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Roof restoration, step by step

From scan to finished roof

The order matters: find out what, if anything, is wet, replace only that, then build the coating system over the roof you already have, with no tear-off and the building open. It starts with a drone moisture scan, and nothing has to be decided until you have seen the map. Below, each step and who does it: you, the installer, Sherwin-Williams and us.

Request a moisture scan Will a scan work on your roof?
Gloved hands brushing white coating over a strip of reinforcing fabric along a roof seam, an open pail beside them

Part one: survey and repair

Before the field is coated

Applied over a sound, dry roof, a restoration system adds 10 to 15 years of service life. These six steps make sure the roof is sound and dry, and they settle restore or replace before anyone budgets for a coating.

  1. The moisture scan

    With your written go-ahead, we arrange a flight on an evening after a sunny day. Wet insulation holds the day's heat longer and shows warmer to a drone's thermal camera. You get a map with any area that looks wet outlined and measured in square feet, video from the flight and a written assessment.

  2. An installer cores the flagged areas

    No contractor yet? We introduce one from our network anywhere in the US, who looks at the roof, says whether it is a good candidate and cuts small cores at the flagged areas, patching each one. The scan marks suspects; the cores confirm them. If so much is wet that replacing wins, you learn it here.

  3. The adhesion test patch

    The installer puts the actual system down on a small area with a strip of fabric embedded, lets it cure and pulls it. For Silicone44 that is three days, and Uniflex looks for at least 2 lb per inch; a lower result goes to Uniflex, which names the primer. Nothing else settles whether it holds.

  4. The scope and the material count

    Once you decide to restore, the installer writes the scope: the system per roof area, the field and any wet area coming out, in square feet, linear feet of seams, the curbs, drains and penetrations, and any system warranty. We count the material off it and reply within one business day.

  5. Materials ordered and shipped

    Genuine Sherwin-Williams Uniflex in the maker's sealed packaging, counted off the scope. Stocked items ship in 1–3 business days: pails by parcel or pallet, drums and totes by freight, with a lift-gate where there is no dock.

  6. Replace what the cores confirm wet

    Each confirmed wet area is cut back to sound material, the insulation replaced to matching thickness and the patch tied back into the field. Coating makers, Sherwin-Williams included, require wet insulation to be found and replaced before a coating goes on: over it, a coating seals the water in.

How the scan works

What step one hands you

A suspect on the map, before anything is cut

A sample from a real scan, with the address, the people and the companies removed and the map re-oriented. Wipe between the daylight photograph and the thermal image of the same patch of roof.

  • A flagged area between two curbs

    The sample roof in daylight: a dark ponding stain on gray membrane between two rooftop curbs, an orange dotted outline wrapped around it in a C shape Daylight
    The same patch in the thermal image: a C-shaped warm band inside a white dotted outline, around a stain that reads no warmer than the open roof Thermal
    Area flagged
    176.2 sq ft
    Warmer than around it
    +8.5 °F
    The ring of roof around a ponding stain reads warmer; the stain itself does not. Nothing in the sample was cored, so this is a suspect until a core confirms it: that is step two.

The sample shows the map and the image pairs; a full scan also comes with video from the flight and a written assessment. On ballasted or heavy-gravel, metal panel, white-coated or closed-cell foam roofs the camera is the wrong tool, and the survey is done another way.

Part two: on the roof

The system, built from the roof up

The order is the same on every roof type; what changes is the primer, the detail materials, the chemistry and whether a base coat goes on. The data sheet names the preparation, the rate and the cure for each coat, and a written specification wins over this list. The installer's crew does every step.

  1. Clean

    The roof is washed and left to dry: dirt, oils, ponded silt and loose granules come off, and rust on metal is treated. The coating bonds to whatever is left.

  2. Repair, then prime by substrate

    Splits, blisters and loose fasteners are repaired. Then the primer: rust-inhibitive on corroded steel, the wash primer on EPDM only, the concrete primer under an acrylic. Under silicone, weathered TPO and PVC, foam and concrete take none; newer asphalt takes a bleed-blocking primer we do not stock.

  3. Detail every seam, fastener and flashing

    Seams, fasteners, curbs, pitch pans, drains, flashings and pipes get fabric set in coating, seam tape or sealant before the field is coated. Under silicone, Uniflex specifies its OneFlash sealant at curbs and penetrations, which we do not stock. Restored roofs are won or lost here.

  4. Base coat, under an acrylic finish

    Over the whole field and every detailed area, in the chemistry the substrate calls for; the single-ply and modified bitumen bases must be topcoated with an acrylic finish. Silicone44 takes no base coat: it goes onto the prepared, primed roof.

  5. Finish coat

    The surface the weather sees: acrylic where the roof drains; where water stands after rain, Silicone44 KST044300 (white) or KST044320 (gray), or on metal, foam and asphaltic roofs the solvent-based pair KST042200 and KST042100. Silicone resists standing water; it does not fix drainage.

  6. Final inspection

    Walk the finished roof with the installer, scope in hand. Where a system warranty is wanted, Sherwin-Williams inspects the finished roof before it issues one.

Find the system for your roof

The build-up, with part numbers

The same order, three different roofs

Read each column from the bottom up, in the order the work goes on. The roof the building already has stays, less what the cores confirm wet; everything above it is what the restoration adds. These are the acrylic build-ups: the substrate decides the primer, the detail material and the base coat, and on modified bitumen the base coat is the first coat. Where water stands after rain, Silicone44 goes on instead, with no base coat under it. The adhesion test patch settles whether the stack holds on this roof.

Metal

  • Finish coat KST041300
  • Base coat KST041320
  • Seam tape KST020804
  • Primer KST034520
  • Existing metal panels

EPDM

  • Finish coat KST041300
  • Base coat KST041321
  • Bonding tape KST058006
  • Wash primer KST038620
  • Existing EPDM membrane

Mod bit, smooth BUR

  • Finish coat KST041300
  • MB base coat KST041510
  • Fabric KST20385B in coating
  • Existing asphaltic roof
Order of application, bottom to top, on a roof that drains. Illustrative diagram — proportions are not to scale.

Roles and decisions

Who does what, from scan to warranty

We arrange the scan, supply the materials and introduce an installer anywhere in the US; we never do the roofing work ourselves. Structural, permit and tax questions belong to the people named here, and nothing on this page is advice on any of them.

You, the building owner The go-ahead for the scan, in writing; access to the roof and the building; and the decision to restore, replace or wait, made after you have seen the map and the cores.
CoatYard Arranges the scan, introduces an installer from our network anywhere in the US, and quotes and supplies the materials to the owner or contractor. Never applies coatings or issues a system warranty.
The installer, a roofing contractor Says whether the roof is a good candidate; cuts the cores, runs the test patch, writes the scope, replaces wet sections and applies the system, naming in the scope who applies for any permit.
The manufacturer, Sherwin-Williams For a system warranty: requires a moisture survey, by a third party for a 15-year warranty; inspects the finished roof; issues the warranty through its authorized contractors, under its own terms.
The building's engineer Anything structural: what the deck can carry, why the roof deflects or holds water, and what may be added to it.
The local building department Whether the work needs a permit, and whether another layer is allowed on the building at that address.
Your accountant How the work is treated on the books. Many owners treat restoration as maintenance for tax purposes — worth a word with your CPA.

Choosing a contractor

While the work goes on

What the building notices

For the people inside, the work happens overhead and the roof over them stays on; only sections the cores confirm wet are opened. Not tearing off is also why it costs less: restoring typically runs $3.50 to $7 per sq ft installed, and tearing off and replacing typically runs $10 to $18. Those are typical installed ranges from published industry figures, not a quote; the roof's condition, the wet area, access and region move them.

  • No tear-off: the existing roof stays on and carries the new surface
  • The building stays open and in use while the crew works overhead
  • Crews work in sections, planned around the parts of the building in use
  • No hot kettle and no open flame on the roof
  • Weather sets the dates: coating goes on a clean, dry roof, with time to set before rain or dew

Run the numbers

A pallet of plain white five-gallon pails and rolls of reinforcing fabric on a flat commercial roof, a roller on an extension pole beside them

Questions

What owners ask before the work starts

How long does a roof restoration take?
It depends on the roof's size, how much, if anything, has to be cut out and replaced, how many seams and penetrations need detailing, and the weather. The installer's schedule is the only answer worth having, and no one can give a real one before the roof has been surveyed and cored. The scan itself usually takes one evening. Ask for the schedule in writing with the scope, and for how weather days are handled.
Can the work be done in sections?
Yes. Crews work a roof in sections, and a building with more than one roof level or area is scoped area by area, so the work can be planned around the parts of the building in use. Spreading one roof over several budgets or years is a different question: in Florida, repairing, replacing or recovering more than 25 percent of a roof or roof section within 12 months can require that whole roof or section to be brought up to the current code, and the building department decides whether a coating job counts.
What weather stops the work?
Rain, dew, and temperatures outside the range on the product's data sheet. A coating goes on a clean, dry surface and needs time to set before rain or dew reaches it, and a water-based acrylic stays sensitive to water until it cures. The silicone data sheet sets a humidity limit as well. Expect the schedule to move with the weather, not the other way round.
What happens if the cores find more water than the scan suggested?
Then the cores win. A thermal scan shows temperature differences, not water: it cannot see under rooftop units, and a saturated roof may read as a mottled pattern rather than clean outlines. More confirmed wet area means more to cut out and replace before coating, so the scope and the price change with it. Manufacturers commonly draw the line for replacement somewhere between 15% and 30% of the roof, as a rule of thumb rather than a code limit. Better to find that now than under a new coating.
Do I need a permit to coat the roof?
The local building department decides, for the building's address: whether the work needs a permit, and whether another layer is allowed on the roof. Departments decide for themselves whether a coating counts as maintenance or as a re-cover, and maintenance does not always mean no permit: in Miami-Dade and Broward, Florida's code requires one for roof maintenance too. Ask each installer who applies for any permit and put the answer in the scope, so you can compare like with like. Nothing on this site is permit or code advice.
Will the building stay dry while the work goes on?
The existing roof stays in place throughout, which is the point of not tearing it off: it is never stripped to the deck in sections. The openings are the small cores, which should be patched the day they are cut, and any sections where wet insulation is cut out and replaced. Ask the installer how those are closed at the end of each day and before rain, and put the answer in the scope. Nobody should promise you more than that.
Can our own roofing contractor do the work, and is there still a warranty?
Yes. If you already have a roofing contractor, we supply the materials to them; if you have none, we can introduce one anywhere in the US. A system warranty is a separate matter: Sherwin-Williams offers UNIGUARD system warranties of 10 or 15 years when one of its authorized contractors applies the system, and it inspects the finished roof before it issues one. The warranty is the manufacturer's, issued under its own terms; we supply the materials. If you want one, say so before the scope is written.

What a restoration involves

Guides

Each step, in more depth

The test patch, the details, the weather window, and how a moisture map becomes a scope and a material count.

All guides

Start with the moisture scan

Send the building's address and we will quote the scan; the price depends on the roof's size and where it is. We arrange scans anywhere in the US, and nothing has to be decided until you have seen the map. Contractors: request a quote for the materials, or ask to join our installer network.

Request a moisture scan Request a quote