Bit concerned about my posi joist installation

[Adsibob]

There is a small gap of about 1mm, possibly less, between the end of the posi joists my builder has installed and the perpendicular wooden beam he has attached to the perpendicular RSJ to facilitate installation. (Ie wooden beam and RSJ are parallel to each other and posis are perpendicular to those). I told my builder this wasn’t good, and will result in too much deflection. Walking across the posi joists with heavy footsteps (I weigh about 100kg) did cause some deflection. I couldn’t feel it, but I could see it when my builder did the same and I observed. Maybe 3mm of deflection, difficult to tell. 
he’s had already installed about a fifth of the posis for the whole house. Is it too late to do anything about this? Builder says I’m unnecessarily worried as he thinks once the 22mm caber deck is glued on top there won’t be any movement as that will help spread the load.
i attach a photo, though it doesn’t show the 1mm or less gap at the edges I’m worried about.

posis are at 400mm centres.

 

[nod]

He’s right once everything is glued together it will feel solid 

I did ours at 600 centers and it feels very solid under foot 

[Adsibob]

2 minutes ago, nod said:

He’s right once everything is glued together it will feel solid 

I did ours at 600 centers and it feels very solid under foot 

That’s reassuring.  Maybe I am being OTT/OCD as I just read the notes to the mitek installation instructions and they say: “Joists should have a full bearing with no more than a 5mm gap between the end of the joist and the face of the hanger.” So the 1mm or less that I’m worried about is nowhere close to 5mm. But part of me still wants to insist he hammers some packers in to fill that gap, as surely gaps at the end are not good. Builder  says it’s all screwed into the joist hangers anyway. I’m bring a bit crazy aren’t I?

[nod]

Ha ha 

Looks a nice job 
Any gaps Even 5 mil ones will quickly fill with glue when the decking goes down 

[markc]

1mm is nothing, factory cutting for Pozi`s is +/- 2mm. hence the 5mm gap note

[saveasteading]

Also, the floor deck spreads the load over more joists, and acts as a very big top flange, taking compression as in a T beam.

[ToughButterCup]

17 minutes ago, Adsibob said:

There is a small gap of about 1mm, possibly less, between the end of the posi joists my builder has installed and the perpendicular wooden beam he has attached to the perpendicular RSJ to facilitate installation.... I told my builder this wasn’t good, and will result in too much deflection.... Builder says I’m unnecessarily worried as he thinks once the 22mm caber deck is glued on top there won’t be any movement as that will help spread the load....  posis are at 400mm centres.

 

@nod has forgotten more than I'll ever know about this subject. 

But I do know a bit about joists (and how to get them wrong) - I put my own POSIs in  . A 1 mm gap - locally (Lancashire) known as a gnatt's bollock - is an excellent result.  Glued and screwed to 22mm boarding will be fine. I've seen 5mm gaps at POSIs put in at 600mm centres  and 17mm boarding.  They didn't flex.....

 

Relax. Think of England Harry and St George.

[Russell griffiths]

Why not ask him to pour some of the D4 glue down the gap when he fits the floor sheets, an extra couple of bottles of glue won’t brake the bank. 

[Adsibob]

Interesting idea.  Although the gap is small enough that I don’t think the glue would get very far down it. The posis are the small ones (size 8 from memory), which I think are 20cm or 22cm high. So glue would probably only get down the first 1cm or 2cm tops. 

[Temp]

Wood expands and contracts with the seasons. I wouldn't be surprised if that 1mm gap dissappear in summer and widens in winter. Its very unlike to be the cause of any deflection in the floor when walked on.

[Digmixfill]

On 06/05/2021 at 20:01, Temp said:

Wood expands and contracts with the seasons. I wouldn't be surprised if that 1mm gap dissappear in summer and widens in winter. Its very unlike to be the cause of any deflection in the floor when walked on.

I've recently put 20 posis in on hangers and aimed for the 1mm gap. I left a gap for the reason Temp mentioned.

I'm expecting everything to lock up nicely when I put the boards in place.