Second opinion on some work, please

[daniel_]

Hi all,

I’ve recently had some major renovation on our house with a number of walls removed and RSJs installed on the lower ground floor.

The builders have now gone and building control signed off the work. There’s still a lot to be done, however.

I need to fix some rotten joists by the front door and have lifted up the floorboards to gain access and noticed a couple of areas of work the builders carried out that I’m concerned about that I’d appreciate your thoughts on:

1) the builders appear have already cut a joist in the sitting room, where it passes through the wall to the hall (to get an rsj beam in) and repaired but I’m concerned it’s been botched. There is a 100mm gap between the two pieces of joists and it’s only sistered on one side (and this is the only bit resting on the wall). I noticed a bit of bounce around there and cracks on the plaster below so this could be the issue. Do you think I should unbolt, add another sister, rebolt? Is the gap an issue too? Do I need to close that?

i’ve attached a couple of photos and a sketch to help illustrate.

2) the second thing is the gap above the rsj is packed with slate but no mortar and the joist hangers are just resting on the steel. Is this normal/ safe?

a couple of snaps attached for that too.

many thanks for your consideration and any thoughts you can offer.

 

[Notch7]

how long is the sister?

the length and number of bolts will give an indication.

it looks to me like there is only 1 bolt set in the centre of the joist -thats not good enough they need to be done in staggered pairs really.
Yes I wouldve thought both sides is better

regarding the joists on the steel, Im not sure -I think Ive seen a timber packer bolted in the web of the steel, then hangers fitted to that.

 

[daniel_]

The sister looks just under a metre. There’s around 40cm either side of the brick sized gap, with 2 centred bolts either side. I’m probably being over cautious but want to make sure it’s solid and correct before all the effort goes into the boards etc.

 

[domdee]

They look like joist hangers that are used on masonary, e.g. a slit is cut into a brick/block wall with a stihl saw/angle grinder and the hangers are then brayed in to the slit. I'd say they are incorrectly fitted as a timber should be bolted to the rsj and regular timber joist hangers used. That said if the slate is packed tight and a good amount of pointing is done to fill the voids and support the slate you'll get the same result.

I'd fit longet sisters either side with staggered botls as mentioned. And use them star/spikey washers between the timber faces to stop vertical movement/sag.

 

[daniel_]

Hi Domdee, thanks for your response. I managed to find similar sort of hangars to steel, where they hang like this (http://www.jji-joists.co.uk/images/interface/downloads/hangers/sst-steel.pdf) but they also say they should be mortared in before any weight places on them. There’s no mortar on mine and I can’t see any other fixings so it looks like they’re just hanging by their own weight?

a couple more snaps for reference.

For the joist repair, I’ve ordered some L shaped steel plates. I’m going to pop a bit of wood, tightly in the gap and use a pair of plates bolted either side.

 

[domdee]

They maybe are the correct hangers then, just poorly executed

 

[daniel_]

Do you think I should try and squeeze some mortar in there or take any other remedial action?

 

[domdee]

yes get it packed in as tight as you can. it needs to be reletively dry mix as if its too wet it will just slump out before curing