Lintel above fire door

[frank999]

I am replacing an old timber kitchen door on a 1930's semi with a new Fire door (1981x762mm).

The chippy has ripped out the old lining - and most worryingly the 2x3" timber lintel above it (stating he needed the extra head room, and advised the lintel is not necessary).
I estimate 4-5 courses of brick (500mm of masonry - could even be early aerated blocks) were supported by this lintel.
The bathroom joists above, are supported by its own trimmer and do not bear on the above masonry.

From a BC perspective this door lining must need some form of lintel above it, even if to support only 500mm of masonry.

I have insisted this lintel be reinstated with at least something, and so to give him the head room he needs a 1&1/2" x 2&1/2" timber lintel has been used to replace the old 2x3" ...

Rather than go hack away 'hanging' brick work (to get more head room and refit a 2x3), I feel a lesser - but still substantial peice of timber is the least problematic way to go about this, but am I the right side of BC on this ?

 

[^woody^]

The plasterboard you put on this timber lintel will last longer than the door and frame below it on a fire.

 

[frank999]

Yes agree, but I'm more concerned about the Structural aspect than the Fire aspect, do span tables go down to such sizes of timber.

Regarding the Fire Aspect though - fortunately there is enough flat area on top of the timber lintel to nail some EML and plaster up to 15mm each side.

I assume 15mm of plaster will give the same fire protection as 12.5mm plaster baord.

 

[^woody^]

If it had a 3x2 timber in before, then that should give an idea as to whether the same thing can go back in

 

[frank999]

Thanks - good point, its a 1 1/2" timber (as opposed to a 2" before), not sure if its CLS or C16/24.

Just made a rough calculation, it has approx 25 bricks sitting above it, @ 2.5 kg's each = 62.5 kg + Mortar (70kg x 0.44 sq mt) = 30.8 kg ... TOTAL WEIGHT 93.3kg. ! (not including plaster, assume 10kg)

To look at it you wouldn't think 100kilo's sat above that door frame.

The above timber then has the 30mm Fire Door Lining screwed firmly to it to provide additional support.

 

[Gerrydelasel]

Presumably that bit of wall is tied into other walls though (?) and might even stay up by itself, completely unsupported. In other words the lintel isn't really supporting 100kg.

 

[noseall]

How much weight would you say this lintel is supporting........

Untitled

• noseall
• 12 Jun 2015
• 1

Untitled

• noseall
• 12 Jun 2015
• 1

 

[frank999]

Yes, when the lintel was removed, the wall didn't fall down and was self supporting, as above - excellent example, is that a Strongboy poking through in pic 2?).

I understand loads transfer diagonally down a wall, and (depending on mortar integrity) like a bridge with a keystone (the very middle part, not including parapets) - the same would apply (to some extent) to an unsupported load like the above - the compressive forces would act to push the bricks together at the top, with the coursing of bricks also providing additional restraint ...

 

[noseall]

Yes, when the lintel was removed, the wall didn't fall down and was self supporting, as above - excellent example, is that a Strongboy poking through in pic 2?).

No, it's a piece of packing slate.

 

[frank999]

Did the two header bricks in that Flemish Course fall out and require the slate packing to help when remortaring - I presume the slate packers are removed when its job done ...

 

[noseall]

Yeah, the bricks de-bonded from the mortar easily. The slate packers were hammered home once the mortar had hardened.

 

[frank999]

Thanks for the pics, said it all.
So the slate packers stayed in and you mortared over them once hammered home.

Do you judge each job differently as to whether to support with strongboys or not (ie how wide do you work unsupported), and is dependent on what forces are coming down the wall from above.

 

[tony1851]

As on Nosey's pics, the brickwork may well stay in position (and if it moved, the door frame would easily support it). The very worst case would be that the beam supports only a triangular area of brickwork, due to the 'arching' effect of brickwork.

BTW, I get a fright everytime I see your avatar! - I think I'm going to be attacked!! can't you change it - perhaps have a self-portrait, like mine?

 

[freddiemercurystwin]

BTW, I get a fright everytime I see your avatar! - I think I'm going to be attacked!!

I'm surprised tony, I'd have thought you'd feel right at home with characters like that?

 

[frank999]

Umm, in a diagonal line through the brick work, would this apply to any block work.

The characters actually a very humourous chap ...