Retro fitting lintel to cavity wall

11 Apr 2006
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United Kingdom
I'm toying with the idea of widening my front door opening so that the new lobby feels less like it used to have a door in the middle.

This would mean removing the two 150mm piers on either side. I'm guessing the existing lintel won't have, say, 250mm overlaps into the walls, so I'll need to fit new, wider ones.

Am I better off trying to get a Catnic type steel cavity lintel in there, with it's massive bulge in the middle, or should I fit two steel box lintels that are only 75mm high so less of an issue?


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It's an old exterior wall that will now become an internal wall. So you'd put the concrete on the outer leaf, and catnic box lintel on the inner?

Its a cavity wall presumably? and though this was an outer wall, it is to become an internal wall? If so a concrete lintel under each skin of masonry will be fine. The chances that the original builder used oversized lintels is smaller than joe-90's brain, you will have to replace them.
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Yes - it's an exterior cavity wall that will become an internal wall, so no particular insulation requirement.

The house is around 1930's, brick, with polystyrene ball insulation. Ex local authority. I've no idea how well they overspec'd the lintels in those days!

Right so you plan an extension etc that means your old entance door is redundant and the wall above it is completely water proof or a cavity tray is being installed.

In that case (unless the wall over has been removed and no roof load is coming down) the wall will be load bearing and a suitably sized lintel needs to pick up both leafs. But it doesnt need to be a tophat lintel and can be 2 concrete or steel box lintels. The depth will depend on the load on the wall from above.
Agree with the above posts, two concrete lintels will do, the spec will depend on the load being carried. As it's an extension I guess BC are being informed and they are likely to ask for calcs on the load and a suitable lintel to carry that, they usually go well over top, belt and braces.
So you may need a structural engineer to give you the correct spec.
Cheers guys, I'll take some plaster off to see what's there now and then see what BC say.


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