Raft foundations

[Smallfry]

Again, still not an issue. You should have shear links in the reinforcement design tying the thickenings (whether shear key, edge thickenings or internal thickenings) into the main 250mm slab.

Say your thickenings are 400mm deeper than the underside of the slab, you’d set your cages on the thickenings to the full depth (650mm in the above example less cover) then pour your thickenings as part of the first stage. Then return, lay your slab reinforcement with adequate laps to your cages which are partially set in the thickenings and pour your slab. If the area of the slab is too large for a single pour then you introduce a shutter with starter bars extending into the next pour zone and cast the first section. Rinse and repeat until the full floor is done.

Depending on how you intend on installing the form work for your retaining walls you may also want to cast a small kicker off the raft for locating the base of the shutter.

Waterbars are critical to all construction joints to ensure the water proofing arrangement is maintained.

The above is obviously an assumption made on the description you’ve provided so if I’ve misunderstood a quick photo of the drawing would be helpful.

This is exactly how I would like to do it, leaving the tops of the cages exposed to tie the understructure to the slab.

Cleaning off the laitance layer before pouring the top slab. Doing this will make the whole job easier for me, as I can then construct the two layers of main slab reinforcement without falling over the bars. Will mean two pours and pump hire though, but hey ho.

I have to have rebar upstands to tie into the walls that will be built on top. Will be using 325mm Anderton Stepoc blocks for that with even more steel.

 

[KaneH]

Sounds like you’ve got it in hand. Just one note on the tie bars between the raft and wall, if the design requires it make sure they’re also lapped and cast into the lower cage and not post drilled and resin anchored. Don’t want to find yourself any issues once the backfilling commences!

Keep us posted once you get into it.

 

[Smallfry]

Sounds like you’ve got it in hand. Just one note on the tie bars between the raft and wall, if the design requires it make sure they’re also lapped and cast into the lower cage and not post drilled and resin anchored. Don’t want to find yourself any issues once the backfilling commences!

Keep us posted once you get into it.

Takes a lot of working out though ! But yes.

When all this is done, after the first course of blocks are laid, I will be pouring more concrete (screed ?) inside the perimeter with DPM under, to bring up the floor level. This will also help the walls from being pushed in.

Going to be a slow job, working on my own. Thats if it ever stops raining !

 

[cocker]

Not local to here, and looking at their website, it looks like they would only do larger commercial projects

I have to keep the costs down too. Don't have the budget. Wish I did, would just pay someone do do it.

They own a lot of the smaller pump companies . Try them , it's only a phone call .