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Removing Old Aluminum Windows

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Why aluminum frames come out differently

An old aluminum window is a thin metal box with a flange around its outside edge. Unlike a wood window that sits in a framed opening with trim nailed over it, an aluminum unit from the mid twentieth century onward was often fastened through a flat fin straight into the wall framing, and then buried beneath stucco, siding or plaster. The removal plan has to follow that construction. Prying at the visible frame without knowing what holds it can tear large pieces of the surrounding wall.

This page covers the specific steps and hazards of taking out single and sliding aluminum windows, the kind common in ranch houses, additions and rental properties built in the decades after the war.

Identifying the type of frame

Two basic styles account for most aluminum windows, and the first job is to tell them apart.

• Flanged or nail fin units have a flat lip around the exterior perimeter. The lip is fastened to the wall sheathing or studs and covered by the exterior finish. These are the ones that tangle with stucco.
• Flangeless or block frame units have no fin. They sit in the opening and are fastened through the frame sides into the framing, with trim or a bead of caulk around them.

Looking at the exterior wall helps. If the stucco or siding runs tight against the frame with no visible trim, a fin is probably hidden underneath. If the frame has a clear gap and sealant around it, it is more likely a block frame.

Start with the sash and glass

Whatever the type, begin by removing the moving parts. Aluminum sliders lift up and out of their track once the stops or screws are released, and fixed lites are held by a bead or glazing tape that can be cut. Taking out the glass first lowers the weight, removes the risk of a pane shattering mid job, and lets the frame be handled as a light metal shell.

Glass handling deserves care. Old windows may contain annealed glass that breaks into long sharp shards. Tape across the pane and a pair of cut resistant gloves reduce the danger, and a drop cloth under the opening catches fragments. Heavy panes should be carried by two people.

Finding the fasteners

Once the sash is out, the frame itself is easier to examine. Screws or nails often sit in the track channel, hidden under the sliding path. Others are located behind weatherstripping or under small plastic caps along the jambs. A magnet or a thin pick helps find them. Count them as they are located: a typical window has several on each side, and missing one leads to a frustrating tug that can twist the whole frame.

Screws are removed with a driver. Rusted or stripped ones may need to be cut instead, using a reciprocating saw with a metal blade slid carefully between frame and framing. Cutting is quicker than fighting a seized screw and creates less vibration in a stucco wall.

Stucco around metal frames

Stucco is a hard cement based coating applied over wire lath. Where it meets an aluminum fin, the plasterers pressed it right up to and sometimes over the edge of the fin, so the two are effectively locked together. Pulling a frame straight out of this arrangement can crack the stucco in sheets, leaving a ragged hole larger than the new window.

The careful way is to cut a clean line first. A thin diamond blade or a stucco knife scores the coating along the edge of the old frame, a short distance outside the opening, so any cracking stops at the cut. Some crews lightly tape or support the surrounding finish before cutting. After the line is cut, the old fin can be released, either by cutting its screws or by freeing it with a flat bar used gently and spread across a wide area.

Dust is a real concern when cutting cement. A vacuum attachment on the cutter, a damp cloth hung below and basic eye and lung protection keep the mess down and protect the person doing the work.

Dealing with the fin

Once the screws are out, a flange may still be stuck behind stucco or building paper. Options include:

1. Cutting the fin flush with the frame using metal shears or a saw, leaving the strip behind the stucco in place, then filling and flashing over it. This avoids any damage to the wall finish.
2. Peeling the fin out slowly with a flat bar, working from the corners, if the stucco has already been scored and the owner wants a flatter opening.
3. Replacing it with a new window that has a flange of its own, in which case the old strip must be removed or at least flattened so the new one lies correctly.

The first choice is often the least risky, particularly in older walls where a damaged finish is expensive to repair and hard to color match.

Rust, corrosion and rot behind the frame

Aluminum itself corrodes slowly, forming a white powdery oxide. The bigger issue is what surrounds it. Steel screws and nails rust, and rust weeps into the framing, staining and softening wood. Window openings in older walls were often built with little or no flashing, so the lower corners are the places most likely to hold hidden rot.

After the old unit is out, inspect the sill and lower jambs with a screwdriver probe. Any soft wood should be cut back and replaced before the new window is set. Skipping this check is how a fresh window ends up sitting on rotten framing, a failure that appears only after the first wet season.

Condensation tracks and weep holes

Old aluminum sliders have small slots at the bottom of the track called weep holes, which let water leave the frame. These holes are often clogged with dirt, which is one reason old aluminum windows leak into the wall. When examining the old frame, notice how much staining is under it. Dark water marks on the sill or interior wall below the opening suggest long term moisture, and the surrounding area should be checked closely before the new window goes in.

Lead and old paint

Aluminum windows themselves seldom carry lead paint, but the surrounding wood trim, plaster or sills on older houses sometimes do. Federal lead safe work rules apply to older homes in general terms, and a contractor who works on pre-1978 structures should follow containment and cleanup practices. For any house of that age, ask how dust will be controlled before demolition begins.

Protecting the interior

Because the removal produces dust, metal slivers and sometimes broken glass, the interior side deserves as much protection as the exterior. Furniture should be moved at least a few feet from the wall, floors covered, and curtains and blinds taken down. A sheet of plastic taped around the opening keeps dust from drifting through the room. Meanwhile, the opening should not be left exposed longer than necessary: a window removed in the morning should have its replacement installed the same day, or the opening should be closed with a temporary cover.

Disposal and recycling

Aluminum is a valuable scrap metal, and many crews or homeowners drop the old frames at a recycling center. Glass should be separated if the center requires it, and any sealed units containing broken glass should be wrapped so they do not hurt anyone handling the load. Screws, fins and scraps of lath go into the same metal stream where permitted.

A sensible order of work

Putting the steps together gives a clear sequence for a clean removal: protect the room, take out sash and glass, locate and remove fasteners, score the stucco or trim around the opening, free the frame, cut or remove the fin, then clean and inspect the opening for rot, rust and damaged flashing. Only after that inspection should the new window be prepared. Rushing straight from removal to installation hides problems that are cheapest to fix while the wall is open.