Roofs

[cric]

How can I draw a roof with a central ridge line and different pitches of roof to either side?

[Kajvin - Robert W]

Hi Cric!
Welcome to the forum, I'm not sure what you mean, but if I'm not wrong it will not work with a central ridge with different pitch that is not trigonometric correct, the ridge will follow the angel of the pitch toward that pitch how are steepest. Because the sum of angels will always be 180 deg in a triangle.

/Robert

[Allan Chesney]

Hi Cric,

This can work. What you need to do is to select the edge that has the shallowest pitch and increase the Support Height, so it effectively increases the wall height on that side. I assume that is what you mean, that one wall is higher than the other and with a shallower pitch on the high side, the ridge will still be central.

There is probably some mathamatical formula that will determine the Suppot Height you need for the pitch you have chosen, but I am no maths expert I am afraid!   My 'formula' would have be to insert the roof with equal pitch and hence a central ridge, mark the ridge point (with a dimension line or something), change the Slope on one side (which will move the ridge of course) and then just experiment with the Support Height to bring the ridge back to the central maker. It works, though not a very scientific method but as I said I am not a mathematician! Maybe someone else can help with a proper formula.

Allan

[Doug.S]

I'll have to experiment but I think I've done it before by accident.  (drag ridge line???)

I'd try doing a plan, add roof, drag out one wall and see what the roof does?

Alternatively what should work is separate roofs on each side of the ridge...install 1/2 then add other 1/2 as separate (add roof by pick points)

Maybe need separate locations for each roof side?   all location settings same (different names), just have roofs on different locations.

May need to be very careful, by zooming in close, that they meet exactly at the ridge.

[Doug.S]

Is this what you mean?

Done by 2 roofs (same location) by pick points, adjust to gables, adjust to meet at ridge line, adjust slope

Then have wall top "extend to roof" (may have to make level then make extend to get it to change)

[Draft Patrick]

Actually, there are 2 ways to do this

1 - If the ridge is in the center and the pitches are different --> then the walls will have different heigths
2 - If the ridge is not in the center --> if you wish, you can create the walls with same heigth and 2 roof panes that will meet at the ridge

Pat

[Allan Chesney]

Hi Cric,

How can I draw a roof with a central ridge line and different pitches of roof to either side?

In your original question you said you required a CENTRAL  ridge line with different pitches each side, so as Pat said in his point 1, the walls will be different heights. 

As you can see in the image below, the Ridge is central and the roof each side a different pitch (one is 23 degrees the other 30 degerees). On the left hand side (30 degree slope) you will notice that the green line representing the edge of the roof is lower than the rest of the line - that is because I have Lowered the Support Height which in turn lowered the wall.  You can do the opposite obviously - on the right side (the shallower slope roof) increase the support height until the ridge line is central and that will increase the height of the wall (as long as the wall is set to Auto Extend to Roof obviously).

So my original suggestion works without the need for separate roofs or locations.  All you need to do is set the two slopes to what you want (the ridge will go off centre) and then increase or decrease the Support Height to centralise the ridge.

You will find the Support Height in roof Properties / Details and Support tab.

Allan

[cric]

Wow! Thanks everyone!
I had kind of got most of the way there but a very long winded route and couldn't quite get the gables to fill in, had to do it in two separate halves which meant that I couldn't put a single window in the centre!
needless to say that this is an existing building, a little old Welsh cottage that I am renovating!
Thanks
Cric

[Allan Chesney]

Hi Cric,

Normally the gable will fill with the wall (set to Auto Extend) or by ticking the Display Gable box in the Roof Properties (especially if you want a different texture).
A window inserted into this wall can then be Elevated into the gable.

What was the problem with the gable? I don't quite understand what you mean by doing it in two halves.

Allan

[Kajvin - Robert W]

Hi Cric! That I didn't thought of different wall heights, that type of roof is variant of Saltbox roof.

Robert