I live in Cornwall and have had a replacement floor installed in the dining room (about 13 sq. metres). The old floor was excavated, a DPM laid, 4" of concrete, and about 2" of screed. Unfortunately the guy made a hash of it and the screed crumbled and had to be removed.
I have had several quotes to replace the screed but they all differ as to what should be done, and none inspire total confidence.
Most builders say they would lay a screed with a 3 to 1 mix. But one said that would not be strong enough and suggested 5 to 2.
Yet another, who comes from out of County, said that the building sand in Cornwall is cr*p. He says a 4 to 1 mix would be best as adding more cement only weakens the screed.
He also advised that the concrete underfloor is unsatisfactory because the guy did not excavate properly up to the edges of the walls and the concrete has hardly any depth at the edges. In fact in some spots the concrete ends before the edge of the walls. So he recommends laying a concrete floor rather than a screed because a screed won't be strong enough.
This seems sensible, but builders merchants advise me that if I'm going to lay concrete I should use ballast, not sand. But the bulk ballast they sell looks extremely rough with big lumps in it, and not suitable for a smooth finish.
The choice available in bulk in my area is grey (granite?) building sand, the grey rough ballast, sharp sand (which I haven't seen), or the more expensive yellow local sand (presumably from a beach).
I think it would be best to go for a concrete floor, but I would welcome advise on what sand/ballast to use, and what would be the best mix. Also would the finish be smooth enough for tiling?
I'm being very cautious about this because I don't want to have to dig the floor out again.
Thanks in advance.
Harry
I have had several quotes to replace the screed but they all differ as to what should be done, and none inspire total confidence.
Most builders say they would lay a screed with a 3 to 1 mix. But one said that would not be strong enough and suggested 5 to 2.
Yet another, who comes from out of County, said that the building sand in Cornwall is cr*p. He says a 4 to 1 mix would be best as adding more cement only weakens the screed.
He also advised that the concrete underfloor is unsatisfactory because the guy did not excavate properly up to the edges of the walls and the concrete has hardly any depth at the edges. In fact in some spots the concrete ends before the edge of the walls. So he recommends laying a concrete floor rather than a screed because a screed won't be strong enough.
This seems sensible, but builders merchants advise me that if I'm going to lay concrete I should use ballast, not sand. But the bulk ballast they sell looks extremely rough with big lumps in it, and not suitable for a smooth finish.
The choice available in bulk in my area is grey (granite?) building sand, the grey rough ballast, sharp sand (which I haven't seen), or the more expensive yellow local sand (presumably from a beach).
I think it would be best to go for a concrete floor, but I would welcome advise on what sand/ballast to use, and what would be the best mix. Also would the finish be smooth enough for tiling?
I'm being very cautious about this because I don't want to have to dig the floor out again.
Thanks in advance.
Harry