# Forum Home Renovation Structural Renovation  Lintel to span 5m over glass sliding doors

## etrader

I'm in the final stages of designing my new house. 
I just purchased a set of glass sliding doors (4.8m x 2.4m). I need a lintel to go over the opening. 
The wall height is 2740mm. It's a single storey, corregated iron, trussed roof with a roof load width of 4.5m. 
There is about a 250mm gap for the lintel after taking into account the top plate and reveal etc. 
What would be the best option for the lintel? 
A light steel beam seems like the best choice, but I'd like some other opinions please.

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## SilentButDeadly

I'd go the LSB.  I don't think you'll fit LVL into that space for that span.

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## jiggy

C section steel beam with timber wedged in it so that you can drill up through it and fix off the timber.

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## etrader

Thanks guys, Can the top of the door frame be screwed straight into the LSB without needing to wedge a block of wood in it?  
This picture gives an idea of what my opening might look like: http://www.litesteelbeam.com.au/lite..._03_big_01.jpg

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## Pulse

Yep you can fix to LSB pretty easily

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## etrader

I think I'll probably use 180PFC steel instead of 250mm LSB just because it will be easier to fit in the gap.  
Apart from weight, are there any advantages/disadvantages of using PFC over LSB?

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## Belair_Boy

> I think I'll probably use 180PFC steel instead of 250mm LSB just because it will be easier to fit in the gap. 
>  Apart from weight, are there any advantages/disadvantages of using PFC over LSB?

  Weight is the biggest difference but depending on the wall thickness and flange width (250 x 75 x 3.0 LSB), the 250 LSB is slightly stiffer than the 180 PFC and hence less deflection over the same span and under the same load.
The flange thickness of the 180PFC is 11 mm and may prove more difficult to fix to although will take a cut thread very well.
The LSB is already protected from corrosion where the PFC will require a zinc primer and paint to stop it rusting. 
I think it all comes down to the depth of the section and how much room you have above the doors.
Overall the LSB will be easier to work with but at the expense of being 70 mm deeper.

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## Gaza

chances are you can get the PFC off the shelf from local steel merchant, LSB maybe a special order, you will also need to consdier posts to support it,

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## barney118

hip or gable roof?colorbond or tile roof? try your local truss company they will plug in the info and come up with a beam. Also try CHH Australia - DesignIT its a good free program to use LVLs etc. If its on the hip of the roof you may get an LVL in there.

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## etrader

@barney118 It will be a gable colourbond roof. Here's a model of my design so far: http://www.bigscrub.com.au/model11-layout1.jpg 
The glass doors will be on the gable end of the roof. The end of the roof will extend out 3 metres past the house to form the covered verandah. 
I guess there would be a lighter load on the gable end? Would that affect the required size of the lintel? 
Just trying to work out my options before I go to the engineer. Thanks everyone for your help.

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## ausdesign

etrader, going by your 'sketch' your RLW figure is incorrect for a truss roof load.
The lintel would be designed for wind loads. Without a knowledge of the project I would suggest - 125TFB, 125PFC, 2/240*45 mgp10 or 240*63 hyspan.

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## barney118

What Peter said, interesting design, technically the truss could be designed to take the load of the span with a different bottom chord, go to a truss designer and they will give you a quote too. It doesnt look like 1 storey from the sketch, I take it some decent LVLs coming out to support the roof over the deck, interested how you plan on bracing. what size posts are you using? It wouldnt look out of shape going for a hip roof and much easier to build

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## etrader

It's actually a split level design. 
I'm planning to support the  verandah roof with two hardwood beams and a ridge beam leading out to a  large timber truss supported by two posts. Then I'll hang some rafters  off the ridge beam. I'll put an extra post under the middle of the veranadah to support the deck. 
Not sure of the size of the posts or bracing yet. Anyone know a good engineer in the Northern NSW/Southern QLD region?

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