Thread: Gazebo stage 2

Pic 1 shows the rafters in place – they do look a bit large but bear in mind that the cleats and batterns for the mini-orb colorbond will take up about half the height of each rafter. Pic 2 shows the end detail of the rafter – the colour is actually primer – I needed to get these up so I could measure accurately for the batterns, so other than a first coat to get things started the painting will be done in-situ (standing on the top of a step-ladder – dammit). I realise the triple-grips are on the inside of the wall rather than the outside, but due to the way I made the panel frames, there wasn’t enough timber to fix on the outside, plus I figure it is stronger this way as the weight is pushing the triple-grip against the wall (I’m open to correction on this point). Pic 3 shows the king post with the plate – I sealed around each join with flexible filler to stop water getting in. BTW, is there a proper name for the round, pointy, decorative thingo sitting on the top of the king post?

I’ve had a real revelation about roofs doing this gazebo and I take my hat off to those of you who build these things for a living! I started cutting out the cleats, which will sit at the bottom of the rafters, as in pic 1 below (rough cut joints with odd sized timbers, just to give me a clue about the angles). I knew I was going to see some compound joins as the rafters rise at 20 degrees and the join betweed 2 rafters is 60 degrees. But I was surprised to see that the cleats were sitting at an odd angle to each other. It made sense when I looked at the finished rafters on the gazebo, but there appears to be an offset of around 8 degrees. I like maths-type puzzles and I muddled around with this one for a couple of weeks, but I eventually gave up and made the small model shown below so I could just copy the angles.

Pic 2 shows exactly what I mean – the top of the small timber cleat shows clearly against the white of the battern – the white above the cleat shows the odd angle when the battern is placed between 2 cleats on neighbouring rafters. The other thing I discovered is that my roof panels will not be 60 degrees at the top – the rafters meet at 60 degrees but that is parallel to the ground – I simulated this by holding a 60 degree set square against the rafters in the little model… as I tilted the set square to match the 20 degrees of fall of the roof panel, the angle grew smaller – I’m guessing it will be around 56 degrees. There must be some mathematical way to calculate the angle, but I’ll stick to the model and just copy it.<O</O

Looking very nice. Very nice indeed.

That looks awesome Chumley.
Some very neat and fancy joinery there.

Originally Posted by Chumley

BTW, is there a proper name for the round, pointy, decorative thingo sitting on the top of the king post?

It's called a finial. The same as you often see at the peak of a gable.

Originally Posted by Chumley

I’m guessing it will be around 56 degrees. There must be some mathematical way to calculate the angle, but I’ll stick to the model and just copy

Basically the same as calculating compound angles, such as a hip. I could do it, but I'd have to have a think about the specific trig formula.

edit: Why don't you just use Blocklayer's calculator?

Originally Posted by Blocklayer's gazebo calculator

The roof has an angle of 20°. The 6 Hip rafters have angle of 17.5°, with a plumb cut angle of 72.5°. The 6 noggings with side cut angle of 61.5°.
Each of the 6 triangular roof segments has an inner angle of 56.96°, 2 outer angles of 61.52°

It gives you all the dimensions as well if you plug your measurements in.
He's got some handy calculators there.

edit2: OK, I was bored so I decided to check up on Blocky's calculator. Someone may get something out of this anyway;
Trig is pretty simple if you memorize one word; SOHCAHTOA, and you understand Pythagorean theorem which states that: In any right triangle, the square on the hypotenuse is equal to the sum of the squares on the other two sides. 3^2 + 4^2 = 5^2, giving the old 3,4,5 triangle.

So all you have to do is break up a roof into right angled triangles, and you can work out any angle or dimension. I worked out the angle at the apex of the roof plane like so:


And the formula in one hit would be: (tan30/(sqrt (1/cos30^2+ tan20^2)))sin^-1*2= 56.962476562679
Of course it's virtually instantanious plugging the numbers into a program, but with the formulae you can work out any complex angle on a roof that may be an irregular shape. I suppose there's other programs that could do that as well though.

Sorry about the thread hijack Chumley, but I thought you may be curious since you were pondering about it. I'm not intending to detract from the great job you're doing on your gazebo.

It looks fantastic, and I'm looking forward to seeing the finished product.

Thanks for the kind words.

Pawnhead, thanks too for the explanation - I'll try to wrap my head around it -- I did look at Blocklayers calculator, but it got a bit complex and I thought I'd try to think it out myself. BTW, I like your new picture!

Cheers,
Adam

Your gazebo is looking good.

I am impressed with how you worked out the angles.

Retirement does have its attractions. Weekend and afternoons can make a job last a long time.

Thanks Scally, it's nice to be able to have something to show rather than just watching everyone else make things.

Blocklayer, I just spent another half hour with your calculator -- I finally figured out what was wrong -- I didn't fully understand that the angle of the roof is different to the angle of the rafters -- makes very clear sense once you get your head around it. Now I have my figures from your calc printed out I can check them against my model -- this will make life much easier when I come to cut the roofing sheets.
Super tool - thanks!
Cheers,
Adam

He doesn't post all that frequently but he was here just recently. Shoot him a PM so he's aware of the thread.
Those calculators of his would come in handy for a lot of people. I've got his site bookmarked

Pawnhead,
Will do.
Adam

Thanks Chumley
Thats the sort of feedback I need to improve the calculators.
(You blokes build the gazebos etc, and I'll build the calculators)
Took me a while to figure out the different angles to. It must trick lots of gazebo builders.

So I've highlighted where the angles are in the results with a yellow background and a stop sign and it says
'Realise roof angle is steeper than rafter angle. This tricks LOTS of people!'

Do you reckon that would have made it easier for you if it was there in the first place?

Your gazebo is looking great. Thanks for helping with the calculator while you build it.

Originally Posted by Blocklayer

'Realise roof angle is steeper than rafter angle. This tricks LOTS of people!'

Well that's still a bit confusing I reckon.
The 'roof angle' is called the 'pitch', and with 'rafter', it depends on which rafter you're talking about.

I'd say something like this;
The 'pitch' is a term that describes the angle of the roof from the horizontal plane.
The pitch of the roof rafters, (crown rafters, or creeper rafters in the case of a gazebo), is steeper than the pitch of the hip rafters.

Originally Posted by Blocklayer

Do you reckon that would have made it easier for you if it was there in the first place?.

If I saw it first thing in the morning I might've gone for a flat roof! Never realised there were so many different bits to a roof. Oh well, never too old to learn - just have to forget something else to make room...

Cheers,
Adam