Joists reinforcement

[TomCow]

Reading online about joist spans and 6x2 timber limit. I was thinking about putting flat bar between two bits of timber maybe 4x2 and using them as support to prevent the sag. Would that work? 

[Dave Jones]

use pozi's.

[Russell griffiths]

What are you actually trying to do. 
better explanation needed. 

[TomCow]

I'm looking at spanning floor joists over 5m and was seeing if sandwiching a piece of flat bar between 6x2 would stop it sagging. 

[joe90]

It’s called a Flitch beam.  https://en.wikipedia.org/wiki/Flitch_beam

 

you might find this helpful.   https://www.timberbeamcalculator.co.uk/en-gb/span-table/floor-joists?load=1.5&class=C24

Edited May 23, 2024 by joe90

[ProDave]

Our 5M span is done with 300mm deep Posi Joists.

[Russell griffiths]

Can you not use a deeper joist, your way will use double the timber, plus the steel, plus the bolts

this will make the whole idea very expensive. 

[ProDave]

4 minutes ago, Russell griffiths said:

Can you not use a deeper joist, your way will use double the timber, plus the steel, plus the bolts

this will make the whole idea very expensive. 

And the steel will make it almost impossible to pass cables and pipes through the joists.  (not an issue with posi joists)

[TomCow]

Would 8x2 timber be OK for that span? How much are posi joists?

[Andehh]

Watching with interest for an outdoor patio cover project is like to do one day!

[Russell griffiths]

We still need more information 

is this a roof over a garden pergola 

a first floor of a house

or the floor of a nightclub with 100 ravers bouncing up and down 

 

5m is getting near the limits of a lot of solid timber and your looking for an engineered solution.