, if you like this video you can subscribe
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