Question for the builders (building regs)

[Stu R]

Morning all.

We're looking at knocking through the kitchen into the dining room very soon. It's a supporting wall that's getting demolished so we'll be putting an RSJ / Catnic steel lintel in it's place.

Some back of a fag-packet maths tells us we need 150mm support at either end of the beam.
One end of the beam is the external wall, brick exterior breeze blocks behind type affair.

My question is whether it's permissable / sensible to knock a breeze block out at the external wall end for the beam to be fixed into or will we have to build the vertical supports inboard of this?

Hope that makes sense, any advice appreciated

[rsv gone!]

You'll need a pier as you'll only (likely) be able to achieve 100 bearing in one skin of the cavity wall. (Maybe 140, but I still wouldn't want to rely on it).

Edited by rsv gone! on Sunday 1st March 07:38

[Stu R]

The plan was to use the 100mm or so of breeze block and build up the remaining 50mm. Just want to be sure we can use the existing breeze block rather than having to build the whole 150mm, gather it's allowed then?

[rsv gone!]

You'd end up with 50mm butted up against the external wall, which I don't think the building inspector would allow.

[Autonotiv]

you will most proberly need a pier, with a padstone on top etc etc.

A structural engineer will do all the calcs and say what bearing you need, it will depend alot on what the load on the beam is.

[ALawson]

Load on beam will determine the reaction at the end, how wide is the internal wall as your lintel will be the same width as this more or less. This combined with the block width on the external skin will give your bearing area.

Simple cal will determine the stress in the blockwork.

As a has been said above either get an SE to do the maths and detail drawing for it, keeps your home insurer happy!

[Stu R]

The maths etc isn't a problem (haven't done them yet admittedly, we only decided to go ahead yesterday). Both myself and my old man know all about beams, but we're engineers not builders hence the questions, apologies for the simpleton nature of them but I'm crap at explaining without making little sketches

I'd hoped we could avoid having the entire 150mm pillar protruding into the room by using the existing breeze block on the external wall end of the room, no big deal that we can't.
Catnic say 150mm support of the beam is required. The load won't be too high, but we'll just build 150mm of pillar and padstone it if we can't use the block that is already there as has been suggested.

Cheers for the replies

Stu

[mrmaggit]

Get a Structural Engineer in. He's paid to get it right, and have insurance in case it doesn't!

He'll also advise on what needs doing, and will provide a drawing & calculations for your builder.