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ROOFING INSPECTION & REPAIR
AMERICAN CEMWOOD ROOFING
BEST ROOFING PRACTICES
BUILT UP ROOFS
CATHEDRAL CEILING VENTILATION
CERTIFICATIONS for ROOFING CONTRACTORS
CHIMNEY FLASHING Mistakes & Leaks
COLD WEATHER ROOF TROUBLE
DECKS, ROOFTOP CONSTRUCTION
EPDM, RUBBER, PVC ROOFING
EXTRACTIVE BLEEDING on SHINGLES
FIRE RETARDANT PLYWOOD
FLASHING on BUILDINGS
FLAT ROOF MOISTURE & CONDENSATION
Green House or Solarium Roof Leaks
HEAT TAPES & CABLES on Roofs for Ice Dams
ROOF ICE DAM LEAKS
MASONITE WOODRUF FIBERBOARD ROOFING
NOISE CONTROL for ROOFS
PLASTIC ROOFING TYPES
PVC, EPDM, RUBBER ROOFING
ROOF ARCHITECTURAL STYLES - PHOTO GUIDE
ROOF CLEANING RECOMMENDATIONS
ROOF COLOR RECOMMENDATIONS
ROOF INSPECTION SAFETY & LIMITS
ROOF LEAK DIAGNOSIS & REPAIR
ROOF NOISE TRANSMISSION
ROOF REPLACEMENT SNAFUs
ROOFING FELT UNDERLAYMENT REQUIREMENTS
ROOFING MATERIALS, Age, Types
SADDLE CONSTRUCTION at CHIMNEYS
SNOW GUARDS & SNOW BRAKES
STANDARDS for ROOFING
STRESS SKIN INSULATED PANELS
TEST LABS - ROOF SHINGLE
TREES & SHRUBS, TRIM OFF BUILDING
TRUSSES, Floor & Roof
UNDERLAYMENT REQUIREMENTS on ROOFS
VENTILATION in BUILDINGS
WALK-ON ROOF SURFACES
WARRANTIES for ROOF SHINGLES
WORKMANSHIP & ROOF DAMAGE
Flat or low slope roof conversion to sloped roof design: this article describes & illustrates the construction of a sloped gable roof over the flat-roofed home shown above. The original tar and gravel low slope roof lasted many years but ultimately a combination of roof age, wear, ponding, and leaks led the owners to construct a gable roof over this building. Photographs of the gable roof conversion structure are illustrated below. We use flat roof conversion photographs from several homes to discuss fire and building code concerns when a new roof is constructed atop an existing structure.
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Our photo (left) makes clear that for this roof-over construction project the original flat interior ceiling and its original structure were retained. The new pitched roof was constructed to bear on the top plates of the original building walls.
Note that there is an important distinction between adding a pitched roof, typically 4 in 12 or more, over an existing flat or low-slope roof - leaving the original roof structure and covering in place - and converting a flat roofed structure to a cathedral ceiling. On a flat or low sloped roof building that includes parapet walls, the builder may construct the new roof to bear on the parapets.
A cathedral ceiling conversion will require complete removal of the original structure, while the simpler addition of a pitched roof over an existing flat roof is typically handled by bearing on the existing building structure, its walls, and possibly by including sleepers and an "overframing" approach.
At below left you can see the intersecting gable roofs that were constructed atop the flat roofed structure shown at page top. Converting to a pitched roof helped eliminate chronic roof leaks in the original structure.
At above right and in additional photographs below construction details include temporary bracing below a valley rafter (below left), and the construction of a knee wall to address original differences between two building section roof heights (below right).
The photos above and at below left show that in these different homes from the one shown at page top the builders left the original tar and gravel built-up roof (BUR) in place, along with original flat roof vents (below left). Should a building fire occur the fire department may not be happy to discover that there are multiple layers of roof structure upon which older roofing was left in place in the building. Building codes refer to this approach as a "Roof Re-Cover". As you will see, there are some easy solutions that avoid having to perform a horrible old-roof tear-off in confined space.
At above right the black stains on the roof sheathing of the "new" gable roof constructed over the original flat roof show that this roof was not adequately vented.
Clearing up the Definition of Roof Re-Cover or Roof Recovering
Building codes and facilities management experts use the term roof re-cover generally to refer to covering an existing roof with additional layers of roofing materials without removing the original material. As expert sources point out,
Watch out: when retrofitting a sloped roof over an existing low slope or flat-roofed building be sure to check with your local building department. Don't just plow ahead building a non-conforming structure. Building permits will almost certainly be required and you may require the services of a design professional, an architect or structural engineer whose drawings will confirm the adequacy of the new structure. Also see FIRE RATINGS for ROOF SURFACES or select a topic from the More Reading links shown below.
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