It’s one of the lesser repairs!
- Thread starter DampedOut
- Start date
Right, makes sense! Our own stone walls have simple soft clay bedding mortar and they do just fine! That’s it, I’m doing it. When we do our foam glass + lime slab floor I’m going to use NHL 3.5.
There have been recent studies that show while StA has a good free lime %age, its setting strength is higher than quoted and more so than other NHLs. My concern with the NHLs is less about their compressive strength and more their ability to squidge and squirm a bit as required without cracking.
The last but one limectete floor I laid was also 3.5 - it was an entrance hallway, no load on it, helping the almost non existent brick wall footings a bit if you stretch your imagination, but frankly it used to be bricks on earth which could move and settle as they wished. We had it uncovered almost a year before the brick pavers went down, never saw anything untoward. That was admittedly laid on a bone dry dusty sub floor.
The kitchen I have just laid, we actual used 5, this was probably more swayed by the fact I needed to erect a scaffold birdcage on it after a few weeks, to pick up the roof and floor above, so more compressive strength probably crept into my thinking. We also had to delay laying it for a few weeks as the water levels under are high and the initial RFG floated like a lilo once compacted and the rains came before we got the slab down.
With the best will in the world, the compacted RFG will always have some movement in it under the slab. I view the slab as almost holding that stuff in place.
In reality, I expect you could use any of the three bags…. But more importantly get the aggregate sizing correct and also fibres to help it knit together well, especially if it might be a shallow slab.
The last but one limectete floor I laid was also 3.5 - it was an entrance hallway, no load on it, helping the almost non existent brick wall footings a bit if you stretch your imagination, but frankly it used to be bricks on earth which could move and settle as they wished. We had it uncovered almost a year before the brick pavers went down, never saw anything untoward. That was admittedly laid on a bone dry dusty sub floor.
The kitchen I have just laid, we actual used 5, this was probably more swayed by the fact I needed to erect a scaffold birdcage on it after a few weeks, to pick up the roof and floor above, so more compressive strength probably crept into my thinking. We also had to delay laying it for a few weeks as the water levels under are high and the initial RFG floated like a lilo once compacted and the rains came before we got the slab down.
With the best will in the world, the compacted RFG will always have some movement in it under the slab. I view the slab as almost holding that stuff in place.
In reality, I expect you could use any of the three bags…. But more importantly get the aggregate sizing correct and also fibres to help it knit together well, especially if it might be a shallow slab.
Nice, good info thank you. What thickness is the lime-slab that you typically lay over the compacted foam-glass? What thickness would you recommend for a fibre-reinforced, St Astier NHL 3.5 slab laid over compacted foam-glass?
This floor I went with this time was 200mm RFG, ish. Then an initial 100mm slab, but I think we came up to 120mm. Plus I’ve got 60mm wiggle room for final floor finish, to be made of lime bedding and slabs, which will likely be 30mm. So all in, 200 RFG and about 150 limecrete.
Our depths were dictated by the FFL which had to align with existing and digging down to a sensible depth, which was around the top surface of the underlying limestone bedrock, so no desire to go deeper!
There are minimum depths recommended, for both layers, if I had to skimp it would be the limecrete slab, as the RFG needs to do the work and be a certain thickness to knit together when whacked to provide a stable compressed sub base.
We used the synthetic fibres from Eden in the ratios recommended and a decent 0-4mm washed aggregate.
We ended up getting the birdcage down after a couple of weeks with no ill effects, spread adequately on double scaff boards.
Our depths were dictated by the FFL which had to align with existing and digging down to a sensible depth, which was around the top surface of the underlying limestone bedrock, so no desire to go deeper!
There are minimum depths recommended, for both layers, if I had to skimp it would be the limecrete slab, as the RFG needs to do the work and be a certain thickness to knit together when whacked to provide a stable compressed sub base.
We used the synthetic fibres from Eden in the ratios recommended and a decent 0-4mm washed aggregate.
We ended up getting the birdcage down after a couple of weeks with no ill effects, spread adequately on double scaff boards.