'normal load' of end terraced req for lintel

[fabgav]

Can anyone advise please.
As an educated guess, what would the load be of this house for a lintel spanning 2700mm at the bottom right starting at white door moving inwards.
House is 1930, 50mm cavity, inner skin is light coloured grey brick (almost sandy) (not breeze)
Room is as pictured.

The reason I ask is the 2 options of catnic i'm looking at 1 being standard duty the other being heavy duty with ratings of
SWL (kN) 1:1/3:1 26 for standard
SWL (kN) 1:1/19:1 45 for heavy duty

done

• fabgav
• 13 May 2012
• 2

Roof

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• fabgav
• 30 Mar 2010
• 3

Many thanks

 

[tony1851]

brick/block cavity walls are usually about 5kN/m2.

for floors, allow 2kN/m2 for the combined dead/live load. (how much of the floor rests on the lintel you will put in depends on the span of the joists - measure to half-way across the room)

for the roof, allow about 1.6kN/m2 (live plus dead loads). Only a small portion of the roof will actually be resting on the wall - it will be approimately the area from the eaves up to half-way up to the purlin. Most of the roof load will be on the purlins

the bedroom ceiling will also rest on that wall - allow about 0.4kN/m2.

also allow for any 1st floor partition which may be supported off the wall.

Probably the heavier load will be on the inner skin, particularly if the floor spans on to the wall.
As a very,very rough guess, I would think you are looking at about 15- 20 kN/m run.

 

[Geps]

A job of this size must be passed through BC and they'll want to see a Structural Engineer's calculations - you're going to have to hire one so you may as well do it now and get their advice.

 

[tony1851]

they'll want to see a Structural Engineer's calculations - you're going to have to hire one

If his opening widths are less than 3m, and the wall in other respects complies with the diagram on p27 of AD A, he will not need an SE. He will have to work out the loads (but that is fairly straightforward) and catnic supply safe loads for their lintels.

 

[Geps]

Not in this area (Birmingham)...I installed a 2.5m span Catnic two weeks ago to replace a single skin interior wall and was asked for calculations from a SE.

 

[tony1851]

Your local council was wrong to insist on an SE doing the calcs, and you should have asked them on what grounds they required that.

It is not a statutory requirement that structural calculations are done by an SE, though a number of posters have said that their LA has asked for figures from an SE.

Building Regs apply nationally and can not be altered by some assumed local policy; if a LA requires calcs, their job is to check them, not to dictate who does them. In the forthcoming review of the Building Regulations, there may be a stipuation that only an SE can supply structural calcs, but that does not apply at the moment.

 

[theoldun]

As a very,very rough guess, I would think you are looking at about 15- 20 kN/m run.

As a rough guess that figure is plenty near enough. From top of ground floor frame to top of ridge, with out knowing dimensions we would have said the UDL including all imposed loads and snow load to be approx 17.50KN/m run.

QUOTE.
SWL (kN) 1:1/3:1 26 for standard
SWL (kN) 1:1/19:1 45 for heavy duty

Will explain this in a little more detail for you.
1;1 means masonry on both inner and outer skins.
3;1 means masonry on both skins and timber joist first floor on inner skin
5;1 means as above but concrete first floor on inner skin.
19;1 can also mean as above or any extreme heavy loading on inner skin.
Regards oldun

 

[fabgav]

Many thanks to all helpful replies.

I am finding it hard to find a SE who actually deals with private house rather than commercial, is there a register anywhere?

 

[fabgav]

Sorry to drag up an old thread.

Having found a SE to do some calcs for me they seem to be very different to the 2 'rough' guesses on here.

He is quoting 46 kN/m and that the panel to the left of new door will be to weak for the wind and I will need a steel prop on the back of the wall and hold the joist above!

It seems way off the estimates provided here.
And yes I know thing are very different from info I provide to someone actually coming and looking.

I have a pdf with a lot of info that I don't fully understand.
I have grabbed a couple of screens of the hand written part.

Could anyone shed some light on this please and advise?

Many thanks in advanced

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• fabgav
• 11 Jun 2012
• 1

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• fabgav
• 11 Jun 2012
• 1

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• fabgav
• 11 Jun 2012
• 1

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• fabgav
• 11 Jun 2012
• 1

 

[^woody^]

Your SE has included a floor load, live loads and factors of safety - which were not mentioned in previous posts.

His figures do seem a very slight bit higher than I use for floor and roof, but not much

Typically for a 3m load in similar situations, it will be just over 40kN/m, so his 44kN (kN/m?) figure is about right

I can't understand the need for a wind post though. Is he being over cautious? I don't know

 

[tony1851]

Hi fabgav.
The figure the SE has given you is not 46kN/m but 46kN over the 2.4m span, which equates to just over 19kN/m. This accords with the rough figures you were given previously. Remember that your SE is in a position to know the lengths of floor/roof/ceiling bearing on the wall; we are not. Also, these things are not an exact science; for example, his choice of dead load for the roof is a little higher than I would use, but that is splitting hairs.

(Woody mentioned 'factored' loads; these are included when designing steel beams and are a way of ensuring an adequate safety margin. It's not clear without seeing all the calcs if your SE has done this. However, when working out the loads for Catnic lintels, Catnic state that the loads are already factored, so you just work out the actual loads without needing to 'factor' them up).

What concerns me just a little is what Woody has also mentioned, and that is the need for a steel post. Your SE has included this because of the narrow bit of brickwork to the right of the existing door. This will be subject to wind load on the side wall and, in theory could crack at mid-height due to the lateral wind pressure. In practice, I very much doubt it would. This bit of brickwork will be subject to considerable dead load from the wall above, which will induce compression into the lower brickwork and reduce the tendency for it to crack under tension. IMO, it should be possible to prove that the brrick pier would be OK without the need for a steel post further along, but the calcs to prove this are tedious and time-consuming. Have a word with your SE, but don't expect him to do too much without being paid!

 

[fabgav]

Thank you both Tony and Woody for your advise.

I have asked him to explain a bit more about the windpost.

It just seems to me that a 80 x 80 steel tube surely can't be much strong than a brick wall that's been standing for 80 odd years!

What I don't fully understand is what is making this panel so 'weak'? Is it the proposed opening shifting the load to that wall or something else?

 

[^woody^]

Where is that post supposed to be going?

 

[RonnyRaygun]

I can't understand the need for a wind post though. Is he being over cautious? I don't know

Looks like he's being cautious to me...where is the calc to prove the wall panel fails under lateral loading?

Also, the new panel size doesn't look to be much different in size than the existing one (although we don't know the exact measurements of the existing panel). Despite the poor flexural strength of masonry, it should be enough to justify the capacity of the new panel by stating that it is similar to the current panel, which has been there for 80 odd years...

Edit
Just checked diagram 14 of Approved Document Part A.
As far as I can tell with a quick check, your wall and openings satisfy all requirements without the need for a wind post.