Mild Steel Bar as a Lintel

[wtrap]

Hi, I am extending and renovating a 1930's cavity brick semi detached. I am replacing 4 windows on upper level - 2 of these openings are 1200mm and the other 2 are 1800mm.  The original windows had no lintel on facing bricks and a wooden lintel on inner leaf. 

 

My builder recommends I get mild steel flat bars (primed to prevent rust) for the outer leaf to hold up the single layer of facing bricks that will sit on top of opening and concrete lintels for load bearing inner leaf. The builder doesn't want catnic lintels because their height combined with the position of the eaves will prevent him from laying the facing bricks from the inside of the house. 

 

Is this approach sound? Can I get away with 6mm mild steel flat bars (80 x 6 x 1500mm for 1200mm openings and 80 x 6 x 2100mm for 1800mm openings) or is more strength required (ie. should I get 8mm or angle bars). 

 

For information, my wife insists on the single layer of facing bricks on outer leaf.

 

Thanks. 

[Mr Punter]

Yoiu could get single leaf lintels.  They will be properly designed for given load capacities and shoud be galvanised.

[markc]

Flat bar is pretty useless as a lintel, all it will do is stop bricks slipping. A galvanised angle lintel would work well. 
if laying bricks from inside how would they point up etc?

sort the access and do it right from outside

[wtrap]

Hi Mr Punter, Thanks for your input. My problem is my builder has told me that he doesn't like the commonly used single leaf lintels because of the height of the lip at around 8 to 10 cm for the lowest ones is still too high for him to fit his hand between the eaves and where he lays the facing bricks.

[wtrap]

7 minutes ago, markc said:

Flat bar is pretty useless as a lintel, all it will do is stop bricks slipping. A galvanised angle lintel would work well. 
if laying bricks from inside how would they point up etc?

sort the access and do it right from outside

 

7 minutes ago, markc said:

Flat bar is pretty useless as a lintel, all it will do is stop bricks slipping. A galvanised angle lintel would work well. 
if laying bricks from inside how would they point up etc?

sort the access and do it right from outside

 

1 minute ago, wtrap said:

Hi Mr Punter, Thanks for your input. My problem is my builder has told me that he doesn't like the commonly used single leaf lintels because of the height of the lip at around 8 to 10 cm for the lowest ones is still too high for him to fit his hand between the eaves and where he lays the facing bricks.

 

[wtrap]

Thanks Markc for your response, I will explore option of galvanised angle lintel with a low lip.

[Mr Punter]

Could you lay the bricks on the lintel and neatly point them, wait for them to go off then lift the whole thing into place?

[JohnMo]

Why are you doing building work without proper structural engineering input.  Flat bar will do nothing for you structurally.

 

Primer does not provide rust resistance, it is porous to provide a key to finishing coats.  It will rust in no time at all. 

[George]

Flat bars appear to 'work' to the yeehaw cowboys but it's a utter bodge job. 

 

Get a single leaf lintel, galvanised and designed for the job. It will avoid cracking and issues in future.

 

Mine were all done this way by cowboys years ago. It is extremely low on the list of priorities but when the windows need replacing, proper lintels will be going in. 

[Ajn]

On 12/08/2022 at 10:33, wtrap said:

Can I get away with 6mm mild steel flat bars (80 x 6 x 1500mm for 1200mm openings and 80 x 6 x 2100mm for 1800mm openings)

Such lengths of 6mm flat bar if held at each end will deflect under their own weight. Just look around all the houses of the pre 70's build that had timber windows replaced with pvc or ali. Most have cracking brickwork where the support provided by the wooden frame has been taken away. Yes it is only a triangle of brickwork above the window but still a problem caused by idiots. A bigger question would be if this is being suggested as a fix then what else has he done you don't know about? You also don't say what else is supported above the window.