Advice on steel or concrete lintel

[robbie77]

Hi,

I have a 1890 built 3 bed detached Victorian house. It has had has had a small extension for a kitchen around 30 years ago or so. The extension has a flat roof and the rest of the house is a slate roof (brick house).

I want to extend the kitchen by opening out the connecting room that is part of the original house. I want to take 3m out of a 4 m wall (chimney stack to be left).

The kitchen door goes through the old outside double cavity wall, this doorway will be extended to create the 3m space.

Do I need 2 steel lintels or 2 concrete? Obviously concrete is cheaper and easier to fit but the building structure is obviously very important.

Please excuse ignorance I am learning as I go...

All ideas and advice gratefully received!

 

[noseall]

It is highly unlikely that a concrete lintel will suffice for a 3m opening.

It may even be that the lintel arrangement needs a squint from an s.e.

Is this being looked at by building control?

 

[Chukka63]

concrete would have to be shuttered and poured in-situ i fear and SE approved.You should be able to get a catnic or similar for that length but BC may want to see calcs in which case you can call catnic techincal( or other manufacturers) for these.ive done similar with these spans and longer with no probs.

 

[robbie77]

Thanks for the replies, it's what I suspected really.
I will look into getting a catnic then. Will they be placed on either cavity wall and then bricked over?

I haven't arranged for building control to come out yet, I was going to peel off the plaster and assess the job first.

I guess its a must for a job like this?

 

[robbie77]

I can see from a bit of research that the catnic's have a plaster key so they sound like a good alternative.

Can someone advise on Arco props for this situation?

Thanks

 

[noseall]

A single needle may be adequate for a 3m opening.

Do the joists sit on the inner leaf?

 

[Chukka63]

try and use a strongboy,less destructive

 

[robbie77]

A single needle may be adequate for a 3m opening.

Do the joists sit on the inner leaf?

Right I've been back up to the house and got my measurement confused with the plans I drew so the actual length needed is 2.4m which will allow the brick and a half overhang at both ends.

I'm still thinking of going for the catnics ?

I knocked the plaster off the wall and above the doorway there is a wooden lintel which I was surprised to see especially as it was covered in plasterboard!

The extended kitchen has a flat roof, the roof timbers seem to be attached with a batten of wood along the top of the wall (original outside wall)

Thanks again...

 

[noseall]

I agree with proprietary Catnic type lintels - less weight and less fuss.

You may even be able to glean a bit of structural information regards loading, from the Catnic techno' division.

 

[robbie77]

I agree with proprietary Catnic type lintels - less weight and less fuss.

You may even be able to glean a bit of structural information regards loading, from the Catnic techno' division.

Do you think I will need a box section type lintel, will this be ok for an original outside wall? Will I need one for each side of the cavity (Victorian brick)?

Or even a link to a product as there seem to be a few different types!

Thanks

 

[robbie77]

Untitled

• robbie77
• 2 Dec 2009
• 1

here is a pic of the wall

 

[noseall]

You will need a pair of lintels which ever way to tackle it.

As i said previously, you will need to speak to an s.e.

The layout of your house, i.e. joist arrangement, roof arrangement, how the masonry naturally 'arches', point loads etc will all need to be assessed by someone in the know.

3m span isn't a hill o beans but still requires some thought.

 

[Chukka63]

as noseall said and i usually use 2 box lintels and let the plasterer plasterboard underneath

thats assuming RSJ's etc havent been requested by an engineer etc

 

[robbie77]

I've had a small set back as the lintels were sb100 (rated to 20 KN) instead of SB100 HD (rated to 40KN). I am collecting them tomorrow and reckon they are up to the job.

The brick where the lintels will sit either end has been removed and is level.
I was going to put a big wodge of cement on the supporting bricks either end and jack the lintel up (both ends) against the top brick. Does this sound right?
Any tips?

 

[Chukka63]

yep sounds good.i normally just acrow the lintel uo tight but dry and then dry pack anywhere the lintel doesnt touch the brickwork and then also dry pack under the lintel ends.this way i dont have to wait till anything goes off/setts and can get on with the next one.