Re-Roofing Loadmaster

RE-ROOFING OVER LOADMASTER ROOF DECK ASSEMBLIES

When a Loadmaster roof deck assembly is to be re-roofed, one must bear in mind that the Loadmaster assembly functions substantially different from a conventional steel deck and rigid insulation. First and foremost, the assembly forms a unique structural composite unit through the engineered attachment of all components.  The structural composite assembly  performs three distinct structural assignments, all vital to the building’s stability and building code compliance. These assignments, gravity load resistance (both uniform and concentrated), diaphragm load resistance (both shear and stiffness) and wind uplift resistance, are specified and detailed by the structural engineer in accordance with local building and insurance codes when the structure is originally designed. For the structure to resist loads as intended after re-roofing, the assembly’s structural composite qualities must be maintained. Operations that remove existing roof coverings will disturb structural composite qualities and will require the installation of a new Duraflex Mineral Board attached with the required engineered attachment pattern to reinstate required structural qualities.  This work must be performed by a trained and licensed Loadmaster Dealer.  Additionally, the assembly must continue to comply with internal fire resistance qualities required by building and/or insurance codes and function as a suitable roofing substrate to support and work with the new membrane. In reviewing these areas, one should be aware of the following:

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GRAVITY LOAD RESISTANCE

On all Loadmaster assemblies installed over the past forty-seven years, the earlier installations used steel deck sections that were almost exclusively 28 gauge Standard Duty or 25 gauge Heavy Duty. While these steel sections, rolled from high tensile steel (min. 80,000 psi), comply with local building code strength requirements, neither will independently comply with live load deflection requirements. To meet building code deflection requirements, they must be anchored to a rigid substrate, such as Loadmaster Duraflex Mineral Board with an engineered attachment pattern to form a structural composite flexural unit.
During re-roofing operations, should the Loadmaster Duraflex mineral board and/or the Loadmaster insulation board be extensively damaged or removed and replaced with something other than the same Loadmaster products or attachment pattern, the resultant assembly will be in violation of building code requirements and not provide the required load resistance.
One might ask, “So what?”, and proceed to use unqualified non-Loadmaster components and unqualified installation techniques for the required repairs. In doing so, the building no longer meets building code structural requirements and, should a casualty loss occur on the building, the owner could find his insurance null and void since insurance underwriters presume and base their policies upon compliance with the building code. Second, the parties who instigated such non-compliant repairs could be liable for their actions and any resultant damages or losses. Third, and most disturbing, should the instigating parties knowingly cause such code violations, which result in physical losses or possible loss of life, these individuals, under the law, would be deemed negligent and could be held accountable under criminal proceedings. As can be seen, this becomes a very serious matter.

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DIAPHRAGM LOAD RESISTANCE

Virtually every structure that utilizes Loadmaster has the roof deck assembly designed as a structural diaphragm to stabilize wall structures under horizontal wind and seismic loading. Utilizing the roof deck assembly for this purpose, in lieu of structural steel bracing, accomplishes these structural functions much more efficiently and cost effectively. The structural engineer determines the diaphragm shear and/or stiffness required in a given structure based upon its size, shape, etc. in accordance with local building code requirements. Under wind and seismic loading, the roof deck assembly actually holds the walls up.
Loadmaster assemblies perform superior to conventional steel deck because of the combined structural performance of the steel sections and the Duraflex mineral board. The composite performance is created through the unique structural attachment of the Duraflex mineral board to the steel section.
The Duraflex mineral board will be damaged by removal of the existing roof covering and if  removed and replaced with non-Loadmaster components, the resultant assembly will not be a structural composite as designed by the structural engineer. The structure will no longer have the engineer’s required shear resistance under wind and seismic loads, will not comply with code requirements and is classified as a “dangerous” building under IBC regulations . Non-compliance in this area could result in the collapse of wall structures under heavy wind or seismic loads, no doubt causing serious damage and possible loss of life. Certainly one can recognize the liabilities associated with such actions. They would be the same as those outlined previously.

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WIND UPLIFT REQUIREMENTS

Wind uplift requirements are regulated by state and local building code bodies and comply with some version of the International Building Code (IBC). All Loadmaster wind uplift performance data, tested by Underwriters Laboratories,  Factory Mutual and certain qualified independent testing laboratories qualifies per IBC regulations and are based upon the performance derived from structural composite units. The ability of the assembly to provide uplift resistance that maintains roof membrane integrity and stability depends upon the assembly remaining in place and its  wind load deflection resistance.
Through excessive damage or removal and replacement of Duraflex by non Loadmaster components utilizing non-Loadmaster structural attachment, the structural composite strength and deflection performance of the assembly is greatly compromised and it will no longer provide the required and/or expected wind uplift resistance. Again, serious penalties could result if this condition is allowed to develop.

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FIRE RESISTANCE

State insurance laws and state and local building codes regulate the fire resistance qualities of roof deck assemblies. Requirements vary greatly depending upon building use, size, location, etc.
The Duraflex mineral board exhibits outstanding fire resistant qualities and performs equivalent to a Type X, one-hour fire-rated board. As such, local code authorities have granted approvals to use Duraflex in certain high-risk fire areas and both code compliance and insurance policies have been based upon these approvals. To replace Duraflex with some material of non-equal fire resistant properties would greatly alter the fire performance qualities of the assembly and, most likely, place the building in a non-compliance position.

Additionally, Loadmaster has numerous hourly fire resistance ratings and in reroofing the fire resistance of the assembly must be maintained.  Should any questions arise concerning fire resistance ratings and its maintenance please consult with Loadmaster’s Technical Department.

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ROOFING FOUNDATION PERFORMANCE

Due to their poor deflection properties, as stated earlier, both Standard and Heavy Duty Loadmaster steel sections do not independently meet code, and neither do they independently furnish a satisfactory base to support an insulation material with a membrane over the top. Should the Duraflex mineral board be damaged or replaced with some non-Loadmaster material, the roofing foundation must then rely upon the steel section alone for stability. Satisfactory, long term roofing foundation performance over these steel sections can only be developed through structural composite action such as provided by Loadmaster Duraflex Mineral Board attached with Loadmaster’s uniquely engineered structural attachment patterns.
While this area carries no code regulations, to create an unstable roofing foundation does, nevertheless, violate good roofing design. This will result in a poor roofing foundation, which will lead to premature membrane failure from stress and a leaking roof. Not a very attractive proposal from an economic point of view.

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NEW ROOF COVERINGS

The selection of the correct roof covering is vital to achieving IBC compliance for the roof assembly.  Only those roof coverings that have been tested as required by the IBC regulations will complete the assembly and make it a lawful assembly. The use of untested and unqualified roof coverings over Loadmaster roof decks place the roof assembly outside the building code and reduces it to an unlawful assembly.  To comply with code regulations the tested and legal roof coverings and manufactures of each are as follows:

Built Up Roofing —————————  GAF – Johns Manville – U, S. Ply, Inc.

Modified Bitumen ————————– Siplast – GAF –  Johns Manville – U. S. Ply, Inc.

PVC Membranes  ————————-  Carlisle – GAF – Johns Manville

TPO Membranes  ————————-  Carlisle – GAF – Johns Manville

EPDM  Membranes  ———————-  Carlisle

NOTE:  All roof coverings are to be adhered to the Loadmaster roof deck.  Loose laid or mechanically attached membranes are not code approved.

For more information on low-sloped roof coverings contact your local Loadmaster Dealer or call the Loadmaster Technical Department at 800-527-4035.

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STEEP SLOPED ROOFING

Shingles, Slate & Tile: These roofing types do not require testing as an assembly inconjunction with the roof deck. They require proper engineering design to function as intended. Loadmaster is compatible and operates very well with all shingle types, slate (both real and synthetic) and various types of tile. For specific information on a particular roof covering contact Loadmaster’s Technical Department at 800-527-4035.

Standing Seam Metal Roofing: This roofing type requires assembly testing for wind resistance. The entire roof assembly (Loadmaster Roof Deck & roof covering) must be wind uplift tested as a unit to establish its wind uplift resistance and code compliance. For current information on metal roofing systems tested and approved in conjunction with Loadmaster, contact Loadmaster’s Technical Department at 800-527-4035.

LOADMASTER AUTHORIZED DEALERS

Any work performed on a Loadmaster roof deck must be performed by a trained and licensed Loadmaster Dealer.  Untrained and unlicensed roofing contractors are not authorized to work on Loadmaster installations. Should that occur the structural composite strength of the assembly will most likely be compromised and the assembly is no longer a Loadmaster assembly and Loadmaster withdraws any and all strength and performance claims for the resulting non-Loadmaster assembly which also will no longer comply with building code regulations.  For a listing of authorized Loadmaster Dealers contact Loadmaster at 800-527-4035.

CONCLUSION
From the above, we trust the reader has gained a better insight into the considerations necessary in developing a course of action for re-roofing a Loadmaster assembly. Loadmaster is a high performance structural system and, prior to re-roofing, requires professional evaluation by a licensed Loadmaster Dealer or Loadmaster’s Technical Department in conjunction with a licensed structural engineer.

Things You Should Know – Before Reroofing Loadmaster Roof Decks