# FAQ — Decks & Patios — Renovate Guide **Author:** Frank Mercer, Licensed GC (Ret.) | HAAG Certified Roof Inspector **Q: How much does it cost to build a deck in 2024?** **A:** Budget $30–$60 per square foot for a pressure-treated wood deck installed by a contractor. Composite decking like Trex bumps that to $50–$85 per square foot. A standard 16x20 foot deck runs $9,600–$19,200 for wood and $16,000–$27,200 for composite. Material costs are about 40% of that total — labor eats the rest. Anyone quoting you under $25 per square foot is cutting corners on fasteners, framing, or footings. --- **Q: Is Trex decking worth the extra money?** **A:** Yes, for most homeowners it absolutely is. Trex runs $8–$12 per square foot in materials versus $3–$6 for pressure-treated wood. But you eliminate annual sealing, staining, and the constant battle against rot and splinters. Trex Enhance carries a 25-year fade and stain warranty. Over a 15-year window, the maintenance savings on a 400 square foot deck typically run $3,000–$5,000. The upfront premium pays for itself by year eight for most people. --- **Q: Do I need a permit to build a deck?** **A:** In nearly every jurisdiction, yes — if the deck is attached to the house or over 30 inches above grade. Most counties require a permit for any deck over 200 square feet regardless of height. Without a permit, you're looking at forced demolition, fines up to $5,000 in some states, and a homeowner's insurance claim denial if someone gets hurt. Pull the permit. It costs $150–$500 and protects your investment. --- **Q: How long does a pressure-treated wood deck last?** **A:** A properly built and maintained pressure-treated deck lasts 15–25 years. The framing treated to UC4B or UC4C standard will outlast the decking boards themselves. The deck surface — the part you walk on — starts showing serious wear at the 10–15 year mark if you don't seal it every 1–2 years. Neglect the maintenance and you're replacing boards at year eight. Stay on top of it and the structure will outlast most homeowners' interest in keeping it. --- **Q: What is the difference between Trex Select, Enhance, and Transcend?** **A:** These are Trex's three product tiers. Trex Enhance is the entry level at $8–$10 per square foot — solid color, basic wood grain, good durability. Trex Select sits in the middle at $9–$11 per square foot with a slightly more realistic grain pattern. Trex Transcend is the premium line at $11–$16 per square foot — deep embossed wood grain, four-sided capping, and the best fade and stain resistance. For most residential decks, Enhance or Select is the right call. Only go Transcend if aesthetics are a top priority. --- **Q: How deep do deck footings need to be?** **A:** Your footings must extend below the frost line for your region — that's non-negotiable. In Chicago that's 42 inches. In Atlanta it's 12 inches. In Minneapolis you're digging 48 inches. Check your local building code for the exact number. The footing itself needs to be a minimum 12 inches in diameter for a standard deck post, poured with concrete to at least 3,000 PSI. Shallow footings heave, posts shift, and the whole structure goes out of square within three winters. --- **Q: Patio pavers vs. concrete — which is better?** **A:** For most homeowners, pavers are the smarter choice. Poured concrete is cheaper upfront — $6–$12 per square foot installed versus $15–$30 per square foot for pavers — but concrete cracks, and once it cracks, repair looks terrible. Pavers crack too, but you replace individual units for under $50. Pavers also flex with freeze-thaw cycles better than a rigid slab. The only case where concrete wins is a very large flat patio where budget is the controlling factor and you're willing to seal it every two years. --- **Q: How far apart should deck joists be spaced?** **A:** Standard joist spacing is 16 inches on center for wood decking boards running perpendicular to the joists. If you're installing composite decking at a 45-degree angle, drop to 12 inches on center — the diagonal run puts more stress on mid-span. Most composite manufacturers including Trex and TimberTech require 12-inch spacing for diagonal installations and specify this in their warranty terms. Go 24 inches on center only if you're using 5/4 or thicker structural decking explicitly rated for that span. --- **Q: What is the best composite decking brand?** **A:** Trex, TimberTech, and Fiberon are the top three and all make a quality product. Trex is the most widely available and has the longest track record — they've been making composite decking since 1996. TimberTech (owned by AZEK) makes an all-PVC capped board that handles moisture better than wood-composite blends. Fiberon is competitively priced and offers comparable warranty terms. I've installed all three. For overall value and contractor availability, Trex wins. For wet climates or pool decks, I lean toward TimberTech's PVC line. --- **Q: How do I stop my deck boards from warping?** **A:** Three things cause warping: wet wood installed before it dries, improper fastening, and inadequate airflow beneath the boards. If you're using pressure-treated lumber, let it acclimate on-site for at least a week before installation. Use two fasteners per board at every joist — never one. Leave 1/8-inch gaps between boards for drainage and airflow. For composite decking, follow the manufacturer's temperature-specific gapping requirements — Trex specifies gap sizes based on ambient temp at installation. Skipping that step is the number one cause of composite deck buckling in summer. --- **Q: Can I build a deck over an existing concrete patio?** **A:** Yes, and it's a clean solution when the slab is in good shape. You build a sleeper frame — pressure-treated 2x6 or 2x8 laid flat on the concrete — and fasten the decking to that. The slab becomes your footing. Make sure the slab has adequate drainage and isn't trapping water against the house. The finished deck surface must sit at least 1 inch below the door threshold. One caveat: if that slab is heaved or cracked badly, you're better off demoing it first — building over a bad slab just buries the problem. --- **Q: What size posts do I need for a deck?** **A:** For most residential decks, 4x4 posts are adequate up to 8 feet of height. Once you're over 8 feet — a raised deck or one with a roof structure — go to 6x6 posts. Many jurisdictions have updated their codes to require 6x6 as a minimum regardless of height, so check your local IRC amendments. Post height also affects lateral stability: anything over 14 feet freestanding height needs engineered connections and diagonal bracing. Don't let anyone talk you into 4x4 posts on a tall deck to save $200 in lumber. --- **Q: How do I find the right slope for a patio to drain properly?** **A:** Minimum slope away from the house is 1/8 inch per foot — that's the IRC standard. I recommend 1/4 inch per foot for concrete and pavers. On a 12-foot-wide patio, that means the outer edge sits 3 inches lower than the edge at the house. Use a 4-foot level and a tape measure to check as you go. Getting this wrong means water pools against your foundation, and foundation repair costs $5,000–$15,000. Get the grade right the first time. --- **Q: How much weight can a deck hold?** **A:** Residential decks are engineered to handle 40 pounds per square foot live load — that's the IRC minimum. A 200 square foot deck can theoretically support 8,000 pounds of people and furniture distributed across the surface. The failure point is almost never the decking boards — it's the ledger connection or the post-to-beam connection. A hot tub changes the equation entirely. A filled 6-person hot tub weighs 5,000–6,000 pounds. If you're adding a hot tub, get an engineer to evaluate the framing before you set it down. --- **Q: What is the best wood for deck framing?** **A:** For structural framing — joists, beams, posts — use pressure-treated lumber rated to at least UC4A for above-ground applications. For posts set in soil or concrete, use UC4B minimum. Southern Yellow Pine is the most common species used for PT framing and it's structurally strong. Do not use cedar or redwood for framing — they're beautiful for decking boards but they don't have the structural density for load-bearing applications. All PT lumber in contact with concrete needs to be rated UC4B to resist the alkaline environment. --- **Q: How do I attach a deck ledger board to my house?** **A:** The ledger gets bolted directly to the house's rim joist — not the siding. Strip the siding back, install flashing that runs up behind the house wrap and over the top of the ledger, then fasten with 1/2-inch lag screws or structural hex bolts per the IRC span table. Minimum bolt pattern for a standard deck is two fasteners per joist bay in a staggered pattern. The ledger-to-house connection is the number one failure point in deck collapses — this is not the place to eyeball the fastener spacing or skip the flashing. --- **Q: How long does it take to build a deck?** **A:** A two-person professional crew builds a standard 16x20 foot deck in 3–5 days once materials are on-site. Add a day for complex angles, multiple levels, or built-in features like benches and planters. Permit approval adds 1–4 weeks to the overall timeline depending on your jurisdiction. The inspection after the footings are poured can add 2–3 days waiting for the inspector. Total project timeline from contract signing to walking on your finished deck is typically 4–8 weeks, with actual construction taking less than a week of that. --- **Q: Can I use regular screws to install composite decking?** **A:** No. Standard wood screws will cause composite boards to mushroom around the fastener head, leave visible marks, and in many cases void your warranty. Use either color-matched composite deck screws specifically designed for the application or hidden clip fasteners. Trex's proprietary Hideaway fastener system is clean and fast. TimberTech requires their specific clip system to maintain warranty coverage. Budget $50–$100 in fasteners per 100 square feet of decking. It's not the place to substitute hardware-store drywall screws. --- **Q: What causes a deck to rot and how do I prevent it?** **A:** Rot happens where moisture sits against wood with no chance to dry out. The highest-risk spots are the ledger board, post bases, and anywhere debris accumulates between boards. Use UC4B pressure-treated lumber for all framing, install proper joist tape (Trex Protect or similar) on top of every joist before laying boards, and keep 1/8-inch minimum gaps between decking boards. Clean leaves and debris out of those gaps every fall. Inspect the ledger flashing annually — a failed ledger seal is the fastest path to structural rot you'll ever find. --- **Q: Are patio pavers slippery when wet?** **A:** Smooth concrete pavers can absolutely be slippery when wet — that's a real safety issue. The solution is texture. Look for pavers with a tumbled, brushed, or sandblasted finish — these are rated for pool decks and wet applications. When shopping, ask for the paver's DCOF (Dynamic Coefficient of Friction) rating. Anything above 0.42 DCOF meets ADA wet surface standards. Travertine and natural stone can be extremely slippery wet unless they're honed with an anti-slip finish. Smooth bullnose pavers look great in photos and are a liability claim waiting to happen around pools.