Fermacell, Verspaanel, Magply for sheathing

[Molynoox]

Hi,
I am building a 9 x 4m workshop / garden room
I am trying to do it in accordance with building regs and permitted development - one of the regs is regarding fire resistance of buildings which are within 1m of boundary fence. I did speak to building control to talk things through and they seem happy for me to use a cement board (instead of OSB) on the outside as sheathing, thus making my build exempt from building control.
There appear to be three options:
1. Fermacell
2. Versapanel
3. Magply

I have heard stories about the weight and difficulty cutting these types of materials

Questions
1. Which is the most recommended product from those three options or are there others I have missed?
2. Am I mad? - most people (even garden room companies) are using OSB, even on builds which are tight on the boundary (<1m)

thanks
Martin

 

[Molynoox]

Here is a picture of my wall section
My walls are actually 5 x 2 now with thicker PIR, don't suppose that matters regarding my original questions but mentioning it for completeness

 

[Molynoox]

and my stud structure below - not sure if that is needed but I like context

 

[Molynoox]

well I didn't get any replies on this, I guess it's too niche, or maybe just boring :-D
anyway, I thought I would provide an update; I bought the Fermacell stuff, it was more expensive than OSB, and three times heavier, and harder to cut. But overall I managed it all on my own, and its now compliant to building regs, or more accurately it is exempt from BR.
I managed to cut the boards no problem with my circ saw (although it is a twin battery one) using a 16 tooth regular wood blade, which was one of the concerns, but it wasn't a problem. You do need a good mask though obviously.

 

[RichardG]

This fire resistance when close to a boundary seems to be a bit open to interpretation. I built a 3 bay garage, one wall was within 2m of a field boundary but tapered to 1m as it ran. There's a page in the building regs which allows you to calculate the fire resistance needed, it turned out that some of the wall had to be fire resistance? One inspector said I could get away with lining the internal wall with fire resistance plasterboard with insulation. Due to delivery issues this hadn't arrived before the final inspection, however, this inspector said it was all fine and issued a completion certificate! I think the key is to keep the inspector onboard and make sure he's the one who signs it off....

Looks a nice job though, don't forget to post an image when its complete.

 

[Molynoox]

Richard, that is pretty interesting, I am not sure on the rules about proximity to field boundaries, I only understand the part about proximity to neighbour's gardens (not sure if that is the same thing?) When it comes to neighbours fences it needs to be minimum 1metre away, or made of mostly fire proof stuff. Mine is 0.5m metres away so I used mostly non-combustible materials.

I did speak to my local building control guy and he is OK with everything I have done and considers it exempt.