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Standards and Guidelines for the Conservation of Historic Places in Canada

Additional Guidelines for Rehabilitation Projects

Within this section:

Mechanical Systems

Heating, air conditioning, electrical and plumbing

Recommended	Not Recommended
PRESERVING elements of mechanical systems — such as heating plants, radiators, vents, fans, grilles, plumbing fixtures, switch plates and lights — that are important in defining the overall heritage value of the building.	Removing or radically changing elements of mechanical systems that are important in defining the overall heritage value of the building.
*Documenting* the form, materials, function and condition of mechanical systems prior to beginning project work.	Undertaking project work that will have an impact on character-defining mechanical systems without first documenting their existing character and condition.
*Protecting and maintaining* mechanical, plumbing and electrical systems and their elements through cyclical cleaning and other appropriate measures.	Failing to provide adequate protection of materials on a cyclical basis, which results in deterioration of mechanical systems and their visible elements.
Preventing accelerated deterioration of mechanical systems by providing adequate ventilation of attics, crawl spaces and cellars so that moisture problems are avoided, and by providing access for servicing.	Enclosing mechanical systems in areas that are not adequately ventilated so that deterioration of the systems results, or in areas that cannot be accessed easily for servicing or maintenance.
Improving the energy efficiency of existing mechanical systems to help reduce the need for elaborate new equipment. Consideration should be given to installing storm windows, insulating attic crawl spaces, or adding awnings, if appropriate.	Installing unnecessary climate control systems that can add excessive moisture to the building. This additional moisture can either condense inside, damaging interior surfaces, or pass through interior walls to the exterior, potentially damaging adjacent materials as it migrates.
*Retaining* sound mechanical systems or deteriorated mechanical systems that can be repaired.	Replacing mechanical systems that can be repaired.
*Repairing and stabilizing* deteriorated mechanical systems until any additional work is undertaken. Repairs should be physically and visually compatible.	Removing deteriorated mechanical systems that could be stabilized, repaired and conserved; or using untested consolidants and untrained personnel, thus causing further damage to fragile elements.
*Replacing in kind* extensively deteriorated or missing parts of mechanical systems where there are surviving prototypes. The new work should match the old in form and detailing and have adequate capacity.	Replacing an entire mechanical system when limited replacement of deteriorated and missing components is appropriate. Using a replacement material that does not match the historic mechanical system element.
Evaluating the overall condition of mechanical systems to determine whether more than protection, maintenance and limited repair or replacement in kind are required; i.e., if more extensive repairs to mechanical systems will be necessary.	Failing to undertake adequate measures to protect mechanical systems.

Additional Guidelines for Rehabilitation Projects

Recommended	Not Recommended
REHABILITATING a mechanical system, if an evaluation of its overall condition determines that more than preservation is required.	Failing to evaluate the overall condition of a mechanical system in order to determine the appropriate method of conservation.
*Repairing* mechanical systems by augmenting or upgrading system parts, such as installing new pipes and ducts, rewiring or adding new compressors or boilers.	Replacing a mechanical system or its functional parts when it could be upgraded and retained.
*Replacing in kind* — or with a compatible substitute material — those visible character-defining elements of mechanical systems such as ceiling fans, switch plates, radiators, grilles or plumbing fixtures that are extensively deteriorated.	Installing a visible replacement element that does not convey the same appearance.

The following REHABILITATION work is highlighted to indicate that it involves a particularly complex technical or design aspect and should only be considered after the Preservation and Rehabilitation concerns listed above have been addressed.

Recommended	Not Recommended
Alterations/Additions for the New Use
Installing a completely new mechanical system, if required, for the new use, while ensuring that it causes the least alteration possible to the building’s floor plan and the exterior elevations, and the least damage to the character-defining building materials.	Installing a new mechanical system so that character-defining structural or interior elements are radically changed, damaged or destroyed.
Providing adequate structural support and vibration isolation for new mechanical equipment.	Failing to consider the weight and design of new mechanical equipment, resulting in a weakening or cracking of character-defining structural members or finished surfaces.
Installing the vertical runs of ducts, pipes and cables in non-character-defining areas (e.g., closets, service rooms and wall cavities).	Installing vertical runs of ducts, pipes and cables in places where they will obscure character-defining elements.
Installing heating/air conditioning units if required by the new use in such a manner that character-defining elements are not damaged or obscured and excessive moisture, which will accelerate deterioration of character-defining elements, is not generated.	Concealing mechanical equipment in walls or ceilings in a manner that requires the removal of character-defining building material. Installing a “dropped” acoustical ceiling to hide mechanical equipment when it destroys the proportions of character-defining interior spaces. Cutting through elements such as masonry walls in order to install heating/air conditioning units.
Installing heating/air conditioning units in the window frames in such a manner that sashes and frames are protected. Window installations should be considered only when all other viable heating/cooling systems would result in significant damage to character-defining materials.	Radically changing the appearance of the historic building or damaging or destroying windows by installing heating/air conditioning units in character-defining window frames.

Additional Guidelines for Restoration Projects

Recommended	Not Recommended
RESTORING a mechanical system, if an evaluation of its overall condition determines that more than preservation is required; i.e., if repairs to mechanical features from the restoration period will be necessary.	Failing to evaluate the overall condition of a mechanical system in order to determine the appropriate method of conservation.
*Repairing* mechanical systems from the restoration period by augmenting or upgrading system parts, such as installing new pipes and ducts, rewiring or adding new compressors or boilers.	Replacing a mechanical system from the restoration period or its functional parts when it could be upgraded and retained.
*Replacing in kind* — or with a compatible substitute material — those visible features of restoration period mechanical systems that are either extensively deteriorated or are prototypes such as ceiling fans, switch plates, radiators, grilles or plumbing fixtures.	Installing a visible replacement feature that does not convey the same appearance.
Installing a new mechanical system, if required, in a way that results in the least alteration possible to the building.	Installing a new mechanical system that alters the structural or interior features of the restoration period.
Providing adequate structural support for new mechanical equipment.	Failing to consider the weight and design of new mechanical equipment, resulting in a weakening or cracking of character-defining structural members or finished surfaces.
Installing the vertical runs of ducts, pipes and cables in closets, service rooms and wall cavities.	Installing vertical runs of ducts, pipes and cables in places where they will obscure features from the restoration period.
Installing heating/air conditioning units in such a manner that features are not damaged or obscured and excessive moisture, which will accelerate the deterioration of historic materials, is not generated.	Concealing mechanical equipment in walls or ceilings in a manner that requires the removal of building material from the restoration period. Cutting through features such as masonry walls in order to install heating/air conditioning units.

The following RESTORATION work has been highlighted to indicate that it involves the removal or alteration of existing mechanical systems and features from periods other than the accepted restoration period; and the replacement of missing mechanical systems and features from the restoration period with all new materials. This work should only be considered after the Preservation and Restoration concerns listed above have been addressed.

Recommended	Not Recommended
Removing Existing Features from Other Periods
Removing or altering mechanical systems and features, such as an elevator or plumbing fixture, dating from other periods.	Failing to remove a mechanical system or feature from another period, thus confusing the depiction of the building’s significance.
Documenting materials and features dating from other periods prior to their alteration or removal. If possible, selected examples of these features or materials should be stored to facilitate future research.	Failing to document mechanical systems and features from other periods (which results in the loss of a valuable portion of the historic record) prior to removing them from the building.
Recreating Missing Features from the Restoration Period
Recreating a missing feature of the mechanical system that existed during the restoration period based on physical or documentary evidence; for example, duplicating a heating vent or gaslight fixture.	Installing a mechanical system or feature that was part of the original design of the building but was never actually built; or constructing a feature that was thought to have existed during the restoration period, but for which there is insufficient documentation.

Restoration of St-George's Anglican Church of Halifax

New mechanical systems should be installed in a way that results in the least alteration possible to the building. In the Restoration of St. George’s Anglican Church, Halifax after a devastating fire, care was taken to ensure that the character-defining structural system and interior features from the restoration period were not altered or obscured when a new fire-suppression sprinkler system was installed in the attic.