Standard timber or engineered joists

[Faceache]

Engineered joists have been calculated for use on the extension we're building but having seen an example of them I'm not so keen.
How do I stand if I want to change them for C16 timber as far as building control are concerned?
Will they require us to submit more calculations with regard to loads, deflection and that kind of thing or would the standard joist tables that can be found almost anywhere be sufficient for the BCO?
It's only a clear span of 4m with 400 centres.
Thanks

 

[AronSearle]

Can't see why spans tables will not suffice.

But why don't you like the engineered timber out of interest (and what type)?

 

[freddiemercurystwin]

Yes use the standard span tables and maybe up them slightly to minimize bounce/squeaks, no need for Se input. It does beg the question why engineered joists have been specified? Need to get services through the floor maybe? Architect a dope? What gives?

I would only specify engineered joists where the spans required them or I needed to get services in the floor.

 

[Faceache]

No it's me that's the dope!
The engineered joists are either JJI 195B or JJI 220A.
It was me who initiated the engineered route because it was suggested that they would be less likely to squeak. Having looked at them they seem a bit flimsy and besides that, with the weather only going to get worse, C16 can take a bit of water whereas the engineered stuff can't.
It also gives a platform to work off half way up which is a practical consideration I'd lost sight of.
I've only got electrics going in and I think overall the bracing/ strutting of C16 would be easier to do than the 'I' shape offered by the engineered beams.

 

[AronSearle]

Metal web joists then.

Engineered timber will cause less squeaking, as it is often properly dried, rather than dry-ish.

Though saying that normal solid timber is perfectly fine if you have decent tradesmen.

 

[jeds]

Having looked at them they seem a bit flimsy..

You've got that wrong. Engineered jji joists will provide a much better floor than standard table C16 joists.

 

[freddiemercurystwin]

Having looked at them they seem a bit flimsy..

You've got that wrong. Engineered jji joists will provide a much better floor than standard table C16 joists.

Not from a bounce point of view John, if they are oversized then may be.

 

[noseall]

DO NOT fit at 600mm c/c. shocking distance apart!