Section 5.7. Surface Water

Transcription

1 Ministry of Municipal Affairs PROPOSED CHANGE TO THE 2012 BUILDING CODE O. REG. 332/12 AS AMENDED CHANGE NUMBER: SOURCE: B Ontario-mNBC CODE REFERENCE: Division B / 5.7. Division B / 5.8. DESCRIPTION OF THE PROPOSED AMENDMENT The proposed change would combine Section 5.7., Surface Water, and Section 5.8., Moisture in the Ground, into a new Section 5.7., Surface and Ground Water. It would also provide a description of the differences between waterproofing and dampproofing and address the need for attention to surface preparation. EXISTING 2012 BUILDING CODE PROVISION(S) Section 5.7. Surface Water Protection from Surface Water Prevention of Accumulation and Ingress Except as provided in Sentence (3), the building shall be located, the building site shall be graded or catch basins shall be installed so that surface water will not accumulate against the building. (2) Except as provided in Sentence (3), the foundation walls shall be constructed so that surface water will not, (a) enter the building, or (b) damage moisture susceptible materials. (3) Buildings specifically designed to accommodate accumulation of water at the building or the ingress of water need not comply with Sentence or Clause (2)(a). Section 5.8. Moisture in the Ground Foundation and Floor Drainage Required Drainage Except where a wall or floor is subject to continuous hydrostatic pressure, or unless it can be shown to be unnecessary, the bottom of every exterior foundation wall and every floor-on-ground shall be provided with drainage. Building and Development Branch Page 1

2 Drainage Materials and Installation Drainage shall be designed and installed to accommodate the drainage load Protection from Moisture in the Ground Required Moisture Protection Except as provided in Sentence (2), where a building element separates interior space from the ground, materials, components or assemblies shall be installed to prevent moisture transfer into the space. (2) Materials, components or assemblies need not be installed to prevent moisture transfer from the ground where it can be shown that such transfer will not adversely affect any of, (a) the health or safety of building users, (b) the intended use of the building, or (c) the operation of building services Protective Material and Component Properties Except where it can be shown that lesser protection will not lead to adverse conditions, or as provided in Article , materials and components installed to provide required moisture protection shall conform to the requirements of this Article. (2) Except as provided in Sentences (3) and (7), materials installed to provide the required moisture protection shall be capable of bridging, (a) construction, control and expansion joints, (b) junctions between different building assemblies, and (c) junctions between building assemblies and elements penetrating building assemblies. (3) Except as provided in Sentence (7), where the material installed to provide the required moisture protection is not capable of bridging construction, control and expansion joints, those joints shall be designed to maintain the continuity of the moisture protection. (4) Materials and components installed to provide the required moisture protection shall have sufficiently low water permeance to resist moisture loads. (5) Except as provided in Sentence (7), moisture protection shall be designed and constructed to resist design hydrostatic pressures as determined in accordance with Section 4.2. (6) Except as provided in Sentence (7), materials covered in the scope of the following standards shall not be installed to provide the required resistance to moisture transfer: (a) CGSB 37-GP-6Ma, Asphalt, Cutback, Unfilled, for Dampproofing, or (b) CGSB 37-GP-18Ma, Tar, Cutback, Unfilled, for Dampproofing. (7) Where the substrate is cast-in-place concrete, and a drainage layer is installed between the building assembly and the soil, and the assembly will not be subject to hydrostatic pressure, (a) materials and components installed to provide the required resistance to moisture transfer need not conform to Sentences (2), (3), (5) and (6), and (b) materials covered in the scope of the following standards are permitted to be installed to provide the required resistance to moisture transfer where those materials conform to the requirements of the standards: (i) CGSB 37-GP-6Ma, Asphalt, Cutback, Unfilled, for Dampproofing, or (ii) CGSB 37-GP-18Ma, Tar, Cutback, Unfilled, for Dampproofing. Building and Development Branch Page 2

3 Installation of Moisture Protection Except as provided in Sentence (2), where materials are installed to provide the required resistance to moisture transfer and their installation is covered in the scope of the following standards, installation shall conform to the waterproofing requirements of the respective standards: (a) CAN/CGSB-37.3-M, Application of Emulsified Asphalts for Dampproofing or Waterproofing, (b) CGSB 37-GP-36M, Application of Filled Cutback Asphalts for Dampproofing and Waterproofing, (c) CGSB 37-GP-37M, Application of Hot Asphalt for Dampproofing or Waterproofing, or (d) CAN/CGSB M, Application of Hot Applied Rubberized Asphalt for Roofing and Waterproofing. (2) Where the substrate is cast-in-place concrete, and a drainage layer is installed between the building assembly and the soil, and the assembly will not be subject to hydrostatic pressure, (a) materials and components installed to provide the required resistance to moisture transfer and whose installation is covered in the scope of the standards listed in Sentence, are permitted to be installed in conformance with the dampproofing requirements of the standards listed in Sentence, or (b) materials installed to provide the required resistance to moisture transfer and whose installation is covered in the scope of the following standards, shall be installed in conformance with the requirements of the respective standards: (i) CGSB 37-GP-12Ma, Application of Unfilled Cutback Asphalt for Dampproofing, or (ii) CAN/CGSB M, Application of Unfilled Cutback Tar Foundation Coating for Dampproofing. PROPOSED CODE CHANGE Revise existing Sections 5.7. and 5.8. including the related appendix notes as follows: Section 5.7. Surface and Ground Water Site Factors Protection from Surface Water Application Prevention of Accumulation and Ingress This Subsection applies to the location of buildings, the grading of building sites, the directing of water, and the provision for drainage. Except as provided in Sentence (3), the building shall be located, the building site shall be graded or catch basins shall be installed so that surface water will not accumulate against the building. (2) Except as provided in Sentence (3), the foundation walls shall be constructed so that surface water will not, (a) enter the building, or (b) damage moisture susceptible materials. (3) Buildings specifically designed to accommodate accumulation of water at the building or the ingress of water need not comply with Sentence or Clause (2)(a) Required Protection The building shall be located, the building site shall be graded, or water shall be directed so as to prevent, or accommodate for, the accumulation of surface water against the subject or adjacent buildings. (2) Drainage shall be provided to direct water away from the assembly separating interior space from the ground, except (a) where the assembly is designed to withstand continuous hydrostatic pressure according to Subsection , or (b) where it can be shown that the lack of drainage will not adversely affect any of (i) the health or safety of building users, Building and Development Branch Page 3

4 (ii) the intended use of the building, or (iii) the operation of building services Protection from Hydrostatic Pressure Application The Subsection applies to waterproofing materials, components, assemblies, and systems applied to building assemblies that separate dissimilar environments and are subjected to hydrostatic pressure Design for Building Elements Under Hydrostatic Loads Waterproofing materials, components, assemblies and systems described in Article shall be designed according to Subsection (2) The hydrostatic design loads shall be determined in accordance with Subsection Required Protection Waterproofing materials, components, assemblies and systems described in Article shall comply with Article Protection from Ground Water Application This Subsection applies to the protection of building assemblies that separate interior space from the ground Required Protection Except as provided in Sentence (2) and Article , building assemblies described in Article shall be protected by waterproofing in accordance with Article so as to prevent the ingress of water into the building or the accumulation of water against the building. (2) Waterproofing is not required where it can be shown that (a) a building is designed to accommodate the ingress or accumulation of water, or (b) the ingress or accumulation of water will not negatively affect (i) the health or safety of building users, (ii) the intended use of the building, or (iii) the operation of building services Waterproofing Waterproofing materials, components, assemblies, or systems installed to provide the required protection shall form a continuous and impervious barrier to the ingress of water and capable of accommodating (a) imperfections, construction joints, control joints and expansion joints (see Appendix A), (b) junctions between different building assemblies, and (c) elements penetrating building assemblies. Building and Development Branch Page 4

5 Where Dampproofing is Permitted Vertical building assemblies described in Article are permitted to be dampproofed where (a) assemblies are not subjected to hydrostatic pressures, (b) the substrate is cast-in-place concrete, and (c) a drainage layer is installed between the building assembly and the soil. (2) Joints, junctions and penetrations shall be designed and constructed to maintain the continuity of the dampproofing. A-5.7. Protection from Interior Sources of Water. Protection similar to that prescribed in Section 5.7. may be required where interior assemblies are in contact with water (such as site-built showers, steam rooms, swimming pool areas) and where adjacent interior spaces need to be protected from the transfer of water through these assemblies. A (2) Drainage. Water should be directed away from the building and, ultimately, to a municipal drainage system, drainage ditch, swale, or other acceptable water management means. This can be accomplished by setting the building grade higher than the surrounding grades, by sloping the grade away from the building, by installing a surface water drainage system, or by a combination of these approaches. The chosen approach should follow generally accepted guidelines, such as the Rational Method of Stormwater Design by David B. Thompson, or other design methods acceptable to the authority having jurisdiction. A (a) Imperfections. Examples of imperfections include shrinkage cracks, air holes, honeycombing, form-tie cone holes, and form joint ridges. A Dampproofing. Dampproofing refers to the application of a material or materials to an environmental separation assembly to protect it and the interior space against the transfer of moisture due to the mechanisms of water vapour transmission, capillary action and pressure differences other than hydrostatic pressure. A dampproofed assembly should be designed such that it can provide short-term resistance to the ingress of water due to occasional hydrostatic pressure from ground water. Section 5.8. Moisture in the Ground Foundation and Floor Drainage Required Drainage Except where a wall or floor is subject to continuous hydrostatic pressure, or unless it can be shown to be unnecessary, the bottom of every exterior foundation wall and every floor-on-ground shall be provided with drainage Drainage Materials and Installation Drainage shall be designed and installed to accommodate the drainage load. Building and Development Branch Page 5

6 Protection from Moisture in the Ground Required Moisture Protection Except as provided in Sentence (2), where a building element separates interior space from the ground, materials, components or assemblies shall be installed to prevent moisture transfer into the space. (2) Materials, components or assemblies need not be installed to prevent moisture transfer from the ground where it can be shown that such transfer will not adversely affect any of, (a) the health or safety of building users, (b) the intended use of the building, or (c) the operation of building services Protective Material and Component Properties Except where it can be shown that lesser protection will not lead to adverse conditions, or as provided in Article , materials and components installed to provide required moisture protection shall conform to the requirements of this Article. (2) Except as provided in Sentences (3) and (7), materials installed to provide the required moisture protection shall be capable of bridging, (a) construction, control and expansion joints, (b) junctions between different building assemblies, and (c) junctions between building assemblies and elements penetrating building assemblies. (3) Except as provided in Sentence (7), where the material installed to provide the required moisture protection is not capable of bridging construction, control and expansion joints, those joints shall be designed to maintain the continuity of the moisture protection. (4) Materials and components installed to provide the required moisture protection shall have sufficiently low water permeance to resist moisture loads. (5) Except as provided in Sentence (7), moisture protection shall be designed and constructed to resist design hydrostatic pressures as determined in accordance with Section 4.2. (6) Except as provided in Sentence (7), materials covered in the scope of the following standards shall not be installed to provide the required resistance to moisture transfer: (a) CGSB 37-GP-6Ma, Asphalt, Cutback, Unfilled, for Dampproofing, or (b) CGSB 37-GP-18Ma, Tar, Cutback, Unfilled, for Dampproofing. (7) Where the substrate is cast-in-place concrete, and a drainage layer is installed between the building assembly and the soil, and the assembly will not be subject to hydrostatic pressure, (a) materials and components installed to provide the required resistance to moisture transfer need not conform to Sentences (2), (3), (5) and (6), and (b) materials covered in the scope of the following standards are permitted to be installed to provide the required resistance to moisture transfer where those materials conform to the requirements of the standards: (i) CGSB 37-GP-6Ma, Asphalt, Cutback, Unfilled, for Dampproofing, or (ii) CGSB 37-GP-18Ma, Tar, Cutback, Unfilled, for Dampproofing. Building and Development Branch Page 6

7 Installation of Moisture Protection Except as provided in Sentence (2), where materials are installed to provide the required resistance to moisture transfer and their installation is covered in the scope of the following standards, installation shall conform to the waterproofing requirements of the respective standards: (a) CAN/CGSB-37.3-M, Application of Emulsified Asphalts for Dampproofing or Waterproofing, (b) CGSB 37-GP-36M, Application of Filled Cutback Asphalts for Dampproofing and Waterproofing, (c) CGSB 37-GP-37M, Application of Hot Asphalt for Dampproofing or Waterproofing, or (d) CAN/CGSB M, Application of Hot Applied Rubberized Asphalt for Roofing and Waterproofing. (2) Where the substrate is cast-in-place concrete, and a drainage layer is installed between the building assembly and the soil, and the assembly will not be subject to hydrostatic pressure, (a) materials and components installed to provide the required resistance to moisture transfer and whose installation is covered in the scope of the standards listed in Sentence, are permitted to be installed in conformance with the dampproofing requirements of the standards listed in Sentence, or (b) materials installed to provide the required resistance to moisture transfer and whose installation is covered in the scope of the following standards, shall be installed in conformance with the requirements of the respective standards: (i) CGSB 37-GP-12Ma, Application of Unfilled Cutback Asphalt for Dampproofing, or (ii) CAN/CGSB M, Application of Unfilled Cutback Tar Foundation Coating for Dampproofing. A Required Drainage. A wall or floor located below the water table or in the path of a watercourse will be subject to continuous hydrostatic pressure. In such cases, the provision of drainage will be ineffective and the wall or floor must be made waterproof to prevent water ingress. Where a wall or floor is subject to intermittent hydrostatic pressure, as may result from seasonal flooding, proper drainage will facilitate the drying out of the soil. In some cases, reducing exposure to high moisture levels will extend the life of the moisture protection. Where a wall or floor is not subject to hydrostatic pressure, drainage again reduces the exposure to high moisture levels and allows less than waterproof treatment of the wall or floor. A Moisture Protection. Moisture protection for building elements in contact with the ground is generally categorized as either waterproofing or dampproofing. Waterproofing provides a continuous protection against water ingress and is intended to resist hydrostatic load. Dampproofing, on the other hand, does not provide a seal against water ingress and cannot withstand hydrostatic pressure. In general, Part 5 requires walls, floors and roofs in contact with the ground to be waterproofed. Properties of waterproofing are specified in Sentences (2) to (5), and waterproofing material standards are referenced in Table Materials intended to be used as dampproofing rather than waterproofing are generally not permitted [Sentence (6)]. Standards for installing waterproofing are also specified [Sentence ]. Part 5 permits the use of dampproofing in lieu of waterproofing where the substrate is cast-in-place concrete, a drainage layer is installed and where the assembly will not be exposed to hydrostatic pressure. Material standards are referenced in Clause (7)(b) and installation methods in Sentence (2). A Required Moisture Protection. The control of the ingress of moisture from the ground into interior space is not related to the type of building, the use of the space, or whether or not the space is conditioned. This recognizes the potential adverse effects of high humidity levels, with or without standing water, on both the health of the building occupants and the durability of the building structure. Building and Development Branch Page 7

8 Although a subject interior space may not be occupied, the assembly separating this space from occupied space often cannot be relied upon to provide adequate protection for the building occupants. Depending on the construction of the separating assembly, it may also be subject to moisture-related deterioration. The exceptions to this requirement stated in Sentence (2) recognize only those cases where the subject interior space is not occupied and where the assembly separating this space from occupied space will provide the required protection and be resistant to a high humidity environment, or where the moisture loads are sufficiently limited as to not adversely affect the building or its occupants. A (7) Drainage Layers. Drainage layers reduce both structural and moisture loading on the building envelope by breaking capillary flow and allowing water to percolate quickly to the drainage system. A drainage layer may consist of permeable materials including granular backfill, geosynthetic drainage products or mineral fibreboard with oriented fibres to facilitate drainage. Where a granular material is used, it should be protected from contamination by fines from the adjacent native soil or additional material should be installed to ensure that an adequate thickness of the granular material remains free of fines. RATIONALE FOR CHANGE Problem/General Background The provisions in Section 5.7 and 5.8. are overly prescriptive and the references to standards, including their limitations in Articles and , are cumbersome and often confusing. Sections 5.7. are not structured consistently with other sections in Part 5. Moisture in the ground is directly linked to surface and ground water and it is therefore logical to deal with both in the same section of Part 5. The construction of site-built fixtures (such as spas, swimming pools, bathing and shower facilities) can cause considerable damage to assemblies that separate such wet environments from other dry interior spaces. They have been addressed in an appendix note. There is a need to better differentiate where waterproofing is required and dampproofing is permitted. Justification/Explanation This proposed change would harmonize requirements with the model National Building Code of Canada. Replacing the outdated CGSB standards with up-to-date ASTM standards and clarifying that the default construction is waterproofing makes the current standard references and qualifications in Articles and obsolete. A series of up-to-date ASTM standards is being proposed, where appropriate, to address more commonly used materials. The context for these material standards has been clarified and re-organized by introducing a new appendix note that addresses interior wet spaces as well as water from the ground. A new Subsection has been introduced to clarify the design procedure for assemblies subjected to hydrostatic pressure and to achieve consistency with changes to structural and environmental load requirements that were introduced. Building and Development Branch Page 8

9 Cost/Benefit Implications There is status quo in the level of performance. Increases in costs are not expected for construction. It is not clear whether the referencing of ASTM standards in lieu of the CGSB will have any cost implications for testing laboratories. It was understood however that the roofing, waterproofing and dampproofing industries are already using these ASTM standards. Enforcement Implications None - The text in Sections 5.7. and 5.8. has been reorganized with the intent of improving enforcement. Who is Affected Builders, manufacturers, warranty providers, building officials, building owners, designers. Objective Based Analysis Provision Objective/Functional Statement Division B [F60-OH1.1,OH1.2,OH1.3] [F60-OS2.3] (2) [F61,F80-OH1.1,OH1.2,OH1.3] (2) [F61,F80-OS2.3] (3) [F60-OH1.1,OH1.2,OH1.3] (3) [F60-OS2.3] Division B [F60-OH1.1,OH1.2,OH1.3] [F60-OS2.3] (2) [F60-OH1.1,OH1.2,OH1.3] (2) [F60-OS2.2,OS2.3] (2) Division B Division B (2) Building and Development Branch Page 9

10 Provision Objective/Functional Statement Division B Division B Division B [F61-OH1.1,OH1.2,OH1.3] [F61-OS2.3] (2) Division B [F61-OH1.1,OH1.2,OH1.3] [F61-OS2.3] Division B [F61-OH1.1,OH1.2,OH1.3] [F61-OS2.3] (2) [F61-OH1.1,OH1.2,OH1.3] (2) [F61-OS2.3] Division B [F60-OH1.1,OH1.2,OH1.3] [F60-OS2.3,OS2.2] Division B [F60-OH1.1,OH1.2,OH1.3] [F60-OS2.3][F21-OS2.2] Division B [F61-OH1.1,OH1.2,OH1.3] [F61-OS2.3] (2) Division B (2) [F61-OS2.3] (2) [F61-OH1.1,OH1.2,OH1.3] Building and Development Branch Page 10

11 Provision Objective/Functional Statement (3) [F61-OS2.3] (3) [F61-OH1.1,OH1.2,OH1.3] (4) [F61-OH1.1,OH1.2,OH1.3] (4) [F61-OS2.3] (5) [F61-OH1.1][F20,F61-OH1.2,OH1.3] (5) [F61-OS2.3] (6) [F61-OH1.1,OH1.2,OH1.3] (6) [F61-OS2.3] (7) (7) [b][f61-oh1.1,oh1.2,oh1.3] (7) [b][f61-os2.3] Division B [F61-OH1.1,OH1.2,OH1.3] [F61-OS2.3] (2) [F61-OH1.1,OH1.2,OH1.3] (2) [F61-OS2.3] OTHER SUPPORTING MATERIALS Building and Development Branch Page 11