Title 24 and Your San Jose Remodel: What the Energy Code Actually Requires

Title 24 is the part of a remodel nobody plans for and everybody pays for. It is not optional, it is not negotiable at the counter, and the cost of complying with it is frequently larger than the cost of the permit itself.

Understanding it before design rather than at plan check is worth several thousand dollars, because most of what it requires is cheaper to build in than to add.

What triggers Title 24?

The general rule: Title 24 applies to whatever you touch. It does not force you to upgrade the whole house, but anything within the scope of the permit has to meet current standards, and “within scope” is interpreted broadly. If a wall is open, the insulation in that wall is in scope.

The requirements that cost real money

1 · Heat pump water heating

California has moved decisively toward electric water heating, and replacing a gas water heater increasingly means a heat pump unit rather than a like-for-like swap.

The relocation line is the one that catches people. Heat pump water heaters are physically larger than tank gas units, they need air volume around them to work, and they produce condensate. A unit that fits in a 1968 San Jose water heater closet is the exception rather than the rule. Establish where it goes during design.

2 · Duct sealing and testing

If you touch the HVAC system, the ducts have to be sealed and then tested by a third-party rater, with measured leakage below a threshold.

• Duct sealing: $1,500 to $5,000
• HERS rater testing: $400 to $1,200
• Duct replacement, where the existing ducts cannot be brought under the threshold: $4,000 to $14,000

On a 1960s or 1970s San Jose house with original flex duct in the attic, replacement is a realistic outcome rather than a remote one. The ducts are frequently at 30% leakage where the code wants a fraction of that.

3 · Whole-house mechanical ventilation

New and substantially remodeled homes require continuous mechanical ventilation, because a tightly sealed house does not exchange enough air on its own.

$1,200 to $4,500 for a fan and ducting, more if it is integrated into the HVAC system. On additions and whole-house remodels this is nearly always required and it is nearly always a surprise.

4 · Insulation in every wall you open

Most San Jose homes built before 1978 have no wall insulation at all. Open a wall for plumbing or electrical work and that wall now needs insulation to current standards.

• Wall insulation in opened walls: $2.50 to $5.00 per square foot of wall
• Attic insulation to current R-value: $2,500 to $7,000 for a typical house
• Floor insulation over a crawlspace: $3,000 to $9,000

This is genuinely worth doing rather than resenting. Wall insulation in a house that has none is the single largest comfort improvement available, and it costs almost nothing while the walls are already open.

Windows

Replacement windows must meet maximum U-factor and solar heat gain coefficient values. Any reputable dual-pane low-E product meets them, so this rarely constrains the choice, but two things matter:

• The certification label has to stay on until final inspection. Removing it early creates a real problem, because the inspector verifies performance from the label.
• West-facing glass is where solar heat gain matters most in San Jose, and a lower gain coefficient there is worth specifying deliberately rather than accepting whatever the standard product is.

Lighting

Kitchen and bathroom lighting has requirements around efficacy and controls. In practice, using LED fixtures throughout satisfies most of it. Where projects get corrections:

• Recessed fixtures must be airtight and insulation-contact rated
• Controls such as dimmers or vacancy sensors are required in certain rooms
• Under-cabinet lighting counts toward the calculation and is often omitted from the submittal

Solar on additions

New residential construction requires solar photovoltaic. Whether an addition triggers it depends on the size of the addition relative to the existing house and how the project is classified.

Where it applies, expect $12,000 to $34,000. This is the single largest Title 24 cost and the one most worth resolving early, because the answer depends on how the project is defined. A conversation with the plans examiner during design is worth having.

The compliance path

There are two ways to demonstrate compliance:

The performance path is the useful one, because it lets you trade. Better windows can offset less insulation somewhere it is hard to reach. A more efficient heat pump can offset glass area you want to keep. A consultant runs the model and produces the compliance forms.

Consultant cost: $600 to $2,200 depending on complexity, and it is the cheapest line item in this entire article. Engaging one during design rather than after drawings are finished is what allows the trade-offs to happen at all.

What the whole thing adds up to

How to keep it from becoming a problem

1. Engage the energy consultant during design, not after drawings are complete. This is where the trade-offs get made.
2. Decide where the heat pump water heater goes before the layout is fixed. It is bigger than what it replaces.
3. Test the ducts before you design around keeping them. If they are at 30% leakage, plan for replacement.
4. Budget the ventilation fan on any addition or whole-house project. It is required and it is always a surprise.
5. Ask about solar early on additions, because the answer depends on classification and it is a $12,000 to $34,000 question.
6. Leave the window labels on. A small thing that causes real problems at final inspection.

The honest framing

Title 24 is a cost, and it is also most of what makes a 1965 San Jose house comfortable. Insulated walls, sealed ducts, real ventilation and dual-pane glass are the difference between a house that works and one that is hot in September and cold in January.

The frustration comes from encountering the requirements at plan check instead of during design, when each one becomes a change order rather than a decision.

DevArt8 Builders remodels homes throughout San Jose, Milpitas and the South Bay, and brings the energy consultant in during design so Title 24 requirements are priced and located before drawings are finished. See our full home remodeling in San Jose page for scope detail.