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Tamko Home Additions & ADU: The San Diego Owner’s Guide
Tamko home additions and ADU construction in San Diego typically runs $53,100 to $153,400 for a complete permitted project, with most homeowners landing between $80,000 and $120,000 depending on foundation work, utility runs, and finish level. We stock and install the full range of Tamko-compatible building materials, flashings, underlayments, and accessory components needed to tie a new addition or ADU into your existing structure cleanly. Most owners discover they need this page because a roof tie-in is leaking, an old flashing detail has failed at the seam, or they’re planning a detached ADU and want to know if Tamko’s waterproofing products will hold up in San Diego’s coastal air before they commit.
Isaac Pruett has walked enough San Diego job sites to know that a failed Tamko flashing detail or improper underlayment lap is usually the quiet culprit behind a musty corner or a water stain that shows up six months after the addition was “finished.” Mason Remodeling Co San Diego is an independent contractor, not affiliated with Tamko, but we handle their product lines every day and know what fails first in this climate.
Key Takeaways:
- Full Tamko home addition or ADU build in San Diego: $53,100 – $153,400 installed
- Roof tie-in and flashing failures are the #1 call we get on existing Tamko additions
- We give you a written price before any work starts, every time
- Every crew member arrives with a photo ID badge and a clean uniform, and you get their name and photo before they show up
Which Tamko Models This Applies To
Tamko’s product line spans the full envelope: Heritage and Elite architectural shingles, MetalWorks steel shingle systems, TW-60 and TW-40 underlayments, and a range of self-adhered flashing membranes that are the workhorses of any addition or ADU project. The compatibility gotcha most San Diego owners hit is that Tamko’s self-adhered flashings are not all rated for the same temperature range. The TW-60 handles high-heat vertical applications; the lower-temp membranes can creep or lose bond on a south-facing wall in Mission Valley or El Cajon during August. If you’re tying a new ADU roof into an existing main house, the underlayment spec matters more than the shingle brand.
Identifying the right Tamko-specific part means reading the product code on the membrane backing or checking the shingle bundle label. For MetalWorks panels, the profile spacing differs between series, so a mismatched panel will not seat properly. OEM Tamko flashing costs more than generic aftermarket rolls, but the adhesive formulation is different, and in coastal San Diego salt air, we’ve seen generic flashings fail in half the time. For full additions and ADU builds, we spec Tamko OEM on all critical seams and use quality aftermarket only where the manufacturer allows substitution without voiding warranty.
Styles & brands we work with
Signs Your Tamko Home Addition & ADU Is Failing
- Water staining at the addition seam: Where the new roof or wall ties into the original structure, a failed Tamko flashing or underlayment lap lets water creep behind the siding. This is the most common failure point we see, and it usually starts small.
- Membrane peeling or bubbling on south-facing walls: High-heat sun exposure in San Diego neighborhoods like Clairemont or Chula Vista can cause non-TW-60 flashings to lose bond. Once the membrane lifts off the sheathing, the waterproofing is gone.
- Granule loss on the addition roof: If the Tamko shingles on your addition are shedding granules faster than the main house roof, the addition was likely roofed at a different pitch or with a mismatched underlayment that traps heat.
- Gaps or cracks at the ADU foundation joint: San Diego’s clay-heavy soils move with moisture. A foundation joint that opens up lets water wick into the ADU floor system, and the fix is never just caulk.
- Musty smell or efflorescence inside the ADU: White mineral deposits on concrete or a persistent musty odor in the addition means moisture is getting in somewhere and sitting. By the time you smell it, the flashing has been failing for a while.
Replacement Cost & What’s Included
For a full Tamko home addition or ADU build in San Diego, plan on $53,100 to $153,400 for a permitted, code-passing project. For isolated repair work, here’s what you can expect:
- Flashing or underlayment repair at an existing addition seam: $710 – $2,950
- Full roof tie-in re-flash on a Tamko addition: $2,360 – $7,670
- Complete ADU roof replacement with Tamko materials: $9,440 – $23,600
- New Tamko ADU or addition build (full project): $53,100 – $153,400
The range swings on foundation conditions, utility distances, whether the design requires structural engineering above standard prescriptive framing, and finish selections. Every price we give you is a written line-item price before any work starts. No verbal estimates that grow. Our workmanship is covered for 365 days from the completion date under the Done Right Promise, and if something fails within that year, we return and fix it at no charge.
See the difference
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AfterDIY or Call Us?
You can safely inspect the visible flashing around your addition: look for lifted edges, cracked sealant, or granule buildup in the gutters. You can also check inside the ADU for water stains along the ceiling-to-wall joint. What you should not do is climb onto a pitched roof to peel back Tamko membrane, especially on a two-story addition. Fall risk is real, and a failed flashing repair means water ingress behind the sheathing that you won’t see until the damage is done. Roof-height and structural work on additions and ADUs is professional territory, full stop.
If you’re in San Diego and you’ve got a seam leaking, a membrane lifting, or you’re ready to price out a Tamko ADU build, call (619) 673-9302. Tell me what’s broken. I’ll tell you what it takes.
FAQs
Tamko architectural shingles on a properly flashed addition will last 25 – 35 years in San Diego’s climate, but the flashings and underlayments often need replacement at the 10 – 15 year mark, especially on sun-exposed walls. Coastal salt air from Point Loma to Imperial Beach accelerates adhesive breakdown on all membrane flashings. Call (619) 673-9302 and we’ll inspect the specific failure points on your addition for free.
Yes, in most cases. If the Tamko shingles are still serviceable and the failure is isolated to one seam or penetration, a re-flash repair runs $710 – $2,950 in San Diego and takes one day on site. Once water has been sitting behind the sheathing for months, though, you may need sheathing replacement, which changes the scope. A free estimate will tell you which situation you’re in.
A detached ADU in San Diego typically takes 12 – 20 weeks from permit approval to final inspection, depending on utility trenching and site access. A bump-out addition attached to the main house usually runs 8 – 14 weeks. We’ll give you a written timeline with your written price.
We keep Tamko flashing membranes, underlayments, and common shingle profiles stocked locally in San Diego, so repairs can often be scheduled within a few days. Specialty MetalWorks panels and custom colors are special-ordered. We also handle parts for KraftMaid cabinetry, Cambria surfaces, and Silestone countertops on full addition and ADU builds.
Get Your Tamko Addition or ADU Priced Before You Move Forward
A written price before any work starts is not a favor we do; it’s how we’ve run every single job since Isaac Pruett started this company in 2004. You’ll know the crew member’s name and photo before they arrive, they’ll wear a clean uniform and show a photo ID badge at the door, and you’ll get a written guarantee that covers your Tamko addition or ADU work for 365 days from completion. Call (619) 673-9302 for a free estimate or to schedule an inspection. A live person answers, every time.
Written by Isaac Pruett, Owner, Mason Remodeling Co San Diego at Mason Remodeling Co San Diego, serving San Diego and nearby areas.
