Lintel what way up??

[BegBorrowSteal]

Hi Guys I have a pre stressed lintel to go above a window but for the life of me can’t figure out what way round it goes it’s a trapezoid shape 4in x 5.5in x 6in with two steels running through the middle and no stamp to say top also it’s going on top off a 100mm block, cheers

 

[JBR]

On the grounds that the top of the lintel will be subject to compression (in which concrete is strong), and the bottom will be subject to tension (which concrete can't handle), the steel rods should be at the bottom as they are much stronger in tension.
How you can tell where the steel rods are, I don't know.

 

[BegBorrowSteal]

Oh that’s easy they are coming out each end I’ll have to trim them off I’ve been reading the lintel should go rough side up for the mortar to get a proper key

 

[^woody^]

It's very rare nowadays to find a concrete lintel with the steel placed below centre and a top and bottom. Likewise for pre-stressed, which will be cambered.

If its tapered in section, put the thinner edge at the top.

 

[BegBorrowSteal]

Here's a photo of the lintels if it helps