Strengthen joist with massive notch

[EAST61]

Hi everyone

I'm renovating an old house at the moment and need some advice for strengthening some joists after some wally has made some massive notches for pipework.

Here's an example:

I don't need the notches anymore so can completely cover them.

Would some strips of steel with screw holes be appropriate? Just a bit of timber maybe?

Thanks

 

[Tigercubrider]

a couple of bits of decent ply on each side?
That might be cheapest, but steel would be fine

 

[foxhole]

18mm ply screwed and glued, better than steel as more contact with original timber.

 

[EAST61]

Thanks guys

Can I use OSB instead of ply? I've got a few sheets.

 

[foxhole]

You need the strength of ply, have seen it used in place of a steel where access was difficult.

 

[Deleted member 174758]

OSB has absolutely no structural strength whatsoever. You need a decent quality (e.g. harwwood) ply and it should be at least 18mm thick

 

[EAST61]

Got it, thanks guys.

 

[big-all]

as an aside
dependent on span the notches may not be as bad as in if the span is only say 8ft and those joists are say 9x2" to match all the floor level 7x2 may be strong enough so a 3" notch in a 9" timber would equate to a 1" notch on a 7" timber so not so bad but even then further infill and support wont hurt

 

[EAST61]

It's a 5 metre span

 

[bernardgreen]

The notch should also be filled with a tightly fitting piece of hard timber.

Under load a beam or joist tries to bend downwards, the lower half is stretched and the top half is under compression due to the attempt to bend. With that notch there is nothing to resist the compression in that area of the joist hence the joist is prone to bend at that point. Inserting a tightly fitting block into the notch will restore the resistance to compression and thus reduce the ability ot the joist to bend