Written by Mid-South on . Posted in Re-Roofing

Thinking of replacing your EPDM (ethylene propylene diene monomer) roof? In recent years, many building owners have opted to replace their ballasted EPDM roofs with white TPO (thermoplastic polyolefin) – a material gaining popularity for its energy efficiency. To make the best investment, building owners and facilities managers should choose functionality over popularity when embarking on re-roofing projects.

An honest accounting of the pros and cons of each roof system reveals three reasons why keeping the existing ballasted EPDM roof is usually the wisest investment.

1. Ballasted EPDM: Just As Energy Efficient as White TPO

White reflects light and heat and of course, black does the opposite. The natural inclination, then, is to replace an EPDM roof with a white TPO roof to achieve a cooler building, lower energy bills, and a green facility.

White TPO is a sound investment for all those reasons — but not if it means dismantling and replacing a healthy ballasted EPDM roof.

Although EPDM is black, a ballasted roof is covered with a layer of river rocks that leave virtually no dark EPDM exposed. The rocks are either white or tan, and they serve the dual function of reflecting light and absorbing heat, which keeps the building just as cool as TPO.

2. Complicated Re-Roofing: The Structural Nature Of The Building

Ballasted roofs with all those river rocks are heavy — and the supporting structures in the building were designed with that weight in mind. Roofers are not structural engineers and replacing a ballasted EPDM roof with white TPO isn’t a straightforward project. Altering the structural nature of a building can have a destabilizing effect. Additional costs for engineering assessments and unforeseen issues can drive up TPO re-roof costs.

3. Switching To TPO: A Major Expense Without a Longer Lifespan

Removing an existing ballasted EPDM and replacing it with a mechanically attached TPO will typically cost twice as much as simply replacing the EPDM membrane.

Ballasted EPDM and TPO offer essentially the same benefits and will hold up the same way to weathering and the elements. They are made by the same manufacturers and installed by the same contractors. Identical warranties are available on TPO and EPDM roofs, so a savvy building owner is getting an identical roof lifespan at half the price. Building owners spend far less initially, without sacrificing long-term value.

In most cases, it is less expensive, (as well as greener and safer) to re-roof ballasted EPDM with the same material. TPO can be a solid investment for a new construction, but owners and facilities managers with an existing ballasted EPDM roof have little to gain from the costly and complicated process of switching EPDM to TPO.