Modified Bitumen Roofing
Torch and self-adhered modified sheets for low-slope.
What modified bitumen roofing involves
Mod-bit in plies with the cap sheet detailed at every edge and penetration.
A proven low-slope system where a membrane is not the right answer.
What matters on modified bitumen roofing
Drainage before material
The first question on any low-slope roof is where the water goes. Ponding is what kills membranes, and a roof that holds water for days after a storm will fail early regardless of which sheet is on it. We look at the slope, the drains and the terminations before we talk about material.
Seams and terminations
Field failures on commercial roofs are rare. Failures at seams, curbs, drains and the parapet edge are common. A hot-air welded seam that has been probed is a continuous sheet. Anything taped or glued and unverified is a scheduled leak.
How the system goes together
Dry-in is the real milestone
The moment that decides whether a re-roof goes well is not when the last shingle goes down, it is when the deck is covered, taped at the penetrations and sealed at the edges. From that point the house is weather-tight and everything after it is finish work. A crew that understands this never leaves at the end of a day with bare deck showing.
Ice barrier goes down first
Eaves, valleys and every pipe before any field underlayment. Working from the bottom up means every sheet laps over the one below it the way water expects.
Then the metal, then the field
In that order, every time.
How long a bead of sealant lasts
Roof sealant is a consumable. In this climate, with the ultraviolet load and the temperature swing, a good product stays flexible for a handful of years and then shrinks, crazes and pulls away from one side of the joint. That is normal and expected behavior for the material.
Design so sealant is a backup
Every joint that matters should shed water by its shape, with the sealant there as a second line. Where sealant is the only thing standing between water and the deck, somebody has signed you up for a maintenance visit every few years.
Ask what is holding a repair together
If the answer is caulk, ask again.
What we check
- Field condition and granule loss
- Valleys, ridges and every transition
- Penetrations and their flashing
- Gutter and fascia condition
How we approach it
Look first
We get on the roof and read what is actually happening before quoting anything.
Say what we find
Photographs and a plain explanation, including when the answer is that you do not need us yet.
Built in sequence
Crews we hire and run, working the right detail in the right order.
Leave it clean
Magnet over the yard, container gone, walked with you.
Ice dams start at the eave
The mechanism is simple and it ruins ceilings. Heat escaping the living space warms the deck, snow above melts, the water runs down to the cold overhang past the heated wall line and freezes there. The ridge of ice that builds up backs meltwater under the shingles.
The fix is not a heat cable
Cables buy a season. Sealing the attic bypasses, getting insulation depth right at the top plate, balancing intake and exhaust, and running ice-and-water shield well past the interior wall line is what actually stops it.
Thermal shock on metal and flashing
Metal moves. On a sunny winter day a standing seam panel or a piece of valley metal can run a hundred degrees warmer than the air, then drop back after dark. That expansion and contraction happens every clear day of the year here. Panels have to be fastened so they can move, clips have to be right, and a valley has to be detailed to slide instead of being pinned tight at both ends.
Pinned metal tears its own holes
When movement is blocked, the fastener holes elongate and that becomes the leak path.
Where roofs go wrong
The shortcut we see most
A membrane laid over wet insulation because tearing off would have cost a day. The roof looks finished, the moisture stays underneath, and the sheet fails early from below.
What good looks like instead
Moisture surveyed, wet sections cut out and replaced, drainage corrected, then the membrane installed and its seams probed.
Signs worth a look
- Ponding water still standing two days after rain
- Seams that have lifted or opened at an edge
- Blisters or ridging across the field
- Interior staining near drains, curbs or the parapet
What to expect
Scheduling around your operation
Most commercial work can be staged so the disruptive part happens when the building is quiet. Tear-off noise, crane or hoist time and material deliveries all get planned against your hours rather than ours.
What the roof survey covers
Before specifying anything we survey the existing assembly: slope and drainage, moisture in the insulation, the condition of seams and terminations, and how the roof is being used. A roof somebody walks on weekly needs a different answer from one nobody touches.
Documentation
Commercial and public work runs on records. We photograph the existing condition, the work in progress and the finished assembly, so there is a file rather than a recollection.
Related work
Commercial covers more than one job, and they are not interchangeable. These are the others in the same family, each on its own page.
Questions we get asked
Not the question you had? Call the shop and ask a person. We would rather talk it through than have you guess from a website.
(801) 382-8898Which membrane is right for my building?
It depends on the traffic, the exposure and what comes out of the exhaust. TPO and PVC are welded and light, EPDM is proven and has fewer seams in wide sheets, mod-bit and built-up are heavier assemblies. We specify for the building rather than for what is on the truck.
Can you work around our business hours?
Usually. Most commercial work can be staged so the noisy part happens when the building is quiet, and we talk about that before the schedule is set.
How long does a commercial membrane last?
It depends far more on drainage and detailing than on the sheet itself. A membrane with standing water on it and a membrane that drains properly will not last the same length of time.
What happens if you find bad decking?
We show you. The decking is only visible during a tear-off, so that is when soft sheathing gets found and replaced. We photograph it rather than just add it to a list.
What makes a Utah roof different?
Snow load, ice at the eaves, canyon wind and high-altitude sun, all on the same roof. A crew that learned roofing somewhere mild has to learn it again up here.
Will you tell me if I do not need a new roof?
Yes. Plenty of what we look at turns out to be a repair, and we say so. A roof with years left in it gets left alone, and you get the photographs either way.
Ask about modified bitumen roofing
Call (801) 382-8898 or send a note. We will look at the roof and tell you straight what it needs.