5 Zero Inc
BDIAMOND BAR, CA 91765
(909) 598 5598View profileLicensed under Class B (General Building)
Find CSLB-licensed second-story addition contractors in Diamond Bar, CA. Every listing shows an active licence number you can check yourself.
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Get matched with a licensed proA second-storey addition in Diamond Bar is the most structural thing most homeowners ever commission. Everything below has to carry what goes above, so the project starts with an engineer looking at the foundation and the existing walls, not with a floor plan.
Expect the house to be open to the weather for a period. The roof comes off, which means temporary protection, and it means the schedule is genuinely weather-dependent in a way a kitchen remodel is not. Ask how the house is protected between tear-off and dry-in, and what happens if it rains.
The staircase is the detail people underestimate. It has to land somewhere sensible on both floors and it consumes real square footage on the level you already live on. A design that adds 800 square feet upstairs while eating 60 downstairs is a different proposition from the one on the drawing.
Adding a storey involves structural, framing, roofing, plumbing, electrical and finish work, which puts it well inside Class B (General Building). It is the classification CSLB defines for structures requiring at least two unrelated trades, and this work requires many more than two.
Each contractor here holds that licence, active, at a Diamond Bar address, with the number linked to the register. On a project of this size it is worth checking the record again before each large payment, not only at signing.
The register says nothing about whether a firm has done this before, and second-storey work is not a scaled-up remodel. Ask how many they have completed in the last three years, whether any needed the foundation reinforced after the engineer looked, and what that did to the budget. A contractor who has a number for that has done the work; one who says it never comes up has not done much of it.
Every licence number below links to its record at cslb.ca.gov, where you can confirm status and expiry yourself.
167 registered in Diamond Bar · 23,334 active CLEAR licences across Los Angeles County · page 1 of 973
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Licence first. References second. Reviews last. Why that order.
Get matched with a licensed proThese sit under the same Class B (General Building) licence, so the same contractors are qualified for them.
That depends on the foundation and the existing wall framing, and only an engineer can answer it for your house. Some homes need footings reinforced or shear walls added first. Get that assessment before you fall in love with a floor plan, because it can change the budget substantially.
The register shows 167 holding an active Class B licence at a Diamond Bar address, and 23,334 across Los Angeles County. Class B is the classification this work falls under, so it lists the same pool as other general building pages.
Often yes, at least for the phase when the roof is off. Ask for that period to be identified in the schedule up front, because temporary accommodation is a real cost that rarely appears in the initial quote.
It varies with engineering, plan check and inspection scheduling in your jurisdiction more than with the building itself. Ask for a schedule that names the inspection milestones rather than a single completion date.
Yes — structural plans, roof removal and new floor area require plan check and staged inspections through Building and Safety Division.