Catnic lintel supported by

[WWilts]

Can a Catnic cavity wall lintel rest on ordinary concrete brick rather than padstone? Or even directly on 7.3N aircrete block without padstone?

Context: 2 storey external wall with an opening at ground floor level.
 

[saveasteading]

8 minutes ago, WWilts said:

Can a Catnic cavity wall lintel rest on ordinary concrete brick rather than padstone?

No. the concentrated load needs to be spread efficiently. 

An ordinary  block is likely to crack and then concentrate the load directly below.

 

Why would you want to not have a padstone? Tell us please.

 

If the geometry has gone wrong then you can make it on site perfectly well, but ask the Engineer to give you new dimensions.

needs high quality concrete,  I would put some reinforcement in it because, why not?

 

You can also buy all sizes of padstone bricks and blocks, and build to suit. Basically it is made from structural concrete without the usual fillers that keep costs down.

 

Assuming someone has designed this for you, ask them for a revised detail if you have to.

 

[WWilts]

56 minutes ago, saveasteading said:

Why would you want to not have a padstone?

Builder has put in ordinary concrete facing brick instead of padstone

[markc]

Not good practice but really depends what load the lintel will be taking and bearing area.

[WWilts]

6 minutes ago, markc said:

depends what load the lintel will be taking

External wall cast stone blocks (2 storeys minus 2.1m tall opening under lintel) plus roof trusses above that. Cambrian slate roof covering (20kg/sqm)

[Moonshine]

you can also use a cut down 140mm concrete lintel, well my SE has told me i can.

[markc]

47 minutes ago, WWilts said:

External wall cast stone blocks (2 storeys minus 2.1m tall opening under lintel) plus roof trusses above that. Cambrian slate roof covering (20kg/sqm)

How wide is the opening? The lintel is going to be carrying a fair load so really should have been on decent pads

[WWilts]

2 minutes ago, markc said:

How wide is the opening?

A little over 1 m

[markc]

2 minutes ago, WWilts said:

A little over 1 m

Ahh, single door will be fine

[WWilts]

1 minute ago, markc said:

single door will be fine

No door. Just an opening in the cavity wall. At this height it is an internal wall. Above the porch roof it turns into an external wall.

 

Question is whether the Catnic lintel (cavity) can rest on not padstone but facing concrete brick (or 7.3N aircrete block). Ample bearing, over 200mm.

[Moonshine]

Just now, WWilts said:

A little over 1 m

 

hold on a minute, i have got my wires crossed, if its just a standard lintel a 7N block will be fine.

 

The catnic will need 150mm bearing at each end

[markc]

Yes no problem on a 7n block with 200 bearing