Getting posts set correctly is the most critical phase of any glass balustrade installation. Poorly set posts mean glass panels that won't seat properly, visible gaps at the channel, and systems that fail inspection. This guide covers the full process for surface-mounted, core-drilled, and spigot-fixed posts on concrete, screed, timber, and decking substrates.

Before you start — what you need on site

A proper post installation requires the right tools and materials staged before work begins. Returning to site for a missed item after grout has started to go off is an avoidable problem.

  • Setting-out equipment: chalk line, steel tape, square, datum pins
  • Drilling: SDS+ or rotary hammer, correct core bit diameter for your post base
  • Fixing: appropriate anchor bolts or chemical anchor system for your substrate
  • Leveling: post leveler sized for your post profile — the Pro Post Leveler is available in 42.4mm round, 48.3mm round, and 40mm square
  • Grout/resin: non-shrink cementitious grout or polyester/epoxy resin depending on spec
  • Temporary support: wedges, packers, or props to hold posts during cure
  • PPE: eye protection, gloves, dust mask for core drilling

For post supply, DIY Balustrades stocks a full range of glass balustrade posts, base plates, and fixings across all standard sizes.

Setting out

Accurate setting out determines everything that follows. Errors here compound — a post 5mm out of line on a straight run will push every subsequent post further off, and correcting it mid-install is far more disruptive than getting it right at the start.

Establishing your line

Snap a chalk line along the full run of the balustrade, set back from the edge by the correct dimension for your system. Check your manufacturer's spec for the exact setback — it varies between systems and determines where the glass edge will sit relative to the structural edge.

Marking post centres

Mark post centres along the chalk line. Standard post spacings for most glass balustrade systems run between 900mm and 1200mm centres, but always confirm with your system specification — glass panel sizes and infill type dictate this. Mark with a punch or permanent marker, not chalk, so the marks survive drilling dust and water.

Checking for services

Before any core drilling, scan the substrate with a cable and pipe detector. This applies even on new builds where you have drawings — installation drawings are not always accurate and services get moved. A punctured underfloor heating pipe or struck cable on the first drill is an expensive and time-consuming problem.

Core drilling and fixing

The fixing method depends on the substrate, the post system, and the structural engineer's specification where one has been provided. The three most common approaches for professional installs are:

Core-drilled with grout or resin

The post sleeve or spigot is set into a core-drilled hole and fixed with non-shrink grout or structural resin. This is the most common method for concrete and screed substrates. Core size needs to be correct — typically 10–15mm larger than the post OD to allow for grout coverage. Too tight and you can't get adequate grout coverage; too large and the post becomes difficult to hold plumb during cure.

Surface-mounted with base plate

A base plate is fixed to the substrate surface with chemical anchors or expanding bolts, and the post connects to it via a collar or socket. This method is faster on site and avoids core drilling, making it suitable for retrofit installations and situations where you can't cut into the substrate. Load transfer into the substrate is via the anchor bolts, so anchor selection and installation torque are critical.

Timber and decking substrates

Posts on timber joists or decking boards are typically fixed with through-bolts or structural screws into blocking or a post shoe fixed to the joist. Timber substrates need more post positions assessed individually — fixings into the end grain of joists are significantly weaker than fixing into the face or through a solid section. If in doubt, double up the blocking.

Setting posts plumb

This is where most installation errors occur. A post that looks plumb by eye or by a casually held spirit level is frequently 2–3mm out — which is invisible on a single post but becomes a visible lean when glass panels are installed and the cumulative error shows across a run.

Why standard spirit levels aren't enough

Holding a spirit level against the side of a post requires you to check two faces separately, and the reading changes if any pressure is applied to the level. On a post that's still moveable in fresh grout, this is a problem — every touch risks disturbing the position you just achieved.

Using a post leveler correctly

A dedicated post leveler sits on top of the post and reads plumb in all directions simultaneously, leaving both hands free to adjust and pack the base. Seat the leveler, check the bubble, adjust the post, and lock it in position before the leveler is removed. Work systematically along the run — set and lock every post before moving to the next.

Tip: On longer runs, set the two end posts first and run a string line between them at handrail height. Use this as a secondary check for alignment — plumb alone doesn't guarantee the posts are in a consistent plane across the full run.

Temporary support during cure

Whether you're grouting or resin-fixing, posts need to be held in position until the fixing has cured sufficiently to resist movement. Wedges and packers at the base work well for grout — use timber packers on two sides and check the bubble again after packing, as packing can introduce movement. For resin fixes, follow the manufacturer's cure time before removing any temporary support — do not rush this on commercial jobs where the installation will be inspected.

Checking your work

Before moving to handrail and glass installation, carry out a systematic check of every post in the run:

  • Plumb check in both axes with the post leveler
  • String line check for alignment across the run
  • Check post heights are consistent — a tape measure from a datum point, not a visual check
  • Check all base fixings are fully torqued or grout is fully cured before applying any load
  • Check post cap or saddle seating — any cap that won't sit flat indicates the post top has been damaged or is not cut square

Any post that fails these checks is easier to correct before the glass goes in. Once the glass is installed, adjusting a post position means removing the glass, which on larger panels means a two-person job and the risk of glass damage.

Set posts perfectly every time

The Pro Post Leveler is available in 42.4mm round, 48.3mm round, and 40mm square.

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