Approved Document A of the UK Building Regulations deals with the structural elements of construction projects, the masonry, the foundations, the steel, and all other supporting items. Lintels are a major part of any project and so they come in for some clear rules.
Building Regulations are there to ensure that construction projects are stable, able to withstand direct, dead and imposed loads, and not liable to collapse. The transfer of a building’s loadings safely down to the foundations makes a lintel an important part of any project.
Where Do I Need a Lintel?
Any opening in a wall will require the structure above it supported by a lintel. Services entering a building below DPC level will require a supporting lintel to direct the loadings of the structure above, safely to the footings below.
Windows and doors will almost all require a lintel in order to transfer the weight of the structure overhead away from the opening. Some specialist steel doors and windows come with a lintel built into their frames, but are more commonly used in commercial construction projects.
Steel cavity lintels are good over very wide openings and some extra heavy duty lintels can be ordered for openings up to 4.5 metres wide. For openings this big, propping will likely be required before the mortar cures.
Lintel suppliers and manufacturers will be able to advise, but you will need the expertise of a structural engineer or building surveyor to determine the safe rating for the lintel required to span your opening.
Part A Lintel Bearing Compliance.
Section 2C24 of the Part A, Approved Document, page 27, under Loading on Walls, sets out the rule that for all openings up to 1200mm must have a minimum bearing of at least 100mm. Openings that are larger than this will require a bearing each end of at least 150mm.
Where there are significant loadings, a pair of padstones may be required to support either end of a lintel. These are pre-stressed reinforced concrete blocks that are designed to transfer loads safely from a lintel to the rest of the wall below.
What Kind of Lintel Do I Need?
In the UK, most homes built since the early 1900s have been of masonry construction with a cavity wall. To bridge the structural openings for doors and windows, very often, a single cavity wall lintel will be required.
It can be thermally broken, for improved insulating properties, or simply insulated between the inner and outer leaf. A single lintel will have a cavity tray built-in to deflect moisture out of the building, so it is important to install it the right way around.
Separate lintels that support either the inner leaf, or outer skin of masonry, will require a cavity tray built across from one leaf to another, usually in the form of 600mm DPC.
How Much Weight Will a Lintel be Expected to Carry?
The calculations a surveyor or engineer will make depend upon the build up of the structure directly overhead. The best way to visualise it is to imagine that the width of the structural opening that the lintel is to span, is the base of an equilateral triangle (a triangle with three equal sides).
All of the material captured within this shape will have to be borne by the lintel. If there is a window within the triangle, the load will increase as the deflected weight from that window’s lintel will have to be taken into account.
Roof structures such as rafter feet carry the load of the roof down to the top of the wall. Joist ends that sit on the inner leaf of the wall also take the load of the floor, sometimes internal walls, and always the imposed loading of the inhabitants, or users of the building.
What Next?
Building Regulations have a lot to say about structural openings, because there is often a lot to consider. Doing the mathematics can seem daunting, but engaging a structural engineer can save time and money in the long run, ensuring compliance and a successful job.
Whatever you need to know about lintels and the regulations give our team at Wade a call. We are the UK lintel specialists and can help get what you need to your project on time and on budget.
Call our expert lintel supply team today, or fill out our online contact form with your requirements, and find out how fast we can deliver the lintel you need for your repair or project.
