Buildsum

Roof Components

click here to watch the video



In this post, 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 in this picture, you can see the entire roof









So I will take it back to the Wall plates and then build it up from there












So the first member is the Ridge. The Ridge is the highest member of the roof should always level and parallel to our external walls












and in this case, we have 2 Ridges one for the larger part of the Roof or the Major Span and one for the smaller part of the roof or the Minor Span.








The ridge is basically held up then by our Common Rafters

and 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.

Then 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.

Then 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

and again we have 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 an 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

In this case, because we’ve got two different spans we end up with a Broken Hip. If you were to extend the line of the Broken Hip all the way through it would line up with where this wall plate would extend. 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

We then have to infill this area around the Broken Hip so we end up with Valley Creepers so you can see these, these are cut into our ridge and down into our valley so they are Valley Creepers,














We also have Cripple Creepers these are cut into our Hip at the top and into our Valley at the bottom. So they are Cripple Creepers because they are cut with plumb and bevel cuts on both ends.













Then on the larger part of 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.

There are 2 types of Struts, Fan Struts and


















Straight Struts. The Struts transfer roof Load from the Purlin down to a Load Bearing Wall or if the is no wall available then we need to install a













Strutting Beam to transfer the Roof Load across to the Walls.









The final member of the Roof is the Collar Ties which tie the Rafters together and are installed on every second set of Rafters.











So now we have covered all the member that go into making up the Roof Frame and while every roof may have a different combination of members they all have some of these members in common