Internal door opening from 33" to 66" help with li

[speedwing]

Ok I wish to increase the size of an internal opening to a 4" ground floor wall.
At the moment there is a 4ft steel box lintel across the old opening.
Above this lintel is 4" of block work which is what the floor joists are sitting on.
When I increase the opening size one more joist will need supporting.
I was going to put a 1800mm steel box section joist in but these seem to cost around the £50 mark.
I see that a concrete one will cost me a lot less.
My question is will a concrete lintel be safe to use over this span.

Cheers

Paul

 

[noseall]

if i were you, i would be inclined to use a steel box section for peace of mind and to cut out the consultation costs of a structural engineer.

it may be worth phoning building control to see if they would like a squint at the work too. you never know, they may turn round and tell you that a concrete lintel would be acceptable.