Typical scope
- Built-up (BUR) repair: felts, hot or cold-applied asphalt, gravel surfacing
- Modified bitumen (SBS and APP): torch-applied, cold-adhered and self-adhered
- Blister, alligatoring and split repair
- Cap sheet replacement and granulated surfacing
- Flashing rebuilds at parapets, curbs and drains
- Reflective coating over aged bitumen to meet cool-roof requirements
Built-up roofing
The original flat roof: alternating layers of asphalt and reinforcing felt, usually surfaced with gravel or a cap sheet. A well-built BUR system is redundant by design, several plies means several chances to stop water, and many are still performing well past thirty years. They are heavy, they need a deck rated for the load, and hot asphalt application is disruptive and increasingly restricted. Typical failures are blistering between plies, alligatoring of the surface asphalt as it oxidises, and splits where the deck moves.
Modified bitumen
Asphalt with polymer modifiers added for flexibility, reinforced and supplied in rolls. SBS modifiers make the sheet rubbery and forgiving of movement, and it can be torched, mopped, cold-adhered or self-adhered. APP modifiers make it more plastic and more heat-tolerant, and it is normally torch-applied. Both are commonly installed as a two-ply system: a base sheet and a granulated cap.
Torch application is a genuine fire risk on an occupied building and is restricted or prohibited in some situations. Cold-applied and self-adhered systems avoid the open flame entirely and are worth asking about, particularly on residential and multi-family work.
Repair or restore
Bitumen roofs repair well. Blisters that are not leaking can often be left alone; blisters that have broken are cut, dried and patched with compatible plies. Splits are bridged with reinforcing fabric and mastic. When the surface has generally oxidised but the plies are sound, an asphalt-compatible reflective coating restores waterproofing and adds a cool-roof surface at the same time, often the most economical outcome on an older California building.