Foundations

[Taff]

Confused.com!

 

Morning can anyone help please. Within my build stage summary see pic.

 

would anyone know what the foundation masonry is?

 

there’s a raft with a block and beam structure on it what else would be required 

 

Ta

[PeterW]

Looks like block and beam has been removed..?

 

Raft with beam and block would be a bit odd tbh - foundation masonry is your below ground/below DPC brick and blockwork

[Taff]

Thanks Peter,

 

Our option was to be raft however For what ever reason due to the ground conditions this had to be re looked at. we were going for piles but they would have incurred a lengthy delay. So engineers came up with 250 raft with an elevated block beam plan. Don’t know why or how as I’m not clever enough. We might even utilise the space under the beam! 

 

So just to confirm the foundation masonry it would be below the block and beam level? 

 

And my thinking that this entry entry would then not be required?

 

thanks

[PeterW]

Have you got any section drawings as that doesn't make sense

[tonyshouse]

All it makes me think of is an in house winter cooling system 

[Taff]

Not too hand I’ll need to dig them out later 

[Taff]

11 minutes ago, tonyshouse said:

All it makes me think of is an in house winter cooling system 

Are we saying it’ll make the house cold?

[tonyshouse]

I am, beam and block does and so do suspended floors 

[Taff]

Even with all the layers we will put in?

 

vapour control layer

polythene membrane 

perimeter screed upstand with pir insulation 

foil faced rigid pir insulation board

floor screed 

[CC45]

how much PIR in the floor?  We've got 225mm - bit ott but that was the phase I was going through then, also matched the depth of a block so easier for the brickies.  Timber frame on top of these blocks.

[Taff]

Wow that’s thick. We’ve chosen 150! Do you think that’s adequate. Ours is a sips build and trying to avoid loss through the floor.

hows yours! is it warm?

 

we using 20mm pir perimeter also wondering if this is adequate too.

 

 

 

[CC45]

I used 20mm on the perimeter.  Thickness = u value you are aiming for.

 

I was going to use 200mm but added 25mm to suit blocks.  Law of diminishing returns applies so there must be a limit somewhere, you could calc it out if you wanted to I guess.

[Taff]

Think that’s getting a bit technical for me, I just need to know if the architect has recommended adequate 

[PeterW]

I think between the architect and the SEng, you've got a bit of a mongrel...

 

So if the SEng wants a raft, you then should be building up from that and looking to reduce your cold bridging. Building a raft, then using a perimeter blockwork and filling the inside with your insulation and capping it off with a concrete screed, and then build up the SIPs off the edge blockwork.

 

You then dispense with the beam and block floor as it becomes an irrelevant cost. Insulation could be EPS rather than PIR - so cheaper - and you can design out the cold bridging.

 

If the SEng still insists on a  beam and block floor then look at one of the insulated ones such as tetris as you can kill two birds and get a better and lower insulation value with a thinner floor build up.