We just bought an Eichler in Green Gables and the radiant heat hasn't been used in years. The previous owner switched to forced air. Is it worth reactivating the in-slab system, and what should we realistically expect to spend?

Great question, and congratulations on Green Gables — that's one of the most intact Anshen & Allen tracts in the peninsula. Reactivating a dormant in-slab radiant system is absolutely worth evaluating, but you need a specialist who has actually worked on copper-in-slab systems, not a general HVAC contractor. The original Eichler systems ran copper tubing embedded in the concrete slab, and after decades of dormancy the first thing you need is a pressure test to check for leaks. A good radiant specialist will pressurize the loop with nitrogen and hold it for 24 hours. If it holds, you're in excellent shape. If it doesn't, you're looking at either a targeted repair — which is possible if the leak is near a manifold — or a full overlay system using PEX tubing run above the slab. Reactivation on a clean system typically runs $3,000–$6,000 including a new boiler. A PEX overlay on a compromised slab can run $15,000–$25,000 depending on square footage. The comfort payoff is real — radiant heat is genuinely superior for these open-plan post-and-beam homes because it heats the mass of the slab and radiates evenly. No cold spots, no drafts, no noise.

I've read that some Eichler tracts used glycol in the radiant loops and others used plain water. Does it matter for a 1960s Sunnyvale home, and how do I find out what's in mine?

It matters a lot, actually. The original Eichler systems were filled with plain water, sometimes with a basic inhibitor. Over the decades, many homeowners or service techs added glycol — either ethylene or propylene — to prevent freeze damage, which is largely unnecessary in the South Bay but became common practice anyway. The problem is that glycol degrades over time into glycolic acid, which is corrosive to copper. If you have an older glycol fill that hasn't been refreshed, you may have acidic fluid actively eating your copper tubing from the inside. The test is simple: a radiant specialist can pull a small fluid sample and test the pH on-site. You want a pH between 7 and 9. Below 7 and you have an acidic condition that needs immediate flushing and inhibitor treatment. I've seen Sunnyvale homes where the fluid was pH 4.5 — that's vinegar-level acidity sitting in copper tubing embedded in concrete. Flush it, refill with treated water and a proper inhibitor like Fernox or Sentinel, and test annually.

The tongue-and-groove ceiling in our Lucas Valley Eichler has about a dozen boards that are warped or water-stained from an old skylight leak. Where do I even source matching Lauan mahogany T&G at this point?

Lucas Valley is beautiful — Claude Oakland's work up there has some of the most expressive rooflines in the Eichler catalog. For Lauan mahogany tongue-and-groove, you have a few realistic options. First, check with Eichler-specific salvage networks — there's a small but active community of people who pull intact ceiling boards from Eichlers being remodeled or demolished. The Eichler Network forum and local Facebook groups for Marin Eichler owners are good starting points. Second, Lauan mahogany is still commercially available as a species — it's used in door skins and marine applications — but the profile has to match. Original Eichler T&G was typically 1x6 with a specific bead profile. You'll need a millwork shop to run custom profile if you can't find salvage. Third, and this is what I recommend for a small repair, pull boards from a less visible location — a closet ceiling, a utility room — and use those for the visible repair, then patch the donor area with new stock. The color match on new Lauan is actually pretty good; it's the patina that differs, and that evens out over a few years.

Our Eichler in the Walnut Creek Rancho San Miguel tract has the original post-and-beam exposed in the living room. One of the 4x12 beams has a significant check — a longitudinal crack running about 6 feet. Structurally concerning or normal wood movement?

Checking in Douglas fir beams is almost always cosmetic, not structural, and it's completely normal in post-and-beam construction. Here's the physics: as the fir dries over decades, it releases moisture unevenly from the outside in, and the surface shrinks faster than the core. The check is the wood relieving that internal stress. A longitudinal check running with the grain — which is what you're describing — does not reduce the beam's load-bearing capacity in any meaningful way. The beam's strength comes from the wood fibers running along its length, and a check parallel to those fibers doesn't interrupt them. What you'd be concerned about is a check that runs across the grain, or a beam that shows signs of compression failure — a wrinkled or buckled appearance on the underside. For a 4x12 in a residential span, I'd want a structural engineer to look at it if the check is more than about 1/3 the depth of the beam, but a 6-foot surface check on a sound beam is just the wood telling its story. Clean it out, treat with a penetrating consolidant if you want, and leave it.

We're getting quotes to replace the flat roof on our Fairglen Eichler. One contractor is pushing TPO, another is recommending a hot-mop built-up system like the original. What do you recommend for an Eichler specifically?

This is one of the most common questions I get, and the answer depends on your priorities. The original Eichler roofs were hot-mop built-up systems — layers of felt and hot asphalt — and a properly installed hot-mop is still an excellent choice for these homes. It's vapor-permeable, it's repairable in sections, and it's what the roof deck was designed for. The problem is finding a contractor who actually knows how to do it correctly. A bad hot-mop is worse than a good TPO. TPO is a single-ply thermoplastic membrane that's become the industry standard for commercial flat roofs, and it performs very well. It's lighter, it's heat-reflective, and a quality installation with proper detailing at the parapets and penetrations will last 20–30 years. My honest recommendation for most Eichler owners is TPO from a contractor who has specific experience with Eichler roofs — the details around the clerestory glazing, the beam pockets, and the fascia are where failures happen, and those require someone who understands the geometry. Get references from other Eichler owners specifically, not just flat-roof jobs.

The original single-pane aluminum-frame sliding doors in our Greenmeadow Eichler are drafty and we want to upgrade. But I've seen some remodels where the new doors look completely wrong. What's the preservation-correct approach?

Greenmeadow is one of the most architecturally significant Eichler tracts in the country — Anshen & Allen at their most refined — so I appreciate that you're thinking about this carefully. The original aluminum frames were typically 3-inch face width, and that proportion is critical to the visual rhythm of the elevation. The most common mistake is installing a modern sliding door with a 4.5-inch or wider frame — it immediately reads as wrong because it breaks the grid. For a preservation-correct upgrade, you have two good options. First, Fleetwood makes a contemporary aluminum sliding door with a narrow stile that reads very close to the original proportion. It's not cheap — figure $800–$1,200 per linear foot installed — but it's thermally broken, double-glazed, and visually appropriate. Second, if budget is a constraint, a quality weatherstripping and reglazing of the original frames with laminated glass is a legitimate option. The original aluminum is actually very durable; what fails is the glazing compound and the weatherstripping. A good glazier can reglaze the original frames with modern insulating glass in many cases, which gets you 80% of the thermal performance at a fraction of the cost.

How do I determine which architect designed my specific Eichler model? I know Anshen & Allen and Claude Oakland are the main firms, but I've seen references to Jones & Emmons and others. Is there a definitive way to trace this?

This is one of my favorite research questions because the answer is more nuanced than most people realize. Joseph Eichler worked with a rotating roster of architects over his building career from 1949 to 1966, and the attribution isn't always clean. Anshen & Allen designed the early peninsula tracts — the Palo Alto X-100 series, Greenmeadow, Green Gables — and their work is characterized by the most refined post-and-beam detailing and the strongest indoor-outdoor integration. Claude Oakland took over as the primary design architect in the late 1950s and designed the majority of the Sunnyvale, San Jose, and East Bay tracts through the early 1960s. His work is slightly more production-oriented but still architecturally serious. Jones & Emmons designed the Southern California tracts — Orange County, Granada Hills — and their work has a slightly different character, more influenced by the Case Study aesthetic. To trace your specific home: start with the original building permit at your county recorder's office, which will name the architect of record. Tract databases that map architect to year range are available through preservation research communities, and the book Eichler: Modernism Rebuilds the American Dream by Paul Adamson and Marty Arbunich is the definitive reference — it has tract-by-tract attribution.

We're actively looking for an Eichler in Sunnyvale and keep losing bidding wars. Every listing goes 15–20% over asking within a week. Is there a realistic off-market strategy, or do we just have to keep competing?

There is absolutely an off-market strategy, and it works — I've placed buyers in Eichlers that never hit the MLS. The key insight is that Eichler owners are a community, not just a demographic. They talk to each other, they're in neighborhood Facebook groups and online preservation forums, and many of them have been thinking about selling for years before they actually list. The most effective approach is a direct mail campaign to specific tracts — not generic 'we want to buy your home' postcards, but letters that demonstrate genuine knowledge of the architecture. Mention the tract name, the architect, something specific about the homes in that neighborhood. Eichler owners are proud of what they own and they respond to buyers who understand it. I've had clients write letters that referenced the specific plan type and the original boiler manufacturer, and those letters got calls. The second strategy is neighbor networking — if you know anyone in a Sunnyvale Eichler tract, ask them to spread the word. The third is working with an agent who has existing relationships in those communities. I maintain a buyer interest list that I share with owners who are considering selling before they list.

We're looking at an Eichler in Lucas Valley that's been heavily remodeled — new kitchen, bathrooms, and unfortunately the original T&G ceiling has been drywalled over. The price reflects the updates but not the lost original fabric. How do you think about valuing a compromised Eichler?

This is the most important valuation question in the Eichler market and most agents get it wrong. The conventional wisdom is that updated kitchens and baths add value, and in a generic house that's true. In an Eichler, it's more complicated. The buyers who pay the highest premiums for Eichlers are preservation-minded — they want the original T&G, the original terrazzo, the original mahogany millwork. When those elements are gone, you've permanently removed what those buyers are paying for. A drywalled-over T&G ceiling isn't just an aesthetic loss — it's a signal about how the previous owners approached the home, and it raises questions about what else was modified or covered. That said, the drywall-over situation is actually recoverable in many cases. If the T&G is intact underneath — which it often is, because drywall is easier to install over it than to remove it — you can restore it. I'd make any offer contingent on an inspection that includes probing the ceiling in an inconspicuous location to confirm the T&G is there. If it is, you're buying a restoration project, not a compromised home. Price accordingly — the restoration cost is real, but so is the upside when it's done.

We want to add a second story to our Eichler in Palo Alto. I've heard there's something called a Single-Story Overlay that might prevent this. Can you explain how it works and whether there are any exceptions?

The Single-Story Overlay, or SSO, is one of the most important and least understood zoning tools in Eichler preservation. Several Palo Alto Eichler tracts — including parts of Green Gables, Greenmeadow, and Duveneck — have SSO designations that restrict new construction to single-story. The overlay was established specifically to protect the architectural character of these neighborhoods, because a second-story addition on an Eichler is almost always architecturally destructive — it breaks the roofline, eliminates the indoor-outdoor relationship, and reads as a completely foreign element on a post-and-beam home. If your parcel is within an SSO zone, you cannot add a second story as a matter of right. There is a variance process, but the bar is high and the neighborhood opposition is typically organized and effective. Before you buy or before you plan, pull the parcel data from the City of Palo Alto's online GIS system — it will show the SSO designation clearly. If you're in an SSO zone and want more square footage, the realistic options are a rear addition that stays single-story, an ADU, or a basement if soil conditions allow. I've seen buyers walk away from Eichlers specifically because of SSO restrictions, and I've seen others embrace it as a feature — it protects their investment by preventing the neighbors from building up.

What is a Single-Story (S) Combining District, and how do I know if a Sunnyvale Eichler neighborhood has one?

The Single-Story Overlay restricts homes within the designated neighborhood to one story to preserve privacy and neighborhood character. You can check zoning details with the Sunnyvale Planning Division or consult the city's zoning map.

Can a neighborhood add or petition for a Single-Story Overlay after I buy?

Yes, individual neighborhoods have the option to petition the city for single-story overlay zone status.

Are second-story additions allowed on Sunnyvale Eichlers if the neighborhood is not in a Single-Story Overlay?

Yes, second stories are allowed in non-overlay Eichler neighborhoods, but they face strict design review guidelines to protect neighboring privacy and maintain architectural scale.

What restrictions apply to second-story additions on an Eichler?

The design must maintain a horizontal emphasis, limit floor-to-floor heights to 10 feet max, avoid shed roofs, and strictly limit or obscure side and rear windows to prevent overlooking adjacent yards and windows.

When is a formal Design Review required by the City of Sunnyvale for an Eichler?

Design review is required for any new home construction, floor area increases of 20% or more, any second-story component, projects exceeding Floor Area Ratio (FAR) thresholds, or exterior modifications that significantly change appearance.

Do the Sunnyvale Eichler Design Guidelines apply to interior remodels?

No, the design guidelines focus strictly on home exteriors visible from the street and adjacent neighbors; they do not apply to interior improvements.

How do Sunnyvale's Eichler Design Guidelines differ from standard single-family guidelines?

They specifically address post-and-beam architecture, flat/low-sloped roofs, vertical siding, and glass walls, ensuring exterior changes remain compatible with modernist architecture.

What exterior siding materials are approved for Eichler repairs or additions?

Vertical-grooved wood siding (such as original-pattern plywood or redwood panels) and concrete masonry walls are standard. Alternative smooth-finish panels may be considered if kept simple and consistent.

What types of replacement windows are allowed under the Sunnyvale design guidelines?

The city guidelines encourage narrow-frame aluminum or wood-trimmed fixed/sliding windows organized in clean rectangular panels. Non-traditional shapes, divided lights, snap-in grids, bay windows, and garden windows are discouraged or prohibited.

Are there rules about replacing front entry or garage doors on a Sunnyvale Eichler?

Yes, entries and doors should remain low-profile and simple. Flush wood entry doors and simple, vertical-grooved garage doors are recommended, while decorative, curved, or multi-panel doors are discouraged.

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Ask the Eichler Realtor

Kevin Limprecht has spent years inside California's most intact Eichler tracts — from Anshen & Allen's Green Gables to Claude Oakland's Sunnyvale corridors. This is the unfiltered archive: radiant heat diagnostics, original Lauan sourcing, off-market acquisition strategy, and the zoning overlays that define what you can actually build.

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