Install a Crittall-Style Steel Door in a Brick Opening in 9 Steps

Start by measuring the opening across three points

A brick opening is rarely as square as the bricklayer believed. Measure the width at the head, the mid-height, and the threshold, then the height at both jambs and the centre. A variance of 6 to 10 mm across those readings is common in openings cut into older solid-brick walls, and it sets the clearance you need to leave around the frame. Most Crittall-style suppliers, including Fabco Sanctuary and Clement Windows, ask for a structural opening 10 to 15 mm larger than the frame on each side so the frame can be packed plumb without binding.

Record the smallest of the three width readings and the smallest of the three height readings. Those two numbers are what the frame must physically pass through. If your ordered frame is 900 mm wide and the narrowest point of the opening is 905 mm, you have 5 mm total to play with, which is not enough to shim both jambs. The frame either gets returned or the brick reveal gets ground back with a diamond cup wheel. Decide that before the delivery arrives, not while it is propped against the hallway wall.

Confirm the lintel is actually carrying load

A steel frame fixed under a cracked or undersized lintel will telegraph every settlement movement straight into the glass. Tap along the brick above the opening and look for stepped cracking in the mortar beds. If the existing lintel is a timber bressummer in a pre-1930s wall, it may have sagged enough to reduce the head clearance below what your frame needs.

Dry-fit the frame and mark the fixing centres

Lift the frame into the opening before any drilling. On a 50 kg frame this is a two-person job, and a pair of folding wedges under each jamb lets one person hold while the other works the spirit level. Check plumb on both jambs with a 1.2 m level, then check the head for level, then check the frame for wind by sighting diagonally across the face. A frame can read plumb on both jambs and still be twisted out of plane.

With the frame held true, mark the fixing positions through the pre-drilled lugs or the fixing flange. Manufacturers typically specify fixings at 150 mm from each corner and then at maximum 600 mm centres down the jambs. For a 2100 mm opening that gives three fixings per side plus the corners, six per jamb. Mark each hole centre with a pencil dot on the brick, then take the frame back out. Drilling through the frame in situ risks wandering the bit across the powder-coated face and chipping the finish.

Drill the brick, not the perp joint

Fix into the solid brick wherever possible. The vertical mortar joint, the perp, is the weakest line in the wall and a plug set there can spin out under the cantilever load of a door. Use a hammer drill with an 8 mm SDS masonry bit for the common fixing sizes. Drill 10 mm deeper than the plug length so brick dust collects below the plug rather than pushing it back out.

For solid brick, Fischer DuoPower plugs in the 8x40 or 10x50 size suit most steel frame fixings because the nylon expands in dense material and knots in voids. If the brick turns out to be a perforated or cellular type, the same DuoPower geometry still grips where a simple expansion plug would pull. Blow the dust out of every hole with a puffer or a length of aquarium tubing before inserting the plug. A hole half-full of dust gives a plug perhaps 60 per cent of its rated pull-out. Insert each plug flush with the brick face and tap it home with a nylon mallet, not the steel hammer that chipped the last one.

Pack, fix, and check plumb again

Return the frame to the opening and reseat it on the wedges. Before any screw goes in, slide rigid plastic packers behind each fixing point so the screw clamps the frame against a solid backing instead of bowing the flange. Steel frame sections are stiff but not infinitely so, and overtightening into an unpacked gap will pull the jamb out of line by 2 to 3 mm, which on a 25 mm sightline is visibly crooked.

Drive the fixings in a deliberate order: top hinge-side first, then top latch-side, then alternate down the frame. Snug each one rather than fully torquing it, recheck plumb and level, then make the final pass. Glaziers from firms like IQ Glass note that the single most common callback on steel screens is a door that fouls the frame because the installer torqued all the fixings on one jamb before the other. The frame walks sideways as you tighten. Work both sides in step and the door leaf will swing free with an even 3 mm reveal all round.

Hang the leaf and set the gaps

With the frame fixed, lift the door leaf onto its hinge pins. A typical single Crittall-style leaf with 4 mm toughened glass runs 30 to 40 kg, so support it on a wedge while you engage the top pin. Swing it through its full arc and watch the reveal. The gap along the latch jamb should be parallel top to bottom; a tapering gap means the frame is still slightly out of plumb and one fixing needs backing off and repacking.

The hinges on most steel systems offer 2 to 3 mm of lateral adjustment through eccentric bushes or slotted plates. Use that range to dial out a tapering reveal before you reach for the fixings. Set the latch engagement so the keep catches with light pressure, not a slam. A door that needs shouldering shut is binding somewhere, and forcing it will eventually crack a corner of the glass where the frame pinches.

Glaze last if the system allows

Many steel screens are supplied with the glass already factory-bonded into the frame, but slimline internal systems often ship as empty frames for site glazing, which keeps the lifting weight down during the fix. If you are glazing on site, set the toughened pane on two setting blocks at the quarter points along the bottom rail, never directly in the corners. The blocks carry the glass weight and stop the pane bearing on the steel.

Press the glazing beads or gaskets home working from the centre of each side outward so trapped air escapes at the corners. A 6 mm laminated pane in a 900 by 2100 leaf weighs around 28 kg, and it should sit dead centre in the rebate with an even shadow gap. If one edge sits proud, the setting blocks are uneven and the pane will rattle once the door swings.

Seal the perimeter without bridging the cavity

Run a low-modulus neutral-cure silicone bead between the frame flange and the brick reveal, tooled smooth with a wetted spatula. Low-modulus matters because the steel and the brick expand at different rates, and a rigid sealant will split along the joint within a season. Backer rod pushed into any gap wider than 6 mm gives the bead the correct hourglass cross-section so it stretches instead of tearing.

Do not gun expanding foam into the gap as a shortcut. Foam exerts outward pressure as it cures and can bow a slim steel jamb measurably, and it offers no useful structural hold once the DuoPower fixings are doing their job. The silicone is a weather and draught seal, not a fixing. Keep it to a clean 6 to 8 mm bead and leave the structural work to the plugs and screws already buried in the brick.

Touch in the finish and final-check the swing

Powder-coated steel chips at the fixing heads and at any point a bit wandered. Most suppliers provide a matched touch-up pen in the standard RAL 9005 black or RAL 7016 anthracite grey. Dab, do not brush, so the repair sits flush with the surrounding coat.

Swing the door twenty times and listen. A faint scrape on the threshold sweep is normal bedding-in; a metallic click at the top of the arc means a hinge pin is high and needs seating. The reveal that read even at install will sometimes shift by a millimetre as the silicone cures and the frame settles onto its packers over the first week. The open question is how the same opening behaves through a full heating season, when the brick has dried out and the steel has cycled cold to warm a hundred times, because that is when a frame that read perfect on day one shows whether the packing was honest.