Case Study
West Roof 1. There are two additions of large units, which have been roofed-in using a torch on membrane tied into the existing built up roof system. This is an acceptable procedure however, a secondary mastic sealant is recommended between the granular surface and the asphalt plies.
Customer:
Project Completed: n/a
Type of Roof: Tar and gravel
Materials: n/a
Location: Surrey, BC
Project Completed: n/a
Type of Roof: Tar and gravel
Materials: n/a
Location: Surrey, BC
Exterior Overview:A 2-building complex having multi-tenant industrial and commercial use.
Roof Analysis:
The roof system is a 4 ply Tar & Gravel built-up roof applied to 4×8 sheets of High-density fibreboard. In turn, this is attached to the primary R-value provider normally using a mop and flop procedure and Type II roofing asphalt. This layer of EPS has been mechanically fastened to the deck with screws and plates. Standard expanded polystyrene insulation is commonly manufactured by Plasti-Fab. The thickness of the insulation and fibreboard has not been determined by a test cut. The deck is metal and has been engineered to provide slope to the courtyard for drainage purposes.
Roof Evaluation:
This roof appears to be in acceptable condition relative to its age. This should primarily be credited to the slope of the deck. However, ponding water is evident as the roof drain count is less than desirable on the low sides of each roof.
Issues of note: West Roof
View image descriptions above
Summary and Recommendations:
It is my suggestion that one could expect to get another 3-5 years of service from the existing roof system with minor maintenance actions. Some of the repairs suggested above have the option to be deferred until re-roofing occurs. It is my professional opinion that when making budgetary considerations for re-roofing in 2007, your costs should not exceed $7 per square foot unless unforeseen circumstances prevail. Potential installation of additional roof drains should be investigated for plumbing options before re-roofing but not to be installed until that time. The suggested new roof system should incorporate assets of the existing roof system. The specification should include maintaining the mechanically fastened EPS insulation and fibreboard as able. An additional layer of fibreboard should then be mop applied followed by a mopped down layer of SBS membrane and a granular cap sheet applied according to manufacturer’s requirements
Prepared on March 8, 2007 by Greg Krushel, T.Q.
Inter-Provincial Trade Qualification # J-23-24221 (July 1991)
Roof Analysis:
The roof system is a 4 ply Tar & Gravel built-up roof applied to 4×8 sheets of High-density fibreboard. In turn, this is attached to the primary R-value provider normally using a mop and flop procedure and Type II roofing asphalt. This layer of EPS has been mechanically fastened to the deck with screws and plates. Standard expanded polystyrene insulation is commonly manufactured by Plasti-Fab. The thickness of the insulation and fibreboard has not been determined by a test cut. The deck is metal and has been engineered to provide slope to the courtyard for drainage purposes.
Roof Evaluation:
This roof appears to be in acceptable condition relative to its age. This should primarily be credited to the slope of the deck. However, ponding water is evident as the roof drain count is less than desirable on the low sides of each roof.
Issues of note: West Roof
View image descriptions above
Summary and Recommendations:
It is my suggestion that one could expect to get another 3-5 years of service from the existing roof system with minor maintenance actions. Some of the repairs suggested above have the option to be deferred until re-roofing occurs. It is my professional opinion that when making budgetary considerations for re-roofing in 2007, your costs should not exceed $7 per square foot unless unforeseen circumstances prevail. Potential installation of additional roof drains should be investigated for plumbing options before re-roofing but not to be installed until that time. The suggested new roof system should incorporate assets of the existing roof system. The specification should include maintaining the mechanically fastened EPS insulation and fibreboard as able. An additional layer of fibreboard should then be mop applied followed by a mopped down layer of SBS membrane and a granular cap sheet applied according to manufacturer’s requirements
Prepared on March 8, 2007 by Greg Krushel, T.Q.
Inter-Provincial Trade Qualification # J-23-24221 (July 1991)
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