Ballast weight for non penetrating roof mount - gibertini 125

[roccky]

Hello!!

I am wondering how much weight is necessary to add as ballast for a non penetrating roof mount installation of a gibertini 125, with polar mount and actuator. In London. Assuming the roof receives some average level of wind, in a 3 storey building

I have found some tables online but the parameters of the formulas behind them are a bit hard to find out. Is there anyone who could help me with some more practical advice?

Also, if you know any good roof mount, that would be helpful. Not sure if this one would provide enough support?

Pro 3

Are you looking to install a home satellite dish system? With quality brands at low prices and years of experience, SystemSAT is the retailer for you

www.systemsat.co.uk

 

[TJExcalibur]

A strong gust of wind at that height on a 1.25 dish would need 8 compressed paving slabs to hold it in place. The wind only needs to lift one side as the stand pivots on the other side. Wire ties to the edge of the roof would help.

 

[Channel Hopper]

I would use a mount with a larger floor profile ( a 5 x 5) but you might get away with adding some bags of ballast overhanging the four corners.

 

[Terryl]

Good rule of thumb, is 5 to 7 times the combined weight of the dish (motor if used) and base, more if you are in a high wind area.

Also be sure to have the mount cover at least 3 roof rafters/joists to distribute the total load.

Also be careful as the roof cant be more then a 4/12 pitch if your mounting the dish on one side, I have seen them slide off a roof.

 

[roccky]

I have found another option:

ALLTRADE 3" x 3' Heavy Duty NPRM PRO from Alltrade

www.alltrade.co.uk

Probably better? 50"x50" floor base this time, and 32 kg instead of 25kg.

I think the Gibertini with the polar mount, actuator, lnb is around 20kg. Plus base makes 50kg. Which means I would need around 300k weight? These paving slabs are around 40kg each:

600x600 50mm Council Paving Slab | Lawsons

The 600 x 600 x 50mm Council Paving Slab, in natural grey colour, is our most popular, cost effective, robust long lasting paving product. It has a lightly pimp

www.lawsons.co.uk

So with eight of those we get 370kg all together. Together with some cables to the edge of the roof it sounds solid, which is the main priority: we def don't want it to fall to the street. But are we sure it is not going to break the roof? What if we can't find those 3 roof rafters... better forget about this option?

Also, I guess "flat roofs" are generally not necessarily flat, and I can imagine that putting stuff in the corners to lift them up is a very bad idea. Is there any smart way to create a flat surface for the base?

 

[Channel Hopper]

Divide the total weight by the floor area and it is unlikely to be more than one person standing on two feet.

For a 1.2m dish I would not expect to lay more than 200kgs of ballast in an exposed area

 

[moonbase]

'ere, go and buy 4 concrete Kerb Stones from Travis Perkins, about a tenner each for 3ft x 6" x 5".
Bolt the NPRM to them, one on each corner.

 

[roccky]

Thanks. Although I couldn't find those 3ft x 6" x 5" kerb stones. But I understand the paving slabs I had found would be the same more or less?

"For a 1.2m dish I would not expect to lay more than 200kgs of ballast in an exposed area" It seems very consistent with the table: 3.25 CuFt is around 200kg. And I guess there are no wind gusts over 120mph in London, no? So it looks like should be enough.

What do you think guys about the last point. "Also be careful as the roof cant be more then a 4/12 pitch if your mounting the dish on one side, I have seen them slide off a roof" Apart from that we want the pole straight to be able to orientate the dish, no?

 

[Terryl]

They make a non penetrating roof mount for pitched roofs, it's called a saddle mount.

VMP PRM-2 Non-Penetrating Pitched Roof Mount for Satellite Dishes & Antennas | Video Mount Products

Buy the VMP PRM-2 Non-Penetrating Roof Mount for Satellite Dishes & Antennas at www.Arcade-Electronics.com. We are a Authorized Video Mount Products Distributor with a big selection of VMP Products in stock ready to ship.

www.arcade-electronics.com

 

[roccky]

Thanks, but that seems to work only for small dishes. And anyway, the pole still not straight apparently

 

[Terryl]

That was just an example, there are many others to look for.

 

[Channel Hopper]

Thanks, but that seems to work only for small dishes. And anyway, the pole still not straight apparently

How far off vertical is the post ?

In most cases a slight angle can be corrected (if near true N/S) with the elevation adjustments and some playing about with the others.