Understanding 3N & 7N Blocks

[Mulberry View]

I'm hoping to infill my overspec'd Beam and Block floor with 7N blocks. I've had a chance to buy a quantity of concrete blocks very cheaply, they are listed as 7N, but no paperwork. There is nothing obvious stamped on them, they weigh just over 15kg each. How can I tell if these are definitely 7N?

[PeterW]

Ok so I would just carry on and not worry as no-one will check … you’ll put insulation and then concrete over the top - a single block will not be taking any load that would cause failure

[PeterW]

23 minutes ago, Mulberry View said:

I've had a chance to buy a quantity of concrete blocks very cheaply

are you getting a VAT invoice ..? As without one they may not be that cheap

[markc]

In a beam and block floor the block compressive strength doesn’t really make any difference, if the blocks are old and crumbly then stay clear whatever and however cheap they are

[Mulberry View]

44 minutes ago, PeterW said:

are you getting a VAT invoice ..? As without one they may not be that cheap

 

These are cheaper than the ex VAT price by quite some margin.

 

35 minutes ago, markc said:

In a beam and block floor the block compressive strength doesn’t really make any difference, if the blocks are old and crumbly then stay clear whatever and however cheap they are

 

OK, fair enough. These blocks aren't crumbly, they're brand new, left over from a build by the looks of it.

[Moonshine]

20 minutes ago, Mulberry View said:

OK, fair enough. These blocks aren't crumbly, they're brand new, left over from a build by the looks of it.

 

I would be a bit nervous about this particularly what they are being used for, especially as any remedials will be expensive and the difference in buying a few hundred blocks won't be massive.

 

When i was looking at blocks for mine i had to make sure that they had a transverse load capacity of 3.5kN