Conservatory Foundation Query

[Fonzarelli]

Hi - I'm a newbie to this, so hope someone can help? I've done a quick search around the forum and couldn't find what I was looking for, hence i'm raising this topic.

We're building a conservatory in our backyard, in-front of a newly built extension. It's going to be 7.5m x 3m with a 2 feet deep foundation and a cavity wall, using blocks on the inside and outside. From the base, the wall is going to go 800cm high, with double glazed windows all around and a PolyCarbonate roof.

As part of the extension work, there was some spare concrete (which I think included sand in the mixture) left over from the original extension work, which they were using for the foundation of the conservatory. They've run out concrete and we've found them to be now using left over screed to fill the remaining foundation. Will this be a problem for us in the future?

Thanks in advance!

 

[noseall]

Screed sand is used in part as an ingredient for making concrete.

Concrete is basically a mixture of 4 parts aggregate, 2 parts sharp sand (screed sand, grit sand etc), 1 part cement and water.

So, there would be little ill effect of adding more screed provided it is not excessive and that it is shared amongst the whole batch.

However if they are simply adding a screed mixture, wholly to the remaining trench then this is not ideal.

If they have in excess of say 225mm of good concrete already in the trench bottom and were adding say an extra couple of inches, again this would not be detrimental to the structure.

 

[Fonzarelli]

Thanks for the reply.

I'm glad I asked the question now.

I believe they were using the aggregate mixture for the concrete, as you've described, but ran out. They seem to have filled the remainder of the trench with a screed mixture we had left over from before.

What are the risks we're likey to see if they've done it this way? I would like to confront the builder now if there could be potential problems with the structure?

Thanks again!