PPS ROOFING / POWER PROPERTY SOLUTIONS
Flat roofing,
made easier to understand.
A roof for your home addition is a different decision from a roof for a busy warehouse. Here’s a practical guide to the options, what they do, and where they may fit.
We help owners with flat-roof repairs and EPDM and TPO roofing. We also explain other systems so you can understand the choices and ask better questions. Serving Arvada, the Denver metro, Colorado mountain communities, and the Western Slope.
START HERE
“Flat” roofs still need
a way to drain.
Most flat roofs have a gentle slope that guides water toward a drain, gutter, or an opening through the roof edge. They need roofing designed for slower-moving water; standard shingles generally belong on steeper roofs.
Think of the roof as a complete raincoat for the building. The broad surface matters, but so do the connections around pipes, skylights, walls, and edges. A good material cannot make up for a blocked drain or a poorly sealed connection.
YOUR OPTIONS, IN PLAIN LANGUAGE
Understand the system.
Picture it on your property.
Each system starts with what it is, using the roofing terms you may see in a proposal. Then we explain where people use it and why, with everyday examples, and a brief installation overview.
EPDM / synthetic rubber roofing
What it is: EPDM (ethylene propylene diene monomer) is a single-ply synthetic rubber membrane. Large sheets form the main waterproofing layer, with seams joined using compatible seam tape or adhesive.
Home additions, garages, and smaller commercial roofs: EPDM is often considered when the roof is too gently sloped for shingles. Its flexible rubber sheets can cover broad areas with relatively few seams.
For example: On a low-slope addition attached to a shingle-roofed home, EPDM can provide the waterproof roof covering while the steeper main roof keeps its shingles. It is also an option for owners who want an established rubber-roof system that can be maintained and repaired as it ages.
How it’s installed: The crew first checks the deck and removes wet or damaged materials within the agreed scope. Insulation and any specified cover board are secured to create a suitable base, with tapered areas laid out to help water reach the drains.
The EPDM sheets are rolled out and positioned, then bonded with approved adhesive, mechanically attached, or held with designed ballast, depending on the assembly. Overlaps are prepared and joined with compatible seam tape or adhesive. Separate flashing pieces seal pipes, corners, walls, and drains. Perimeter securement and edge metal finish the roof, followed by a check of seams and details.
TPO & PVC / thermoplastic single-ply roofing
What they are: TPO (thermoplastic polyolefin) and PVC (polyvinyl chloride) are different reinforced single-ply membranes with heat-welded seams. Both are commonly available with light-colored surfaces.
Where and why they’re used: TPO is commonly considered for warehouses, shops, offices, and low-slope homes. PVC is also used on these buildings, and certain products are particularly useful where rooftop grease or chemical exposure affects the choice.
For example: A shop owner replacing an old roof may choose TPO with new insulation and improved drainage. A restaurant owner may evaluate a PVC product approved for the kitchen exhaust that reaches the roof. Both provide welded sheet roofing, but their formulations and exposure limits differ.
How they’re installed: After checking the deck and addressing wet or damaged layers, installers secure the specified insulation and cover board. Tapered insulation may be used to improve drainage. TPO or PVC sheets are rolled out, positioned with overlapping edges, and secured using the approved adhesive or fastening system.
Hot-air equipment welds the overlapping sheets together. Large automatic welders handle suitable open seams; handheld equipment is used for smaller details. Compatible flashings connect the membrane to walls, pipes, curbs, and drains. The crew checks completed welds, addresses any gaps, and finishes the perimeter and edge metal. TPO and PVC require their own compatible accessories and welding procedures.
Mod bit / modified bitumen roofing
What it is: Modified bitumen, often called “mod bit,” is reinforced asphalt roofing improved with polymers. SBS adds rubber-like flexibility; APP uses a plastic modifier. Factory-made rolls are typically installed as a layered system with a base sheet and cap sheet.
Where and why it’s used: Mod bit is used on low-slope additions, garages, apartments, and commercial buildings where owners want a layered asphalt roof. The selected product and installation method can be matched to the building and access conditions.
For example: An owner replacing an older roll roof on a garage may choose mod bit for a reinforced, layered covering. An apartment building may also use it around rooftop equipment, with protected paths for service visits.
How it’s installed: The deck and existing roof condition are checked first, then the specified insulation or supporting boards are installed. A base sheet is followed by the required reinforcing layers and cap sheet. The overlaps are staggered as specified so the layers work together as a waterproof covering.
Depending on the selected product, sheets may bond through a factory-applied self-adhering backing, cold adhesive, hot asphalt, or a professionally controlled heat-applied method. Walls, corners, pipes, and drains receive matching flashing details. The crew checks bonded laps and transitions, then completes edge metal and drainage details. The specific SBS or APP product determines the installation method.
BUR / built-up roofing
What it is: BUR (built-up roofing) combines multiple plies of reinforcing felt with asphalt to create a layered waterproofing system. A protective surfacing, such as aggregate or a cap sheet, completes the assembly.
Shopping centers, offices, and other commercial buildings: Built-up roofing uses several reinforcing layers and asphalt to form the waterproof roof. Owners may choose it for its layered construction and long-established use on commercial properties.
For example: An owner replacing an existing built-up roof may consider a new version because the building was designed around that type of assembly. The structure must support the proposed weight, and removal and installation need to be planned around the occupants.
How it’s installed: Installers prepare the deck and supporting layers, including insulation and a suitable substrate where specified. Reinforcing felts are embedded in asphalt in successive overlapping plies, building the waterproofing in place rather than relying on one sheet.
The assembly receives its specified protective surface, such as aggregate or a cap sheet. Flashings tie the roof into walls, drains, and penetrations, and perimeter metal completes the edges. Access, material handling, and odors are planned around the building’s occupants. Final checks focus on complete coverage, sound flashings, and clear drainage.
SPF / spray polyurethane foam roofing
What it is: SPF (spray polyurethane foam) roofing uses closed-cell foam sprayed onto a prepared substrate, then covered with a protective roof coating. The foam provides insulation; the coating protects it from sunlight and weather.
Suitable commercial roofs where insulation is part of the goal: Spray foam forms an insulating roof surface around many shapes and details, with a protective coating over it.
For example: An owner evaluating an eligible roof with many pipes and irregular areas may consider foam to add insulation and form a continuous surface around those details. It suits an owner prepared to maintain and renew the protective coating; the existing roof must first be checked for moisture and damage.
How it’s installed: Trained applicators evaluate the existing roof for moisture, damage, and compatibility. Unsuitable materials are addressed, and the surface is cleaned, dried, and prepared; a primer may be required. Weather conditions must suit both the foam and coating products.
The foam is sprayed in controlled passes to the specified thickness, with the planned shape and details formed around roof features. A compatible protective coating is then applied at the required coverage, with additional treatments where the system calls for them. The crew checks foam and coating coverage, flashing details, and drainage. The coating remains part of the roof’s ongoing inspection and renewal plan.
OTHER APPROACHES
Sometimes the answer
is more than a new sheet.
Roof coatings
A coating can help extend the useful life of a suitable existing roof. Think of an aging but otherwise sound roof that needs a planned restoration rather than full replacement. First, the roof needs repairs, preparation, and a check for trapped moisture. Coating over rotten decking or wet insulation hides a problem instead of fixing it.
Coating types & product information ↗
Liquid-applied roofing
Some systems use liquid material with reinforcing fabric to create waterproofing around complicated shapes. For example, a tight cluster of pipes may call for a carefully detailed liquid system. These are designed roofing products with specific preparation and application requirements.
Low-slope metal
Certain metal roof systems work on gentle slopes, such as some long, simple commercial roof areas. Every panel has limits, and a metal roof needs the right slope and seam design. A panel chosen for its appearance may not suit a nearly flat roof.
Metal panel options & technical resources ↗
Roof decks & green roofs
A rooftop patio or planted roof needs more than waterproofing: it needs planned drainage, weight capacity, protection, and access for maintenance. An ordinary exposed roof is not a walking deck. These projects require a coordinated design.
WHAT’S UNDERNEATH?
The surface is only
part of the roof.
A sound base
The roof deck supports everything above it. If wood is rotten or another deck is damaged, it needs attention before new roofing goes on.
Insulation & a path for water
Insulation helps control heat loss and gain. Sloped insulation can also help water reach the drains. For example, a low spot behind a skylight may need a change in shape, not just another patch.
A protective roofing layer
The waterproof sheet or layered system keeps weather out. A firm protective board beneath it may be part of the design to help resist damage.
Well-finished connections
Flashings are the waterproof connections at walls, pipes, and edges. Drains and overflow outlets give water a route out. These smaller details often make a big difference to leak prevention.
INSULATION + DRAINAGE
What’s keeping the heat in?
What’s helping water leave?
Roof insulation slows heat moving into or out of the building. R-value describes resistance to heat flow: a higher value means more resistance. We select the insulation as part of the complete roof, considering space, drainage, moisture conditions, and the building’s energy requirements.
Polyiso / polyisocyanurate rigid foam
What it is: A lightweight, closed-cell foam board with factory-applied facers. Polyiso provides substantial insulation in a relatively thin layer and is widely used beneath commercial roof membranes.
Where and why: A heated shop or office getting a new TPO roof may use polyiso above the deck to improve thermal performance without adding unnecessary height. Boards can be installed in multiple layers with staggered joints as the design requires. The specified product and design R-value matter more than thickness alone.
EPS / expanded polystyrene rigid foam
What it is: A lightweight, closed-cell foam made from expanded polystyrene beads. Roofing-grade EPS is available in different strengths and thicknesses, including tapered shapes.
Where and why: An owner with room for a thicker insulation layer may evaluate EPS as an economical way to meet the roof’s insulation needs. It can also be shaped into drainage layouts. The correct density, compatible materials, and any required protective or separation layer must be selected for the roofing system.
XPS / extruded polystyrene rigid foam
What it is: A closed-cell foam board manufactured by extrusion. Roofing products are selected for their moisture resistance and compressive strength, among other properties.
Where and why: In a designed protected-membrane roof, insulation may sit above the waterproofing beneath ballast or pavers. Roofing-grade XPS is often considered for this moisture-exposed location. For example, a planned rooftop terrace needs insulation and protection suited to that assembly. Ordinary wall foam is not automatically an acceptable substitute.
Mineral wool / stone wool roof insulation
What it is: Rigid or semi-rigid roofing boards made from mineral fibers. Stone wool roof products offer thermal insulation along with fire-resistance and sound-control properties.
Where and why: A school, apartment building, or commercial property may consider stone wool when fire performance and noise control are priorities alongside insulation. It must be a roofing-grade product in an appropriate assembly; weight, attachment, and compressive performance are part of the selection.
Tapered insulation / shaping a path to the drain
What it is: Insulation boards made in sloped shapes. “Tapered” describes their shape, not a separate insulation material. Polyiso and EPS are common options.
Where and why: If water collects behind a skylight or between drains, a planned tapered layout can help guide it toward an outlet. Small raised, sloping areas called crickets divert water around obstructions. The layout must coordinate with roof edges, drains, and overflow provisions; insulation alone cannot fix every drainage or structural problem.
The insulation inside an attic or ceiling is a separate part of the building. Above-deck roof insulation needs to work with those existing layers and the building’s air and vapor-control design. Wet or damaged insulation needs investigation before it is covered.
THE PROTECTIVE LAYER
What is DensDeck,
and why use it?
DensDeck® is Georgia-Pacific’s fiberglass-mat gypsum roof board. When used as a cover board, it is typically installed above the insulation and directly beneath the roof membrane. It creates a firm, durable surface for the roofing system.
Why we use it: In a suitable roof assembly, a gypsum cover board helps protect the insulation and supports resistance to punctures and impact. It can also contribute to the assembly’s fire and wind performance. Selected products, such as DensDeck Prime, provide a surface designed for compatible adhered roofing systems.
A practical example: On a shop roof with rooftop air-conditioning equipment, technicians will need access for maintenance. DensDeck beneath the membrane adds a firmer protective layer over the foam insulation. Designated walkway pads still belong along service routes; the cover board does not turn the roof into a patio.
How it’s installed: Boards are laid over the supporting roof layers and secured with the specified fasteners or adhesive before the membrane is installed. Board type, thickness, joint layout, and attachment are matched to the approved roof assembly.
DensDeck is a cover board, not the main thermal-insulation layer or the waterproof roof membrane. It does not make a roof hail-proof or waterproof by itself. Performance ratings apply to the tested assembly, not just the board.
Georgia-Pacific DensDeck products & technical resources ↗ · Why use a gypsum cover board? ↗
How does it stay in place?
Depending on the system, roofing may be bonded with adhesive, secured with fasteners, or held by a designed layer of stone or pavers. The roof structure and local wind conditions help determine the method. We’ll explain the proposed approach and why it fits your building.
BUILT AROUND YOUR PROPERTY
Same state.
Different roofing needs.
- A mountain home: snow, ice, access, and safe drainage deserve close attention.
- A Denver-area shop: hail exposure, wind, and access to rooftop equipment may shape the roof design.
- A Western Slope building: summer sun, insulation, and how the space is heated or cooled belong in the conversation.
- A restaurant: exhaust may affect the material choice. We need to know what actually reaches the roof.
No roof is hail-proof, and no material is the automatic winner for every Colorado property.
BEFORE YOU COMPARE QUOTES
Ask what the price
actually includes.
Two proposals can name the same roofing material and still describe very different jobs. Ask about removal, damaged decking, insulation, drainage improvements, roof edges, permits, and cleanup. Those items can matter more than a small difference in sheet thickness.
Can we repair it?
A localized leak on an otherwise sound roof may have a practical repair. Recurring leaks, widespread wear, or wet layers underneath can make replacement the better discussion. We start with the condition, not an automatic replacement pitch.
Can the old roof stay?
Sometimes a new system can go over an eligible existing roof. That requires checking its condition, moisture, weight, and applicable requirements. Keeping a wet roof underneath can turn a shortcut into a bigger problem.
What will maintenance involve?
Keep drains clear, have damage addressed promptly, and plan inspections after significant weather or rooftop work. Foam and coating systems also need planned coating renewal.
What does the warranty cover?
A long warranty does not mean a maintenance-free roof. Ask what is covered, what is excluded, and what the owner must do to keep coverage in place.
LET’S LOOK AT YOUR ROOF
You don’t need to learn
all the acronyms.
Tell us how you use the building, what problems you’ve noticed, and what you want the next roof to do better. We’ll explain the practical options and the scope for your property. If a leak has damaged the rooms below, we can also discuss interior drywall, texture, and paint repairs.
SINGLE-PLY / MATERIAL RESOURCES
Explore Versico.
Plan the complete system.
We use Versico for single-ply roofing. Explore their product information, then we can walk through what the complete roof would include for your building.
Versico Roofing SystemsSingle-ply roofingExplore materials ↗QXORoofing & building-material supplierExplore materials ↗We’ll confirm the specific products, availability, and warranty terms in your proposal. Manufacturer warranties depend on the selected system and eligibility requirements.