Notes:
- Please see roof system schematics following for the sequencing and materials of the roof system components.
- Please review the Comparison Chart – comparing and contrasting the characteristics – of the Three Roof Systems.
THREE POSSIBLE ROOF SYSTEMS FOR A NEW BUILDING PROJECT – ACTUAL SELECTION MUST BE BASED ON ALL CONSIDERATIONS AND INFORMATION
ROOF SYSTEM 1 – BASIC
SINGLE PLY, LOOSE LAID, 45 MIL EPDM ROOF SYSTEM
¾ -1 ½ inch, round river stone ballast OOOOOOOOOOOOOOOOOOOOOO
applied at 15 lbs per square foot
One layer of 45 mil, EPDM rubber ______________________________
sheet, loose laid under the stone ballast
Top course of insulation – 2.1” ______________________________
polyisocyanurate insulation – _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
adhered with urethane adhesive ______________________________
Bottom course of insulation – 2.1” ______________________________
polyisocyanurate insulation – _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
adhered with urethane adhesive ______________________________
One ply kraft paper vapour retarder
With adhered, sealed seams ______________________________
ROOF SYSTEM 2 – BETTER
2 PLY MODIFIED BITUMEN ROOF SYSTEM
Granule surfacing embedded on cap ply ***** *************************
Cap ply of 4.0 mm, 250 gram granulated ______________________________
polyester ply sheet embedded in a
solid mopping of hot type II asphalt
1 ply of 180 gram polyester base sheet ______________________________
embedded in a solid mopping of hot
type II asphalt
Top course of insulation – 1/2” asphalt ______________________________
saturated fibreboard adhered in a solid ______________________________
application of hot type II asphalt
Tapered fibreboard as designated
Intermediate course of insulation – ______________________________
2.0 “ polyisocyanurate insulation – _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
fully adhered in a solid application ______________________________
of hot type II asphalt
Bottom course of insulation – 2.0” ______________________________
polyisocyanurate insulation – _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
mechanically fastened to FM 1-90 ______________________________
One ply kraft paper vapour retarder
With adhered, sealed seams ______________________________
ROOF SYSTEM 3 – SUPERIOR
4 PLY HYBRID BUILT-UP ROOF SYSTEM
Gravel surfacing embedded in a heavy OOOOOOOOOOOOOOOOOOOOOO
floodcoat of hot type II asphalt
1 ply of type IV fibreglass ply sheet ______________________________
embedded in a solid mopping of hot
type II asphalt
1 ply of type IV fibreglass ply sheet ______________________________
embedded in a solid mopping of hot
type II asphalt
1 ply of type IV fibreglass ply sheet ______________________________
embedded in a solid mopping of hot
type II asphalt
1 ply of 180 gram polyester base sheet ______________________________
embedded in a solid mopping of hot
type II asphalt
Top course of insulation – 1/2” asphalt ______________________________
saturated fibreboard adhered in a solid ______________________________
application of hot type II asphalt
Tapered fibreboard as designated
Intermediate course of insulation – ______________________________
2.0 “ polyisocyanurate insulation – _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
fully adhered in a solid application ______________________________
of hot type II asphalt
Bottom course of insulation – 2.0” ______________________________
polyisocyanurate insulation – _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
mechanically fastened to FM 1-90 ______________________________
One ply kraft paper vapour retarder
With adhered, sealed seams ______________________________
Comparison Chart For Three Roof Systems – BASIC, BETTER, SUPERIOR
| Comparator | System 1 – BASIC – 45 Mil EPDM Rubber Sheet Single Ply Roof System | System 2 BETTER –2 Ply Modified Bitumen Roof System | System 3SUPERIOR – 4 Ply Rubberized Base Sheet And 3 Ply Fibreglass Felt Asphalt Built-up Roof System |
| Substrate | Metal Deck | Metal Deck | Metal Deck |
| Vapour Retarder | One layer of Kraft Paper With Adhesive Sealed Seams | One layer of Kraft Paper With Adhesive Sealed Seams | One layer of Kraft Paper With Adhesive Sealed Seams |
| Base Insulation | 2.1 inch polyiso insulation, loose laid over the kraft paper vapour retarder | 2.0 inch polyiso insulation mechanically fastened min. FM1-90 | 2.0 inch polyiso insulation mechanically fastened min. FM1-90 |
| Intermediate Insulation | 2.1 inch polyiso insulation, loose laid over the base course – Total R value = 24 | 2.0 inch polyiso adhered in a solid mopping of hot asphalt | 2.0 inch polyiso adhered in a solid mopping of hot asphalt |
| Top Course of Insulation | N/A – none | ½” asphalt saturated fibreboard adhered in a solid mopping of hot asphalt – Total R value = 24 | ½” asphalt saturated fibreboard adhered in a solid mopping of hot asphalt – total R value = 24 |
| Base Ply Of Membrane | 1 layer of 45 mil EPDM Rubber Sheet with adhered Seams – loose laid | 1 ply of 2.2 mm, 180 gram polyester reinforced base ply in a solid mopping of hot asphalt | 1 ply of 2.2 mm, 180 gram polyester reinforced base ply in a solid mopping of hot type II premium asphalt |
| 2nd Ply of Roof Membrane | N/A none | 1 ply of 4.5mm, 250 gram polyester reinforced cap ply in a solid mopping of hot asphalt | 1 ply of type IV fibreglass felt adhered in a solid mopping of hot premium asphalt – shingle style |
| 3rd ply of Membrane | N/A none | N/A none | 1 ply of type IV fibreglass felt adhered in a solid mopping of hot premium asphalt – shingle style |
| 4th ply of Membrane | N/A none | N/A none | 1 ply of type IV fibreglass felt adhered in a solid mopping of hot premium asphalt – shingle style |
| Membrane Adhesive | N/A none – loose laid | Type II roof asphalt applied hot | Premium type II asphalt applied hot |
| Surface Finish | Large – 3/4 to 1/1/2 inch round, river stone – loose laid | Granulated surface of cap ply is finished surface | Gravel surfacing embedded into a heavy floodcoat of premium asphalt |
| Renewal of Surface Required During Service Life of System? | No, large stone is in place for the life of the rubber membrane | Yes, granulated surface will deteriorate in approximately 15 years – must be overlaid with another cap ply | No, gravel and floodcoat are essentially permanent |
| Top Floodcoat Material – Weight | None – weight of system – 15 lbs per square foot | N/A none – surface material on cap ply – minimal | Hot applied,premium asphalt with exceptional weathering resistance applied at a rate of 70 lbs. per 100 sq. ft. |
Warranty | Standard – typically 10 years – more can be purchased – see Notes | Moderate – typically 15 years – more can be purchased – see Notes | Premium – typically 20 years – more can be purchased – see Notes |
| Estimated Service Life of System | 10-15 years plus | 15 years, then resurfacing required – then another 15 years | 35 years, plus – a very long term roof system |
| Resistance To Leakage | Poor to Fair – only one layer of rubber sheeting with adhered seams – water can migrate below the membrane | Good –two heavy, rubberized polyester plies -essentially seamless | Excellent – the multi-layer membrane features redundant waterproofing, exceptional toughness and resistance to puncture – essentially seamless |
| Resistance to Traffic | Poor to Fair – the membrane can be damaged by foot and other traffic | Good – 2 plies of polyester reinforcement provides good resistance to traffic – the granulated surface does not provide much protection from traffic and damage | Excellent – the membrane is extremely tough and robust and the adhered gravel surfacing provides excellent protection from traffic and damage |
| Ease of Leak Source Identification | Very Poor – punctures great enough to cause leaks will allow water to migrate and flow under the loose laid membrane and over and through the insulation layers | Good – punctures great enough to cause leaks will be apparent – 2 ply membrane is tough and well adhered – both layers are fully adhered | Excellent – the multi-layer membrane is extremely tough, all layers are completely adhered together – holes in the membrane are extremely unlikely. If a hole is made by great force – water will not be able to migrate and the hole will be obvious |
| Low Temperature Flexibility | Good – rubber sheet | Very Good – 2 polyester reinforced plies of base sheet are rubberized | Very Good – entire system tough and rugged |
| Resistance to Thermal Shock | Good – roof membrane is flexible | Very Good – roof membrane plies are rubberized both layers are solidly adhered | Excellent – entire system is movement tolerant, rugged and solidly adhered |
| Elongation and Recovery | Very Good – rubber roof membrane is very flexible | Good –both polyester sheet plies are rubberized and flexible | Good – elongation with recovery – robust system |
| Puncture resistance | Very Poor – thin rubber sheet punctures easily – single ply – no redundancy – leaks very damaging if roof surface is flooded | Very Good – rubberized plies and polyester reinforcement combined– provide a tough, puncture resistant roof membrane | Excellent – the roof membrane is composed of a polyester, flexible base sheet and three extremely durable, fibreglass ply sheets that are very resistant to puncture – in addition the asphalt provides “bulk thickness” puncture resistance |
| Perimeter Base Flashing System | Fair – one layer of 45 mil rubber sheet | Very Good – base ply of high strength, solid, rubberized flexible, polyester reinforced flashing sheet is covered with a solid cap ply of flexible, rugged polyester cap sheet – both layers solidly adhered in hot asphalt | Excellent – base ply of high strength, solid, rubberized flexible, polyester reinforced flashing sheet is covered with a solid cap ply of flexible, rugged polyester cap sheet – both layers adhered in and coated with premium asphalt which provides movement tolerance |
| Resistance To Ponding Water | Good – the system is non-rotting – but ponding water will attract and promote sharp particles and debris – seams can separate | Fair – the top surfacing is only moderately resistant to the effects of moderate ponding – granule separation from the cap ply is accelerated in ponding conditions | Excellent – the top floodcoat of premium asphalt and gravel surfacing are resistant to the effects of ponding – entire system is non-rotting – full system is resistant to ponding conditions |
| Resistance to Ultraviolet and Heat aging | Good – thestone surfacing resists the effects of ultraviolet and heat aging | Good – the top coating of granules will resist the effects of ultraviolet and heat aging while still adhered to the cap ply | Excellent – the floodcoat of premium asphalt is resistant to heat aging and the thick coat of asphalt and gravel surfacing that is system integral is highly resistant to ultraviolet attack |
| Controlled Quality of Asphalt | N/A none | No – commodity grade roofing asphalt – non rubberized | Yes – premiumasphalt whose characteristics and performance is predictable and whose service life is extremely long |
| Quality of Asphalt | N/A none | Type II asphalt is pre-aged to raise the softening point to enable use on the roof | Type II asphalt is pre-aged to raise the softening point to enable use on the roof |
Most Prominent Fault or Weakness of System | Very Poor Puncture Resistance and Loose Laid, Single Ply Membrane Allows Water Migration Under the Membrane | Granule Surfacing Will Degrade and Fracture Away From The Surface Of The Cap Ply Allowing Ultraviolet Attack and Deterioration | Essentially None – The Entire System Is Seamless, Tough, Robust and Provides A Very Long Service Life |
Notes: Extended Warranties – extended warranties are sold by the manufacturers as a marketing tool – purchasing an extended warranty typically does not necessarily provide more significant protection than the standard, typical warranty – the cost of an extended warranty is significant and in the case of a claim – the warranty document does provide exclusion clauses and other “out” conditions that can allow the manufacturer to not honour the warranty in spite of the extra cost. The best assurance for a good roof system is “good design, good materials and good labour”.
