Okay, let's break this down. You've identified several red flags that scream "potential for cost overruns" and are rightly concerned about a fixed bid. Here's a structured approach to deciding if T&M is the right choice, and how to approach it if you go that route

Understanding Your Concerns (and why they're valid):
Concrete Walls and Ceilings

This is the biggest driver of risk. Cutting concrete is unpredictable. You don't know what's inside the concrete (rebar, conduit) until you're cutting. Each encounter adds time and cost.

Chase Issues

The incomplete chase is a problem. You're essentially tasked with creating a new pathway.

Floor Saw Cutting

This is time-consuming, messy, potentially noisy (impacting neighbors), and can be unpredictable in terms of subsurface issues.

Baseboard to Cove Heat Conversion

While seemingly simple, moving heaters to the ceiling often involves more than just relocation. You need to verify the existing circuit capacity is adequate, the structural integrity of the ceiling can support the heaters (especially if filled with water/glycol), and consider running new wire to the ceiling and tapping into existing junction boxes.

Surface Mounted Lights

Relatively straightforward, but still adds to the overall complexity and requires careful planning to conceal wiring.

Kitchen Island and Wall Removal

Re-routing existing circuits, adding new circuits for the island (especially if there's an induction cooktop or other high-power appliance), and dealing with potential asbestos or lead paint concerns in older condos all add to the uncertainty.

Arguments FOR T&M



Unforeseen Conditions

Concrete is the enemy of fixed bids. The unknown potential for rebar hits, unexpected obstacles, and difficulty in running conduit makes cost control difficult.

Flexibility

T&M allows you to adapt to problems as they arise without having to negotiate change orders constantly. This is critical in a remodel with so many unknowns.

Fairness

T&M is fair to both you and the client. They pay for the actual work done, and you get compensated for the actual time and materials invested.

Protects Your Profit

With a fixed bid, you are risking eating into your profit (or even losing money) if unexpected challenges arise.

Client Buy-In

You can sell T&M by explaining these risks to the client. They may understand that some uncertainty exists and appreciate the transparency.

Arguments AGAINST T&M (and how to mitigate them)



Client Perception

Some clients are uncomfortable with "blank check" T&M. They fear costs spiraling out of control.

Potential for Abuse

While you wouldn't do this, the perception exists that T&M can lead to inflated hours.

Difficult to Budget

Clients need to budget, and T&M makes that harder.

How to Approach T&M (If You Choose It)


Transparency and Communication (MOST IMPORTANT)

This is everything with T&M.

Detailed Scope of Work

Clearly define what's included and, more importantly, what's excluded. Specifically mention the concrete work as an area of potential unknown expense.

Hourly Rate and Material Markup

Be upfront about your rates and how you mark up materials. Provide a detailed breakdown in your proposal.

Regular Updates

Provide daily or, at a minimum, weekly updates to the client on progress, hours worked, and materials used. Be proactive in communicating any potential changes to the estimated budget before they happen.

Photographic Documentation

Take pictures of the existing conditions before you start, document the work as it progresses, and photograph any challenges you encounter. This provides visual proof of the work performed.

Daily Time Sheets

Use clear, detailed time sheets that the client can review.

Itemized Invoices

Provide invoices that list labor, materials, and any subcontractors separately.2.

Provide a "Not-to-Exceed" Estimate (Highly Recommended)

This isn't a fixed bid, but it gives the client a ceiling. Explain that you've built in a reasonable contingency, but that unforeseen issues could still push costs higher (with their approval, of course). Explain how the "not-to-exceed" number was calculated and break it down by areas of work (demo, concrete cutting, circuit routing, heater relocation, island wiring, lighting).

Example

"Based on my initial assessment, I estimate this project will cost between \$20,000 and \$28,000. However, due to the potential challenges with the concrete work, I propose a Time and Materials contract with a 'Not-to-Exceed' price of \$28,000. I will provide you with daily updates and will seek your approval before exceeding this amount."3.

Phased Approach

Break the project into phases. For example, Phase 1 could be the demo and concrete cutting needed to assess the situation. After Phase 1, you and the client can re-evaluate and decide how to proceed with the remaining phases. This reduces the client's risk and allows you to get a better handle on the unknowns early on.4.

Contingency

Even with T&M, build a contingency into your own internal estimates (not necessarily the one you give the client for the "not-to-exceed"). This protects you from minor cost overruns on materials or unexpected delays.5.

Negotiate a Kill Switch

Consider adding a kill switch clause to the contract. This allows the client, after any phase, to terminate the contract and have you stop working.

Alternatives to Straight T&M



Fixed Price with "Concrete Cutting Allowance"

Give a fixed price for the rest of the work, but include a separate allowance for concrete cutting. Anything under the allowance is returned to the client; anything over requires their approval.

Cost-Plus Fixed Fee

You charge for your costs (labor and materials) plus a fixed percentage (your profit). This is similar to T&M but provides more certainty for the client.

Should You Do T&M?

Based on the information you've provided, T&M with a Not-to-Exceed estimate is likely the most appropriate approach. The concrete work is too much of an unknown to reasonably bid a fixed price.

How to Discuss with the Client



Focus on the Benefits of T&M

Explain how it protects them from paying for work that isn't needed and ensures they only pay for the actual cost of the project.

Be Honest and Upfront

Explain the challenges with concrete and the potential for unforeseen issues.

Emphasize Your Experience

Highlight your experience with similar projects and your ability to manage the project efficiently.

Provide References

If possible, provide references from clients who have worked with you on T&M projects.

Give a Range, not just one number

Instead of stating "$25k", provide a range such as "$22k-$28k."

In conclusion: Don't be afraid of T&M, but approach it professionally and transparently. Your communication and documentation will be key to a successful project and a happy client. If the client is uncomfortable with any form of T&M, you may need to walk away. It's better to lose a job than to lose money and damage your reputation. Flag for review