Aluminum vs wood deck railing
Wood railing is cheap per foot and expensive per year. Aluminum is the reverse. The comparison that matters is not material cost, it is post count and the maintenance you will actually do.
Cost and spacing
| Wood (treated or cedar) | Aluminum | |
|---|---|---|
| Material per linear ft | $12–22 | $28–55 |
| Installed per linear ft | $25–45 | $45–75 |
| Max post spacing | 6 ft typical | 6 ft, some systems 8 ft |
| Baluster spacing | Field-built, 4″ rule | Factory-set, usually 3⅝″ |
| Maintenance | Stain every 2–3 years | Wash annually |
| Life | 12–20 years | 25–40 years |
| Repairable | Yes, individual parts | Yes, but colour match is per batch |
The post spacing line is where the arithmetic changes. A 48 ft railing run needs 9 posts in wood. Some aluminum systems allow 8 ft bays, which is 7 posts — two fewer footings, two fewer post bases, two fewer holes. On an elevated deck that can offset $300–600 of the material premium.
What aluminum does better
- Consistency. Factory-made sections have the same baluster spacing everywhere, which means the 4″ rule is satisfied by design rather than by layout.
- No finishing. Powder coat does not need re-staining, and it does not check or splinter.
- Weight. A 6 ft aluminum section is a one-person carry; a wood section with balusters is not.
- Straightness. Extruded rails do not bow, which is the most common complaint about long wood top rails.
What wood does better
- Matches the deck. A cedar deck with cedar railing reads as one object; aluminum reads as an addition.
- Field modification. Cutting and fitting wood on site is normal. Aluminum sections are cut to length but the infill and brackets are less forgiving.
- First cost. Roughly half, installed.
- Repair. A broken baluster is a $4 board, not a $60 factory part in a colour that has been discontinued.
The post is the weak point in both systems
A railing must resist a 200 lb concentrated load applied in any direction at the top. That load reaches the deck through the posts, and the post-to-frame connection is what fails — not the rail.
For wood posts, that means through-bolts or a manufactured post base with a structural screw pattern, not two lag screws through the rim. For aluminum, the manufacturer supplies a post base and specifies the fasteners; substituting different ones voids the compliance. In both cases, blocking inside the rim joist is what the fasteners actually bite into.
What this comparison does not cover
- It does not cover cable or glass infill, which cost more and demand tighter post spacing; see cable railing.
- It does not account for the view. That is the reason most aluminum buyers give, and it is not a number.
- It does not check local code on guard height or infill; those are in guard requirements.
- It does not include the cost of the extra footings that closer wood post spacing requires.
Questions people actually ask
Is aluminum railing worth the extra cost?
Over 10 to 15 years, usually. The material premium is roughly $20 per linear foot, and a wood railing re-stained every three years costs $300–600 per cycle on a typical deck, plus the labour or the weekend.
How far apart can aluminum railing posts be?
Six feet for most residential systems, eight feet for a few premium ones. The limit comes from the rail's deflection under a 200 lb load, not from the post.
Can I put aluminum railing on a wood deck?
Yes, and it is the most common installation. The aluminum posts bolt to the wood frame with manufacturer-supplied bases, and blocking inside the rim is usually required.
Does aluminum railing meet code?
A listed system installed per the manufacturer's instructions meets the guard load and infill requirements in most jurisdictions. Mixing components from different systems generally does not.