Supporting joist

[RickH]

I have built 4 stone pillars (only 2 course each) ontop of 18x18x4" concrete pads.
The pillars are to provide support under joists on a decking area .....

Additional supports in readiness for HotTub going on the decking.
The joists are already in place ... so I can't remove, just need to 'fill the gap' to provide load bearing.


There is a gap of about 1.5"-2" between top of pillars and underside of joist ...... which I need to fill with a mix.

I had thought about Grano (3:1) but can't find it anywhere local to me.
So I could use builders sand (3:1) or go buy some sharp sand
or even some 10mm pea gravel and do a 1:2:3 concrete mix

Thoughts ?

 

[phatboy]

Why not just use some timber, on some DPC? Would be nice and quick.....

Even a concrete mix with 10mm would be tough with a 15mm gap, you could use a strong mortar mix and pack it in I suppose.

 

[RickH]

My 2 neighbours had suggested mortar/concrete, hence my thoughts in that direction.
The concern is getting really good fit of timber .....
I could play around with plane until it fits ..
the joist is 38mm wide CLS .... so I could look to use some of that ..... or even go up to 47mm CLS, so it overlaps joist

 

[Mr Chibs]

You could use 2:1 mix with as little water as possible. Nail a piece of ply to one side, so you can ram in the dryish mix.

Or pack with stone, slate, or wood

 

[RickH]

I think my approach will be block one side as you say, jack up joist with bottle jack by a couple of mm.
mix up a 1:1 mix of stone dust & cement .... good stiff mix and pack in well, then remove jack .....
1:1 won't shrink and it very hard ..... used on bedding in steel stancions,

 

[^woody^]

Pin two folding wedges on a DPC of some sort.

 

[cdbe]

Large sections of the roof structure of my 1930's house are help up by what I can only describe as bits of scrap wood on top of brick piers.