Aluminium Window Frame Repair in Dunedin

Aluminium here fails at the corners and the fixings long before the extrusion gives up. On the coast, from St Clair round to Brighton and up the harbour to Port Chalmers, salt drives that and the coating needs washing every three months. Inland it is age plus a frame that has never been cleaned in forty years.

The chalky white bloom is the coating failing, not dirt

White powder on an aluminium frame is aluminium oxide. The powder coat has been breached and the metal underneath is corroding. Wiped early and treated with a non abrasive restorative cleaner made for powder coat, the finish comes back and the frame is fine.

Left long enough it pits, and pitting cannot be polished out. That is the point where a frame stops being repairable, so it is worth acting on the first sign rather than the fifth.

Corner joints let water into the wall, not just the room

Aluminium frames are mitred and joined at the corners with cleats and sealant. Thirty years of thermal movement and Dunedin wind loading opens those joints. Water then tracks into the frame cavity and out the back, where it reaches framing instead of your sill.

We strip the failed sealant, clean the joint properly and reseal with a neutral cure silicone rated for the substrate. It is a small job that prevents a very large one.

Racked sashes are a hardware problem

If a sash leaves a wedge shaped gap or catches on one corner, the frame is almost never bent. Worn hinges, stays or rollers let the sash drop, and the gap follows. Replacing the hardware and rehanging the sash closes it.

What we can save and what we cannot

Surface oxidation against pitting

Chalky white bloom is aluminium oxide sitting on the surface, and at that stage a wash and a restorative cleaner made for powder coat brings the finish back. Run a fingernail across it. If it is smooth under the bloom the frame is fine.

Once you can feel craters, the metal has lost section and no polish puts that back. Frames get to that point surprisingly quickly on the coast, which is why the three monthly wash is not fussiness.

Resealing a corner without pulling the frame

Mitred corners are joined with cleats and sealant. Thirty years of thermal movement opens them, and the water that gets in runs down inside the frame and out the back into framing rather than into the room, which is why nobody notices until there is a stain on the lining.

We cut the failed sealant out, clean the joint back to bare metal and reseal with a neutral cure silicone rated for the substrate. It takes under an hour a corner and it prevents a repair that costs many times more.

Aluminium Window Frame Repair at a glance

Corner joints

Failed sealant cut out and resealed with neutral cure silicone

Coating

Non abrasive restorative cleaner, never solvents or scouring pads

Fixings

Corroded screws replaced, 316 stainless near the coast

Sash squaring

Hinges, stays and rollers replaced, sash rehung

Drainage

Slots cleared and water tested

When to replace

Pitting through the extrusion, or corners beyond resealing