Help with equation for roof loading: [2x (3/2)Cos(45) x 1 ] x 2.25 = 9.54

[rooflog]

Hi,

I have an equation for a roof area/loading I am trying to understand, can someone help.

The equation is:

[2x (3/2)Cos(45) x 1 ] x 2.25 = 9.54

I am told this equation works out as:
4.24x2.25 = 9.54

When I work it I get a different figure - what am I doing wrong:

[2x(1.5x0.707106) x1] x 2.25

which works further as:

2 x 1.0605 x 1 = 2.121 x 2.25 = 4.77

I should be getting 9.54 - but I get 4.77.

Thanks

 

[stapel]

I have an equation for a roof area/loading I am trying to understand, can someone help.

The equation is:

[2x (3/2)Cos(45) x 1 ] x 2.25 = 9.54

If this is the equation, where is the variable for which you're needing to be solving? (As a "statement", having no variables, it is false, since the left-hand side does not equal the right-hand side. The sides are off by a factor of 2.)

I am told this equation works out as:
4.24x2.25 = 9.54

When I work it I get a different figure - what am I doing wrong:

[2x(1.5x0.707106) x1] x 2.25

which works further as:

2 x 1.0605 x 1 = 2.121 x 2.25 = 4.77

Not knowing what the original formula or actual equation was, it is difficult to advise. However, your computations are correct.

 

[rooflog]

Hi, Sorry for the late reply, but here is hopefully all the official info to explain the equation (link to PDF below) - you will see the equation under 'Roof Load', top right of the PDF:

http://postimg.org/image/y5tyi0bsr/

Hope someone can explain. Thanks

 

[stapel]

Hi, Sorry for the late reply, but here is hopefully all the official info to explain the equation (link to PDF below) - you will see the equation under 'Roof Load', top right of the PDF:

http://postimg.org/image/y5tyi0bsr/

Hope someone can explain. Thanks

There's nothing to "explain". Assuming they posted the correct formula and the correct inputs, then their output is wrong. Otherwise, one must assume that their inputs or formula were incorrect. However, since we don't have access to the document (which is, I think, a British construction codebook) which served as the basis of their derivative document, there is no way for us to know wherein the error occurred.

As your image suggests at the bottom, if you're unsure (and need to be sure), consult with a licensed, bonded, qualified local construction company or contractor.