Cracks in lintel above front door

[ns33]

Hi.

I own a 1960s ex-council house. Lived here 15 years.
Cracks in plaster is common in my house, most of it hairline cracks.

However the cracks above the front door frame were causing the paint to peel, with some powdery deposits indicating water ingress. I decided to remove some of the plaster to see whats going on. Most of the render sounds like its blown, as it makes a hollow sound when knocked.

Whats bothering me is a crack running along the lintel, when looked at from beneath.

Time for a structural engineer?

 

[tony1851]

Yes the lintel has failed, caused by expansion rusting of the steel reinforcement. Water has obviously been getting in somewhere. In the 1960s, they generally didn't bother too much about cavity trays above lintels.
Ultimately it would need to be replaced by a couple of steel beams running parallel (one under each skin). But I don't envy anyone who has to get that beast out first!

 

[ns33]

Thanks Tony. Is this the kind of thing I can keep an eye on for movement or will it need replacing ASAP? Not expecting a "concrete answer"...

I checked outside and there is no other signs of movement. There are a few small gaps where the outside portion of the lintel meets the outside wall. I could fill those to see if it stops the water ingress.

 

[stuart45]

Is it a boot lintel?

 

[ns33]

Hi,

I have one of these on the outside...

So I dont think it is?

 

[Ivor Windybottom]

Is that all one piece of concrete? If so then the outside is cantilevered from the lintel.

Is it a cavity or solid wall?

Is the top of the concrete waterproofed in any way?

Are there any brown stains or puffed up parts on top or below?

Have any been removed from neighbouring houses, especially any that are still council or housing association?

Worst case, which looks fairly likely from here, is you may need to remove the whole thing and replace the lintel.

 

[stuart45]

They were either cast insitu or precast in one piece reinforced concrete. As stated above, it's cantilevered from the wall. Quite common on the council houses back then.
The canopies have been known to suddenly collapse.

 

[Ivor Windybottom]

The canopies have been known to suddenly collapse.

That's what I was thinking. Looking where the crack is, it's lost its cantilever against the weight of the inner wall on top of it. The outer wall is just a pivot point.

Not meaning to sound alarmist, that could well be fatal if it goes just as you slam the door shut from outside.