As specialists in opening load-bearing walls, reinforcement with steel structures and the creation of floor openings, OMPT GROUPE offers you this comprehensive glossary, in the interest of transparency.
To understand a quote for opening a load-bearing wall and to choose an underpinning company properly, the client needs to be able to judge the nature of the work being carried out, by knowing the precise technical definition of the terms used. How can you compare quotes for opening a load-bearing wall if you do not know, for example, the difference between a column and an IPN beam?
TECHNICAL GLOSSARY
Bay (baie): any opening in a wall, later closed by a window. When it is not fitted with joinery, the opening is said to be open (baie libre).
Bastaing: a carpentry term for a large timber member of rectangular section, used mainly for joisting.
(see joist)
B.E.T (structural engineering office): a body that works ahead of the specialist trades to carry out technical studies and calculations and to produce drawings. Made up mainly of engineers and specialist technicians, it can be an independent company or simply a department within a larger company.
CONCRETE: a major construction material made from a hardened mixture of cement, sand, gravel and water. Very strong and excellent value for money, concrete is widely used in building to make walls, columns, slabs or any other load-bearing structural element.
The quality of the concrete determines the quality of all the structural work.
Reinforced concrete: concrete strengthened by adding a steel structure, in the form of rods or mesh, to make it more resistant.
Prestressed concrete: the steel is tensioned before the structure is loaded and is not necessarily in direct contact with the concrete.
Bolt: a hardware term for the assembly of a screw and its nut, used to join parts through which the screw passes. Tightening the nut ensures contact and cohesion of the assembly. The male part is called the threaded rod.
Bolts are regularly used to join columns or beams.
Caulking: a flexible, more or less elastic material used to fill the gaps in a joint to ensure it is watertight.
Calfeutrement (bedding): a masonry term for the mortar placed around a part to be sealed in. Not to be confused with caulking, used for waterproofing.
Tie beam (chaînage): a steel or concrete structure, in the form of a chain linking two load-bearing walls to prevent them from moving apart.
Roof structure: a steel or timber assembly that supports the roof of a building and provides its covering, making it weatherproof and airtight.
Trimmer beam (chevêtre): a small horizontal beam forming the upper part of a frame, tying the columns together and transmitting to the trimmer joists the support loads carried by the tail joists.
PARTITION: a vertical dividing element inside a home, less than 10 cm thick. Unlike a load-bearing wall, a partition has no structural function.
A partition can be made from different materials: plaster (easy to install, especially in renovation), cellular board, terracotta bricks (an ecological material for effective insulation), concrete (maximum strength) …
Angle bar: a metal section with an L-shaped profile, used to connect two perpendicular elements. The two legs of the L can be equal or unequal.
Pocket (empochement): classically used in renovation, this is a temporary recess in an old masonry wall, made so that a reinforced concrete beam or horizontal tie beam can be sealed in later. Spaced about every one to two metres, this method avoids cutting a chase in the wall during renovation, so as not to weaken it.
Infill space (entrevous): the gap between two consecutive timber members, such as joists for a floor or studs for a partition. This gap is then meant to be filled with masonry or plaster on laths.
Splice plate (éclisse): a metal device in the form of a flat bar of varying size, intended to reinforce various connections. Used in pairs, splice plates are fixed on either side of a joint with bolts or screws (countersunk or square-head screws).
Prop (étai): any supporting element on a structure, intended to prevent sagging by carrying loads.
Propping (étaiement or étayage): the act of placing a prop (see this term).
Reinforcement (ferraillage): the whole steel framework cast within reinforced concrete, increasing its strength and rigidity.
Gusset: a carpentry term for a metal piece connecting a beam to a stabilising element, to give the whole assembly rigidity and cohesion.
Hollow block (hourdis): prefabricated masonry infill elements intended to fill the gap between the joists or beams of a floor.
There are several varieties:
Terracotta brick hollow blocks
Concrete hollow blocks: load-bearing (integrated into the compression slab) or non-load-bearing
Polystyrene hollow blocks: light and very good insulators (thermal insulation), they are used specifically for crawl-space floors or floors over cellars.
IPN (standard-profile “I” beam), see beam
Lintel: a structural element of the wall located above a window, a door or, more broadly, an opening.
Project manager (maître d’œuvre, MOE): an individual or legal entity appointed by the client to manage the operational running of the works in accordance with the specifications.
A MOE has no authority to carry out the work themselves.
Client (maître d’ouvrage, MOA): the individual or legal entity for whom a project is carried out.
Mezzanine: an intermediate floor installed in a room with a high ceiling, dividing it vertically.
Twin-beam clamping (moisage or moisement): a joinery or carpentry term for a device that reinforces and holds in place two parallel timber pieces (the “moises”), framing a third reinforcing piece. The notch may be cut only in the moises (single clamping) or in all 3 pieces (double clamping).
By extension, moisage applies to reinforcement systems on concrete beams, to reduce the risk of spreading or cracking caused by the mechanical stresses acting on these beams.
Mortar: a masonry term for the pasty bonding mixture made of cement, sand and water. The cement base can be replaced if necessary by lime, clay or even asphalt.
Mortar is used to join bricks, concrete blocks, breeze blocks and even tiles.
WALL: a generic term for a vertical, rigid, fixed masonry element that delimits or separates two spaces.
Façade walls: these are the visible exterior walls that make up the façade of any building or house. They most often comprise a main façade, two side façades and a rear façade. Any façade wall can be made of different materials, each with a specific function: structural materials, insulating materials (sound insulation, thermal insulation), decorative and facing materials, protective materials (waterproofing)…
Load-bearing wall: in architecture, a load-bearing wall (or partition) is a structural wall that helps support the whole structure, including the floors and the roof framing. A structuring element of any building, the load-bearing wall can be made of concrete, brick, concrete blocks, or even plaster if combined with a timber or steel structure. Work on a load-bearing wall requires a load-bearing wall expert, usually after numerous calculations by a structural engineering office: the load-bearing wall guarantees the integrity and durability of any built structure.
Interior bearing wall (mur de refend): a type of load-bearing wall located inside a home and linking the façade or gable walls together. By supporting these façade walls, it helps maintain the structure and the weight of the upper floors, strengthening it vertically and horizontally. A transverse bearing wall is called a “bracing wall”. As a major structural element, an interior bearing wall should only be touched by a specialist, for example when a span that is too long needs to be reduced.
Party wall: an essentially legal concept, a party wall is any dividing wall between two properties, whether buildings or land (enclosures, gardens…). Legally, a party wall is jointly owned by the respective owners. Most of the time, work on a party wall must be paid for by the different parties.
Concrete block (parpaing): a concrete masonry material in the form of solid or hollow rectangular blocks. Assembled, they are used to build load-bearing walls or simple partitions.
Partition, see load-bearing wall
Floor: a joinery or carpentry element forming the horizontal platform of an upper storey or a ground floor.
Composite floor: a type of floor using steel and concrete poured on site. The steel component combines metal reinforcement and thin ribbed steel sheet formwork, whose inclined ribs allow the poured concrete to bond with the steel.
Precast concrete floor: prestressed or reinforced concrete joists, between which concrete hollow blocks are placed.
Plasterboard: the original material of the renovation partition, plasterboard is made of moulded gypsum between two layers of cardboard. The terms Placo (France) or Gyproc (Canada, Belgium), abbreviations of registered trademarks, are still used. This dry partition is installed by fixing to a frame, without a binder. This high-performance and widely used material gave rise to the trades of plasterboard fitter and plasterboard jointer.
Base plate (platine): a metal plate fixed to the end of a steel column or beam, most often perpendicular to its longitudinal axis, ensuring the mechanical continuity of a system by assembly.
Column (poteau): a vertical structural member of a building, bearing mechanical stresses and distributing the loads of the superstructure (such as the roof framing) to the infrastructure.
Beam: a horizontal structural member of a building, placed between walls.
I-beam or IPN or H-beam: a steel beam with a standardised I profile, meeting very precise standards (NF A 45-209). Extremely strong and resistant, they are widely used in renovation by OMPT or any load-bearing wall specialist to replace a load-bearing wall or an interior bearing wall.
Joist (poutrelle): a small beam, most often with an I or H section, used as a load-bearing element of a concrete floor.
Stiffener: a reinforcing piece of a structure, intended to reduce play, bending or buckling of the whole. A stiffener can be steel or timber.
By extension, a stiffener also refers to a concrete admixture that allows mortars or concretes to bond as soon as they are poured, without deformation.
Acceptance of the works: defined legally and contractually, this is the act in which the client checks, in the presence of the builder, that the work has been properly carried out, with or without reservations: everything is recorded in the acceptance report. It is an important step, which sets the starting point of many tax and insurance deadlines (completion guarantee 1 year, functioning guarantee or two-year guarantee 2 years, ten-year guarantee 10 years)
Provision (réservation): a small floor opening (see floor opening)
Sealing-in (scellement): the act of fixing a loose part in a hole, ensuring its permanent fixing with a hardening material (plaster, cement, lead).
Foundation footing: an infrastructure element, most often in reinforced concrete, whose function is to distribute the loads of the superstructure to the ground. A good foundation footing is the basis of all masonry work, especially for foundation walls.
Isolated footing or pad footing: a foundation localised at limited points of the structure, for example under a column. The isolated footing corresponds to localised point loads.
Strip footing: a continuous footing that can support several columns and posts, or a load-bearing wall.
Raft foundation: the foundation is spread over the whole surface of the building, allowing a better distribution of loads. A raft foundation is recommended when these loads are heavy, or the ground is of poor quality.
Joist: a carpentry term for a horizontal member that supports the floor and bears on the walls or beams.
Continuous joist: a joist that runs the whole length of a ceiling
Ceiling joists: parallel timber members that carry the load of the ceiling and bear on the load-bearing walls.
Concrete padstone: a horizontal masonry element placed on the top edge of a wall to ensure proper distribution of loads (beams, joists, etc.) without crushing the concrete blocks beneath. Plain concrete provides compressive strength, while reinforced concrete also provides tensile strength.
Structural investigations: a set of diagnostic methods used to determine the structural qualities of a building to be rehabilitated or renovated.
In addition to the BET's calculations, these structural investigations and tests aim to determine exactly the load-bearing capacity of the existing structures. These diagnostic methods include non-destructive tests (radar, corrosion measurement, ferroscan…) and destructive investigations (taking samples for analysis, by core drilling, chiselling, cutting…).
Chimney stack: also called a roof outlet, this is the external masonry part of the chimney flue, visible on the roof.
Welding: a joining technique that creates continuity between two different pieces of the same material (metal, glass, synthetic products…). Welding can be done hot or cold.
Welded mesh: reinforcement for reinforced concrete made of crossed and welded bars, unlike the individual bars of reinforcement cages, which are tied together and not welded.
Welded mesh comes in sheets as well as in rolls.
Floor opening (trémie): an opening left in a slab by means of a trimmer frame, to allow vertical circulation such as a staircase or a duct.