Concrete lintel

[Night Owl]

Hello all, after some advice on a concrete lintel replacement. Single skin non loadbearing wall had a cracked concrete lintel above it.  Have removed old one and looking for best practice on installing new one. Have installed it smooth side down.  Do I bed it on mortar or use slate under the lintel?

 

Thanks

 

 

[George]

Usually bedded into mortar with slate to level if needed. 

[Redbeard]

If it's to a SE's spec, usually on pre-cast concrete 'padstones' too, not just the brick.

[George]

Padstones aren't usually necessary for lintels because the spans are shorter (so the reaction loads are less). Looking at that photo, the bricks appear to be solid and not on a perpend joint so shouldn't be an issue.

[scottishjohn]

6" is minimum you want the ends of your lintel to sit on-more the better 

picture shows that one is not on enough  as its only on half a brick ,which is not 6"

 same goes for others inpicture --not long enough 

 I can,t see how you going to get a full mortar bed above the lintel  as it is  at present as it was never fitted  right to start with --too tight  a hole and you can see bricks have sagged in middle  over time as lintel bent  + bricks above the lintel at left end have joint in wrong place -nearly sraught line down lintel end

 or it was not fitted right way up 

 most have an upside marked on them

 probaly fine .but not correct

 never understand why you would fit short lintels --they not expensive anyway 

 

Edited July 26 by scottishjohn

[Night Owl]

Thanks for the responses.  I think the Lintel failed as it had been cast badly, probably 70 years ago.  Only two bars in it and both next to eack other.  All of the lintels in the property are of this type and set in brick that wouldn't meet current best practice.  In the end I set it on a mortar bed and packed out above with slate before pointing up.  Very little weight, bungalow non load bearing wall.  All of the remaining lintels look solid with no signs of any movement.  S.E didn't raise any concerns.

 

 

[Gus Potter]

1 hour ago, Night Owl said:

Thanks for the responses.

Fair enough. For all on BH when we are dealing with old structures you get a lot of lintels that were known to work compositely with the brickwork above. The lintels can also be timber with some gently arched brickwork... these old builders were clever folk!

 

Over the years you get folk changing windows say and hammering things about, installing ducts for extract fans.. which breaks the composite action.. hence the failures..

 

An easy way of quantifying this is to go to the load tables of modern concrete lintel suppliers. Some lintels are called composite lintels.. which interact with the brick above.. don't go putting in DPC's or cavity trays with these as the plastic make a slip plane which make them ineffective. Some are called non composite which hold everything up above on their own.

 

 

[Night Owl]

Thanks for the info Gus, makes sense.

 

Just for clarity, when I posted earlier that all of the lintels at my property are the same, I didn't mean they had all been cast incorrectly.  Just the one rogue one as far as I can tell! 

 

There are a couple of doorway formed from brick arches which look quite impressive from an old school builders point of view.  I won't post any pictures of them as it could lead this thread down a whole new debate.

 

Thanks again for all the input.