alternatives to steel joists

[neilw]

Hello,
I'm having a loft conversion, but the engineering drawings have stated to use the heaviest gauge 10inch steel, which is weighing in at a hefty 90kg per metre. Which in my loft will comprise of 6 lengths weighing quarter of a ton each side (three per side bolted).

We are looking at getting it lighter by making it taller - apparently it's the deflection that counts.


There was a product we saw which was a dwarf lattice wall but our loft wasn't suitable as there are no eaves.

But I wondered if there are any other alternative materials or methods around, e.g. carbon fibre (though I expect the cost is prohibitive), etc. that anyone might know about?

Thanks.

 

[noseall]

Can't you just extend?

 

[neilw]

already have! it's upwards now

 

[The-brickie]

Glulam beams?

http://www.glulam.co.uk/framesetGlulam.htm

 

[Deluks]

What is it about the spec that you are not happy with? The cost or the difficulty in getting them up there? How long is each section?

Go back to the engineer with your concerns and ask if there are any alternative options. PFC bolted back to back can be easier to manhandle although you're looking at more expense for the cost of the product and the extra fabrication (bolt holes/plates) required.

 

[neilw]

What is it about the spec that you are not happy with?

It's really the weight (and therefore the ability to get it up there due to a crane being out of the question), there are two steel joists spanning the length of the house (it's the only way it can go) and each one is split into three parts and bolted. Each third section weights about a quarter of a ton and it is the heaviest gauge 10inch joist you can get. They will be mounted on 4ft steel lengths to spread the load.

My builder tells me it's like this because the engineer is covering himself and naturally will over compensate.

I'll look into GLTA, thanks.