I have had a fibreglass flat roof installed on the garage which ajoins the house; unfortunately I did not have the roof timbers replaced as well. As a result of this, I now have pools of water collecting on the roof which because of the very cold weather is now freezing. The ice seems to move making very loud cracking noises; is there anything that I can do tp prevent this? I have thought of putting gravel on the roof to prevent large shards of ice forming; would this damage the fibreglass or would it be OK? I can't really afford to have the roof re-done.