Cushion Foam FAQ: Answers to the 25 Most Common Questions
Whether you are replacing sagging sofa cushions, upgrading your boat seating, or building a window seat from scratch, the same questions come up for almost everyone who is new to ordering custom foam. This FAQ compiles the 25 questions our customers ask most frequently — with clear, direct answers and links to our detailed guides when you want to go deeper.
Bookmark this page. It is the fastest way to find answers about foam types, measuring, ordering, pricing, and care.
Foam Types and Selection
1. What types of foam do you carry?
We carry two foam types — intentionally. After evaluating dozens of formulations, these two cover every real-world cushion application with professional-grade quality:
Indoor Cushion Foam: 2.8 lb/ft³ high-resiliency (HR) cold-cure polyurethane. Medium-firm feel. Best for sofas, chairs, benches, headboards, RV interiors, and any dry indoor seating. Priced at $0.07 per cubic inch.
Outdoor & Marine Foam: 1.8 lb/ft³ Dry Fast reticulated foam. Available in soft, medium, or firm. Best for patio furniture, boat cushions, poolside seating, and any application where the foam gets wet. Priced at $0.14 per cubic inch.
Both are CertiPUR-US certified. For a full comparison, see our indoor vs. outdoor foam guide.
2. What is foam density and why does it matter?
Density measures how much foam material exists per cubic foot, expressed in lb/ft³. Higher density means more material, which means greater durability, better weight distribution, and longer lifespan. Our indoor foam at 2.8 lb/ft³ is professional-grade — the same quality used by custom furniture builders. Most retail sofas ship with 1.5 to 1.8 lb foam that wears out in three to five years.
Full guide: Foam Density and Firmness Explained
3. What is the difference between high resilience and high density foam?
High density describes the weight of foam per cubic foot (a quantity measurement). High resilience describes how the foam performs under compression (a behavior measurement). HR foam is manufactured using a cold-cure process that creates variable cell sizes for progressive support — softer on contact, firmer as you sink deeper. Standard HD foam has uniform cells and a one-dimensional feel.
Our foam is both high density (2.8 lb) and high resilience (cold-cure). Full guide: High Resilience vs. High Density Foam
4. Which foam should I use for my sofa?
Indoor 2.8 lb HR foam in medium-firm. This is the right choice for the vast majority of sofa cushion replacements. It works for seat cushions, back cushions, and sofa bed mattresses.
Full guide: How to Replace Foam in Couch Cushions
5. Which foam should I use for outdoor furniture?
Dry Fast outdoor foam — always. Standard indoor foam absorbs water, grows mold, and falls apart outdoors. Dry Fast foam drains water instantly through its open-cell structure, dries in minutes, and resists mold with built-in antimicrobial properties.
Full guide: Patio Furniture Foam Replacement
6. Which foam should I use for a boat?
Dry Fast outdoor foam for all topside and exposed seating. For below-deck sleeping berths that stay dry, indoor HR foam is more comfortable. Many boat owners use both — HR foam for sleeping below deck, Dry Fast for everything above deck.
Full guide: Boat Cushion Foam Replacement
7. What foam is best for heavier people?
Our 2.8 lb HR foam in medium-firm handles most body types up to 350 pounds. The key for heavier individuals is combining high density with adequate thickness — 5 inches minimum for people over 200 pounds, 6 inches for 300+ pounds.
Full guide: Foam Density and Firmness Explained
Measuring and Sizing
8. How do I measure my cushion for replacement foam?
Measure the cushion cover from seam to seam — not the old foam. Old foam has compressed and distorted, so its dimensions no longer reflect what the cover needs. Measure width, depth, and thickness from inside seam to inside seam. Add half an inch to width and depth for a snug fit. Keep thickness exact.
Full guide: How to Measure Couch Cushions
9. What if my cushion is a weird shape (T-shape, L-shape, circle)?
Our configurator handles rectangles, T-shapes, L-shapes, circles, and bullnose (rounded front) shapes. For truly irregular shapes, make a paper template by tracing the outline on butcher paper and send it to us for a custom cut.
10. Should I order the foam slightly larger than my cover?
Yes — add half an inch to width and depth for a full, professional-looking fit. The foam compresses slightly when inserted into the cover, which is what creates a plump appearance. Do not add extra to thickness — order the exact thickness the cover measures.
11. What thickness should I order?
| Application | Recommended Thickness |
|---|---|
| Sofa seat cushions | 4–6 inches |
| Sofa back cushions | 3–4 inches |
| Dining chairs | 1.5–2 inches |
| Window seats / benches | 3–4 inches |
| Sleeping surfaces | 5–6 inches |
| Patio seating | 3–4 inches |
| Bar stools | 2–3 inches |
Full guides: Window Seat Foam | RV Cushion Upgrades | Van Life Foam
Ordering and Pricing
12. How does pricing work?
Price = Foam Rate × Length × Width × Thickness (all in inches)
Indoor HR foam: $0.07 per cubic inch. Outdoor Dry Fast foam: $0.14 per cubic inch. Minimum order: $15. Free shipping on orders over $199.
Enter your dimensions in the configurator to see your exact price instantly — no quotes, no waiting.
Full guide: Sofa Cushion Foam Replacement Cost
13. How much does it cost to replace sofa cushion foam?
A typical three-cushion sofa costs $60 to $210 for complete seat cushion replacement with our 2.8 lb HR foam. Add back cushions and you are looking at $100 to $350 total. Compare that to $600 to $1,800 for professional reupholstering or $1,000 to $5,000+ for a new sofa.
Full guide: Sofa Cushion Foam Replacement Cost
14. What shapes can you cut?
Rectangles, T-shapes, L-shapes, circles, bullnose (rounded front edge), and custom shapes from templates. Select your shape in the configurator. For custom shapes, contact us.
15. How long does shipping take?
Most orders are cut and shipped within 2 to 5 business days. Shipping time depends on your location — typically 3 to 7 days for transit after shipment. Free shipping on orders over $199. We ship to all 50 states.
Installation and Care
16. How do I install new foam in my cushion covers?
Remove the old foam from the cover. Optionally wrap the new foam in Dacron batting for a softer, rounded look. Fold the foam in half, slide it into the cover opening, unfold inside, and work it into the corners. The plastic bag technique (wrapping foam in a garbage bag before insertion) makes this significantly easier.
Full guide: How to Replace Foam in Couch Cushions
17. What if my cushion covers do not have zippers?
Many sofas use a slip-stitch on the back seam. Open it with a seam ripper, insert new foam, and hand-stitch it closed with a curved needle ($5 from any fabric store). Alternatively, a local upholsterer can open and close the seam for $15 to $30 per cushion.
18. Will new foam smell?
New polyurethane foam may have a slight odor from manufacturing off-gassing. With CertiPUR-US certified foam, this odor is verified to be within safe limits and dissipates within 24 to 48 hours. Unwrap the foam in a ventilated area and let it air out before installing.
19. How do I clean foam cushions?
Indoor foam: Blot spills immediately. Spot-clean with mild soap and water. Never submerge, machine wash, or put in a dryer.
Outdoor Dry Fast foam: Rinse with a garden hose. Scrub with mild soap and a soft brush if needed. Dries in minutes.
Full guide: How to Replace Foam in Couch Cushions
20. How should I store outdoor cushions in winter?
Store upright (not stacked flat) in a dry, climate-controlled space. Use breathable fabric covers, not sealed plastic. Clean covers before storing. The foam itself does not need any special treatment — just keep it dry and out of direct sun.
Full guide: How to Replace Foam in Couch Cushions
Durability and Replacement
21. How long does cushion foam last?
| Foam Type | Daily Use Lifespan |
|---|---|
| Budget foam (1.0–1.5 lb) | 1–3 years |
| Standard HD (1.5–1.8 lb) | 2–5 years |
| Quality HD (1.8–2.2 lb) | 4–7 years |
| HR foam (2.8 lb) — ours | 8–15 years |
| Dry Fast outdoor — ours | 5–8 years outdoors |
Full guide: How Long Does Cushion Foam Last?
22. How do I know when foam needs replacing?
Five signs: visible sagging, body impressions that take more than five seconds to recover, the fold test (foam folds easily and does not spring back), bottoming out (feeling the frame through the cushion), and gradually shifting your sitting position to avoid the worst spots.
Full guide: How Long Does Cushion Foam Last?
23. Is it worth replacing foam in a cheap sofa?
Yes — if the frame is solid and the fabric is intact. A $500 sofa with $100 in new 2.8 lb HR foam will feel better than a $2,000 sofa with its factory 1.8 lb foam. The frame and fabric are where real furniture value lives. The foam is a replaceable consumable.
24. What is CertiPUR-US certification?
CertiPUR-US is an independent testing program that verifies polyurethane foam is made without harmful chemicals (ozone depleters, PBDE flame retardants, heavy metals, formaldehyde, regulated phthalates) and meets low VOC emission standards. Both of our foam types carry this certification.
Full guide: What Is CertiPUR-US Certified Foam?
25. Can I use your foam for my specific brand of sofa (Pottery Barn, IKEA, West Elm, etc.)?
Absolutely. Custom-cut foam works with any sofa brand because it is made to your exact measurements, not to brand-specific templates. We have detailed guidance for the most popular brands including Pottery Barn, IKEA, West Elm, Restoration Hardware, La-Z-Boy, and more.
Full guide: Replacement Foam for Popular Sofas
Still Have Questions?
This FAQ covers the most common questions, but your project might be unique. We are here to help:
- Browse our detailed guides: Every topic above links to a comprehensive blog post with full instructions, pricing examples, and expert tips.
- Use our configurator: Build your custom cushion → and see exact pricing for your dimensions instantly.
- Check our How It Works page: See the full process from measuring to delivery.
- Explore our product pages: Custom sofa cushions | Outdoor & patio cushions | Boat & marine cushions | RV & camper cushions | Foam cut to size | Upholstery foam
- Talk to a human: Contact us or call 1-877-75-FOAMZ. We are happy to help you measure, choose foam, or plan your project.
