Cutting out steel door frames in reinforced concrete walls up to 10 cm

In many concrete blocks of flats, especially those built from prefabricated panels, steel door frames were placed in the formwork or in a prepared opening and then grouted or cast in. The frame is not just screwed in place. It is effectively part of the wall. Its hollow profile is often filled with concrete or mortar, and fixing lugs reach into the wall. If you knock a frame like this out by force, the concrete around the opening cracks, the corners break away, and sometimes the plaster or tiles next to the door come loose too.

Cutting avoids this. The cut runs along the frame, usually just outside its outer edge or through the steel profile itself, so the bond with the concrete is broken. The frame is then split into several pieces and taken out. The result is an opening with straight edges that only needs minor cleaning and making good.

When you are likely to need it:

• When replacing internal doors with doors that use a lining-type frame
• When renovating a bathroom or WC pod and the partition around it is being changed
• When the old frame is bent, rusted or the wrong size for the new door
• As a first step before widening or heightening the opening, which is a separate job and needs a structural engineer's assessment

The price-list unit is one piece, meaning one frame. This assumes a standard single-leaf door frame. Double-leaf, sliding or non-standard frames are usually assessed separately.

The price list has two items: cutting out steel frames in reinforced concrete up to 10 cm and up to 15 cm. What matters is the thickness of the concrete wall the frame sits in, and therefore how deep the cut has to go. It sounds like a small difference, but in practice it changes the tools, the method and the time.

• Typical wall: walls up to 10 cm are mostly non-loadbearing concrete partitions, for example between bedrooms, along a hallway or around the bathroom pod. Walls up to 15 cm are usually the internal loadbearing walls of the building.
• Tools: a wall up to 10 cm can often be cut with a large angle grinder and a diamond blade of roughly 230 mm, which cuts about 6 to 7 cm deep. The wall is therefore cut from both sides and the cuts meet in the middle. At 15 cm this is no longer enough, and a hand-held concrete saw with a larger blade or other equipment is used.
• Structural risk: a partition up to 10 cm is usually non-loadbearing, so cutting out the frame is a smaller intervention. With a thicker loadbearing wall, care matters even more. Even with a thin wall, though, do not assume it is non-loadbearing until someone has checked.
• Vibration and stability: a thin partition vibrates more easily under rough handling and can crack some distance away from the opening. That is why calm, steady cutting matters even more here, and the frame should never be wrenched out.
• Time and effort: a shallower cut means less cutting time, less slurry or dust and less wear on the blade. One frame in a thin wall is usually quicker to do.

If you are not sure which variant applies to you, measure the wall in the opening itself: the thickness of the concrete without plaster or tiles. If it comes to about 10 cm and the depth of the frame matches the partition, this is the right item. If the wall is between 10 and 15 cm, or it is loadbearing, order the other variant.

Cutting out a frame does not change the shape of the opening, but it is still work on the reinforced concrete structure of a block of flats. Be careful about the building and about the rules.

Building management, owners' association and the local authority

In a block of flats, let the building management or owners' association know in advance. Many buildings have their own rules on alterations, noisy work and waste removal. Whether your work needs approval or notification depends on local building regulations, so check with your local building authority. Do not assume that replacing a door is automatically too small to matter, especially if the opening or the layout changes at the same time.

If you plan to enlarge or move the opening, or you are not sure whether the wall is loadbearing, have it assessed by a structural engineer. Cutting the reinforcement around an opening is a structural decision, not a trade decision.

What needs to be ready in the flat

• Doors taken off, handles, locks and threshold removed, unless agreed otherwise
• Rooms on both sides of the opening cleared for at least a few metres
• The floor covered with solid protection, and for wet cutting with waterproof sheeting and boards
• The circuit for the light switch and sockets near the door switched off and secured against being switched back on
• Cables, and any water or heating pipes near the frame, located
• A socket available for the tools and space set aside for waste
• Neighbours told about noisy work, within the hours allowed by the house rules

Next to doors in concrete flats there is almost always a cable running to the light switch, often in a chase or conduit right beside the frame. If the cable needs moving or disconnecting, that is a job for a qualified electrician, not for the concrete cutting crew.

Inspection and marking out

The operative first measures the wall thickness, checks whether the frame is surrounded by tiles or another layer, and scans for services with a detector. Cut lines are marked on both faces of the wall. The cut is placed so that no more concrete is removed than necessary. If a new frame of an exact size is going in, the future clear width and height are taken into account as well.

Wet or dry cutting

Cutting concrete produces fine silica dust, which is harmful to health. With wet cutting, the blade is cooled with water, the dust is bound into slurry and the blade wears less. The downside is the water and slurry, which have to be caught and vacuumed up continuously. In an occupied flat with wooden floors, dry cutting with on-tool extraction is often chosen instead, using an industrial dust extractor of a suitable class, usually M or H, with the crew wearing at least FFP3 respirators. Agree the method in advance, because floor protection is prepared accordingly.

Cutting from both sides

With a wall up to 10 cm, the crew usually cuts from one side as deep as the blade allows, then from the other side along the same line. The cuts should meet in the middle. The operative cuts slowly, in several passes, so the blade does not overheat and the partition is not set vibrating. At the corners of the frame the cut stops where it needs to, so the concrete above the head of the opening is not weakened.

Cutting the profile and removing the frame

The steel profile is usually cut in several places, typically near the top of the jambs and in the head. This splits the frame into smaller sections that can be removed one by one, in a controlled way. Any fixing lugs left sticking out of the concrete are cut off flush. If the hollow frame was filled with concrete, part of the fill comes out with the profile and the rest is carefully cleaned away.

Cleaning up

Finally the reveals are cleaned of leftover mortar, sharp edges are ground down and the waste is sorted. Metal is kept separate from concrete rubble, because it is disposed of differently. Slurry or dust is vacuumed up and the area is handed over ready for the next trade.

How long it takes

For a standard single-leaf frame in a partition up to 10 cm, in a well-prepared room, cutting and removal usually take a few hours. Tiles, services to work around, wet cutting with more clean-up or awkward access all add time. Nothing needs to cure, but after wet cutting let the reveals dry before plastering or fixing a new frame, usually at least a day or two depending on ventilation.

The price per piece is based on a typical situation. Real jobs vary in both directions, and it helps to know why.

Things that make it easier:

• Clear space on both sides of the wall, so it can be cut from both faces
• A plain concrete wall without tiles or thick layers of plaster
• Known positions of services and the power switched off
• Several frames in one flat, done one after another without moving equipment around
• Being able to cut wet without worrying about the floor

Things that make it harder:

• Ceramic tiles in a bathroom or hallway, which first have to be cut carefully so they do not crack further
• A frame right next to a room corner or a built-in wardrobe, where the tool cannot be positioned properly
• A wall thicker than expected, or concrete with an extra layer of masonry on it
• Dense reinforcement right next to the frame, which slows the cut and wears the blade faster
• Unknown or poorly recorded services, especially cables running tight against the profile
• An occupied flat, where furniture and floors need protecting and dust must be kept to a minimum

Cutting out a frame is usually one of the first strip-out jobs. What comes next affects how precisely it needs to be cut, so it helps to plan ahead.

• Electrician: ideally marks or moves the switch cable before cutting, and after the frame is out installs new wiring in a prepared chase
• Plasterer or bricklayer: straightens the reveals, fills chipped areas and prepares the opening to the exact size of the new frame
• Flooring fitter: door replacement often involves the threshold and the transition between floors, so they need to know where the opening ends and what the finished floor height will be
• Door supplier: a lining-type frame needs straight, square reveals and the correct wall thickness including plaster, so measuring should happen only after the old frame is out and the reveals are made good
• Tiler and decorator: come in at the end, once the reveals are dry and the new frame is fitted

It often happens that doors are ordered to fit the old frame, and once it is removed the opening turns out to be a different size than expected. It is better to measure the clean opening, even if that delays the order by a few days.

Most problems with this job are not visible straight away. They appear when the new doors are fitted, or months later.

The cuts did not meet in the middle

When cutting from both sides, the lines on each face can end up offset. A ragged step is left in the middle of the wall and breaks away unevenly. The reveal becomes jagged and the plasterer has to build up a lot of material. You notice it when the new lining will not sit straight or there are voids behind it.

The frame was forced out

If someone gets impatient and levers the frame before the bond is fully cut, a thin partition can crack. The crack sometimes appears only after decorating, running diagonally from a corner of the opening. With a partition up to 10 cm this is a bigger risk than with a thick wall.

A cable or pipe was cut

A cut cable means a dead circuit and, in the worst case, an injury. That is why cutting never starts without the power off and the services located. A damaged heating or water pipe in the bathroom pod shows up as a leak and damp patches, sometimes in the flat below.

Reinforcement above the opening was cut

If the corner cuts run on above the head or out to the sides, the concrete and reinforcement around the opening are weakened. In a non-loadbearing partition this can lead to cracks; in a loadbearing wall it is a serious problem. The cut should end exactly where the frame ends, unless a structural engineer specifies otherwise.

Water damage and dust in the flat

With wet cutting and no proper water containment, wooden or laminate flooring soaks up water and swells. With dry cutting and no extraction, fine dust spreads through the whole flat and keeps settling on furniture for weeks. Both come down to preparation, not bad luck.

Cutting reinforced concrete in an occupied building is not a DIY job. It is work on the structure, the tools are powerful and can kick back, and the dust is a health hazard. There is also almost always electrical wiring near the frame. What you can do is save the crew time and reduce the risk of damage by preparing the room:

1. Take the door off its hinges and remove the handle, lock and architraves.
2. Clear the area around the opening and cover the furniture with sheeting, taped down.
3. Lay solid boards over sheeting on the floor and tape up the doors to other rooms.
4. Ask the building management when noisy work is allowed and where waste can go.
5. Gather any floor plans or photos of the wiring and pipes from earlier work.

Leave disconnecting and moving wiring to an electrician. If you are not sure whether the wall is loadbearing, have it checked by a structural engineer.

Inspect the work straight away while the crew is still there. A spirit level, a tape measure and a torch shone at a low angle along the reveals will help. Check these points in particular:

• The whole frame has been removed, including the fixing lugs, and no metal sticks out of the concrete
• The reveals are straight, without deep breakouts or a step in the middle of the wall
• The corners of the opening have not been cut further than the original frame reached
• There are no new cracks in the wall, ceiling or nearby plaster
• Electrical cables, water and heating pipes are undamaged and the circuits work
• The clear dimensions of the opening suit the new frame
• Floors and furniture show no damage from water, slurry or debris
• Metal waste and rubble have been removed or stored as agreed
• The area has been vacuumed and is ready for the next trade