With the vast array of lintels on the market, it can be tricky to know how you select the correct lintel for the correct application. It is a scary thought when you consider that choosing an incorrect lintel could result in not adhering to building regulations, excessive cost increases, and in the worst case – structural failure.
This is why, here at Stressline, we believe it is essential for those handling housing construction to be armed with the knowledge to select the right lintel…. So without any further ado…
Step 1 – Establish the construction material
The first step is to consider the wall construction, as this will have a huge bearing on the type of lintel you will require. The image below shows 3D images of two types of lintel; very different because of the wall construction.
You will also need to establish the floor and roof construction as these will impact on the load and thus the correct lintel for the construction.
Step 2 – Determine the opening width and cavity width
The opening width obviously impacts the length of lintel you will require and the wider the opening, the more consideration will be needed for the type of lintel.
Top Tip:A rolled steel lintel is often required for widths of 3.6m and above.
The lintel length will have to be 300mm wider than the opening to allow a 150mm bearing on both sides of the opening. At widths of less than a metre, a bearing of 100mm would be required on each side.
Step 3 – Calculate the load incorporating triangulation
Triangulation is a structural engineering term, and in the case of lintel selection, is used to establish the load of masonry. Triangulation in its simplest term is achieved if the opening has a clear 600mm of brickwork both sides and no other obstructions (e.g. a higher floor window) within the ‘triangle’ frame.
The load to be calculated as well as the brickwork also includes the inner brickwork, floor loads, roof loads and any other load being applied to the opening (e.g. a stair trimmer point load)
For more information on understanding triangulation, sign up to our newsletter. We have a monthly newsletter with product tips, advice and best practice tips for builders, engineers and specifiers. You can also have a look at our blog post on lintel specification tips for further information.
Step 4 – Interpret the load span tables and ratios
Understanding load span tables and lintel load span calculations is the crux of selecting the correct lintel. Once you know what the figures mean, it is fairly straightforward to apply all the other information to the load span tables.
Load ratios are also important to understand but basically if the load ratio is 5:1 then you allocate 5 times the SWL to the inner leaf over the outer leaf, for example:
This means the load distribution on this lintel would be 65.8kN on the inner leaf and 13.2kN on the outer leaf
We have much more information available on this in our newsletter tips and tricks, but it would also be worth reading our blog post on a beginner’s guide to load span tables.
Step 5 – Selecting the correct lintel
Once you have established the construction material and load and identified the type of lintel you need, you can use this knowledge to select the correct lintel.
Top Tip:For rendered properties, concrete lintels are the ideal solution because of the bond to concrete.
One thing that builders often overlook is the lintel material. There are many obvious benefits of using steel lintels instead of concrete, but concrete lintels do have their uses. Check out our blog post on 7 reasons to specify concrete lintels.
For more information on lintel selection or help with lintel specification, feel free to contact our technical department on firstname.lastname@example.org.