Sound‑Proof Flooring Hacks for Multi‑Level Homes

Introduction: Why Quiet Floors Matter in a Two‑Story House

Living in a multi‑level home has perks—extra space, better views, easy zoning for bedrooms and living areas—but noise bleeding between floors isn’t one of them. Footsteps, dropped toys, barking dogs, or even the hum of a treadmill can echo downward and ruin the peace on the floor below. Spokane’s booming housing market means more remodels, more rentals, and more families sharing space, so noise control has become a high‑priority upgrade.

Soundproofing a floor doesn’t require ripping your home apart or paying studio‑level prices. With the right materials and installation tricks, you can carve out a haven of calm on each level—often while upgrading style, durability, and resale value at the same time. This guide walks you through eight proven hacks that deliver real decibel drops without breaking the bank.

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Table of Contents

1. Understand How Sound Travels
2. Hack #1 – Quiet the Subfloor First
3. Hack #2 – Pick High‑Density, Resilient Flooring Materials
4. Hack #3 – Add an Acoustic Underlayment (and Install It Correctly)
5. Hack #4 – Float the Floor to Break Vibration Paths
6. Hack #5 – Boost Mass with MLV or Double Subfloors
7. Hack #6 – Seal the Edges, Gaps & Penetrations
8. Hack #7 – Deploy Strategic Soft Surfaces
9. Hack #8 – Treat the Ceiling Below for Extra Insurance
10. Cost & Performance Cheat Sheet
11. DIY vs. Pro Install
12. Maintenance Tips
13. Frequently Asked Questions
14. Key Takeaways & Next Steps

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Understand How Sound Travels

Before you buy a single plank, it helps to know what you’re fighting:

Sound Type	Example	How It Moves	Best Counter	Metric to Watch
Impact (Structure‑borne)	Footsteps, dropped objects	Vibrations through joists & studs	Mass + Isolation	IIC (Impact Insulation Class)
Airborne	Music, voices	Sound waves through air gaps	Mass + Sealing	STC (Sound Transmission Class)

Pro tip: Aim for IIC ≥ 60 and STC ≥ 55 for true multi‑family comfort. Spokane’s residential code doesn’t yet mandate these numbers, but they’re a solid benchmark if you’re future‑proofing a rental or ADU.

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Hack #1 – Quiet the Subfloor First <a name="hack-1-quiet-the-subfloor-first"></a>

Even the best acoustic vinyl won’t cancel a squeaky subfloor. Start with these steps:

1. Tighten the decking. Walk the entire floor, marking squeaks. Add 2½" decking screws alongside the existing nails to pull sheathing tight to joists.
2. Fill gaps & knot holes. Use a high‑grade, non‑shrinking construction adhesive or acoustic caulk on every visible crack.
3. Level dips with self‑levelling compound. An uneven base transmits impact shocks more easily.
4. Decouple where possible. If height allows, install ⅜" rubber or cork sheets under the subfloor (before underlayment) for an extra isolation layer.

Cost: $0.40–$1.20 per sq ft in materials—cheaper than retro‑fixing squeaks after the new floor is in.

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Hack #2 – Pick High‑Density, Resilient Flooring Materials <a name="hack-2-pick-high-density-resilient-flooring-materials"></a>

Density + flexibility = quiet. Here’s the quick‑rank from quietest to loudest for typical Spokane installs:

1. Carpet tiles with dense rubber backing – unbeatable for impact but lags in spills/pets.
2. Cork planks (10 mm+) – natural shock absorber, warm underfoot.
3. Engineered hardwood with HDF core – heavier than solid softwood, still refinishes once or twice.
4. SPC rigid‑core luxury vinyl (5 mm+) – stone polymer core adds mass; waterproof.
5. Traditional laminate – fiberboard core helps, but hollow click joints can “drum” without proper underlayment.
6. Tile over backer board – great for airborne noise, terrible for impact unless paired with rubber crack‑isolation mats.

When in doubt, ask for published IIC/STC lab ratings at the showroom. If a product rep can’t supply them, keep shopping.

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Hack #3 – Add an Acoustic Underlayment (and Install It Correctly) <a name="hack-3-add-an-acoustic-underlayment-and-install-it-correctly"></a>

Underlayment often matters more than the surface material. Look for:

Underlayment	Thickness	Typical IIC Boost	Notes
High‑density foam (2–3 mm)	2–3 mm	+10–15	Budget‑friendly, pairs with laminate/Vinyl.
Recycled felt/rubber composite	3–5 mm	+20–25	Handles minor subfloor flaws, eco‑friendly.
Cork roll	6 mm	+25–30	Mold‑resistant but hates standing water—great over basements with a vapor barrier.
Rubber acoustic mat (10 mm)	10 mm	+30–35	Commercial‑grade; heavy but killer impact control.

Installation keys:

• Roll out perpendicular to flooring direction to avoid joint stacking.
• Overlap or tape seams per manufacturer—gaps = noise leaks.
• Run 1½" up the wall, then trim after flooring to prevent flanking paths.

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Hack #4 – Float the Floor to Break Vibration Paths <a name="hack-4-float-the-floor-to-break-vibration-paths"></a>

A floating floor sits unattached over underlayment, separated by a small expansion gap at walls. This gap + underlayment = two mechanical breaks in the vibration chain. Engineered hardwood, LVP, and laminate click systems all float well.

Spokane Tip: Homes built before 1980 often have sloped or uneven second‑story sheathing. Floating installs hide minor imperfections without costly joist shimming.

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Hack #5 – Boost Mass with MLV or Double Subfloors <a name="hack-5-boost-mass-with-mlv-or-double-subfloors"></a>

Sound physics 101: more mass = less vibration.

• Mass‑Loaded Vinyl (MLV). A 1 lb/ft² sheet adds ~10 dB airborne attenuation. Staple or lay it loose directly over OSB before underlayment.
• Double‑layer subfloor. Screw a second ½" plywood layer with Green Glue damping compound sandwiched between. Adds heft and viscoelastic damping.

Yes, it raises floor height—but in a single‑room studio or home office, the silence is worth the threshold ramp.

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Hack #6 – Seal the Edges, Gaps & Penetrations <a name="hack-6-seal-the-edges-gaps-penetrations"></a>

Airborne noise slips through even hairline joints. After laying planks but before baseboards:

1. Backer‑rod + acoustic caulk in the expansion gap.
2. Grommets where plumbing or HVAC ducts penetrate the floor.
3. Acoustic putty pads behind floor‑level electrical boxes.

Small effort, huge STC gains.

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Hack #7 – Deploy Strategic Soft Surfaces <a name="hack-7-deploy-strategic-soft-surfaces"></a>

Even with the best underlayment, hard‑surface floors still generate some impact sound. Layer on:

• Area rugs with thick natural‑rubber pads in high‑traffic zones.
• Runner carpets on stair treads—bonus: safety + style.
• Felt pads under furniture legs to stop chair screech.

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Hack #8 – Treat the Ceiling Below for Extra Insurance <a name="hack-8-treat-the-ceiling-below-for-extra-insurance"></a>

Sometimes you can’t touch the finished floor—e.g., a rented upstairs unit. Attack from underneath:

• Resilient channels + ⅝" Type X drywall: decouple the ceiling, adds 10–12 STC.
• Blown‑in cellulose between joists: affordable, adds mass & insulation.
• Acoustic panel clouds in media rooms double as décor.

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Cost & Performance Cheat Sheet <a name="cost-performance-cheat-sheet"></a>

Solution	Material Cost (per sq ft)	Typical IIC/STC Gain	Height Added	DIY Difficulty
High‑density foam underlayment	$0.45–$0.70	+12 IIC	2–3 mm	★☆☆☆☆
Cork + floating SPC vinyl	$4.50–$6.00	+25 IIC / +20 STC	11 mm	★★☆☆☆
Rubber mat + engineered hardwood	$6.00–$8.50	+35 IIC / +22 STC	15 mm	★★★☆☆
MLV + laminate	$3.50–$5.00	+20 STC	5 mm	★★☆☆☆
Double subfloor w/Green Glue	$2.80 + base floor	+10 IIC / +12 STC	13 mm	★★★★☆
Resilient channel ceiling	$2.25–$3.00	+12 STC	⅝"	★★★★☆

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DIY vs. Pro Install <a name="diy-vs-pro-install"></a>

DIY advantages: cost savings (30–40%), weekend schedule flexibility, satisfaction factor. DIY drawbacks: warranty limits, steep learning curve on stair landings, risk of sub‑par STC results if layers aren’t tight.

When to hire Spokane pros:

• Projects > 400 sq ft or spanning multiple rooms.
• Structural modifications (sistering joists, double subfloors).
• Needing documented IIC/STC ratings for condo boards or rental compliance.

Local installers can often source trade‑only rubber mats and pass bulk savings to homeowners—ask for at least two competing quotes.

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Maintenance Tips <a name="maintenance-tips"></a>

• Keep it dry. Moisture weakens cork/rubber and kills STC over time.
• Re‑caulk perimeter gaps every 3–4 years, especially after seasonal shifts.
• Check felt pads quarterly; worn pads re‑introduce impact thumps.
• Avoid high‑PSI cleaners (steam mops) that can force water into seams.

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Frequently Asked Questions <a name="frequently-asked-questions"></a>

Q: Will thicker floors always be quieter? A: Thickness helps, but density and isolation layers matter more. A 7 mm SPC vinyl over rubber can outperform a ¾" solid oak nailed to joists.

Q: Can I lay new underlayment on top of old felt paper? A: Remove it; mixed underlayments create uneven compression and void most warranties.

Q: What about radiant heat? A: Use cork‑backed LVP or engineered hardwood rated for ≤ 85 °F surface temps. Rubber mats labeled “radiant‑ready” keep R‑value low so heat still passes.

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Key Takeaways & Next Steps <a name="key-takeaways-next-steps"></a>

• Target IIC 60 / STC 55 for multi‑level serenity.
• Start with the subfloor—no product masks squeaks.
• Pair a dense surface with a quality underlayment; installation is 50% of success.
• Seal every perimeter gap; airborne leaks undo your investment.
• For bulletproof silence, supplement with a resilient‑channel ceiling below.

Ready to reclaim your quiet? Book a free in‑home measurement with Cabinets Plus today or visit our Spokane showroom to feel the difference rubber‑cushioned floors make. Your ears—and your downstairs neighbors—will thank you.

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Written by the Cabinets Plus media team. Proudly serving Spokane, Airway Heights, Cheney, and Coeur d’Alene