Lintel end bearing

The planning portal link was useful, it's given me a better idea of how the building notice works, thanks.

Basically yes, you need to be confident that what you do will meet the regs

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A good few years ago I lived down Milton Keynes & extended my house with a single storey living room extension on the side. I did all the work myself, apart from the brickwork & initially only had one problem, the lintels.
I submitted plans for approval which showed a large chunk of the gable end removed & a lintel in place. The bco rejected the plans & asked for calculations to show the lintel was up to the job. I sent a copy of the plan to catnic & they sent back a sheet of gobbledygook figures & told me I needed two lintels, (one for each leaf of the cavity wall.)
That is what I am worried about with this work, I might install a lintel then the inspector says it isn't substantial enough. I want to use a concrete lintel but have had conflicting info from different manufacturer sites.
Naylor's site shows a 145 x 100 is enough (going off shytalkz 5kn figure) but another site recommends a 215 high lintel. I'd rather use one 145 high, for the weight of putting it up & appearance, but I might go for the 215 high to play safer.

If you really want to be 100% sure get Naylor to do a calc for you.

freddymercurystwin said:

If you really want to be 100% sure get Naylor to do a calc for you.

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I've done that, cheers. I read somewhere though, that lintel manufacturers don't like giving calcs incase the job goes t*ts up & they are liable.
I emailed a drawing & the info I have, so hopefully they will get back to me. I say hopefully because I sent the same email yesterday & it came back today with a mailbox error. I've found another email addy for Naylor so maybe this one will get through.

Hi again.
Naylor couldn't help me, so I contacted Birtley & they were very helpful.
I sent them a drawing of the downstairs, one of the upstairs & all relevant information I had.
I never mentioned when I started this thread that there is a block built wall upstairs, which sits on two joists screwed together.
I also found the joists were! in two parts, overlapped & resting on the wall I wanted to demolish
These joists with the wall sitting on them will be resting on the lintel & create a point load 500mm from the 100mm bearing end of the lintel.

They have sent me the calcs below but I'm not sure about a couple of things.
Why does it say 2550 clear span & then 2700 effective span. The 2550 is obviously the opening in the wall, but where does the 2700 come from?
Also at the bottom it says lintel 2850 with 150 bearing.
Does that mean 150 at both ends, because I had said that I wanted 100mm bearing at the right side, but 150 will be ok if 100 not possible.
Has the point load from the block wall stopped me from having the 100mm end bearing & maybe the overlapped joists sitting on the wall?

Also I'm thinking of using a RSJ (H beam) if it can be smaller in height than the Birtley lintel. Can anybody tell me what would be a suitable beam going off the loading figures below?
Thanks for any help, sorry to drag this on


Birtley supergalv calculations

2550 clear span 2700 effective span.

Floor load 2.700 x 2.500 x 2.1 KnM2 = 14.18 kn

Point load from block wall built off joists-
2.032 x 2.700 x 1.5-km2 = 8.23 kn

Point load is aprox 500 from end of lintel
equivalent u.d.l (Bs5977 part-1:198)

We = K+W = 1.280 x 8.23-kn = 10.53 kn
_______
24.71 kn

Bending moment = 24.71 x 2.70 = 8.34 knM
____________
8

End reaction R1 = 14.18 + 8.23 x 0.8 = 13.67 kn
____
2

End reaction R2 = 14.18 + 8.23 x 0.2 = 8.74 kn
_____
2

Proposed lintel = SB100-HD 2850 long
Moment of resistance = 22.40KnM
Web buckling at support-
with 150 end bearing = 31.70 Kn

Lintel Satisfactory
___________________________________________

Below is the sketch of downstairs I sent Birtley, with the upstairs walls shown in red.



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They've obvioulsy missed/ignored your point about 100mm bearing at one end. When designing a beam like this the clear span is 'what it says on the box' but the effective length (that you use in your design) is the distance between the centre of each end bearing. They've assumed 150mm bearing each end so effetive length = clear span + 2 x 1/2 bearing = 2700. In effect, they're actually being conservative in their design as in your case the effective length would be 2550 + (1/2 x 100) + (1/2 x 150) = 2675.

As they're only trying to sell you the lintel they won't be pushed into discussing bearings reduced from the standard 150mm as they know nothing about the wall it's to rest on. Reducing it to 100mm won't cause you any problems though, you're not really supporting too much. Any BCO worth their salt should realise this.

Ok Ossy, thanks for that explanation. I've often seen the words "effective length" mentioned but never knew what it meant.
I think now I'll just leave the extra 50mm of wall sticking into the room, or if the bco visits before I start i'll have a word with him about it.

Now that I know the loading that will be on the lintel, does anybody know how I can work out what RSJ I could use? Is there a manufacturers website( like catnic or birtley) where I can select a beam that is the equivilant of the birtley lintel. I'll almost certainly now use the birtley lintel (they are a company local to me) but would prefer to use something that isn't as high in profile as the SB100-HD.

152x89UB16 based on the above figures

That's great Shytalkz.
The 152mm height of that beam will be less imposing than the 215mm of the Birtley lintel.
Thanks again for everybodies help, I've learned a lot from this forum.