Over the top garage reinforcement

[jamiehamy]

Hi all, 

 

As some will have seen, we've now had the area for the garage excavated. It's going to be pretty much underground, with a BnB roof+ topping, or Comflor on top ( to take the weight of a car)

 

The spec for the slab is 150mm with mesh all round and rebar upstands round the perimeter at 200mm centres. The perimieter is 300mm deep with mesh and rebar to a width of 1500mm

The walls are specced as ICF with a 250mm core, with mesh up the middle. 

 

Whilst I have budgetted for this, the excavations have revealed rock round all three sides of the garage - and I'm wondering if there is scope to reduce the wall core down or the amount of reinforcements required - or if we could use fibres instead. 

 

Putting mesh up the middle of the ICF whilst not difficult per se, is much more work that say running rebar vertically or horizontally. 

 

So - wondering what people's thoughts are on scope to reduce the wall spec? Is this worth speaking to my engineer about or will he stick to what we have - which was prepared before we knew the ground conditions around the garage?

 

Thanks, Jamie 

 

 

 

 

 

[Mr Punter]

The B & B floor should help if it restrains the walls.  I have done an ICF basement and had a similar spec, with chalk soil.  I think you could end up spending more on engineer costs than you save in mesh.  I don't think you will get away with fibres either, but it is worth asking.  How are you waterproofing?

[jamiehamy]

15 minutes ago, Mr Punter said:

The B & B floor should help if it restrains the walls.  I have done an ICF basement and had a similar spec, with chalk soil.  I think you could end up spending more on engineer costs than you save in mesh.  I don't think you will get away with fibres either, but it is worth asking.  How are you waterproofing?

I was thinking that about engineering costs. I've not decided on waterproofing yet - we will be backfilling with Gravel to let water drain down and out. Will either go for a bituthene membrane or some sort of paint on option - Alan has given me a contact for a product.   

[MikeSharp01]

6 hours ago, jamiehamy said:

bituthene membrane or some sort of paint on option

Use a membrane not a paint, they last longer. I did an underground building a long time ago and the only bit that was ever damp was the paint on tanking portion, the bit with the membrane was never damp and probably still isn't.

[Vijay]

A friend who did basements always said he doubles up, membrane and paint