Subfloor Repair & Preparation services in Chicago
Flatten. Fasten. Fortify. The right base for any floor.
The foundation of a quiet, long‑lasting floor
Every great floor starts below the surface. At Costello Carpentry, our subfloor repair and preparation services give your new finish floor the stable, squeak‑free base it needs. We evaluate framing, sheathing, fasteners, moisture, and levelness before a single plank or tile is laid. The result is a solid feel underfoot, tight joints above, and finishes that stay put through Chicago seasons.
We begin with a clean assessment: map high and low spots, locate loose panels, identify deflection or bounce, and check moisture at concrete and wood substrates. From there, we choose the right fix—re‑screw or re‑nail, add blocking, shim low areas, plane crowns, install underlayment, or self‑level as needed. For concrete, we grind, patch, prime, and pour where necessary, ensuring the manufacturer’s flatness and moisture requirements are met for your chosen material.
Preparation is not guesswork. We follow product specifications for LVP/laminate, hardwood, and tile so warranties remain valid and performance matches expectations. Expansion gaps, vapor control, sound underlayment, and transitions are planned up front. That diligence prevents telegraphing seams, hollow spots, tenting tile, and the squeaks that drive homeowners crazy.
Why Choose Costello Carpentry?
Clean, seamless installations with expert-level precision
Experienced in all major flooring types and materials
Honest recommendations and upfront pricing
We respect your space and leave it spotless
Our Subfloor Repair & Preparation Services Include:
Wood Subfloor Repair & Reinforcement
Stiffen, flatten, and secure wood substrates so finish floors feel solid and stay quiet.
We offer:
- Re‑fastening with screws and adhesives to eliminate squeaks
- Blocking and sistering to reduce deflection and bounce
- Panel replacement for damaged OSB/plywood
- Surface planing/shimming to remove crowns and fill dips
Concrete Grinding, Patching & Leveling
Get in‑spec flatness and bond for resilient, wood, or tile over slab.
Our process:
- Moisture testing (RH/MC) and vapor mitigation options
- Crack repair and control joint treatment as specified
- Primer and SLU pours for large low areas; grinding of high spots
- Feather‑finish patching at transitions and doorways
Underlayments, Sound & Vapor Control
Choose the right layer between subfloor and finish floor for performance and code.
We install:
- Acoustic underlayments for condos and multi‑family requirements
- Vapor retarders/barriers sized to product and slab conditions
- Cement board/uncoupling membranes for tile in wet and dry areas
- Rosin, felt, or foam where appropriate for wood and LVP/laminate
Transitions, Heights & Door Clearances
Plan the edges so rooms connect cleanly and doors swing freely.
We handle:
- Height planning at tile‑to‑wood, carpet, and vinyl interfaces
- Reducers, thresholds, and stair noses aligned with layouts
- Door trimming and jamb undercutting for smooth operation
- Expansion gaps and perimeter details per product specs
Free Consultations & Estimates
Floor failures almost always trace back to what’s underneath. Fix the base and the finish takes care of itself. Share a few photos and room sizes or book a quick site visit. We’ll measure, test, and provide a clear plan with options and pricing before any install begins.
Let’s get your subfloor ready the right way.
Your Trusted flooring installation Contractor in Chicago
As a trusted subfloor repair and preparation contractor in Chicago, we deliver flat, quiet, code‑compliant bases for hardwood, LVP/laminate, and tile.
From small patches to whole‑home leveling, we bring the tools, materials, and sequence your project needs—with clean protection and predictable timelines.
Ready to start? Contact us to schedule your free subfloor assessment.
Frequently Asked Questions
How do I know I need Subfloor Repair?
Signs include squeaks, bounce or deflection, hollow spots, cracked tile, telegraphed seams, and doors rubbing after a new floor was laid.
What does your Subfloor Repair assessment include?
We map highs and lows, check fasteners, measure deflection, test moisture in wood and concrete, and review height transitions and door clearances.
Can you eliminate squeaks and floor movement?
Yes. We re-fasten panels with screws and adhesives, add blocking or sister joists, and address loose or damaged sheets to make the floor quiet and solid.
Do you level both wood and concrete substrates?
Yes. Wood gets planing, shimming, and panel work. Concrete gets grinding, patching, primer, and self-leveling pours to meet flatness specs.
Is moisture testing part of Subfloor Repair?
Yes. We use RH and MC methods to confirm moisture is within product limits and add vapor mitigation if needed so warranties stay valid.
What underlayments do you install?
We match acoustic, vapor, and uncoupling layers to the finish floor: foam or felt for wood and LVP, cement board or membranes for tile, and vapor retarders over slabs.
Will Subfloor Repair change finished floor heights?
It can. We plan reducers, thresholds, stair noses, and door trims so rooms connect cleanly and doors swing freely.
How long does Subfloor Repair usually take?
Small rooms often finish in a day. Larger areas or self-leveling pours may require additional cure time before the finish floor goes in.
Can you work around existing kitchens or built-ins?
Often yes. We protect cabinets and appliances, plan heights at toe kicks and transitions, and keep lines straight through doorways.
Is Subfloor Repair required before every new floor?
Not always, but verifying flatness, fastening, and moisture protects your investment and prevents hollow spots, lippage, and early failures.
Do you handle condo sound and code requirements?
Yes. We install rated acoustic underlayments and provide product data to meet building or HOA requirements.
What warranty do you provide?
Workmanship is covered for one year. Manufacturer warranties for underlayments and compounds remain in place. We document products and dates for future reference.