Oldcastle Home Additions & ADU Nationwide

Oldcastle Home Additions & ADU: The Boca Raton Owner’s Guide

We stock and install Oldcastle-compatible materials for home additions and ADU projects in Boca Raton, with typical installed additions running $45,000-$130,000 and ADU construction at $90,000-$220,000 depending on foundation type, square footage, and whether the project ties into existing utilities. Most Boca Raton homeowners discover their Oldcastle system needs attention when they see settlement cracks in the CMU (concrete masonry unit) veneer, water intrusion at the weep screed line, or efflorescence blooming on the block face after our summer storms. The issue is rarely the block itself - it’s the moisture management system, the mortar mix, or the structural connection detail that was specified for a different climate zone.

Call (754) 254-8065

Which Oldcastle Models This Applies To

Oldcastle’s residential construction products span multiple series, and the part you need depends on what was specified in your original plans. The Oldcastle Architectural line includes the Masonry Series concrete block in 4-inch, 6-inch, 8-inch, and 12-inch widths, with face dimensions of 8 inches by 16 inches - the standard you’ll see in most Boca Raton additions built after 2010. The Oldcastle Coastal series, developed specifically for high-wind and salt-air environments, uses a denser aggregate mix and is marked with a “C” prefix in the block stamp.

To identify what you have, check the raised manufacturing stamp on the block web - it’ll show the plant code, date, and series letter. If your addition was built between 2005 and 2015, you may have the Oldcastle Standard series, which used a Type S mortar specification rather than the Type M that Florida’s wind-borne debris code now requires for structural masonry. The OEM replacement is always available through Oldcastle distribution, but we also source quality-equivalent block from Belgard and Techo-Bloc when the lead time on Oldcastle stock runs long, which it does in Q1 after hurricane season depletes regional inventory.

One compatibility gotcha in Boca Raton: additions built on the east side of the Intracoastal often used Oldcastle’s lighter-weight block to reduce bearing load on the coastal sand substrate. Swapping in standard-weight block without recalculating the footing can stress the foundation. We check the original geotech report before specifying replacement material.

Signs Your Oldcastle Home Additions & ADU Is Failing

• Stair-step cracks in the CMU veneer. These follow the mortar joints diagonally and usually indicate differential settlement - common in Boca Raton where the sand layer depth varies block by block. The crack widens during our dry season when the soil desiccates, then narrows after summer rains. It’s not cosmetic; it’s a structural movement indicator that needs a footing assessment before any block replacement.
• Efflorescence on interior or exterior block faces. That white, powdery deposit is dissolved salts carried through the block by moisture migration. In Boca Raton’s humidity, it means your weep screed or through-wall flashing is compromised, or the cavity drainage plane behind the veneer is blocked. The block isn’t failing - the moisture management system is, and replacing block without fixing drainage just repeats the cycle.
• Spalling or flaking of the block face. This happens when water saturates the block and freezes, which seems impossible in South Florida until you realize it’s the interior face that sees AC-cooled air against hot, humid exterior conditions. The thermal shock pops the surface aggregate. Oldcastle’s Coastal series resists this better; Standard series block in a conditioned addition is prone to it after 8-12 years.
• Sagging or separated lintels above windows and doors. The steel angle or precast concrete lintel that carries the block load above openings can corrode or deflect. You see it as a step-down crack pattern radiating from the corner of the opening. In Boca Raton’s salt air, ungalvanized lintels can lose section thickness in 15 years. We measure remaining section with ultrasonic testing before deciding repair vs. replacement.
• Water staining on interior drywall at addition-to-existing junctions. This is the flashing detail where the new roof meets the existing wall, or where the addition’s CMU wall ties into the original structure. Oldcastle doesn’t make this flashing - it’s a field-fabricated detail, and it’s where most Boca Raton additions leak. The stain means the through-wall flashing or counterflashing has failed, not the block.

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Replacement Cost & What’s Included

Home addition and ADU work in Boca Raton breaks into three cost tiers based on what’s actually failing:

What drives the range: foundation type (slab-on-grade vs. stem wall vs. pile), whether we’re tying into existing utilities or running new service, and the finish level. A pool cabana ADU in Boca Raton’s Royal Palm Yacht & Country Club area runs higher than a simple garage conversion because the municipality requires architectural review and impact fees that a basic addition doesn’t trigger.

Under Clause 1 of The Haven Standard, you get a written price before any work starts - every line item, every material spec named. No change proceeds without a signed change order. Our 365-Day Done Right Promise covers the workmanship, and the documented photo record on every visit shows you what we found and what we did, included as standard.

DIY or Call Us?

There’s a safe middle ground here, and then there’s the line you shouldn’t cross.

What you can check yourself: walk the perimeter with a level and look for new cracks that weren’t there six months ago. Photograph them with a coin or ruler for scale. Check that your weep screed holes at the base of the veneer aren’t packed with mulch or sediment - a wire brush clears them. Look at your downspout terminations; water dumping at the foundation is the single biggest cause of the settlement cracks we see in Boca Raton’s older neighborhoods like Camino Gardens.

Where DIY goes wrong: CMU veneer is structural. Removing even a single course without temporary shoring can redistribute loads unpredictably, especially in a multi-wythe wall. The mortar mix matters - Type M has minimum 2,500 psi compressive strength, and site-mixed batching without a mason who tests slump and unit weight is guesswork. And any work on the addition’s structural connection to the existing house triggers permit and inspection requirements under Florida’s wind-borne debris code; unpermitted structural modification voids your homeowner’s insurance and complicates resale.

We’re not affiliated with Oldcastle - we’re an independent contractor who sources their material and knows its behavior in this climate. If you’re seeing the symptoms above, call (754) 254-8065 and we’ll schedule a free estimate with a written scope and price before any work starts.

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