Concrete Lintel vs Steel I shaped RSJ

1 Oct 2013
Reaction score
United Kingdom
I'm considering knocking a 1.5m wide opening in an internal 4.5" brick wall between the kitchen & dining room.

The wall continues upwards dividing the bedroom & bathroom and into the roof-space level with the bedroom / bathroom ceiling joists..... with the exception of a few bricks 6 courses high that support a horizontal roof truss (presumably this is defined as a supporting wall). The house is a semi with a pyramid shaped roof.

Do I need to a steel I section RSJ or a steel reinforced concrete lintel?
Sponsored Links
The ones available from Wickes are 100mm wide x 65 thick x 1800 long. Would that be adequate or should I 'double deck' a pair of them?

While removing some plaster elsewhere in the house I see that the 'over door' lintels are really substantial (at least 6" thick). The house is 1938 built.

thanks for your advice
If your floor joists above go into that wall the lintel you are thinking of would be on the lightweight side. What you need is the 140 high x 100 wide x 1800 long version. For that span on the ground floor I would not use less.
Sponsored Links
A 65 deep r/c lintel will be too shallow for that span and loading - go for the 140 deep.
I'm very surprised you can even get an 1800mm that is only 65mm, can't think of any application where that would be suitable, get the 140mmx100mm
You can get them to at least 2700mm. I've never heard of one break yet,
but I'd use a 140 deep one myself :) or a box-section Catnic.
Thanks for all your help guys.

Now I have a secondary question.... is there a minimum requirement for headroom (floor to finished underside of lintel)?
No there isn't but you would be wise to get it at least 2m up to allow the option of fitting a door frame/doors later if you wanted to.
thanks for that - was going to make it around 2m in keeping with the adjacent doorway.
Hello again guys. I got the lintel today and lifted it in place (dry run).

Does it need sit on bed of mortar at the supported ends or just on bare brickwork?

With the lintel resting on bare brick the gap above the lintel is 45mm (or about 35mm if I bed the ends on mortar).

Do I 'wedge' the gap with brick & slate or just fill it with mortar or concrete / pea shingle mix?

I can easily raise / lower for bedding using a couple of car scissor jacks
might be better to smear mortar right along the top, jack it up so it squeezes out a little all along, and then pack up under the bearings - use slate bedded in mortar,

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Sponsored Links