rsj / lintel - what size?

27 May 2011
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United Kingdom
Im looking to remove 2 internal doorways from kitchen to utility and open up.
the house is a bungalow. internal wall is in effect the external house wall leading to what used to be an outside tool shed which we have changed to get internal accessed utility room.
this involves removing 70cm length brick wall (double skin, cavity) creating an opening of approx 2.2m. the room dimension is 4m. At either end of this opening are existing brick walls, approx 90cm each end.

so - do i use rsj, or concrete lintel.
how long / what dimensions should it be.
are there any other factors i need to consider.

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If it's a structural supporting wall, the best advice is employ a structural engineer and get calculation from them. You will need them anyway to satisfy building controls that it's structurally safe & sound.
As far as I understand it Concrete lintels are used for load bearing single skin internal walls, and 'Catnic' style lintels for Cavity walls.

I made a new opening in an existing wall last year and installed a 'Heavy Duty Lintel'.

I looked at the Catnic website for info and options, then rang the Catnic technical helpline and spoke to a guy that asked a few questions, and ended up saying that a Heavy Duty one would be required, because of the possible load from above.

I then got an equivalent lintel from my local Buildes merchant - Not a Catnic after all that, but an equivalent (and cheaper) one from a different manufacturer.

The new lintel will need to bear on 150mm of solid brickwork at either end, so the overall length will have to be at least 300mm longer than the overall opening.
As for load calculations.

The building control officer was happy with a Heavy Duty Lintel, becasue it was probably over specified.

From my point of view, it was cheaper to buy it over specified, than it was to get the calculations done and then buy the right size one.

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As it is an external wall to an extension then a standard lintel probably wouldnt be sufficient.. all depends on the spans of the roof loading the wall.. you can go down the route of phoning a lintel manufacturers tech dept.. they sometimes can be helpful..

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