Concrete Lintel

[alanfrank]

Apologies, originally posted this in Plumbing by mistake.

Hi, i am looking for a bit of advice or guidance from any builders (or possibly even Structural engineers !) regarding a concrete lintel fitted above the original front door of my 1960's Wimpey build property.
The original house had a tiled pitched canopy running the full width of the ground floor of the house which extended about four feet from the first floor elevation. The original door was set back about two feet or so in a covered porch.

I have recently had an additional porch built onto the original wall (see Pic1) and in an attempt to open up the hallway I was hoping to use the porch door as my main front entrance door and take out the wall incorporating the original door and small window. I knocked off all of the pebble dash and render to expose the brickwork and saw that there was a concrete lintel which spans the entire porch area (see further pics). On checking I saw that the lintel only sits on the outer skin of brickwork by about 3 or 4 inches either side. The lintel measures about 90 " (2300 mm) in length, about 12" (300 mm) deep and 7" (180mm) high. An elderly neighbour who has lived in a similar house since it was built thinks the lintel may have been made by concrete poured in situ but I cannot confirm this.
My main issue is whether the lintel will support itself if I remove the door frame and brickwork underneath. There is nothing of any significance above the lintel just a couple of the now defunct roof joists, all of the tiles having been removed so there is no real weight on the lintel. I am more concerned that the lintel may split and collapse if I remove the brickwork underneath.
Can anybody assist ? Thanks in anticipation.[

Read more: //www.diynot.com/forums/plumbing/concrete-lintel.407933/#ixzz388YBpYOJ

 

[tony1851]

There is no way of knowing whether or not the lintel could span the whole gap, without knowing the size and position of the reinforcing steel.

If it is an insitu lintel, bear in mind that any rebar would likely be minimal because the original builders would have allowed for the centre support.

To take that out would in any case be a difficult job - you really need to speak with an SE before contemplating that.

 

[alanfrank]

Thanks for your reply Tony. Sorry I'm a bit confused now. When you refer to the reinforcing steel what do you mean? The lintel seems to be concrete only, I haven't, and was hoping not to have to. replace it with an rsj. As I said there is no real weight above the lintel my concern was that the lintel would collapse under its own weight if I remove the brick pillars. Does that make sense? regards Alan

 

[tony1851]

Concrete lintels are almost invariably reinforced with steel bars, otherwise the plain concrete would crack due to the tensile stress developed.

Your lintel may not be supporting much weight (apparently), but the lintel itself will weigh about a quarter of a ton. A concrete beam of unknown reinforcement supporting that load + whatever else, spanning that distance, is not an ideal situation.

 

[alanfrank]

Ok now I understand thanks. Are you aware of what options would be available to me? Are we talking removal of the concrete lintel or someway of reinforcing it, maybe by a nib at each side. Any ideas mate?

 

[tony1851]

Sorry, but the only risk-free approach is to replace the beam with a steel beam - simple as that, unfortunately.

 

[alanfrank]

Tony, thanks for your advice. If I'm honest I sort of suspected that might be the case but hoped it wouldn't be. Cheers