# Octagon roof with change in angle



## SummitSeeker (Dec 11, 2011)

I am pretty new to woodworking but i am sure i can build this with a little guidance and have read lots of great help on here so I'm excited to hear your suggestions... 

I want to build a roof like the one pictured below where the towers are octagon shaped and the angle of the roof changes about 1/4 of the way up (I don't care about including the chimney)... They will be constructed small, like for a childs play castle... They will be constructed from plywood, 1x2 pine for framing and other materials... Really i want the roof to be constructed so it is flat on a piece of plywood so it will sit flat on top of the tower

I can build framed hip roofs and understand the angles needed to cut the octagon towers and could probably build the octagon roofs but the change in the angle of this roof is throwing me off and I need some help... Thanks for any help you can provide...!!!


----------



## Itchytoe (Dec 17, 2011)

Just do 2 octagonal roof sections and join them in whatever manner you want. If you want a single piece of wood for each section (top and bottom) then I'd suggest making them thick and using a bandsaw/scrollsaw to cut out the outside angles before glueing it up.


----------



## woodnthings (Jan 24, 2009)

*Yep*

Kinda like a Pilgrims hat with a witches hat on top, two complete units. You can build the bottom unit first then based on the chords across the sections go up from there, but I'd want a center section pole to reference from. You'd have to have an accurate layout for it to work without a center pole, but it could be done. A full size 1/4" plywood template that you could duplicate would also help. Some math involved if you do a layout. Otherwise it's build and fit as you go. Two different approaches. I suck at math, so I'd be a buildin' and a fittin' myself. Strings and nails are a great help in this realm. JMO bill

Maybe think of it as 3 stacked octagons of decreasing size. The top one being as small as practical and use a separate cone for the finish.


----------



## SummitSeeker (Dec 11, 2011)

Okay so maybe this is going to be a little more than i thought... I think I am understanding that it should be made in two parts, but that's about it... 

Where would i start for just the base...?

From looking at the pic and putting a protractor over it it seems that the two angles of the roofs are 68 degrees for the cone part and about 34 degrees for the base...

FYI: I make the octagon towers using 1"x3"x24" material that is cut on both sides at 60 degrees then the 8 sections are assembled with glue.


----------



## woodnthings (Jan 24, 2009)

*Do you use Sketch UP?*

Model it in that if you can.
What I would do is layout 3 octagons, one for the base, another the size at the intersection and a small one 6" down from the top. Raise the middle one off the bottom the height at which the angle changes. Connect the indices with narrow strips of uniform length and the angles mating the horizontal octagon planes. It will take some trial and error and may require raising the middle one a bit and fitting to suit the length required. I would repeat the process to make the upper section. Then I would cover the faces with 3/8" plywood based on a template tested on the faces for an accurate fit. 

If you can do the math or make a projection drawing from a plan view and side view then that's another method. You will need drafting skills, a large sheet of paper or plywood and a T square and triangles, a 45 degree especially, since 360 divided by 8 is 45 degrees.  bill

BTW If you can't accurately lay out an octagon, you are in over your head.


----------



## BWSmith (Aug 24, 2010)

To add to Bills excellent response.......I simply cannot express how important "layout" skills are!


It starts with the design,then framing.....ranges through the sheathing....roofing material...and finishes with moulding.In each of these,layout is a fundamental building block.

Will spare a looooong boring diatribe on the steeples and cupola's that we've designed and built....just have to wait for the upcoming book,haha.But in anycase,each and everyone...the overiding criteria was the "practical side" of layin the bloomin thing out.IOW's,technically you can design just about anything on paper......getting that transfer'd into/onto a working example in "steeple world" is what seperates the haves and have nots.

I'm not gonna waste your time explaining the ins and outs of design....as books have litterally been written on the subject.Also won't go into exact build concepts and their practical applications......as each is a case upon itself.What I will suggest is you try your roof project with paper or mead bd construction first.This forces you to layout,duh....but its gonna show where some of the critical areas are in transfering design to reality.IOW,s if you're having problems getting the paper/const bd to "come together",then the wood is going to be difficult.Because of the joinery complexity's.

Not in the least being negative here,despite how it might read.These roof systems when properly designed/built are so amazingly,just flat out PRETTY that its no wonder they're used.Further...the sense of satisfaction and pride one gets from these builds is simply a drug that has NO equals......but it all starts with layout.Good luck,looks like an awesome project!BW


----------

