Best suited to
small, cut-up roofs with lots of walls and transitions, and any deck that takes regular foot traffic.
Modified Bitumen Roofing, at a glance
Modified bitumen is asphalt sheet reinforced with polyester or fiberglass, installed in two or more plies. It is tough underfoot, forgiving on complicated roofs, and common on older St. Louis commercial buildings and church halls. John Beal Roofing installs and repairs mod-bit with free inspections. Call (314) 429-6000.
The Short Version
Whether This System Fits Your Building
Service life
15 to 20 years for a two-ply system installed and flashed correctly.
What to watch
The laps and the base flashing up the parapet — that is where an aging mod-bit roof starts letting go.
Installation
Where These Roofs Actually Fail
Membrane failures are almost never in the middle of the sheet. They start at the details — the curb flashing, the pipe boot, the wall termination, the drain.
That is why we spend the time on the parts nobody photographs. A field seam takes minutes; a properly rebuilt curb takes an afternoon and it is what decides whether the roof makes twenty years.
We also register the manufacturer warranty on your building, so the coverage exists in writing under your address rather than in a folder somewhere.
Common Questions
How long will this roof last in St. Louis?
15 to 20 years for a two-ply system installed and flashed correctly. Our freeze-thaw cycles and summer heat are hard on any membrane, so the install details and a twice-yearly inspection matter as much as the material.
Can we recover over the existing roof instead of tearing off?
Sometimes. If the substrate is dry and the deck is sound, a recover saves real money. If a moisture scan shows wet insulation, tearing off is the only honest answer.
Do you install this system yourselves?
Yes. Our own crews do the work, and we hold manufacturer certifications for the systems we install, which is what makes the full system warranty available.
What does a repair on this system cost versus replacement?
A localized repair is a fraction of a replacement, and on a roof with remaining life it is the right call. We will tell you which one your roof is — with photos.
How disruptive is the installation?
Low-slope work happens on the roof, not inside the building. We coordinate hot work, odor and noise windows with the tenants or residents before we mobilize.
Free Roof Evaluation
Tell us about the building and a dispatcher will call to schedule.