To be honest it is difficult to give ideas for me with out knowing about your young bird training system and the background for the birds behavior.
I don't want to talk about something that you are already doing or you already know.
So, if you don't mind I am going to say a few things in general that might help anyone who face a similar situation:
In the TRAINING
article I mentioned briefly about the dropper system.
I think, this is probably the most crucial phase of the training process to avoid the issues you are having.
Getting the young birds to land when they see other birds released to the ground in front of the loft or a single dropper being released is very important.
A lot of the fanciers use this system but since many of us want to see the young birds performing as soon as possible we start pushing them to fly longer and longer.
It might be smarter to take about a week to get them to practice landing for the droppers on the ground.
Even after this period always keep a bird in hand and never let the young birds land on their own.
If you see one coming down release the bird in your hand to the ground.
It should become automatic for the young birds that they will only land if there is a bird on the ground.
Only after this phase is established we should start pushing them to increase their flight time.
Now, even with the dropper system established and the birds are flying hungry (they don't necessarily have to be starving, especially if you are unable to increase their flight time. Then it is more practical to feed them about 1/3 of their daily feed in the morning and give them the 2/3 after they come back from their training flight in the afternoon) you might get a bird or two misbehave and land on any where but the ground in front of the loft.
This should not be acceptable for any age of a bird.
When we first let the young birds out of the loft and they don't know the surroundings, it is ok for them to fly up and land on top of the loft for a few minutes.
However, they should not get comfortable up there.
I would say after a few minutes it is good to move them with a stick or your arm and encourage them to fly down next to the other birds on the floor.
After a few times the young bird lands on the loft's roof top, it should no longer be allowed to do so.
Rule should be when released from the loft you fly and when the dropper(s) are released to the ground you land next to them.
No where else!
If these steps are followed strictly then the possibility of young birds landing on roof tops or trees should be almost none.
I say almost because whatever you do at some point there will be a bird landing somewhere other then the landing strip in front of the coop.
What do you do?
Well, why is the bird landing there?
A hawk attack maybe (which is a very valid reason to land if the hawk is avoidable doing so).
Bird has flown the time frame it has been conditioned to and a dropper is not shown (which can be avoided by paying attention to details during training and knowing the limits of each bird, which change almost daily).
Bird has flown the time frame it has been conditioned to and the dropper is on the ground but the other birds he is training with in the kit are still wanting to fly and it is unable to decide what to do (which can be avoided by flying the longer flying birds first and adding the shorter flying birds later into the kit to insure they all are ready to land about the same time)
Any way, the bird landed there.
If it is looking down at the loft and acting like it wants to come down, don't be alarmed.
It is a one time deal and it will be ok.
Just make sure the next day’s flight is a bit shorter for him and if he comes down from where he had landed after all the other birds land he does not get any feed that day.
To do this it is important to condition your birds that as soon as the last bird lands they will all be walked to the coop and feed will be given and the door will be closed.
So, if the birds all land get them all into the coop and feed them.
While they are eating, if your roof-lander comes down don't let him in until every piece of grain is eaten by the other birds.
Then, he goes in and has to wait for the next days feeding.
If the bird lands in to the same place or any other place other then the landing strip we talked about the next day, I would ground that bird for a couple of days and until I make sure he knows how to land I will not let him fly with the rest of the birds.
I think most fanciers make the mistake here.
Bird lands somewhere and it is flown again with the kit the following day again.
If the bird lands again in an out-of-bounds place, I would bet, it is going to take him longer to come down to the coop this time.
(There is an exception to this, there are some young birds that develop a habit of landing at an off location for about a second or two then come down. I would treat this behavior as if they spent the whole afternoon there)
So, the bird is flown with the kit again and lands on the roof of the house again and it is taking longer for it to come down.
What you are going to see next is another bird also landing or attempting to land on that area, because now that bird sitting on the roof top became the closest dropper to the flying birds.
Not all the birds we fly are boneheads so some birds are going to respect your strict training and land as they should.
However, I would not allow what is happening on that roof top to continue because soon you will have no young bird do what you want and you can kiss your training goodbye.
Can't you just let them do as they wish? Some might even start performing like this?
The answer is no.
They will never perform the way they would with a disciplined training for one.
More importantly, if they ever get their performance to develop and start flying for couple of hours, then you have a bigger problem.
After 2 hours they land there.
Sit there for another couple of hours then decide to come down to the coop.
But, wait as soon as they get airborne, what happens?
They do a combination and they are gone flying again.
After 45 minutes to an hour they will land back on the roof exhausted.
After that I think it is safe to say if they are not picked up by an hawk, sitting out there waiting to be picked up, they will most likely spend the night out there.
The following morning you will find them in front of the coop.
This might happen a few times more but for sure one morning you will not see that bird any more.
Owl, cat, what ever, that roof top will be the end of it.
I am not even talking about al the possible problems with the neighbors and what kind of additional problems that could cause.
What to do if they already have this bad habit?
Never fly what some of us call tree-huggers with other birds.
If you think you can retrain them go for it but alone or with other tree-huggers.
Unfortunately, this bad habit is just like any other bad habit, very difficult to quit!
In most extreme cases you will have a situation where you can no longer fly these birds.
You throw them up in the air and they go land on the roof or the tree where ever is their favorite place.
What do you do with these boneheads?
If you can't separate from them then there is one thing to do and that is playing the homer guy.
You have to get these guys in a box and before leaving the house, release your droppers in front of the coop (Keep the coops door closed. You want to let them in yourself.)
Then drive a few blocks down and release them (throwing them up or tossing them is a better bet).
Go back home and get the ones that came back and landed on the ground in to the coop and feed them.
Wait for the ones that came back and landed on the roof top or the tree to let them in when they decide to come down and not feed them.
If you still want to work with these guys, the following day release the droppers and put your tree-huggers in a box and drive twice the distance of the previous day and release them.
Now, when you release them and come back home and they are still flying you do not need to increase the release distance the next day)
Any way, these are the things that come to my mind right now.
I am sure there are a few other things also.
Good luck and keep us posted on the developments please.