Gibdog Posted February 21 Posted February 21 Hi there Buildhubbers, Hoping someone might be able to offer some advice. We've excavated (for a raft slab) and are now backfilling but the engineer/groundworks team have marked FFL below the level of the surrounding area (triple checked with laser against fixed points on road and pavement). I attach a couple of pics looking east and west showing the FFL (blue line). Both neighbours' FFL would be higher and, to make ours 150mm above ground level, it will require reducing the surrounding ground which just doesn't sound right to me. I've attached our topo survey and a screenshot of the architect's section detail - FFL is set to 100.15. Can anyone help/comment...?! I feel like there must be a simple answer but I'm flummoxed!
lizzieuk1 Posted February 27 Posted February 27 Gibdog - cant help with the query but your details aren't redacted on the pdf. 1
Canski Posted February 27 Posted February 27 That seems odd. Did your engineer not take the DPC levels of the adjacent houses ? Higher is better than lower but not for the muck away guys.
Mr Punter Posted February 27 Posted February 27 Something very strange here. Like @Canski says, survey should have included the neighbouring buildings. On the basis that the surrounding ground on the survey is about 100.00 and your FFL is 100.15, the blue lines are wrong if they are FFL. Maybe they are reduced dig levels or top of foundation or slab and you have insulation, screed and finishes on top?
Russell griffiths Posted February 27 Posted February 27 Looking at the topo your ffl is more or less exactly the same as outside ground level. this should have been picked up ages ago. do you have elevation drawings showing how the house sits in the plot. I would stop work, your ffl needs lifting 300mm or more depending on what you want. do you have any ridge height restrictions for planning.
Gibdog Posted February 27 Author Posted February 27 Ah thanks for jumping in on this everyone. We did more checks and the topo was wrong - they had marked a fixed point in the pavement incorrectly. I'm trying to get them to at least refund the cost of the survey given the extra costs we've now incurred to backfill it to the correct level. Pretty annoyed as I kept telling the GW team that it wasn't right and the guys on site agreed but the head guy assured me his engineer had tripled checked it all and our architects must have designed it to be lower. My first big lesson! Having to tell myself that BC might have asked us to dig that deep anyway to find the right ground.
Gibdog Posted February 27 Author Posted February 27 Just now, Canski said: Room for more insulation ? That would have been good! But already doing a passive raft foundation...
Mr Punter Posted March 3 Posted March 3 On 27/02/2025 at 13:39, Gibdog said: the topo was wrong The topo looks OK. What is wrong with it? It looks like the site setout was wrong.
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