Lintel Advice Please

[andsally]

Hi there

I want to instal two 1150mm wide windows on a load bearing wall of a detached garage. I have previously inserted door and fireplace lintels but would like advice on this one please.

Load bearing wall is 5.1m long, single skin block with 3 brick pillars.
The wall supports half the load of a 30 degree pitch clay tiled roof, with 13 5x2 rafters (the other half of the roof load is supported by another wall).
I estimate that the load on the wall where I wish to insert windows is:

900 tiles@ 1.08kg 972kg = 9.53Kn
13 5x2 rafters 91kg = 0.89Kn
Total 1063kg = 10.42Kn

Half load 531kg = 5.21 Kn
Load per meter 531kg / 5.1m = 104kg/m
Load per rafter 531kg / 13 = 40.84kg

Questions:

Will the 100x65x1500mm steel reinforced concrete lintels from wickes suffice (they don't provide any data)?

How to prop wall before inserting lintel?:
The wall is only 2.1m high and only one course of blockwork will be between top of window and timber wall plate that supports rafters.
Wondered if I could get away with using four strongboy props inserted directly below wall plate and below rafers?

Many thanks in advance.

 

[Static]

http://naylor.co.uk/CMS/xinha/plugins/ExtendedFileManager/demo_images/pdf/Economy_Lintels.pdf

You forgot to add any imposed loading for snow, wind or a couple of (fat) builders on the roof..

At a guess go for 2.5kN/m2 roof total loading (which include, snow, tiles, battens, boarding, joists, ceiling rafters, little storage load), so say the garage is 3m wide.. that would be 3.75kN/m run.. then add a little for the block course above the lintel say .5kN/m so all in 4.25kN/m

Meaning,.. no a 65x100 lintel is not suffient.. go for a 140dp or 100dp

 

[tony1851]

The very shallow (65mm) lintels are really only intended for being built-in as work proceeds, so that the lintel acts as a composite with the brick/blockwork above.
This won't apply if you have only 1 course of block above.
Besides, these lintels can crack easily when being handled and IMO are not totally reliable.
As Static suggests, go for a deeper lintel, pref. 140mm

 

[andsally]

Thank you so much for swift replies and the link. A 140x100 lintel it will be then.

I had intended to calculate for snow load later on but was interested in the roof load in terms of load on props.

How best to prop prior to inserting lintel into Thermalite blocks? Exterior is pebble dashed and I want to minimise damage. Accrows or stongboys?

Thanks

 

[andsally]

Anyone else please?

The only way I can think of to insert lintel is as follows:

insert four tallboys immediately below wall plate, under four roof rafters 400mm centres)
take out 1500mm width of block is immediately below wall plate
bed in lintel
insert row of bricks above lintel
pack mortar between top of the bricks and wall plate (except where stongboys are)
let mortar cure, remove strongboys; add mortar where these were inserted

any thoughts please?