Hi, usual kind of message - I already have a single doorway from my
lounge through to the dining room, through a wall in the middle of the
house, and I want to make this opening into a double one.

The wall is blockwork but there are no internal block or brick walls
upstairs. I had a look & the current lintel is an inch deep, 4 inch
wide piece of corrugated steel. The upstairs joists rest on this
middle wall, therebeing one joist rear-to-middle, then another
middle-to-front of the house.

I want to get an understanding of what is required so, of course, I
downloaded superbeam 4 to have a bit of a play.
The example in there is for a loadbearing wall with a brick wall
upstairs so I changed that to loadings for a stud wall. Am I right
that I can delete the roof load? The upstairs floor load is half of
the length of each joist - i.e. half of the distance from front ot rear
of the house multiplied by the loading factor?

For the current door this gives me "r1comp=4.66, r2comp=4.66, Max
S.F=4.66" Are any of these the UDL? Going to the catnic website they
ask for UDL. The max UDL of the catnic corrugated beam is 7kN.
It would appear that just about any beam long enough would do for the
double door opening. Is there any advantage of using a catnic over a
UB?

In terms of bearing area, am I right in thinking that the bearing area
of the beam (the part in the wall) needs to be enough so that the
pressure is spread and within the limits of the block work i.e. the
large the loading the more of the beam needs to go into the wall. The
catnic website simply states "150mm".

Cheers!

wrote:

I want to get an understanding of what is required so, of course, I
downloaded superbeam 4 to have a bit of a play.
The example in there is for a loadbearing wall with a brick wall
upstairs so I changed that to loadings for a stud wall. Am I right
that I can delete the roof load?

I would expect so...

The upstairs floor load is half of
the length of each joist - i.e. half of the distance from front ot rear
of the house multiplied by the loading factor?

If the joist in uniformly loaded, then you will see half the reaction of
the total down force at each end. Hence the load on your lintel will be
the weight of the blocks/bricks above it, plus the sum of the downforces
of all the beams resting on the lintel.

For the current door this gives me "r1comp=4.66, r2comp=4.66, Max
S.F=4.66" Are any of these the UDL? Going to the catnic website they

I presume UDL is Uniformly Distributed Load (as opposed to a point load)...

ask for UDL. The max UDL of the catnic corrugated beam is 7kN.
It would appear that just about any beam long enough would do for the
double door opening. Is there any advantage of using a catnic over a
UB?

Don't know...

In terms of bearing area, am I right in thinking that the bearing area
of the beam (the part in the wall) needs to be enough so that the
pressure is spread and within the limits of the block work i.e. the
large the loading the more of the beam needs to go into the wall. The
catnic website simply states "150mm".

You don't want it concentrated on a tiny section, but once you have got
to something like 150mm I would expect you will need a fairly serious
load to raise the pressure at the contact point to something that would
crush even fairly light blocks.

--
Cheers,

John.

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In article ,
John Rumm wrote:
For the current door this gives me "r1comp=4.66, r2comp=4.66,
Max S.F=4.66" Are any of these the UDL? Going to the catnic
website they ask for the UDL

I presume UDL is Uniformly Distributed Load (as opposed to a
point load)...

Yes: if the load is uniformly distributed it can generally be higher
than if concentrated at one point. The R1comp and R2comp are the
reaction R1 and R2 components of each load so if all the OP's loads
are UDLs it would appear that his total UDL is 9.32kN, more than a
Catnic corrugated lintel will take, according to his figures.

--
Tony Bryer SDA UK 'Software to build on' http://www.sda.co.uk
Free SEDBUK boiler database browser http://www.sda.co.uk/qsedbuk.htm

Ok, so I took the measurements properly last night :-) ..and using a 7
metre length of house rather than guessing at 8 and using a span of
80cm for the *opening* (not the length of the lintel) I got 3.44kN on
each end which I guess is more or less 7kN UDL so the corrugated lintel
is within spec. I guess that the point loads of the joists above are
more or less converted to uniform loads by the presence of the
brick/blockwork inbetween them & the lintel. Opening up the span to
1.6m I get a total load of about 18kN.

Now to factor in the full size snooker table going in the room
above.... :-)

In article .com,
wrote:
I guess that the point loads of the joists above are
more or less converted to uniform loads by the presence of the
brick/blockwork inbetween them & the lintel.

Joists at 600mm centres or less are treated as a UDL. The alternative
is too horrible to contemplate!

--
Tony Bryer SDA UK 'Software to build on' http://www.sda.co.uk
Free SEDBUK boiler database browser http://www.sda.co.uk/qsedbuk.htm