Free written scope consultation - allowances, timeline, and change-order rules on paper before a single trade is scheduled
Tremron Home Additions & ADU: The San Jose Owner’s Guide
We install and service Tremron-compatible home additions and ADU projects across San Jose, with full builds typically running $53,100 – $153,400 depending on square footage, foundation work, and finish level. Most owners reach out because their existing addition or ADU has a structural issue, a failed connection to the main house, or they’ve outgrown the space and need a properly permitted expansion. The most common failure we see is a tie-in problem where the original addition meets the house: settling, water intrusion at the seam, or roofline sag that was never flashed correctly in the first place.
Which Tremron Models This Applies To
Tremron manufactures concrete pavers, retaining wall block, and segmental wall systems rather than structural framing, so when we talk about Tremron home additions and ADUs in San Jose, we’re usually addressing the hardscape and foundation elements that carry the structure: paver patios that abut the addition, retaining walls that hold back grade against a new ADU, and driveway approaches that connect to the new build. The compatibility question owners really need answered is whether their existing Tremron block or paver line can be matched when we add on. Most Tremron products use a modular dimension system, which means blocks are designed on a 4-inch module. If your original installation used Tremron’s Highland Stone or Diamond Pro series, we can match the color batch from the plant’s San Jose distribution, though we always recommend ordering 5 – 7% extra for cuts and future repairs. One gotcha we see regularly: aftermarket block that claims to be “Tremron-compatible” but doesn’t match the actual joint spacing or chamfer profile. The edge bevel on Tremron block is tighter than most generic equivalents, so the wall reads differently in direct sunlight. We source genuine Tremron material or verified matches through local Bay Area supply yards before we touch the project.
Penhallow Remodeling San Jose is an independent general contractor. We are not affiliated with Tremron, but we work with their products every week and know their San Jose availability trends better than most suppliers’ own phone reps.
Styles & brands we work with
Signs Your Tremron Home Additions & ADU Is Failing
- Separation at the wall-to-paver junction. You see a widening gap between the base of the addition and the paver patio. This usually means the base under the pavers is eroding from poor drainage, and the pavers are creeping away from the structure. If left alone, the gap lets water run straight down alongside the footing.
- Cracks running through multiple Tremron pavers in a line. A single cracked paver is normal wear. A crack that jumps across five or six pavers in a nearly straight line points to a sinking base layer, often from a leaking sprinkler line or a downspout discharging too close to the addition.
- Retaining wall tilting toward the ADU. If the wall block is leaning into the structure by more than roughly 3/4 inch over 4 vertical feet, the wall has lost lateral support. In San Jose’s clay-heavy soils, winter saturation pushes walls hard, and a tilted wall puts real pressure on any structure behind it.
- Doors or windows in the addition starting to stick. When the doors that used to swing clean now drag against the jamb, the addition’s foundation or the adjacent paver base has shifted. This isn’t a hinge problem; it’s a grade or settlement problem under the slab or stem wall.
- Water staining on the interior wall where the old house meets the new addition. This is the classic failed tie-in detail: roof flashing, wall intersection flashing, or a missing weep screed at the stucco junction. In San Jose’s rainy winters, the stain shows up within two seasons if the flashing was ever done wrong.
See the difference
Before
After
Before
After
Before
AfterReplacement Cost & What’s Included
| Scope | Installed Price Range (San Jose) |
|---|---|
| Full home addition (single room, 300 – 500 sq ft) | $53,100 – $153,400 |
| ADU construction (attached or detached) | $106,200 – $259,600 |
| Garage conversion to living space | $35,400 – $94,400 |
| Paver patio replacement (base rebuild + pavers) | $4,130 – $12,980 |
| Retaining wall rebuild (Tremron block, up to 4 ft) | $3,540 – $11,800 |
The range on a home addition or ADU in San Jose comes down to four things: square footage, foundation condition, how much site work the lot requires, and whether you’re matching existing Tremron hardscape or starting fresh. A flat Willow Glen lot with an attached addition and a simple gable tie-in lands on the lower end. A detached ADU on a sloped Almaden Valley lot with retaining walls and a new paver driveway approach pushes toward the top. Every quote includes the parts, labor, hauling, and a written scope. We price the job before we start, and the number on day one is the number on the final invoice. Trevor Nash has spent enough years running jobs across San Jose to know that a homeowner who gets a firm written number is a homeowner who doesn’t flinch when the crew shows up.
DIY or Call Us?
You can safely inspect a few things yourself. Walk the paver line with a level, check for water pooling against the addition, and look at whether downspouts discharge at least three feet from the foundation. If you find a cracked paver, you can pull it and check whether the sand base underneath is damp or washed out. What you shouldn’t do is start pulling retaining wall block, cutting into wall flashing, or re-grading next to the structure. A failed retaining wall under load can release suddenly, and a homeowner who disassembles one course without shoring the rest can cause a cascade that was completely avoidable. And any work that touches the structural connection between an addition and the existing house requires permits in San Jose. We pull them, we schedule the inspection, and we stand behind the work for 365 days after we leave. If something isn’t right, we come back and fix it at no charge. Give me the real problem and I’ll give you the real number.
FAQs
A properly permitted home addition or ADU built with correct flashing and drainage will last 50+ years as a structure. The hardscape elements around it, like paver patios and retaining walls, typically need base or leveling attention every 15 – 25 years in San Jose’s clay soil, depending on drainage and earthquake movement. Call (669) 274-2362 and we’ll give you a straight answer about what yours needs.
Yes, in most cases the failed connection between an existing addition and the main house can be repaired by opening the seam, installing proper flashing and weep screed, and re-anchoring the framing. The repair is only worth doing if the underlying foundation is sound. We inspect first, and if the slab or stem wall has moved beyond tolerance, we’ll tell you before any demo starts. Call (669) 274-2362 to schedule the inspection.
A straightforward addition sits around 8 – 14 weeks depending on permit turnaround in San Jose, which currently runs 4 – 8 weeks for residential additions. An ADU runs longer, usually 14 – 24 weeks. The paver and retaining wall components of the job move faster: a paver patio replacement is typically 3 – 5 working days on site. We commit to a real arrival window and a written schedule before the first truck rolls up.
We order genuine Tremron block and pavers per job because San Jose projects vary too much in color batch and series to keep static inventory. What we do maintain is a current list of which Tremron lines are available from Bay Area yards that week, so we never spec a product you can’t actually get. We also install and service fixtures and cabinetry from KraftMaid, Cambria, and Silestone where the addition calls for a new kitchen or bath.
Written by Trevor Nash, Owner, Penhallow Remodeling San Jose at Penhallow Remodeling San Jose, serving San Jose and nearby areas.
