ALUMISSION INSTALLATION GUIDE

How to install an aluminum fence on a deck.

Create a clean horizontal fence with a properly supported surface-mount system. Plan the deck connections, fit the steel bases and aluminum posts, then assemble the slats with our 3D video and illustrated guide.

Deck mounting · Complete tool checklist · 42 answers by topic

Gray horizontal Alumission aluminum fence surrounding a furnished deck
A finished Alumission horizontal fence on a deck.

WATCH BEFORE YOU BUILD

Aluminum fence installation in 3D.

This 2-minute 5-second Alumission animation shows the base-mounted assembly: steel bases, aluminum sleeves, slats and spacers, retaining connections, covers and caps.

Use the video for the assembly sequence. It does not show the blocking, waterproofing or complete anchorage design for your deck. Its example post spacing must match the particular fence system—not be copied into a different railing layout.

Watch the 3D installation video on YouTube

PREPARE FOR MORE THAN PANEL ASSEMBLY

Tools, equipment & supplies.

Gather the tools for the deck connection as well as the aluminum fence. Wood framing and concrete need different drilling, fastening and preparation equipment.

Measure & lay out

  • Tape measure, pencil/marker and square
  • Long level or post level; string line or laser for multiple posts
  • Masking tape, cut list and photos of the framing below each post

Prepare the support

  • Access to the underside or edge of the deck as the connection requires
  • Carpentry tools for specified blocking and framing repairs
  • Specified blocking, structural connectors, fasteners and compatible cut-end treatment

Cut the aluminum

  • Saw rated for aluminum with a compatible non-ferrous blade
  • Clamps, padded work supports and support for long slats
  • Deburring file/tool and a brush or vacuum for metal chips

Drill & fasten

  • Drill/driver, metal and wood bits; masonry drilling tools only for concrete
  • Correct sockets, extensions, wrenches and torque wrench where specified
  • 5/16-inch driver for the listed #12 sleeve-to-steel screws
  • Anchor-specific hole cleaning tools for concrete connections

Seal & assemble

  • Caulking gun and sealant compatible with the deck waterproofing and metals
  • Specified flashing, isolation pads or durable shims where required
  • Correct slat spacers, retainers, covers and caps; rivet tool if specified

Protect & clean up

  • Eye and hearing protection for cutting and drilling
  • Handling gloves for sharp profiles; follow tool rules near rotating parts
  • Suitable dust control and respiratory protection for the materials
  • Safe work access and temporary edge protection on elevated decks

START BELOW THE SURFACE

Confirm the support and the purpose.

The fence loads must reach suitable deck framing or structural concrete through the selected post connection. Deck boards, composite decking and decorative fascia do not establish that connection by themselves.

  1. Decide whether the project is a decorative fence, privacy screen or required guard.
  2. Inspect the supporting structure and locate the framing beneath each post.
  3. Confirm the system’s height, post layout, anchors and any blocking.
  4. Plan waterproofing, clearances, corners and gates before cutting.
At an elevated edge: use a system and complete attachment suitable for the required guard. This fence assembly guide does not establish guard approval.

CHECK YOUR ORDER

Materials to confirm before starting.

  • Compatible steel post bases, aluminum sleeves, base covers and caps
  • Selected slats, spacers and the correct retention/cover system
  • Specified base-to-deck structural fasteners, washers and backing hardware
  • Sleeve-to-steel screws for the compatible assembly
  • Required blocking, connectors, flashing, sealant and approved shims

Check the actual kit contents. Site-specific mounting hardware, blocking, waterproofing materials and tools are separate planning items.

Planning a deck railing?

Review the railing kits and confirm the complete installation requirements for your deck.

Explore aluminum railing kits

FROM SUPPORT TO FINAL CAP

Install your deck-mounted fence in 10 steps.

The 3D schematics show assembly relationships, not engineered blocking or anchor designs. Use the detail for your actual deck, post profile and selected system.

Step 1: Confirm the deck and the purpose of the barrier — 3D assembly schematicSTEP 01 / DECK ASSEMBLYInspect belowCheck the deck structure before adding a barrier
Assembly view 1 of 10. Components and support geometry simplified.

STEP 01

Confirm the deck and the purpose of the barrier

Decide whether you need a decorative fence, a privacy screen or a required guard at a fall edge. Inspect the deck framing, connections and foundations before adding posts. Confirm the system, finished height, openings, post spacing and loads for the actual use.

Check before moving on: A decorative fence assembly is not automatically an approved deck guard. A taller privacy screen can add substantial wind load to the deck.

Step 2: Lay out posts over suitable structural support — 3D assembly schematicSTEP 02 / DECK ASSEMBLYSystem-specific layoutPlace every base over the designed support
Assembly view 2 of 10. Components and support geometry simplified.

STEP 02

Lay out posts over suitable structural support

Mark end, corner and intermediate posts from the approved layout. Check base-plate footprints, cover clearance, walking space and any gate opening. Locate the framing beneath every fixing point and confirm edge distances before drilling.

Check before moving on: The video’s 73.75-inch post centers are an example for that fence assembly. The current railing kit uses a different nominal 4-foot layout; do not transfer one spacing to the other.

Step 3: Install the required blocking and connections — 3D assembly schematicSTEP 03 / DECK ASSEMBLYBlockingBlocking must connect to the deck framing
Assembly view 3 of 10. Components and support geometry simplified.

STEP 03

Install the required blocking and connections

Provide the structural blocking, joist/rim connections and repairs required by the mounting design. Confirm how each base fastener transfers load into sound framing. Inspect the underside before it is concealed and make sure nuts or other hardware remain accessible where needed.

Check before moving on: Fastening only to wood or composite deck boards is not the structural connection shown by this guide. Blocking must itself be properly connected to the deck.

Step 4: Prepare holes and the waterproofing detail — 3D assembly schematicSTEP 04 / DECK ASSEMBLYSealing detailCoordinate penetrations with the waterproofing
Assembly view 4 of 10. Components and support geometry simplified.

STEP 04

Prepare holes and the waterproofing detail

Use the specified pilot or clearance holes for wood fasteners. For concrete, use the selected anchor’s bit, hole depth and cleaning procedure. Coordinate all penetrations, base contact surfaces and flashing with the deck or membrane manufacturer’s detail.

Check before moving on: A bead of silicone alone is not a complete waterproofing design for a roof deck or membrane-covered balcony. Keep drainage paths open.

Step 5: Fasten and align the steel post bases — 3D assembly schematicSTEP 05 / DECK ASSEMBLYConfirm line and plumbPlumb stems · supported plates · specified fasteners
Assembly view 5 of 10. Components and support geometry simplified.

STEP 05

Fasten and align the steel post bases

Position the compatible steel bases on the prepared supports. Install the specified fasteners through the base holes, using an approved bearing or shim detail where needed. Check each stem for plumb and the line of all posts before the final tightening sequence.

Check before moving on: The listed base has four 3/8-inch mounting holes. Hole size does not specify anchor diameter, length, embedment or capacity; use the actual connection schedule.

Step 6: Fit base covers before sleeving the posts — 3D assembly schematicSTEP 06 / DECK ASSEMBLYSleeveCoverBase cover first, then the aluminum sleeve
Assembly view 6 of 10. Components and support geometry simplified.

STEP 06

Fit base covers before sleeving the posts

Slide the matching aluminum base cover over the steel stem first. Prepare the aluminum post and covers to the required finished height, including the base cover and cap or top-rail allowance. Sleeve the post onto the steel with the receiving channels facing the next panel.

Check before moving on: The current base cover is 1 inch high, and the post sits on top of it. Confirm this stack-up before cutting; the cover is a finish component, not a substitute for anchorage.

Step 7: Secure the aluminum posts to the steel cores — 3D assembly schematicSTEP 07 / DECK ASSEMBLYSleeve-to-coreSleeve fasteners are separate from deck anchors
Assembly view 7 of 10. Components and support geometry simplified.

STEP 07

Secure the aluminum posts to the steel cores

Check plumb, rotation and the alignment of opposing channels. Fasten the aluminum sleeve to its steel core with the specified connection. Alumission lists #12 × 1-inch self-drilling screws for compatible sleeve-to-steel assemblies, driven with a 5/16-inch nut driver.

Check before moving on: Confirm fastener quantity, location and drilling capacity for the actual post and core. These screws do not replace the base-to-deck structural fasteners.

Step 8: Measure, cut and test-fit one slat — 3D assembly schematicSTEP 08 / DECK ASSEMBLYTest one cut slatMeasure installed channels; test-fit one slat
Assembly view 8 of 10. Components and support geometry simplified.

STEP 08

Measure, cut and test-fit one slat

Measure between the installed receiving channels for each panel. Apply the profile’s required engagement and fitting allowance, then cut and deburr one slat using an aluminum-rated cutting setup. Test both ends before cutting the rest of that panel’s slats.

Check before moving on: Clear opening, post-center spacing and slat cut length are different measurements. Correct a tapered opening instead of forcing the posts apart.

Step 9: Assemble the infill and secure its top connection — 3D assembly schematicSTEP 09 / DECK ASSEMBLYRetain both endsBuild the pattern, then secure the top slat
Assembly view 9 of 10. Components and support geometry simplified.

STEP 09

Assemble the infill and secure its top connection

Seat the first slat on the specified bottom support and insert the selected spacers at both ends. Continue the style’s sequence, checking level and cumulative height. Secure the top slat using the correct retainers; the demonstrated older profile uses L-brackets. Fit compatible channel covers.

Check before moving on: Current screw-channel profiles can use another fastening detail. Follow your actual kit; caps and silicone do not replace the slat-retaining hardware.

Step 10: Finish the caps and inspect the whole installation — 3D assembly schematicSTEP 10 / DECK ASSEMBLYCheck the full assembly and supporting structure
Assembly view 10 of 10. Components and support geometry simplified.

STEP 10

Finish the caps and inspect the whole installation

Fit the matching caps and any selected top rail using their specified attachment. Clean chips from the deck, inspect seals and drainage, and check all posts, connections and retained slats. Where this is a required guard, complete the applicable inspection before relying on it.

Check before moving on: Confirm finished height from the walking surface and all opening limits. Investigate movement at its source; do not hide loose anchorage beneath the base cover.

CHOOSE THE CONNECTION FIRST

Surface mount or side mount?

Surface-mounted base

A steel plate attaches to the top of a suitable support. The base cover goes over the stem, followed by the aluminum sleeve. This is the assembly covered by the video and the steps above.

On a framed deck, establish blocking and the structural fastener detail. On concrete, establish the anchor and substrate requirements.

View the steel post base

Side or fascia mount

The post extends below the walking surface and connects to suitable structural framing or a supporting face. This can preserve walking space, but it needs its own connection and waterproofing detail.

Current Alumission railing listings describe 5-foot side-mount post stock. The required lower extension and fastener layout depend on the project.

Review a current railing kit
Do not mix layouts. A railing module, tall privacy fence and side-mounted post can have different spacing and support requirements. Choose the actual application before ordering bases or cutting stock.

What to record before ordering

DetailRecord for your project
Use and heightFence, privacy screen or guard; required finished height above the walking surface
Deck constructionWood/composite surface, framing and blocking, or structural concrete; any membrane
LayoutRun lengths, post locations, corners, stairs, gates and cover clearance
ConnectionsBase or side mount, fastening detail, access below and waterproofing plan
Field cutsActual installed channel spans, engagement allowance and one test slat
Alumission tutorial detail showing the base cover and aluminum sleeve installation
Original installation detail: fit the cover before the aluminum sleeve.
Alumission tutorial detail fastening an aluminum sleeve to its internal steel base
Original installation detail: sleeve-to-steel screws are separate from deck anchors.

ANSWERS FOR YOUR DECK PROJECT

Aluminum deck fence installation FAQs.

Browse six categories or search for “blocking,” “composite,” “anchors,” “waterproofing” or “caps.”

42 questions in 6 categories

Planning, height & choosing the system

Can I install an aluminum fence on a deck?

Yes, when the deck and the post connections are suitable for the proposed fence. Start with the framing beneath the surface, the panel height and the loads—not just the deck boards. This guide covers a compatible surface-mounted steel-base and aluminum-sleeve assembly.

Is a deck fence the same as a guardrail?

No. A fence can provide separation or privacy, while a guard protects an open edge where a fall is possible. A required guard must satisfy the applicable requirements for the complete system, including height, openings, posts, anchors and supporting structure. Choose the system for its actual purpose before installation.

Which Alumission products should I consider?

For a railing project, start with Alumission railing kits and confirm the mounting and approval requirements. For a decorative fence or screen, compare the fence styles and obtain the correct support detail. Do not choose a tall fence kit as a guard solely because it fits the opening.

How tall should the installation be?

Establish the required finished height from the walking surface for your location and use. Current Alumission railing listings describe approximately 40–42-inch finished installations, but that product range does not determine your local requirement. Include the base cover, cap and any top rail when calculating cuts.

How far apart should the posts be?

Use the layout for the selected system and application. The 3D fence video shows an example at 73.75-inch centers; current railing kits are organized around nominal 4-foot modules. Neither is a universal spacing rule for all deck fences, heights or exposure conditions.

Can I add a tall privacy fence to an existing deck?

Only after confirming that the deck, posts and connections can resist the added loads. Height and reduced openness can increase wind effects, and an existing railing connection may be unsuitable. Provide your intended height, pattern, location and deck framing details before selecting a design.

Do I need a permit or inspection?

Check with the local authority before changing a deck guard, adding a screen or modifying the structure. HOA and property requirements may also apply. Obtain the applicable height, opening, structural and inspection requirements before ordering or removing an existing barrier.

Wood decks, composite boards & blocking

Can I screw the bases into the deck boards alone?

Do not rely on deck boards alone for the structural post connection. Fixings need the support and engagement required by the mounting design, commonly involving sound framing and properly connected blocking beneath the surface. Verify each fastener location before drilling.

Can the fence be installed over composite decking?

Yes, if the complete attachment is suitable for that decking system and the structure below it. Composite boards are a walking surface, not a substitute for post support. Coordinate penetrations, movement allowances and bearing with the decking manufacturer's instructions.

What is blocking and why might it be needed?

Blocking is added structural material between or alongside framing members to support the planned connection. Its size, orientation and attachment must suit the design. A loose block under a board is not equivalent to blocking that transfers post forces into the deck framing.

How do I know whether my existing deck is strong enough?

Inspect the framing, connections, supports and foundations, including hidden areas at post locations. Look for decay, splits, corrosion, looseness and earlier alterations. A sound walking surface alone is not evidence of adequate capacity; have uncertain conditions assessed before adding the fence.

What if I cannot reach the underside of the deck?

Resolve access before choosing hardware. Some connections require through-bolts, backing plates or inspection below the surface. Removing selected boards or using a specifically designed alternative may be necessary; do not shorten fasteners or omit backing hardware to avoid access work.

Can I fasten a post to the fascia board?

Only with a side-mount detail that transfers loads into suitable structural framing. Decorative fascia, cladding and trim do not establish a structural connection. A fascia-mounted post also needs the correct stock length, attachment geometry and waterproofing detail.

Can I reuse old railing posts or old holes?

Assess the existing material, foundations and connections for the new system and loads. Old holes can be oversized, damaged or poorly positioned. Reuse only where the connection design permits it; do not assume an old wood-railing detail supports a new aluminum privacy fence.

Bases, fasteners & concrete mounting

Which steel post base does Alumission list?

The current zinc-coated steel base has a 4 × 4 × 1/8-inch plate, four 3/8-inch mounting holes and a 1-1/4-inch square steel stem with a 1/8-inch wall. It is offered with an 18-inch or 4-foot stem. Select the compatible version for the actual system and loads.

Does a 3/8-inch base hole mean I should buy a 3/8-inch anchor?

Not automatically. The hole is a component dimension, not a complete fastener specification. The selected connection must establish the fastener type, diameter, length, washers, engagement and installation method while remaining compatible with the plate.

Should I use lag screws, structural screws or through-bolts?

Use the fastening arrangement specified for your deck and post system. These options have different installation and support requirements. Ordinary deck screws are not interchangeable with a rated structural connection; confirm pilot holes, washers, backing and tightening instructions.

Which screws secure the aluminum sleeve to the steel stem?

Alumission lists #12 × 1-inch 410 stainless self-drilling screws with a 5/16-inch hex driver for compatible sleeve-to-steel connections. Confirm the pattern and drilling capacity. They are separate from the structural fasteners securing the base to the deck.

Can I mount the bases on a concrete deck or patio?

Yes, where the concrete and anchor arrangement are suitable for the loads. Confirm slab thickness, condition, reinforcement, edges and any waterproofing before drilling. A thin topping, paver or unsupported tile surface is not automatically a structural anchor base.

What size concrete holes and anchors should I use?

Follow the selected anchor's instructions and the project connection detail. Bit diameter, hole depth, cleaning, embedment, spacing and edge distance all matter. Avoid selecting an anchor solely because it fits through the steel plate.

Are the deck or concrete mounting fasteners included?

Check your exact order. Site-specific anchors, structural screws, blocking, sealant and tools should not be assumed included. Keep the kit assembly fasteners and the substrate mounting fasteners separate on your materials checklist.

Waterproofing, corrosion & base details

How do I waterproof the post-base penetrations?

Use the deck or waterproofing system's approved penetration and flashing detail with compatible materials. Seal where specified and preserve drainage. The correct method depends on whether the deck is open-board timber, concrete, tile over a membrane or a roof assembly.

Can silicone alone waterproof a rooftop deck mounting point?

Do not assume so. A roof or balcony membrane needs a coordinated detail that maintains its continuity at every penetration. Consult the membrane requirements before drilling; a surface bead around the base may not address water below the finish.

Should I put sealant under the base plate?

Use the specified contact and penetration sealing detail for that support. Check compatibility with zinc-coated steel, the deck finish and any membrane. Avoid creating a pocket that traps water or blocking required drainage paths.

Can I level a post base with loose washers?

Use the bearing and shim arrangement permitted by the connection design. The plate must have appropriate support without distortion or an unstable stack. The old tutorial's washer example is not a universal detail for every wood deck or guard connection.

Can the metal touch pressure-treated lumber?

Confirm material compatibility with the treatment, exposure and chosen fasteners. Use the specified corrosion protection and any approved isolation or flashing material. Do not substitute a soft pad that compromises the designed bearing or connection.

When does the aluminum base cover go on?

Slide the base cover over the steel stem before installing the aluminum sleeve. The current cover has a 4.375-inch square footprint and is 1 inch high; the sleeve sits on top. Include its height and clearance in the layout.

Does the base cover strengthen or waterproof the connection?

It conceals the base fasteners and finishes the appearance. It does not replace structural anchors, blocking, flashing or the specified sealing detail. Inspect the underlying connection rather than relying on a cover to hide movement or leaks.

Cutting, slats, caps & special layouts

How do I calculate the aluminum post cut length?

Start with the required finished height from the walking surface and account for the actual mounting stack, base cover, cap and any top rail. Side-mounted posts also need the designed lower extension. Stock length is not the same as finished above-deck height.

How long should I cut the slats?

Measure the installed receiving channels for each panel and use the profile's engagement and fitting allowance. Test one cut slat before cutting the batch. Do not subtract a generic number from the nominal kit width or copy a gate cut formula.

Do I need an aluminum-specific saw blade?

Use a saw and blade combination rated for cutting the aluminum profile. A compatible non-ferrous blade, secure clamping and support for long pieces help make controlled cuts. Deburr the edges and remove metal chips from the deck promptly.

Can I change the slat gaps for more privacy?

Confirm the alternate pattern, finished height, parts count and structural suitability before making changes. On a required guard, every completed opening must meet the applicable requirements. A more closed pattern also changes wind loading.

What secures the top slat?

The demonstrated older assembly uses L-brackets and compatible screws at the top-slat ends. Current profiles with screw channels can use another retention detail. Follow the exact kit rather than mixing methods; a cap or silicone bead is not structural slat retention.

How do I attach the caps and optional top rail?

Use the matching parts and their specified fastening method. Some cap details use compatible silicone; the current Side Post Cap uses mechanical attachment. If a top rail is selected, account for it before cutting and follow its connection detail.

Can I use these steps for stairs, corners or a gate?

Use these steps as a level-run assembly overview. Stairs need their own angles, transitions and any required graspable handrail; corners need a compatible post layout. Gate posts must resist hinge and operating forces as well as fence loads. Confirm those details separately.

Troubleshooting, care & project help

Why does my deck fence wobble?

Find which part moves: the deck framing, base fasteners, steel stem, aluminum sleeve or infill. Loose sleeve screws and inadequate blocking are different problems. Stop using a questionable guard and have the affected connection corrected; adding silicone to the slats will not repair anchorage.

What if a slat will not slide into the posts?

Check for burrs, debris, an overlong cut, rotated posts or a tapered opening. Compare the channel spacing at the top and bottom and confirm the parts match. Correct the cause rather than hammering the slat or bending the posts.

What if the last slat or cover does not fit?

Check the post cut, bottom support, slat count, spacer sizes and accumulated height. Keep room for the required retention, covers and caps. Do not cut away a structural connection to disguise an incorrect stack.

How do I clean and maintain the installation?

Use mild soap, clean water and a soft cloth, following the finish-care directions. Clear chips and debris, keep drainage open and inspect fasteners, seals, caps and the supporting deck. Rinse salt or poolside deposits more frequently and investigate new looseness or staining.

Will horizontal slats keep animals from climbing onto the deck?

Do not assume a horizontal slat fence is animal-proof. Gaps, height, nearby furniture and the animal's climbing ability all matter. Plan pet containment separately and do not alter a required guard's geometry without confirming the complete design.

What affects the cost and installation time?

Include deck inspection and repairs, blocking, access below the surface, waterproofing, mounting hardware, field cuts and assembly. Stairs, corners, gates and tall screens add work. The short video shows the sequence, not a two-minute or same-day installation promise.

What should I send Alumission for a quote or technical help?

Send run lengths, desired height and style, deck height above grade, your ZIP code and photos above and below the proposed post locations. Include decking and framing materials, any membrane, corners or gates, and the kit or order number. Use technical support for component questions.

Installation references

Use current Alumission component instructions and the fastening and waterproofing details for your project. The external resources below explain deck connection principles; their product-specific fastening schedules should not be transferred to an Alumission base.

PLAN A CLEAN, COMPLETE INSTALLATION

Get the right parts for your deck.

Send the run lengths, desired height and style, ZIP code and photos above and below your proposed post locations. Include the deck material, any waterproof membrane, and whether the project needs a required guard or a decorative fence.

Use the project form below or call (888) 615-5001. For other mounting conditions, see installation between columns or installation in soil with concrete footings.

This field is for validation purposes and should be left unchanged.
Full Name(Required)