ETA I'm presuming that you have a skirt of 36" wire buried all the way around it so that nothing can dig its way in.
If it were I, I'd put at least six inches of construction sand down for the run's floor.
Its been about 2 years with the chickens and the coop and some valueable lessons along the way..
First,
The grass...WHAT GRASS??? LOL Gone long long long time ago..But I knew that..Just thought it was funny reading some of the original comments..
Next,
The 'deer netting roof'...The funny thing was that is that it DID survive our snowmageddon January 2011 where we recieved 6 FEET of Snow here in CT in one month..GOOD GRIEF!.. The freekish Oct 2011 snowstorm did take it out. Which did have a negative affect on the chickens..read on :-(
The Chickens...
They have been incredibley enjoyable! We've even let them free range at times when we are outside around the yard..they dont go far and have their favorite spots..
So since the coop was secure, I would leave the coop door open at night during the Summer and early Fall months...Well after the roof netting collapsed and in between replacing the roof, I left it open too long..Something came in from above where there was no longer a roof around 5 am and grabbed the Golden Laced..I found it a day later on the roof of the coop. I felt horrible and of course responsible. I believe it was a Fisher Cat.
Well I replaced the roof with 2x4 wire wrapped over each edges and secured in place with wire and galvanized staples. Only predators with bolt cutters or a torch should be able to get in now and its spaced enough for snow to go through it and strong enough as well.
2 weeks ago we lost a Dominique who became egg bound. :-( The Dominiques are the best of the bunch. Now were are down to 4 but not for long. We have ordered 4 more (2 RIRs and 2 GLWs) and we should be getting them next week. Now the whole long process of raising and integrating with the rest begins...