The Problem with Tar and Gravel on Flat Roofs
If you own an Eichler home in the Bay Area, you already know that your flat roof is both a defining architectural feature and a constant source of anxiety. When it comes time for a roof replacement, Eichler owners generally face two choices: stick with the traditional tar and gravel (built-up roofing) or upgrade to a Spray Polyurethane Foam (SPF) roof.
While tar and gravel was the standard when Joseph Eichler built these homes in the 1950s and 60s, it is rarely installed on new projects today — most contractors now default to TPO or modified bitumen. That said, many Eichler owners still have original tar and gravel roofs that are decades old and overdue for replacement. Here is a direct comparison of foam roofing versus tar and gravel for Eichler homes.
Tar and gravel roofs are incredibly heavy, putting unnecessary stress on the post-and-beam structure of an Eichler. More importantly, they are not seamless. The multiple layers of roofing felt and asphalt create seams — and on a flat roof where water tends to pond, seams eventually become leaks.
Furthermore, tar and gravel offers virtually zero insulation value. In an Eichler home with no attic space and radiant floor heating, a poorly insulated roof means your home will be freezing in the winter and sweltering in the summer.
Why Spray Foam is the Ideal Eichler Solution
Spray Polyurethane Foam (SPF) roofing addresses every vulnerability of the traditional Eichler roof:
- Seamless Waterproofing: SPF is sprayed on as a liquid and expands into a solid, seamless barrier. There are no joints, seams, or overlaps for water to penetrate, making it the ultimate solution for flat roofs prone to ponding water.
- Superior Insulation: Foam roofing provides the highest R-value per inch of any roofing material. Because Eichlers lack attic space, adding a foam roof is the single most effective way to insulate the home, dramatically lowering heating and cooling costs.
- Lightweight: Foam is incredibly light, removing thousands of pounds of dead weight from your home’s structural framing compared to a tar and gravel roof.
- Custom Sloping: During application, skilled foam contractors can build up low areas to create a custom slope, ensuring proper water drainage toward your scuppers and downspouts.
The Verdict
While a tar and gravel roof might have a slightly lower initial installation price, the long-term energy savings, leak prevention, and structural benefits make spray foam the undisputed best choice for preserving and protecting an Eichler home.
If you are considering a roof replacement for your Eichler, contact Foam Roof Solutions for a free estimate or learn more about our residential foam roofing services. We have protected hundreds of mid-century modern homes across the Bay Area and Sacramento.
