Marvel-Works
Interior of a Marvel-Works whole-home build and expansion on Gardendale Drive in Houston, TX

More house, built like it was always there.

Bump-outs, single-story additions, primary suites, and second stories — engineered from the foundation up and finished so the seam between old and new disappears.

Get a free in-home estimate

A remodel works inside walls, a roof, and a foundation that already exist. An addition has to create all three before a single finish goes in — new foundation, new framing, a roof married into your existing roofline, new mechanical systems — and only then does it become the room you pictured.

That makes an addition the most structural work we do, and the part most contractors get wrong is the part you can’t see: the foundation tie-in, the roof flashing, the load path. We run the whole thing as one project, with one Project Manager, with the structural, mechanical, and finish trades on our crew working from the same playbook. You’re not handing off between a framer, a roofer, and a finish contractor — you’re working with us.

Want the numbers first? Our room addition cost guide breaks down what each tier costs and where the budget actually goes.

What a room addition involves

Every line below shows up as a discrete item in your scope and quote — we don’t bundle. You see the cost of each phase and decide what stays in.

Foundation
engineered slab or footings, tied into your existing foundation
Framing & structure
walls, sheathing, and load path verified by an engineer
Roof tie-in
new roofline married into the old with correct flashing
Exterior match
siding, brick, or stucco blended to the existing house
Windows & doors
matched to your existing lines and openings
HVAC
right-sized system or dedicated mini-split — not just extended ducts
Electrical & plumbing
new circuits, panel upgrade if needed, plumbing where the room calls for it
Interior finish
insulation, drywall, flooring, trim, paint — and bath or kitchen if included

Common addition types: a bump-out to enlarge a kitchen or bath, a new bedroom or home office, a primary suite with en-suite bath, a sunroom or enclosed patio, or a full second story.

Process

  1. 1

    On-site visit (about 45 minutes, free)

    Gabe or a senior PM walks the property with you, looks at the existing foundation, roofline, and setbacks, and talks through build-out vs build-up. You'll get a written scope and an honest budget range within a few days.
  2. 2

    Design & structural engineering

    We develop the addition design and bring in a structural engineer for the foundation and, on a second story, the load path. Every assembly is documented before anything is ordered or poured.
  3. 3

    Permits & HOA approval

    We submit engineered plans to the city or county and, in master-planned communities, take the design through architectural review. This phase runs in parallel with selections so it doesn't stall the build.
  4. 4

    Foundation

    Site prep, forming, and an engineered slab or footings tied into your existing foundation so the two move together. On expansive Houston clay this is the step we never rush — everything above it depends on it.
  5. 5

    Framing & roof tie-in

    Walls framed, sheathed, and tied into the existing structure; the new roof married into the old roofline with correct flashing. The house stays weather-tight throughout — we don't open more than we can dry in.
  6. 6

    Mechanical rough-in

    HVAC, electrical, and any plumbing roughed in and inspected. If the addition pushes your panel or system past capacity, the upgrade is scoped here, not discovered later.
  7. 7

    Insulation, drywall & exterior

    Insulation and drywall inside; siding, brick, or stucco matched to the existing exterior outside. The transition between old and new is detailed so it reads as one house.
  8. 8

    Interior finish

    Flooring, trim, paint, doors, and — if the addition includes a bath or kitchen — the full finish on those, built to the same documented standards as our remodels.
  9. 9

    Walk-through

    You inspect with the PM. Anything you want adjusted gets a punch list. We don't sign off until you do.

Timeline & Investment

  • Bump-out / small addition
    4 to 8 weeks
    $25,000 to $70,000
  • Single-story room addition (bedroom, family room, primary suite)
    10 to 16 weeks
    $90,000 to $200,000
  • Second-story addition
    16 to 26 weeks
    $200,000 to $450,000+

Roughly $250 to $500 per heated square foot, finished and permitted. We give you a real number after the on-site visit — see the cost guide for the full breakdown.

For the technical homeowner

The structural and building-envelope standards our crews work to on every addition — the work behind the finishes that decides whether an addition lasts.

Standards we hold our crews to on additions

Foundation

  • Slab and footings engineered for the site’s soil, not a generic spec
  • New foundation tied into the existing one so the two move together on expansive clay
  • Vapor barrier and reinforcement per the engineer’s drawings, inspected before pour

Framing & structure

  • Load path verified by a structural engineer — mandatory on any second story
  • Existing structure reinforced where the addition imposes new loads
  • Framing inspected before it’s closed up

Roof tie-in & building envelope

  • New roof married into the existing roofline with proper step and counter-flashing
  • House kept weather-tight throughout — no more opened than can be dried in
  • Flashing, drainage plane, and vapor profile detailed at the old-to-new seam, the spot leaks start

Mechanical

  • HVAC load recalculated for the added space — right-sized system or dedicated mini-split, never a hopeful duct extension
  • Electrical service verified against the new load; panel upgraded to 200A where required
  • All rough-ins inspected before insulation and drywall

Sign-off

  • Project complete only when you sign off, not when we’re tired

Frequently asked questions

How much does a room addition cost in Houston?
A bump-out or small addition runs $25,000 to $70,000. A single-story room addition on a new foundation — a bedroom, family room, or primary suite — runs $90,000 to $200,000. A second-story addition runs $200,000 to $450,000 and up. The honest way to check any quote is per square foot: a finished, permitted, foundation-included addition in greater Houston runs $250 to $500 per heated square foot. We give you a real number after the on-site visit. See our room addition cost guide for the full breakdown.
How long does a room addition take?
A bump-out runs 4 to 8 weeks. A single-story addition runs 10 to 16 weeks. A second-story addition runs 16 to 26 weeks. Those windows include the foundation cure, framing, the roof tie-in, mechanical rough-ins, inspections, and finishes — but not the design, engineering, permit, and HOA-approval phase that comes first, which can add several weeks on its own.
Do I need a permit for a room addition?
Yes. Any addition that increases your home's footprint or conditioned space requires a permit, and an addition with new foundation requires engineered plans. In master-planned communities you'll also need architectural review from your HOA before the city will issue anything. We handle the permit submittal, the engineering coordination, and the inspection cycles end-to-end.
Can you match the addition to my existing house?
That's the whole job. A good addition looks like it was always there — matching brick or siding, rooflines that tie in cleanly, windows that align with the existing ones. Sometimes a brick or window line has been discontinued, so we source the closest match and, where needed, blend the transition so the seam doesn't read. It's one of the things that separates a real addition from one that looks bolted on.
Should I build out or build up?
Building out (a single-story addition) is simpler and usually cheaper per foot — but it costs you yard and requires the lot space and setbacks to allow it. Building up (a second story) keeps your footprint but is the more involved project: an engineer has to confirm the existing foundation and walls can carry the load, you lose some downstairs space to a staircase, and the house has to stay weather-tight while the roof is open. We walk both options at the on-site visit and tell you which actually fits your house and budget.
Will my foundation and HVAC handle an addition?
Those are exactly the two things we check first. New conditioned space adds load your existing HVAC may not be sized for — the fix is either a right-sized system or a dedicated mini-split for the addition, never just extending ductwork and hoping. On a second story, the existing foundation gets engineered review before anything goes up. Skipping either is how additions end up that never heat right or that crack a year later.
Do you handle the whole project, including the interior finish?
Yes. Foundation, framing, roofing, exterior, plumbing, electrical, HVAC, and the full interior finish all run under one Marvel-Works project manager. If the addition is a primary suite or includes a kitchen, the bathroom and kitchen work is on the same crew and the same playbook — you're not handing off between a framer and a finish contractor.

Service areas

We build additions across The Woodlands, Spring, Magnolia, Conroe, Montgomery, Tomball, Cypress, Sugar Land, Pearland, and the rest of greater Houston.

  • The Woodlands, TX
  • Magnolia, TX
  • Spring, TX
  • Conroe, TX
  • Montgomery, TX
  • Tomball, TX
  • Cypress, TX
  • Sugar Land, TX
  • Pearland, TX
  • Houston, TX

Schedule an on-site estimate.

We'll look at your foundation, roofline, and HOA situation, then give you a written scope and a real number — no pressure, no upsell.

Get a free estimateCall 832-390-8685

Free in-home estimates in The Woodlands area. For projects outside that area, a travel fee applies.