If the elevation of 30W is 24.6 degrees above the horizontal, you can visualize (or draw) an angle of 24.6 degrees, and check if the angle of the roof is steeper or flatter than that. So you can first check roughly, if there should be no problem at all, or that it might probably be problematic.
A rough estimate using the sun position could also help (you can use this calculator:
Satellite Look Angle Calculator ): as it is winter now, the sun is always beneath the clarke belt (seen from northern hemisphere), so if the sun is visible at your intended dish position at the calculated hour, there is no problem at all.
For exact measurement you should wait till the next sun outage, though.
Or make a construction of that 24.6 degrees, with bottom purely horizontal, and look along the top line of it to see if you have free line of sight towards the satellite at your intended dish position.
greetz,
A33