pressed steel joists in loft.

[Matt1979]

Hi, i am going to be putting some flooring into my loft to A.) increase storage capacity in the house and b.) use it as an ocasional office.

the only problem i have is the fact that it is not a standard construction - it has pressed stell joists that are quite a way apart - i assume i am not able to lay sheet material straight on top of the joists due to the unsupported expanse - what would you all suggest is the way forward - wooden frame with flooring on that? thick timber planks striaght on on top the joists?? any suggestions would be gratefully recieved.

Matt

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[JohnD]

that's interesting!

what are the dimensions and spacing of the steels?

I am a bit surprised they are not clad in plasterboard or sprayed - steel loses strength and colllapses very fast in fire (like the Twin Towers)

Is it a conversion, or built as a house?

No sign of insulation... must cost you a fortune to heat

 

[Deluks]

Timber joists spanning between, and sitting on the bottom flange of the steels, and flush with the top of the steels.

You'd then use solid noggins between your new joists, to ensure they won't 'fall over' Although once the floordeck is screwed down they won't go anywhere anyway.

Anyway, as John has mused, that's interesting! If they are strong enough, (they look plenty enough...) you could do a proper official loft conversion for a bargain basement price.

 

[noseall]

you could do a proper official loft conversion for a bargain basement price.

he he he, good play on words.

 

[Matt1979]

the house was built with Pre-cast re-inforced conctrete - and subsequently changed to a conventional build under a regeneration project run by the council - therefore my exterior walls are about 1 foot thick (nice big window sills!) -

i am not sure what the strength of the steel would be, as they are only a pressed steel joist there is not as much tensile strength - or instance if yo stand on the edge of the steel it allows an amount of flex. if i were to put the timber inside the joist as deluks suggested would there be too much pressure on the bottom plate of the steel? this would be ideal as keeping as much height as possible is crucial!

 

[oldman2]

They look much like z purlins used in industrial building projects, not much strength in them, usually they are tied together to stop them twisting. Cant think you would be allowed to put much extra weight on them, you would need a structural engineers report.

 

[JohnD]

what are the dimensions and spacing of the steels?

 

[Matt1979]

i will have a measure and post it up tomorrow. - to guess-timate the second picture has a metre rule in it to give it a sense of scale.

 

[Deluks]

you could do a proper official loft conversion for a bargain basement price.

he he he, good play on words.

Was totally unintentional, well spotted bignose!

 

[Matt1979]

what are the dimensions and spacing of the steels?

ok - dimensions...

The width between the joists is 75cm (to the two inside edges)
The joist itself is 18cm (2 X 5cm steel with a 8cm gap) which is joined by blocks every 84cm - hope that all makes sence!

 

[JohnD]

you mean each joist is 5cm wide?

And how deep? And how thick?

 

[Matt1979]

no, each joist is 18cm - this consists of two steels shaped like ] [ a wooden block has been position and bolted 84cm apart to keep the rigidity. the actual thickness isn't very much - hopefully the attached pictures will help.

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[Deluks]

Very odd. Do they deflect in any way if you bounce up and down (a little bit) The construction is such that they are much stronger doubled up in that manner, but if the steel is only thin then no you shouldn't let anything rest on the bottom flange.

Ultimately the depth is what really matters, and from the pics they don't look deep enough to support a 'proper' floor. They will probably be as good if not better than any standard 4x2 joists that you'd normally find in a loft. So you can probably just board the loft as normal following previous advice on this site, couterbattens and all that.

Someone give Shyz a choccy biscuit and see what he says.

 

[JohnD]

I think he's drowning his sorrows tonight











If he can persuade her to accompany him to the canal.

 

[Shytalkz]

Lol, she's arguing with me via text over the dog atm .

Will have a read through.