Walking on some roofs causes damage: These are the very “footprints of damage” which occur on fragile, old, worn roof shingles.
A little story: A “failed” roof was not leaking until the fellow who was asked to inspect it walked across this fragile surface. From a ladder at the roof edge one could clearly see the virtual footprints of broken shingle edges where the “inspector” had walked. In this case the “inspector” was a roofing contractor who came back down to the ground and told the home owner that she needed a new roof right away.
She was upset because her ASHI-certified home inspector had said that the thought she could use the roof for another two to five years. Our opinion was that she did need a new roof very soon but that had not been the case until “bigfoot” had stomped all over it.
Worn out fragile roofs: The roof should not be walked-on. I would stay off of worn, brittle, or cupped-shingle roofs, particularly in cold weather (shingles are more likely to break).
If we absolutely have to walk on such a roof, we would tiptoe carefully, avoiding stepping on the raised or cupped shingle sections, or if doing repairs, we would prop a ladder up off of the roof surface and work from that scaffold as is sometimes done with slate or other fragile roof surface repairs.
Guidelines for Direct Walking-On Inspection of Various Roof Surfaces & Roof Conditions
Some home inspectors reduce their workload and speed the the job by asserting that they do not walk on any roof surface under any condition, citing reasons of safety or fear of damaging the roof surface. But expert inspectors generally agree that there are many roof areas, conditions, and important roof defects, even total roof failure (such as thermal splitting), that are simply not visible except direct access to the roof edge (by ladder or other means) or by walking on the roof.
Do not try to walk on any roof which is: too high, steep, wet, slippery, fragile, for safe access, and do not walk on any roof which is installed over an incomplete, damaged, or rotted surface, as you might, like my helper on one roofing job, fall right through the roof surface!
The determination of the safety and reasonableness of inspection method of any roof (or any other building component) is the sole responsibility of the building inspector, with the exception that the building owner also has the right to ask that the inspector omit or not access any building component or system. The inspector is required in all cases to describe how an inspection was performed or if it was not performed, to explain why and to explain the implications of this to his or her client.
Cement asbestos roof shingles: these shingles are as fragile as slate; it’s best to stay off of this surface. Though we’ve walked carefully on a few such roofs it’s easy to damage them.
Cupped roof shingles: stay off in cold weather; inspect the shingles from the roof edge, from upper building windows, or if the roof must be walked-on, step carefully in the cupped portions on tiptoe, avoiding stepping on the raised curled portions of the shingles as otherwise you’ll break off large corners and may lead to an immediate need for re-roofing. If the shingles are also brittle, even in warm weather, do not walk on the roof.
Cracked roof shingles: vary in fragility, depending on shingle age and reason for cracking. Some “cracked” roof surfaces such as roofs damaged by thermal splitting, are not likely to be further damaged by careful direct inspection by walking their surfaces.
Curled roof shingles: as with cupped shingles, stay off in cold weather; inspect the shingles from the roof edge, from upper building windows, or if the roof must be walked-on, step carefully on the flat portions of the shingle, on tiptoe, avoiding stepping on the raised curled edges of the shingles as otherwise you’ll break off the edges. If the shingles are also brittle, even in warm weather, do not walk on the roof.
Fishmouthed roof shingles: are fragile and may be damaged if you step on the raised portion of shingle. If the fishmouthing is on a fairly new roof and the shingles are not otherwise brittle it may be possible to walk on such a surface.
Low-slope or single membrane roofs: can often be safely walked-on but beware of fragile, worn roll roofing which may be damaged by careless foot traffic, and beware of raised blisters, ridges, wrinkles which can also be damaged by careless walking.
Metal roof surfaces: can be walked-on provided (1) the roof is not too steep and (2) the metal roofing was installed over closely-spaced nailers or sheathing. Beware that some metal roofs may be installed directly over rafters and widely spaced horizontal nailers, and may be fragile or subject to denting. Do not step on raised seams or other flashing areas that may be damaged; beware, metal roofs are very slippery when wet. The metal roof in the right-hand photo above was high, steep, and slippery. We would not consider walking on such a surface.
Slate roofs: are fragile and are likely to be damaged by foot traffic; it’s best to stay off of slate roof surfaces during a building inspection.
Wood shingle roofs: are fragile and will be damaged by any foot traffic. We’ve walked on new, good-condition wood shingle roofs but they are easily damaged by foot traffic which can cause splits in the shingles. In addition wood shingles are often slippery and dangerous to walk on and absolutely slippery when wet.
Wet, Icy, Steep, Snow-Covered roofs: are unsafe to walk on in most circumstances.