In times past flat garage roofs were often covered with a layer of waterproofed felt that was protected in turn by a layer of gravel. The general idea was that these roofs would last for years, provided that they were not interfered with. Over-and-above the obvious hazards of small children enjoying squishing on sharp stones, nothing lasts forever, leaks develop and drip onto whatever you use your garage for, and its time to Find a Builder fairly urgently, to effect repairs.
We have all kinds of rated general builders listed on Mr-Skill. You can Find Recommended London Builders here, as well as trusted building firms in the Home Counties, and as far afield as Wales and Scotland too. When you do, these are the procedures that they should follow after you accept their Building Quote, give or take the peculiarities of your particular flat roof.
o On a clear day with no sign of rain the next day either, clear the gravel off the roof. Sweep the area clean, and blow all the dust away with one of those clever gadgets gardeners use instead of rakes these days.
o Inspect the roof felting very carefully for any signs of damage. Don’t be shy to prod and probe as dentists like to do – if there is a problem it must be found. Mark a circle around any dodgy points with bright paint.
o Obtain some asphalt plastic cement, and work this well into all the dodgy points you noted. Take your time here, as this could make or break the job. And do wear rubber gloves too. This stuff sticks to skin like you know what. As you go along, work pieces of roof patching fabric into the cement, remembering to cover it fully and to “feather” the edges.
When the patches are nice and dry inspect them carefully, adding a generous dollop of asphalt plastic cement if in any doubt at all. When you are completely satisfied that this cement is dry too, you can gently sweep the old gravel back over the roof again. Or spoil your roof with some brand new gravel, so you can enjoy looking down on your garage roof again from upstairs even more.