Existing Timber Joist Floor Strenthening 1

[Contraflexure74]

Hi,

I have an existing timber joist floor which spans 3.6m. Joists are 44x225 at 450 centres. The client wishes to add an additional floor to the house above these joists. So now I will have a line load (load bearing stud wall) going perpendicular to these joists at mid span which supports the flat roof of the new storey.

I'm concerned that the joists may fail and I will have deflection issues from live and wind load from the roof. Anyone have any ideas how to strengthen the existing floor which may work? Putting in a beam below the line load is not desirable.

Any comments would be appreciated.

 

[DaveAtkins]

If you cannot add a beam below the line load, you will need to add additional joists between the existing joists. Alternatively, you could sister a joist to each existing joist.

DaveAtkins

 

[phamENG]

Can you give a cross section of the house? Is it already 2 stories, or is there a basement below?

Dave's right, of course. You either need a beam, or you need more floor joists. If the floor is already supporting walls and has plumbing and electrical running through it, adding new joists may not be an option.

Another possibility - add another plate to the perimeter and span all the way across with a wood I-joist or truss. As long as your exterior walls can take it, it saves modifying the floor.

 

[LittleInch]

Contra,

This isn't the sort of thing this forum was set up to do - you will need a structural engineer to look at all the loads and issues, timber quality etc and apply whatever local building regulations you have.

you talk about a client - what is your position and responsibility in all this? designer, builder, friend?

A drawing or sketch also helps though.

You say this is a ground floor floor, but then say the now rather narrow rooms ( 1.8m wide) are bloew a new floor?, but then talk anbout a flat roof?

If you can't support mid span then you might either need some steel work somewhere or lots of extra timber.

Then you need to know if the foundations are OK

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Enable]

If a beam below is not architecturally palatable is there any way to place a beam ABOVE the timber in line with the load and bring it down to some nearby columns?

 

[XR250]

Can you install a beam above the wall to support the flat roof?