What is a Load Bearing Wall? Understanding Structural Home Conversions
So, you are just starting out thinking about a home conversion, and you would like to know “What is a Load Bearing Wall?” We know the feeling that maybe if you remove a wall, the house will fall on you. Of course, get it wrong, and you are right! It really might! Never knock down a wall unless you are certain that it is not a loadbearing wall. Read on, and we will do our best to explain how to identify loadbearing and structural walls and how to distinguish them from non-structural walls or living-space partitions.
What Is Load Bearing Wall? A “Load Bearing Wall” Definition
A load-bearing wall or structural wall is a wall that is a structural part of a building, which supports the weight of the parts of the building over it. A loadbearing wall holds up what’s above it by “conducting the force created” by its weight down into a foundation (footing) structure beneath it.
But that’s pretty obvious. When you plan or do a home conversion, what matters is distinguishing between the loadbearing walls and non-load bearing studding. Here are a few ways to assist budding “home converters” to distinguish between load-bearing and non-load-bearing walls that can be demolished. The first step to identification is to understand the design of the building.
Load Bearing Wall Types Used in Construction
Very often, just looking at a wall from within a house won’t provide any evidence to decide if it can be demolished. Architect-designed modern houses and old properties that have already undergone structural alteration, such as having extended floorspace added or rooms added, are tough to interpret. In those cases, the best way to find out is to ask an architect, a structural surveyor, or an engineer before you start putting it under the hammer. (In your location, there may also be restrictions to ensure only qualified technical experts decide for structural walls versus non-structural walls, so contact your local council’s building inspection or building regulations department.)
Timber-framed buildings can be the most difficult to interpret but can be the easiest to strengthen with a strategically placed additional beam or two. However, while that may be possible, care still needs to be taken that any added beam has an adequate strength to support the beam ends where the additional load from the span will be transferred.
Much of the modern timber commercially designed and framed home stock provides an internal space designed so that the developer can partition the space flexibly. In these homes, flats (apartments, etc.), non-lead-bearing partition walls can be erected anywhere within the external walls’ curtilage. For those designs which span the full floor space, all structural loads are (in theory) carried out to the external walls. That means that it may remove virtually any internal wall.
However, removing every wall for a completely open-plan living space may result in a rather “springy” or “lively” upper floor. This happens because, without the restraint of non-load bearing walls, the floor is not as stiff as is normally provided when walls are present. While not dangerous, the occupants may become concerned about floor movement. Hence, once again, the expertise of a structural engineer is advisable. Some risk is also present that heavily loaded areas of upper floors may, over time, settle, causing cracked plaster, creaking floorboards, etc. An example of heavy-loading maybe a library or even a large-double waterbed!
In Europe, most detached and semi-detached homes built since the 1930s have been brick cavity wall designs. However, to keep construction costs low and minimize wood use, internal load-bearing walls may have been used. Even so, the uppermost floor internal walls are more likely to be non-loadbearing. Meaning that the roof structure spans across the full width, the lower floor(s) may have load-bearing walls usually constructed in brick or breeze blocks with mortar joints.
Homes may look like brick-built cavity-walled homes but may not be. Some houses will be structural steel or wood, framed with heat-insulated, uninsulated, dry-lined plasterboard internal finishes. Less common are wide-variety of proprietary concrete and modular building systems houses, about which the general comments given here will indicate very little.
Returning to traditional forms of construction. Just because an internal wall in a cavity-wall type-construction property is made of wood does not conclusively show it is a non-load-bearing wall. So, let us next consider some basic indications of load-bearing walls:
How To Tell A Loadbearing Wall (LBW) from a Non LBW
However, beware of making judgments on house structural forms without entering the roof-spaces and picking up hints on the structural form using some easy methods that can help distinguish a load-bearing wall from one the is simply a partition.
The following are easy methods to detect a loadbearing wall:
- By Sound: Tap the wall in a way that will not damage plastering or decorations. Even a gentle knock with your fist or knuckles may help here! An engineer may use the rubberized handle of a hammer, for example. Listen. Does the wall sound hollow, or even vibrate? With experience, this provides a good guide for walls that are merely in insubstantial plasterboard dry lined over a wooden studding. In such instances, there can be reasonable confidence a wall being non-load-bearing.
- External Visual Inspection: As the original external walls of a building will normally have been load-bearing and older properties have often been extended so that external walls have become internal walls, always look for telltale signs of building extensions. If you find a wall that you want to demolish was once an external wall, it is usually best to assume that it is load-bearing. Extensions to properties can usually be detected from differences apparent from the roof heights and spans, tile type and color differences, etc. Looking lower down at walls, the brick or plaster types and color may also vary between original construction and extensions and alterations added later. A bit of detective work can raise questions in your mind, which should then be checked in this method’s next step.
- By Loft (Roof) General Space Inspection: Before carrying out a roof space inspection, identify all hazards and ensure that the entry made is with the property owner’s permission and in a safe manner. While taking due care while moving into and around the roof space, look for which walls to roof loadings where rafters or trusses rest upon “wall plates.” Wallplates are usually beams laid horizontally on the top of walls. They rest on the single skin of early stone-built and brick houses. Where there is a cavity wall, they usually rest on the internal leaf of cavity walls. They serve to avoid excessive point loads being placed on small areas of walls that would otherwise exert an excessive “shear force” and crack or distort the wall members’ bricks, blocks, etc., upon which they rest. Wherever rafters and roof beams in general rest on a wall, that wall is load-bearing. However, any wall extending above a wall at one level should also be considered load-bearing because it supports the wall above’s the weight.
- By Loft (Roof) Space Inspection: The way that floor joists run and where they end and rest on internal walls is an important guide to load-bearing that we give it a separate mention here. You may need to lift insulation to see the joist. It is important to do that over the full area above any wall you would like to remove. Don’t damage the insulation material. Take care to avoid inhaling dust and always wear a mask and other suitable PPE (Personal Protective Equipment). Wherever you see joists resting on a wall or wall plate, you have a load-bearing wall. Where joists span over a wall below and have no connection through which they can transfer any loads to the wall below, you don’t have a load-bearing wall immediately below that point.
- Basement Inspection: Basement inspections are vital wherever a building possesses a basement. A good indication that a wall above is probably load-bearing is where that wall extends downward and therefore passes its load on down into the building’s foundations. Conversely, if by inspection from the basement, there is no wall or support column or beam beneath an internal wall above, that can be a good indication that it is a non-load-bearing wall (partition) and can be removed.
- Looking into built-in cupboards, metering cabinets, and space under the stairs: In fact, shining a torch into any space that reveals the building’s structure is always worth doing. It will confirm the building structure, and in older properties also help identify later additions to the structure through differences in construction type and materials used.
Load Bearing Wall (LBW) Design
For a structural engineer, load-bearing wall design is a complex subject in which complex mathematics very soon features heavily. The simple concept of conducting the force created by the load above into a foundation has to be considered with a detailed knowledge of the physical strength, stiffness, and creep under load characteristics of the materials used. Factors of safety, design life and such factors as local wind velocities and earthquake risk may also need to be considered.
Thankfully, in-house building, all this has been rendered down into the standard, tried and tested using bricks, blocks, mortar, etc. As long as the wall height is not excessive and point loads are dispersed using wall plates, standard building details will be all that is needed to design a satisfactory load-bearing wall.
For the person contemplating demolition of a structural wall for a home conversion, we recommend that a non-expert become involved in their design, beyond the normal standard details listed in Building Regulations and accepted “Codes of Practice,” is not feasible. A few hours spent reading up on the requirements will not help. Short of taking training courses and taking professional examinations, lasting years to complete, you will not succeed in creating load-bearing wall designs ready to be approved by most nations’ legal bodies. This is an area where the DIY’er should accept the need for professional help and seek it out.
Deciding to carry out a load-bearing wall removal is similar to the design of these as walls. Whether it can be done or not, the province of engineers qualified to do structural engineering calculations unless common solutions exist. If a full wall removal is required, the circumstances will be particular to the load, which must be supported. The forces will need to be assessed and loads supported by beams and lintels etc. The loads which will flow through beams, lintels, etc., will also need to be adequately supported at the beam ends. These displaced forces will then need to be considered for the additional weight they load onto the footings in the new support pathways created. Such concepts as stiffness, slenderness ratios (for columns, etc.), and creep over time will also need to be applied.
However, no such professional advice may be needed where only part of a loadbearing wall is removed, say for a door opening. It could equally be for another type of load-bearing wall opening, such as a window. If a DIYer does this, one method is to ask an online lintel manufacturer to provide a suitable lintel that their structural engineers have designed to perform a stated function to support the brickwork (for example) above a new door opening of a stated width within a larger wall.
How To Replace an LBW With a Beam?
Replacing a load-bearing wall with a beam is a common and effective way to continue to hold up a building after removing a load-bearing wall. All the comments we made previously apply to the need for professional advice. There will be a need to specify and provide dimensions for the beam itself and add whatever plates or reinforcement support at each end of the beam are necessary. The concentrated “beam forces” will be conveyed downward into the foundations.
Load Bearing Wall Removal Cost?
When a loadbearing wall is removed, there are a whole host of factors that affect the price. Not least is the amount of work needed from a qualified structural designer, but other factors will be the:
- ease or complexity of the demolition work needed first to remove the wall
- cost of propping the wall while the new beam or other structural support is provided
- cost of removing the rubble and its reuse or disposal
- cost of the permanent beam or other provision for the permanent support of the structure above.
How to Determine Load Bearing Wall?
Determining whether a wall to be removed by demolition is a load-bearing wall has already been discussed in this article. We covered this subject in the section titled: “How To Tell A Loadbearing Wall.” Please scroll back up to that section above.
Load Bearing Wall Beam
A load-bearing wall beam is any horizontal structural part (beam) to take the distributed and any point loading forces imposed on that part and convey those forces to the ends of the beam where they are thrust onto suitable plates, blocks, or bricks with mortar, or other fixings. This is done without the beam bending or deflecting at a percentage of the total span beyond a maximum permissible within the relevant Codes of Practice in force in any jurisdiction.
Load Bearing Wall Beam Calculator
The purpose of a load-bearing wall beam calculator is to size the required beam to withstand the forces applied to it. Beware of using such a calculator online unless you know what you are doing. Have you been able to fully assess the loads being applied to the wall by the structure above? Unless you have been trained in structural building works to design and are aware of any local legal requirements, you should not do this/ rely on your results. Regulations may exist which must be applied where you live. We do not recommend the use of a load-bearing wall beam calculator to a novice or DIYer. However, at https://sites.google.com/view/localplumbershrewsbury/home the business owner carries out many home conversions each year and is highly skilled in building work and plumbing; and is anything but a novice!
How Much Of A Load Bearing Wall Can Be Removed?
To say how much of a load-bearing wall can be removed by writing down even the most general advice here is not worthwhile. There are so many variables, any of which will be unique to a particular project home or office building, that rule of thumb guidance here would not be helpful.
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