Exploring Octagonal Roof Framing Part One

hi and welcome to the digital job site where the boards are straight the weather is great and there really is a board stretcher this is the video tour du jour for the exploring octagonal reframing with Sketchup post at the digital job site at fine home building comm and in this tutorial this first video section just want to explore the various framing members and their the way they are attached to each other to form an octagonal roof and in this model I created for this tutorial that you're looking at here is just a straight forward octagon framed walls and no openings or anything windows doors etc basically because I'm focusing on the framing of the roof itself in this sort of construction so to get going on this you can see I've kind of opened the model up and left some of the sheeting off the walls and rough to get a better look at the inside of it and how the components come together then turn off the shadows here so speeds up and I've layered various things in this model so that we can peel it back a layer at a time and look at the different components and rafters and things that make up this sort of a roof so we'll go up in here to the layers and take a few things out hide a few things I'm going to take the 1 by 8 sheeting off the roof to open that up and I think we'll take off the wall sheathing so you know just took out the wall framing which is the studs in this case and I'll zoom in here as I delete the wall sheathing all right not delete but hide the wall sheathing layer and you can see up here that the rafters the birds Mouse and these rafters are notched out so that they'll clear the half and sheathing that leaves a space in in between typically the wall would be cheated first before the rafters are fit and attached that's why the bird's mouth is a little bit bigger and let's see let's take out the floor that I have in here I have the floor let's just go like this beside this this thing can I put that on a layer and maybe I didn't so what I did for now which leaves us just with our octagonal roof framing and I'm gonna roll that back here by taking out the ceiling joists and the rafters and I've got the fascia here somewhere there's the fascia so that leaves just the octagonal plates if I go in here to view hidden geometry and unhide these things then I can show you how the the bottom plates if we use the move tool and raise these up you can see that the bottom and top plates are identical and basically in the way this would be framed to be framing the deck sheathing the deck using plates and building walls before sending any rafters on there and if you notice on these drawings just to organize them organize the different pieces and help align them I've got in these different groups and components I have a center mark you see this little mark and I use that as a point at center of the octagon so that I can easily pick up and and move these various pieces and getting get them to index in a line with each other so those dots aren't part of the construction they're just part of the model in Sketchup that helps create the model and align the parts but the main point here is for an octagon roof we have a set of octagon plates each side is equal in length and in this case they turn out to be 64 in 1964 so what's that 1/4 inch in length each of the octagon phases is the same and the first part of this as far as building a model and understanding that geometry is this piece I called an octagon core which a typical roof that's the ridge the ridge beam or the ridge board as you'd call it but an octagon it ends up just being one Methodist to just make it a core and in this model I chose to make it a core 8 sided and the reason I did that was for the primary common rafters and a comma after runs perpendicular to a plate which is what we have here 8 plates 8 common rafter that's wrapped one up into this Center core piece and like I said if this was a typical roof that would be a ridge board but I made that core for the model sake and also a good way to the frame is to make this core with eight facets each facet is an inch and a half wide so that the rafters fit neatly on those on those faces to help align the structure with the common rafters centered on a plate down here and nailed on to that core this whole roof will come out geometrically correct assuming that that the octagon is true and it's the level that sort of thing so the exploration continues here covered the plates this is the primary common rafters and the next step in framing this sort of roof well would be putting in the ceiling joists which are these but I'm gonna leave those out for now we can just because this is a digital model in the real world those ceiling joists need to be in there too to keep the integrity of the walls but for explanation purpose I'm just gonna leave those hidden for now and look at the next batch of rafters if you will which are I've got here in a layer called 45-degree hips in a typical rough regular hip roof like I covered in the model and measured series and touched on briefly in the offing a roof framing series those rafters are typically hip rafters are typically at 45 degrees to the wall plates and unless the off angle when it was it was a somewhat random angle that those rafters ran at nevertheless the point is that the hip rafters will bisect the angle that they're that they're dividing in this case it ends up being these were on 45 degrees to the plates which were used to take the protractor tool click on the click on the plate see if I can get this to get on this little intersection there here click against this a they actually run it 22 and a half degrees I've been saying 45 but it's 22 and a half because they're bisecting up essentially a 45 degree angle so I stand corrected and should probably rename the layer here 22 and a half degree hips but I'm thinking of them as bisecting the 45 degree angle nevertheless that's the next set of rafters that are used to create this type of roof and when i zoom in towards the top here you can see that these hips have a very sharp top plumb cut angle on them let's take one of these and move it out to see what I'm talking about so these are sharp angles those are a bit difficult to cut on the job site with a with a skill saw it can be done it's a little tricky but if a person was to make this block in the center make it 16 sided and each one of the 16 faces at be an inch and a half then all of these these first 16 rafters the eight Commons and the eight hips could all fit against that block with just a regular plumb cut but those are some of the things that are involved in framing this sort of rough the next set of rafters that would be needed in a roof of this size I set up as the secondary common rafters here in this model which show up when I click those in the layers dialog box and what those are is just 16 inches off the Commons 16 inch on center which is standard framing they could be 24 inches or whatever the structural design or structural requirements would be but in this case I just show them at 16 inches on center and that allows for strengthen the sheathing that's used to cover the roof but each one of these eight phases has two of two rafters of this length and these are just a mirror image of each other a left and a right same length same angles everywhere and they're just duplicated around the octagonal roof and because of the size of this the gazebo I chose to use for this model and if I go to one of these center points and to the outside this is 78 it's about seven foot four to these faces I could not I don't remember which diameter I chose for these points but what I'm getting at is that the larger or the longer each of the eight faces of the Octagon are the more sets of rafters are required to maintain the sixteen inch on center spacing so when I put in the tertiary common rafters put a fancy name on them you can see how the sixteen inch center on Center spacing is carried out until the distance between the last rafter and the hip is less than 16 inches bigger octagon would require more sets or after as a smaller would require fewer and the idea is that each one of these rafter groups see if I can get one of these to separate out here and get it that way not too bad though just gonna pull one of these out to look at this hip rafter out of here so in in this relation or this perspective each one of the facets of the octagonal roof it's actually just like a mini gable roof or Stan ruff with that that's all one slope and one roof at one pitch I'm pretty sure in this roof I use the 712 pitch but it gives you an idea how the rafters when they're all assembled looks fairly complex but when you dissect that are explore a little bit separate some these things out it's it's easier to understand so with all the rafters in place I'm going to go up in here and put fascia on here I'll show bring the fascia back and can see how the fascia is miter twenty-two and a half degrees at each of the hips and the level cut here for the soffit etc all these cuts line out for a nice flat surface and go ahead and put the ceiling joists in at this point so you can see how the one set of joists run side to side completely side to side which would give the roof or the structure strength and then the intermediate joists are run next to this to the rafters so they can tie in these are just turned at 45 degree angle it that gives enough nailing surface for paneling or sheetrock or whatever might be used on the ceiling and this is just one way of doing it it's fairly straightforward and effective but there's plenty of reasons that that might get built differently and notice here that I've doubled up I show these main ceiling joists doubled up because they're carrying extra ceiling load from the sides of that ceiling structure but that gives a pretty good idea of how that roof goes together we'll put the sheeting on the roof and for whatever reason I just made it one by eight would probably be plywood but it was fun drawing the boards with Sketchup so I just put in all one by each heating there and then just to dress up the model put the wall framing wall studs in there the wall sheeting I got this plates moved out of position at some point in the discussion here so we'll just move him back up I've got something moved there I must have raised or lowered no I'm happy anyways so that's the things that are involved in framing an octagonal roof and this one is neatly a standalone roof often in construction there's an octagonal bump out or a hip roof or a gable roof might intersect this which complicates the the framing but the geometry really stays the same so I hope that's beneficial helpful I'll upload this model under C I'll put it under tagging all exploring octagonal roof framing with Sketchup I'll put it in the Trimble Sketchup component warehouse under that title if you search that out at the component warehouse you can download this model and and work with what I've shown you here I'm going to do another video as part of the exploring octagonal real framing the Sketchup blogpost at the digital job site in that tutorial we'll go through some of the techniques that I used to build to create this model in Sketchup there you have it for now thanks for stopping by the digital job site

Channel: The Digital Jobsite

Views: 66,452

Keywords: octagon, octagonal, roof, framing, hip, rafter, tutorial, digital jobsite, timber tailor, fine homebuilding, aidan chopra, joist

Id: q4ARYPwCH_s

Length: 16min 32sec (992 seconds)

Published: Mon Jan 28 2013