Restoring the Streng Roof Beam
Can My Roof Beams Be Restored?
The short answer, in most cases, is yes. Like any restoration project, the limiting factors are usually time and cost. Dry rot decay rarely leaves a roof beam so far gone that the only answer is a full replacement. The key is to act quickly once you discover you have a problem.
The Streng Beam
One of the hallmarks of the Carter Sparks and Eichler mid-century modern homes are the sleek lines of exposed roof beams spanning throughout the interior and exterior spaces. The use of large high windows keeps the exterior portion of the beams visible. Carter Sparks designed his homes for the Streng Brothers with roof beam projections that extend six inches beyond the roofline.
The Streng Beams draw the outside in and the inside out, which follows a Carter Sparks "theme" seen in his designs, especially with the interior atrium model. But, there is a clever illusion employed. While there are single, full-length beams in some Streng homes, the majority are in fact multiple beams run end-to-end. The illusion comes from the ends abutting inside interior walls, hidden from view. In over 25 years, I've rarely seen a case of dry rot so deep that it damaged the exposed interior beams. The majority of the decay is typically isolated to the exterior overhangs and projections.
[Prominent roof beam overhangs were artfully used to support the expansive eaves on these homes. A roof beam overhang extends from an exterior wall to the roof-edge and is the "tail" of a much longer interior beam. Any part that goes beyond the roofline is called a roof beam projection. To read more on the anatomy of a roof beam, click the photo below]
Most Streng homes were built in the greater Sacramento - Davis - Elk Grove area. Our summers here helped inform Carter Sparks' differentiation of these homes from the Eichlers populating the bay area. Sacramento area's very dry summers have weeks of over 100 degrees, but average in the high 90's. But, unique to this area is the nightly moisture-laden Delta Breeze, our built-in air conditioning system that drops our temps to the high 60's at night. Those extremes cause daily expansion and contraction (swelling and shrinking) in wood beams, not to mention the rapid and uneven drying of any newer "wet" wood. Now add in our foggy, rainy winters and you can see the long term threat to those unprotected 6" projections (some in service for over 60 years). Those same conditions can also undermine the success of roof beam repairs. Climate factors must be considered in the design and execution of any roof beam restoration project.
First Things First
The Streng roof beam has a purpose -- it holds up your roof. The primary consideration of every Streng Beam restoration must be restoring the structural integrity. There's not much point in restoring the appearance of roof beams if the structural integrity is compromised.
In the case of dry rot, eliminating the ongoing problem is essential to prevent its spread and the need for further restoration work.
But restoration isn't worth your time and money if it doesn't incorporate prevention in its design. A restored Streng Beam is still subject to our climate, so you'll want it done right the first time. The old adage that "the definition of insanity is doing the same thing over again and expecting different results" most definitely applies.
Roof Beam Restoration: Addressing The Functional Problems
Not every wood beam with dry rot is structurally compromised. But, for those that are, the determining factor will come down to the amount and location of the decay. If the dry rot has spread extensively, leaving decay in its wake, the exterior roof beam overhang cannot be restored safely; it will need to be extracted and replaced in its entirety. The older the dry rot infestation, the more likely this becomes required. Do not believe anyone who says that you can cut back a load-bearing roof beam as far as is necessary to remove the decay and simply splice on a new end. But don't take my word for it, ask your local building department; I'm sure they'll have something to say about it.
If the rotten beam is salvageable in place, you'll need to get bids for the work. I highly encourage you to read Before You Repair before seeking any bids.
Much of my work over the past 25 years has been restoring others' previous "repairs." One of the underlying factors in many failed roof beam repairs is the very nature of the timber industry today. Most of the available lumber today is from tree farms. These trees are rapidly grown (and harvested young) under ideal conditions before being cut. But older trees are predictably strong because they were forced to adapt to harsh conditions and limited resources, sometimes for centuries. Farmed trees, in contrast, are pampered. For some construction, this is not an issue. But in a Streng Beam restoration, the problem is two-fold -- the lumber sold from farmed trees is usually weaker and wet. That means in our climate they will dry and shrink rapidly, a process that also leads to warping. The end result is that in a few years, a spliced-on end will distort; this leaves it as an eyesore and vulnerable to water damage once again.
To see some of the worst of the "cut it back and stick new wood on it" restoration and repair attempts, watch this 41-second video from my YouTube channel. (BTW, you'll also find videos of me hand feeding and playing with wild hummingbirds there.)
To read more about these repairs seen in the video, click the photo.
To see a gallery of the results of a variety of "Insufficient Repairs" and roof beam restoration attempts, click the photo.
One of the things you'll find on many failed repairs is a beam cap. Sadly, many beam cap installations only cover the end grain. It rarely rains sideways here. So what about the top of the Streng Beam projection? Water pooling on the surface most exposed to the sun is a recipe for wood-rotting fungi to set in. A well-designed beam cap is one that not only protects but safely sheds water away from the beam top and sides. But, you can't just nail one on either. Nail holes are yet another avenue for water and fungi to get together in your beam. And, occasionally we do get serious wind-driven rain events. So there needs to be a quality sealant involved as well. Roof beam caps must be expertly fabricated and fit to individual beams to avoid the gaps that let water in.
And, all of the above has yet to address the dry rot fungi that are already in the wood. So no, you can't just cover it up without dealing with the fungus growth already present. Metaphorically speaking, that's like having your dentist just throw a crown on a rotting tooth -- not a good plan if you want to save your teeth!
So as you can see, Streng Beam Restoration isn't as straightforward as it might sound. Now add in the potent mix of the love of these homes and their innate value. Maintaining the architectural flow while restoring and preserving function is a challenge. In fact, it's a unique issue, so I went to the source -- Carter Sparks -- all the way back in 1995 to game out the complexities of these repairs. He was open and very generous with his time and talent.
The effective restoration of the Streng Beam is such a challenging task that shortsighted repairs have left many homeowners with recurring roof beam damage -- including Bill & Karmen Streng. I was hired to restore their original Streng Brothers Home after another's method failed. Below is what I found when I arrived: roof beams with ongoing dry rot that were simply cut back to the roofline along with sheet metal end-caps (with no "top") that channeled and trapped rainwater between the two. This miscalculation, to come full circle, nourished the remaining internal dry rot fungus with as much water as it could possibly hold.
Streng Beam Restoration: Evaluating Aesthetics
The clearest answer to perfectly preserve the aesthetics of the architecture is to locate old-growth lumber, then extract and replace each rotted beam. However, that is an extremely costly and time-consuming endeavor -- one that is unlikely to be an affordable solution for the vast majority of homeowners.
When considering the option of cutting the Streng Beam flush with the roof edge (even if the dry rot is treated completely), remember to add in the loss in resale value to the overall cost as it is no longer really a "Streng Beam" without a projection beyond the roofline.
So the answer, at least for me, was to engineer an effective restoration that will last the life of the home (with basic timely maintenance, like painting), restore the functional integrity to load-bearing roof beams, and not abandon the Carter Sparks intentional design which maintains the feel and value of the home.
The Century Beam
See what I did there? It's an intentional play on words with the idea of a long-lasting roof beam restoration on a mid-century modern home.
The reason I feel confident in the name Century Beam is that my repair uses hot-dipped galvanized structural steel splice plates that are primed and painted to match the color and luster of the existing roof beam. This unique design has been engineered for strength and longevity and has been approved by local city and county building departments. Steel plates work to overcome the lost structural integrity of extensively rotted Streng Beams.
I do not use any farmed lumber in my restoration work; I work exclusively with seasoned reclaimed (or upcycled in the new vernacular) old-growth beam stock in all my repairs. I usually acquire this premium timber from older homes that have been deconstructed (the booming trend of buying large lots and replacing the original home with another McMansion has provided me with an ample supply). This dry lumber is of the same quality and strength as the beams typically used in Streng homes, thereby eliminating the shrinking, cracking, and warping common to the farmed wood sold in stores today.
I custom fabricate and install water-shedding beam caps to complete the restoration. Paintable elastomeric sealants are used as well to guarantee a weather-tight installation. The roof load itself also helps to ensure that the beam caps stay where I put them (the top photo is of my work showing The Century Beam Restoration).
One of the things I got from my discussion with Carter Sparks was a deeper understanding of perspective (architecturally speaking) and the modernist's take on the blending of materials (his use of open aggregate as flooring is an example), including steel, stone, and wood.
Incorporating perspective into the design of a load-bearing part of the home was the key. The steel does its job without detracting from the architecture as one views the home. But, I guess like most things in life, it's all about perspective.
Below is a 30-second video that highlights the blending of two essential qualities: the restoration of structural integrity with enduring aesthetic appeal.
Below is the documentary created by D.L. Stern for the preservationist group Sacramento Modern for the 60th anniversary of the Streng Brothers. It gives us the history of the Carter Sparks' vision. If you're a Streng Brothers homeowner, you'll want to take a few minutes and watch.
To learn more visit
To go to my home page click