Reinforcing opening in supporting wall - who is right?

[Mara]

Hi, what reinforcing method should be used to bridge a 5.5 ft wide 4.5 ft high opening through a ground floor, concrete block, load-bearing wall in a 2 storey building which has a concrete ceiling/floor between the two levels? Our current builder has installed a reinforced concrete lintel turned on its side with approximately 6 inches of lintel beyond the opening on either side, but another builder has just told us that this is not sufficient support and should be replaced as it is potentially dangerous. Who do we believe?? and if this is wrong, what is best to use for the job?? Thanks in advance Mara

[Phil]

If you ask a builder, then some used egg-boxes might suffice.

[Roger]

The message from "Mara" contains these words:

If it is a proprietary lintel it should be up to the job if used properly but turning it on its side suggests it hasn't been used properly.

No doubt these days there are guidelines that I am not familiar with but I wouldn't have thought that a 6 inch long seat was any cause for alarm.

Is your builder working from plans already agreed with the local BCO or is he working under a building notice? Either way the BCO has the final say.

[Mara]

PS, the wall is 3 inches wide, and the building was put up in the

1960s......

[Lobster]

That was my thought too. Building control should certainly have been involved in a job like this, and should have approved this; both the lintel selection and the manner in which the work was done - sounds to me like this hasn't happened?

The BCO might demand to see calculations to back up the choice of lintel, which if it was me, would mean I would be hotfooting it to a structural engineer.

David

[Homer2911]

Using what? Leggo?

[Owain]

Hey, some of the stuff I built with Lego 20 years ago is still standing.

(I wonder what the U-value is of a Lego wall)

Owain

[somebody]

In message , Mara writes

A reinforced concrete lintel will typically have a proper orientation. (ie "this way up"). The structure of the reinforcing requires it. Basically the steels in the bottom of the beam are under tension while the concrete at the top of the beam is under compression.

Turning the lintel on its side would result in little or no reinforcing of the concrete.

Have a look here, about half way down, left hand side, for a sketch.

Hth Someone

[Chris Bacon]

Many *pre-stressed* (one brick deep) lintels have pieces of wire rope running through them in the middle - these should bear more load "on edge".

[Rick]

The lintel should not be on its side.

The ends should be 150mm (or more) on the old wall, ahd have a concrete pad stone - this otem means concrete bricks, of 7N blocks.

As to the strength, only a strutrial engineer can tell you for sure.

You have got the BCO involved in this have you ?

Rick