Structural Openings & Steel Beams
Taking out a load bearing wall, and the calculations, padstones and Building Control sign off that go with it.
Fig. 01
Nearly every other trade gives you a warning before it fails. A roof drips, a wall cracks, a floor squeaks. Structural work does not always do that. Get an opening wrong and the first sign can be the last one. This page explains how the job is done properly and what it costs to do it that way.
What a structural opening actually is
Removing part of a wall that is holding something up, and replacing it with something else that will.
The phrase covers knocking two receptions into one, taking out a back wall so an extension reads as part of the house, widening a doorway, and removing a chimney breast. What they share is that masonry which was carrying load is coming out, and that load has to be picked up, carried to two points, and taken down to the ground from there.
We are asked to do this as a standalone job at least as often as we do it inside an extension. Plenty of Colchester houses need nothing built at all, because the rooms are big enough and simply in the wrong relationship to each other.
It is also the work most often handed to whoever is cheapest, because from outside it looks like a day of demolition and a lump of steel. It is not. It is a designed alteration to the load path of a building somebody is living in, with a phase in the middle where the house stands on props.
Is that wall holding anything up
The first question on any job, and the one most often answered wrongly with a knuckle.
A load bearing wall carries something besides itself: floor joists, a roof, a stair, another wall, a chimney. A partition divides space. Taking out the second is a skip and a day. Taking out the first is a structural alteration with calculations behind it.
Joist direction is the usual starting point. Joists span the short way across a room and bear onto the walls at each end, so a wall at right angles to the joists above is likely to be carrying them. You can read the direction from the floorboards upstairs, because boards run across joists. Lift a board or cut a small hole in the ceiling and you can see it rather than guess.
Thickness tells you something: a 100mm block or a timber stud is doing less than a 225mm solid brick wall. But thin walls carry load all the time, and thick ones sometimes carry nothing. What sits above matters more. A wall on the same line at first floor is standing on the one below, and a chimney breast, a stair trimmer or a purlin strut off a partition in a 1930s roof all come down through something.
Then the one that catches people out. A wall can carry no floor whatsoever and still be essential, because it is providing lateral restraint, holding a long flank wall straight against wind load. Nothing about the floorboards will tell you that. Which is why “it sounds hollow, it must be a stud wall” is not an assessment. It is a guess about a building with people asleep in it.
Will you need planning permission?
Four questions, an honest answer, and nothing sent anywhere. This runs entirely in your browser.
What are you extending?
Permitted development rights for extensions apply to houses. Flats and maisonettes are a different route entirely.
Is the property listed?
Listed building consent is a separate decision from planning permission, and work without it is a criminal offence rather than a planning irregularity.
Has the house been extended before?
Depth is measured from the ORIGINAL rear wall, so a previous owner's extension has already used part of your allowance. This catches almost everybody.
Is it in a conservation area?
Colchester has a number of them, including the historic core, the Dutch Quarter, part of Lexden and several village centres. The boundaries rarely follow the roads you would expect.
Answer the four questions for an indication
Whatever the answer, Building Regulations approval is always needed. We check the planning history, the designation and the deeds on your address before anyone draws anything, because it decides the design rather than the other way round.
This is an indication based on four questions, not advice on your property. Planning rules change and the position depends on your specific address, its planning history and its designation.
The structural engineer, and what the calculations contain
A third party we bring in, whose drawing is the thing everything else is built from.
We are builders. We do not size beams ourselves. On every opening we engage an independent structural engineer, they visit the house, and they produce calculations and a detail drawing. That goes to Building Control with the application and it is what we build to. The fee for a domestic opening is commonly a few hundred pounds, which makes it the least contentious money on the job.
What is in it is more than a beam size. It starts with a load take-down: the weight of the masonry above, the floor joists bearing into the wall and whatever those floors carry, the roof if the load comes down that line, and any point load landing on the beam from above.
From that come the bending, shear and deflection checks, and a check on the web where the load arrives. Then the bearings: bearing length at each end, padstone size and material, and the stress in the masonry beneath. Then connections, whether joists sit on the beam or hang from it, and any restraint straps needed to replace the stability the wall was providing.
Beam sizing, and why deflection usually governs
Everybody wants the widest opening with the slimmest steel. The relationship between the two is arithmetic, not opinion.
Beam depth is a function of span and load. Bending moment rises with the square of the span, so doubling the width of an opening does not double the beam, it does considerably worse than that.
What surprises people is that strength is frequently not what decides the size. Deflection is. A beam comfortably strong enough can still sag, and deflection under a uniform load rises with the fourth power of the span. Double the span and, all else equal, the sag goes up sixteenfold.
What makes that matter is the material on top. Masonry and plaster are brittle, so a steel that drops a few millimetres cracks the wall above it and the ceiling either side, along the whole line of the opening. Beams supporting masonry are therefore designed to tight deflection limits, and on a domestic opening that limit routinely sets the size rather than strength.
This is why asking for a smaller steel gets you nowhere, and why asking for a stronger grade gets you nowhere either. All structural steel has essentially the same stiffness whatever its grade, so where deflection governs, upgrading the grade buys you nothing. What can change is the problem rather than the physics: keep a nib of wall or introduce a column and the span drops, which shrinks the beam and eases the bearings.
Want this checked on your actual address?
Planning history, designation and deeds. We look at all three before anyone draws anything, and it costs you nothing.
Padstones, and the masonry underneath them
The beam collects the load and delivers all of it to two spots the size of a shoebox.
A padstone stops that concentration crushing the wall. It is a block of dense precast concrete, or a course or two of engineering brick in cement mortar, sized by the engineer and set into the wall so the beam bears on it rather than on ordinary brickwork. It resists the crushing stress itself and spreads the load over enough of the wall below that the wall can take it. Bearing length is specified too, and is not a detail to shave.
Leave the padstone out and the failure is entirely predictable. Soft Victorian stock brick in lime mortar simply crushes under the bearing. The beam settles, the wall above settles with it, and stepped diagonal cracking appears above each end. Putting it right means propping the whole thing again.
Then the bearing check below the padstone, which is where the money hides. That masonry has carried a spread load for a century and is now being asked for something else. On sound engineering brick in cement mortar it is usually fine. On soft lime mortared stock, on rubble filled village walls, or on some post war blockwork, frequently it is not, and the load has to go further down: a pier built up under the bearing, or a new concrete pad cast beneath the floor, hand dug inside the room. It is the single biggest reason two apparently identical openings differ by thousands of pounds.
Temporary support, and the days that carry the real risk
The wall is out and the beam is not in. That is the condition, and it is where serious failures happen.
Before any masonry moves, the load above it is picked up temporarily. On a modest opening that means adjustable steel props with wall support heads, slotted into a raked out bed joint above the line of the opening. On anything wider it means needles: beams or scaffold tube passed through holes cut through the wall and propped either side, so the wall above stands on the needles while the masonry below is taken out from under it. Size, spacing and prop capacity are designed rather than guessed.
The question that matters most is what the props are standing on. A prop puts everything it carries into a single point on the floor. Set one on a suspended timber floor and it is standing on boards and a joist designed for furniture, not for a storey of brickwork. It will punch through, overload the joist, or quietly deflect enough to let the wall above move. Propping onto a suspended floor without tracing the load down is one of the genuinely dangerous shortcuts on domestic work. So the load is followed to something solid: propping in the room below onto a slab, or breaking out floor and setting the props on a spreader over the ground.
Sequence matters as much as the props. The wall comes down in stages. The beam goes in, is bedded on its padstones, and the gap above it is pinned solidly with slate and dry pack so the masonry bears on the steel rather than hanging over a void. Only once that pinning has taken load do the props come out, in a controlled order. This phase is dated with you and run in one continuous go. We do not start it on a Friday.
The same wall, before and after
Drag to reveal. A real job in the Colchester area, photographed as it went. No staging and no borrowed images.
During
Finished
Downstands, flush ceilings, goalposts and corners
Where the beam sits, and what happens when there is nothing sound at one end to bear on.
A downstand sits below the ceiling line and is boxed in. It is the cheapest and quickest arrangement, and kept shallow it reads as a deliberate threshold rather than an apology. A flush ceiling means the beam sits up within the floor zone and the joists are cut back and hung off it instead of bearing over it: ordinary work, and more of it, with the floor above opened up and a wider area of ceiling made good. On a wide span it does not fully solve the problem anyway, because the beam ends up deeper than the joists and a shallow downstand appears regardless.
The third option is to leave the steel visible, with clean end junctions and a protective coating. On a wide opening in a plain room that is frequently the better answer, and it costs less than concealment, but it has to be decided before ordering. Either way, allow for the casing: a boxed steel finishes noticeably thicker than the steel inside it.
A goalpost frame is a beam with steel columns under one or both ends, standing on its own concrete pads. It is the answer where the masonry at a bearing cannot take the reaction, where an opening runs to the end of a wall with no return to bear into, and where a wall is removed at a corner. Corners are underestimated: two walls meeting at a right angle stiffen each other and stiffen the building, so taking one out usually means moment resisting connections between beam and columns.
Openings on two floors on the same line change the answer again. Replace the wall above with a beam of its own and the whole upper load arrives at two points on the lower beam, which is far harder on it than the same weight spread along its length. Say so at the survey if there is any chance of opening up upstairs later.
Chimney breasts, and stacks standing on nothing
The most common thing removed alongside an opening, and the most common thing we find already done badly.
A chimney breast eats a metre out of the middle of a wall. What makes removing one structural is that the breast at first floor, the breast in the loft and the stack above the roof are all standing on the part you want to take out, and a stack is heavy.
There are two sound approaches. Remove the whole thing from the ground up and out through the roof, weather the roof and make good the ceilings, and there is no residual load. Or support what remains, traditionally with gallows brackets, steel angle brackets bolted back into the breast wall each side. Those are acceptable in limited circumstances only: sound solid brickwork of adequate thickness to bolt into, a modest load above and a stack in good order. Building Control looks at them closely and often asks instead for a beam bearing onto padstones.
The genuine hazard is the one somebody else left. We are regularly called to a house where a ground floor breast was taken out in the eighties or nineties and there is nothing identifiable holding up what remains above it. Sometimes a bracket rusted into soft brickwork. Sometimes a timber. If your house has a first floor chimney breast and no breast beneath it, ask for the Building Regulations paperwork. Its absence does not prove the support is inadequate, but it does mean nobody has checked.
Where the breast sits on a party wall, which on a terrace it usually does, removal is notifiable under the Party Wall Act, and a retained stack still needs weathering and ventilation.
Five things you can check yourself.
Trust on a building job should be verifiable, not asserted. Every one of these can be confirmed without taking our word for it.
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01
Real company
Essex Probuild Ltd, company 15979928, registered in West Bergholt. Checkable on Companies House in a minute.
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02
Real cover
£2m public liability cover in place. Evidence available on request rather than a badge on a website.
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03
Real reviews
4.6 out of 5 on Google from 10 reviews, shown as they were left. We do not curate them.
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04
Real photographs
Every project image on this site is a job we built. No stock, and no fabricated before shots.
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Real accountability
We notify Colchester City Council Building Control and manage the inspections through to your completion certificate.
Steel, timber, fire and corrosion
Steel is the default, it is not automatically the right answer, and either way it needs protecting.
Most domestic openings use a rolled steel section. People still call them RSJs, from a section shape now largely obsolete: what turns up is a universal beam with parallel flanges, or a pair of channels bolted back to back where a flat face is wanted. Steel is compact for the load it carries, which is what you want when headroom is tight. Its drawback is weight. A deep beam over four or five metres runs into hundreds of kilos and needs six people, a gin wheel over scaffold, or splicing into two sections bolted on site.
Engineered timber is worth asking about. Glulam and laminated veneer lumber are stable, predictable and far lighter than steel for the same job, which matters when access is bad and when you want a warm exposed beam rather than a painted one. Timber needs more depth for the same load, so it suits a downstand. Flitch beams, steel plate bolted between two timbers, suit a shallow floor zone where access rules out a single heavy section.
Fire protection is the item people forget. Steel loses strength as it gets hot, so a beam holding up part of a house has to be protected for long enough for everyone to get out. In a normal two storey house that is usually thirty minutes, rising where the building is taller, with the figure confirmed with Building Control. It is achieved by encasing the steel in fire rated plasterboard, typically two layers to the boxing; by a continuous ceiling below a beam within the floor zone; or, where the steel is to be seen, by an intumescent coating applied to a specified thickness.
Corrosion matters less often and matters absolutely when it does. A steel in a dry heated room needs nothing beyond a primer. One in an external wall, in a cavity, near the damp proof course or in an unheated garage wants galvanising or a paint system, which cannot be added later.
The Party Wall Act
Cutting a pocket into a shared wall to take a beam is notifiable work, and the notice period is two months.
On a terrace or a semi, one or both ends of the beam frequently bear into the party wall. Cutting into a party structure for any purpose, including forming a bearing pocket, is section 2 work under the Party Wall etc. Act 1996. So is removing a chimney breast off a party wall.
Where section 2 work is proposed you serve a party structure notice on the adjoining owner. It describes the work, includes drawings where the work involves cutting into the wall, and it is served at least two months before the work is due to start. The adjoining owner then has fourteen days to respond. If they consent in writing that is the end of it, and by agreement work can begin sooner. If they dissent, or say nothing within those fourteen days, a dispute is deemed to exist and surveyors are appointed to settle it with an award. Silence counts as dissent, which is the part that catches people.
The award records the work, the condition of the neighbour’s property beforehand, working hours and who pays, and the fees fall to you. None of this is a reason to avoid the work, but it is a reason to start the notices early, because two months served after the steel has been ordered is two months of nothing happening.
What might it cost?
A realistic range rather than a single number, with what it excludes shown as prominently as what it includes.
£44k to £60k
- VAT
- Kitchen and appliances
- Flooring
- Decoration
- Drawings and calculations
- Planning and Building Control fees
- Party wall surveyor
- Service diversions
Indicative only. The biggest variable around Colchester is foundation depth, because most of the ground is shrinkable clay and mature trees are common. We price the job after seeing it.
Get a real price
Building Regulations and Building Control
Removing a load bearing wall is notifiable work even when there is no extension and no planning application anywhere in sight.
Taking out an internal wall is a material alteration: it affects the structure, so it needs Building Regulations approval and inspection. Planning permission is a separate matter and is not usually required for internal alterations, though a listed building or a flat changes that entirely.
The Approved Document doing the heavy lifting is A, for structure: the loading the beam is designed for, its strength and stiffness, the bearings, and the stability of the building once the wall has gone. B for fire covers protection to the steel and the escape route where an opening changes how the stair is enclosed, and C and K come in where the opening is in an external wall or creates a change of level.
There are two routes. A building notice tells the authority you are starting and they inspect as work proceeds, with no advance check of anything. A full plans submission means the drawings and the engineer’s calculations are checked before anybody touches the wall. On structural openings we use full plans without exception, because a disagreement about a beam size is very much cheaper to have on paper than with the props already in.
We notify Colchester City Council Building Control and manage the inspections. The one that matters is the visit before anything is covered up, when the beam, the padstones, the bearings, the pinning and the fire protection can all still be seen. At the end you get a completion certificate, which belongs with your deeds, because it is the document a buyer’s solicitor asks for.
What we find in older Colchester houses
The housing stock decides the shape of the job more than the drawing does.
Victorian and Edwardian terraces through New Town and the streets off Magdalen Street and Military Road are built around a spine wall dividing the two receptions, with chimney breasts in it and the stair alongside. That wall carries the first floor joists, often the stair, both stacks and a full height of masonry above, and the beam replacing it bears into party walls on both sides. Those walls are typically 225mm solid in lime mortar and have never carried a point load, which is why this is the bearing check that most often comes back asking for a pier or a pad.
1930s semis across Lexden, Prettygate and the older parts of Shrub End give us the most common openings we form. They are usually straightforward, but two things recur. The roof is often a purlin roof with struts landing on an internal partition, so a wall carrying no floor is carrying the roof. And the chimney breast is nearly always in exactly the place you wanted the opening.
Post war and later housing in Greenstead, Monkwick and Old Heath has simpler load paths, but watch for non traditional construction on part of that stock. Village property around West Bergholt, Dedham and Boxted brings timber framing, rubble filled walls and unpredictable load paths, along with listed building consent as a separate approval.
Then unauthorised previous work, which we find on all of it. Beams with no padstones. Breasts removed with no support anyone can identify. We survey what is already there before we design what is going in, because the load path we are joining has to be sound too.
Get a real number, not a range.
We come out, look at the ground, the access and the structure, and price the job we have actually seen. The survey and the quotation are free.
What a structural opening costs
A range with its basis stated, because a number from somebody who has not seen the wall is worthless.
Costs move with materials, labour and specification, so treat this as indicative at the review date at the foot of this page rather than as a quotation. As a working range, a structural opening in a Colchester house typically runs £3,000 to £8,000, with straightforward jobs below that and difficult ones above it. The things that move the number are span, load and access, in that order.
| Situation | Effect on the range | Why |
|---|---|---|
| Opening up to about 3m, modest load, good access | Lower end | Props rather than needles, light beam, sound bearings |
| Full width opening, 4m and over | Upper end | Deeper beam, needled temporary works, more making good |
| Bearings into a party wall | Add notice period and fees | Pockets cut into shared masonry |
| Bearing check fails, new pad or pier needed | Add a substantial sum | Hand dig inside the house, spoil carried out through it |
| Flush ceiling instead of a downstand | Add | Floor above opened up, joists trimmed and hung |
| Goalpost frame, or a corner removed | Well above the range | Fabricated frame, designed connections, concrete pads |
That normally includes temporary works and propping, taking down the masonry, the beam and its delivery, padstones, pinning up, fire protection casing, forming the reveals, plastering the opening and the affected ceiling, and taking the spoil away.
It normally excludes VAT, the structural calculations, Building Control fees, party wall surveyor fees where a neighbour dissents, a new pad or pier if the bearing check asks for one, flooring across the line of the removed wall, skirting and architrave to match, decoration, and anything found inside the wall. Old walls contain gas runs, pipes, cables and, in some post war construction, asbestos board, none of which can be priced before the plaster is off.
How long it takes, and living through it
A few weeks of paperwork you can overlap, then a short and noisy spell on site.
The front end is the engineer’s visit and calculations, usually one to two weeks, then the Building Regulations application. A full plans submission is determined within five weeks unless a longer period is agreed. Steel fabrication runs one to three weeks and is the item most likely to hold a programme up. Where a party wall is involved, the two month notice period sits alongside all of it, which is why it goes out first.
On site, a single opening with making good back to a decorated wall is commonly two to four weeks, of which propping, taking the wall down and getting the beam in is two or three days. Several openings, or an opening plus a chimney breast, is nearer four to six weeks.
Living through it is short and intense rather than long and grinding. The rooms either side are emptied completely, including pictures on the walls upstairs, because taking out masonry shakes the whole house. We put up zipped dust barriers, protect the floors and the route in and out, and cut wet or on extraction wherever we can. Dust still gets everywhere, and anyone who tells you otherwise has not done it. Breaking out masonry produces fine silica dust that needs managing for the health of the people doing the work as much as for your carpets.
The days the wall comes out mean props standing, possibly a needle through the middle of the house, and breaking out noise that is not compatible with a work call. Upstairs stays usable and so does the stair. Once the beam is in and pinned, the pace changes and the rest is quiet.
Fig. 01
What actually happens, in order
Three of these eight stages happen before anybody digs anything. Get the order wrong and you pay to redo work.
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Survey
We look at the ground, the trees, the access, the existing structure and where the drains actually run.
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Drawings
A technician produces existing and proposed plans and elevations to a standard the council will accept.
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Permissions
Permitted development, prior approval or a full application. We submit it and handle the correspondence.
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Structure
The engineer calculates the beams, the padstones and the foundation depth for your ground.
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Groundworks
Dig, concrete and drainage. The messiest phase and the one that decides whether the rest stands still.
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Structure up
Walls, steel into the opening, roof on, windows and doors in. The day the back wall comes out is planned with you.
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Fit out
First fix, plaster, second fix. From here it stops being a building site and starts being a room.
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Certificate
Final inspection and your Building Control completion certificate. Keep it with the deeds.
Questions we get asked
Can you take a wall out without an engineer?
Not on any wall carrying load, and not on any wall we cannot confirm is carrying nothing. Anybody offering to remove a load bearing wall without an engineer is offering to do it without approval, and that becomes your problem when you sell.
How wide can the opening be?
Wider than most people expect, given the right beam and adequate bearings. The practical limits are how much steel you are willing to see, whether the masonry at each end takes the reaction without new pads, and whether the beam can physically get into the house, since a five metre section coming through a terraced hallway is a different proposition to one lifted over a side gate.
We had a wall removed years ago with no paperwork. What now?
A common position, and retrievable. An engineer can inspect what is there, and where the work is sound a regularisation application to Colchester City Council Building Control puts it on record. Where it is not sound, you find out before a surveyor does, which is very much the better order.
How we do it
One contract, one contact, and the paperwork is our job rather than yours.
Our team has 25+ years in the trade and comes out. The first visit is a survey rather than a sales call. We look at joist direction, what stands above the wall, the condition of the masonry at every likely bearing, how a beam would physically get into the house, and whether anything already done to the building needs putting right first.
Most people who call us already have drawings and permission and want a builder to price the work and build it. That is the ordinary job here, and we are glad to work to somebody else’s plans. Where the drawings do not exist yet, we bring in the structural engineer who calculates the beam, the bearings and any pads, we submit full plans and notify Colchester City Council Building Control, we serve party wall notices where a shared wall is affected, and we plan and carry out the temporary works ourselves through to the completion certificate.
Probuild Extensions Colchester is the extensions arm of Essex Probuild Ltd, company number 15979928. We carry £2m public liability cover, we work from West Bergholt about three miles north west of the city, and we cover Colchester and roughly thirty miles around it. If we think the opening you want is the wrong one, or that a nib of wall in the right place would give you a better room for less money, we will say so at the survey. The survey and the quotation cost nothing.
Last reviewed August 2026. Planning rules and Building Regulations change, and your property may differ, so treat this as a guide rather than advice on your specific job.