25–27mm dished beam-and-EPS structural ground floor — likely cause and remediation?

[sisturix]

20 minutes ago, saveasteading said:

What failed, exactly,  please?

 

The LVT installed started delaminating at the edges, but nothing really suddenly failed till I figured I'd rather have engineered wood floor and UFH, and that would need SR1. I was planning to groove the screed for UFH, but just decided to do a laser survey just in case. And that was catastrophic. However, floor was likely similar since I bought the house, seems i remember installing bookshelves and wondering why i need to shim so much, and noticing how skirting board is not the same height toward patios doors, etc.

 

20 minutes ago, saveasteading said:

If there is ongoing development you have enormous clout. First get more help on here, then visit the sales office.

 

 
It's not ongoing, but they have many other ongoing sites. I did have lots of other problems with the house, they change most floorboards upstairs, had to retrofit insulation, replaced ceiling boards, etc. I think house built during covid lockdowns like this ones are really problematic since they were left at whatever stage the lockdown caught them at.
 

 

20 minutes ago, saveasteading said:

Sorry to question this  but I'd question myself too..... are you sure the laser level is accurate?  They do go wrong.

 

Feels like even without the laser it's evident, repeatable pattern. The laser error is insignificant at the spans tested. I do like gadgets though, so can definitely hire some proper rotary laser and receiver. I also talked to some guys doing Ground Penetrating Radar surveys but they explained that it's not much of a use in this case

[-rick-]

2 minutes ago, sisturix said:

It's not ongoing, but they have many other ongoing sites. I did have lots of other problems with the house, they change most floorboards upstairs, had to retrofit insulation, replaced ceiling boards, etc. I think house built during covid lockdowns like this ones are really problematic since they were left at whatever stage the lockdown caught them at.

 

Well that's an unpleasant situation to be in. My sympathies.

 

This is the strongest argument for getting a professional in, primarily to look at the floor but also to look at everything else. Deal with everything while you still have a warranty. There were various things wrong with my place that I could have had NHBC deal with but didn't because I was dealing with the property manager of the block (leasehold flat) and initially thought the fixes were easy and now I can't. If you've already found so much wrong, what else is there?

[Nickfromwales]

Is the LVT failing due to the same bloke who screeded the floor laid it? 
 

Or, and this is important, is the slab surface becoming friable?

 

You can tell by seeing if the LVT and adhesive have screed material stuck to them, or has the LVT parted ways as the glue wasn’t used properly / contaminated slab / incorrect glue used?

[sisturix]

28 minutes ago, -rick- said:

 

Well that's an unpleasant situation to be in. My sympathies.

 

This is the strongest argument for getting a professional in, primarily to look at the floor but also to look at everything else. Deal with everything while you still have a warranty. There were various things wrong with my place that I could have had NHBC deal with but didn't because I was dealing with the property manager of the block (leasehold flat) and initially thought the fixes were easy and now I can't. If you've already found so much wrong, what else is there?

Yes, I think the issue is that the NHBC only covers structural things year 2-10, but I suppose the concrete screed is considered structural, and I also made developer aware of it in the first 2 years. I think / hope not much can go wrong, but in a nutshell I didn't have issues with the bricks / foundation yet, pretty much everything else required some intervention (floorboards, plumbing, ceilings, roof, insulation, windows, stairs, driveway, soakaway drainage). Best part was when site manager proposed to fix upstair floorboard by using glue as self leveller because that's what he had on site.

If I ever buy a new house again, I will get a proper surveyor to check everything. I'm also wondering why factory built houses like in Scandinavia is not a think in the UK. Feels like you have so much better tolerances and less issues overall.

[sisturix]

33 minutes ago, Nickfromwales said:

Is the LVT failing due to the same bloke who screeded the floor laid it? 
 

Or, and this is important, is the slab surface becoming friable?

 

You can tell by seeing if the LVT and adhesive have screed material stuck to them, or has the LVT parted ways as the glue wasn’t used properly / contaminated slab / incorrect glue used?

I think screed / concrete was laid by groundworks, while LVT was laid over a smoothing compound by a flooring contractor. I think the issue is the screed being not levelled, and LVR requiring SR1. I guess screed issue, but flooring contractor should have never accepted to lay the LVT given the subfloor issue (in my interpretation).

[Nickfromwales]

9 minutes ago, sisturix said:

I think screed / concrete was laid by groundworks, while LVT was laid over a smoothing compound by a flooring contractor. I think the issue is the screed being not levelled, and LVR requiring SR1. I guess screed issue, but flooring contractor should have never accepted to lay the LVT given the subfloor issue (in my interpretation).

LVT done via the developer? I guess so, as they clearly had to dial down their GAF and get this done “regardless”. 

[saveasteading]

33 minutes ago, sisturix said:

The problem with drilling is that I would compromise the DPM.

Whatever you do, don't touch the beams. they are reinforced by just a couple of tensioned wires,

These beams don't tend to curve much, unlike planks which curve up a lot. They are strong so won't be sagging. either

 

The existing slab that is intended to be 75mm  thick may only be 75mm - 27mm thick = 48mm in places.

The good news is that it is still stronger than the eps underneath it, and won't collapse. But either it is level and hiding that the beams are in wrongly, or it is on an extreme slope and your furniture will wobble, door clearances may be wrong, and simply look squint. I'd mostly be concerned that workmanship like that suggests other errors, like the mesh will be missing or on the bottom, and may have been left exposed.

 

The most important measure of acceptability for real use is with the straight edge. Getting a properly straight 3m edge usually involves  a costly spirit level although I recently used a dry-liner's C strut and that was good. For an offficial test you can lay it in any or every position , parallel to a wall or any other angle at all. The gap is measured not only by what shows under the middle or end when laid down , but also if you push down an end, if a big gap appears at the other end. 

I was talking to our floor tiler about some areas of our screed that are poor, but he said it was nothing compared to most floors he sees..... so poor levelling is standard.

 

If I had personally laid that slab so badly, or managed it badly, and it was my house, and it was definitely the only problem, then  I would relevel it with screed  because that will suffice. 2 people 1 day and disruption of course.

If it was for a client I would redo it or discuss the screeding option with them.

 

BUT If a housebuilder has done it then it is entirely their responsibility, including consequential losses like redoing skirtings, any wrong doors, especially patio doors, and of course a new floor covering. Plus removal of furniture, and some compensation.

They will resist as they have lots of practice in hiding problems.  Your gentle threats are of telling the press, or of putting up a banner saying, "come and see the quality of a non show-house here".

[Nickfromwales]

Just now, saveasteading said:

Whatever you do, don't touch the beams. they are reinforced by just a couple of tensioned wires,

These beams don't tend to curve much, unlike planks which curve up a lot. They are strong so won't be sagging. either

 

The existing slab that is intended to be 75mm  thick may only be 75mm - 27mm thick = 48mm in places.

The good news is that it is still stronger than the eps underneath it, and won't collapse. But either it is level and hiding that the beams are in wrongly, or it is on an extreme slope and your furniture will wobble, door clearances may be wrong, and simply look squint. I'd mostly be concerned that workmanship like that suggests other errors, like the mesh will be missing or on the bottom, and may have been left exposed.

 

The most important measure of acceptability for real use is with the straight edge. Getting a properly straight 3m edge usually involves  a costly spirit level although I recently used a dry-liner's C strut and that was good. For an offficial test you can lay it in any or every position , parallel to a wall or any other angle at all. The gap is measured not only by what shows under the middle or end when laid down , but also if you push down an end, if a big gap appears at the other end. 

I was talking to our floor tiler about some areas of our screed that are poor, but he said it was nothing compared to most floors he sees..... so poor levelling is standard.

 

If I had personally laid that slab so badly, or managed it badly, and it was my house, and it was definitely the only problem, then  I would relevel it with screed  because that will suffice. 2 people 1 day and disruption of course.

If it was for a client I would redo it or discuss the screeding option with them.

 

BUT If a housebuilder has done it then it is entirely their responsibility, including consequential losses like redoing skirtings, any wrong doors, especially patio doors, and of course a new floor covering. Plus removal of furniture, and some compensation.

They will resist as they have lots of practice in hiding problems.  Your gentle threats are of telling the press, or of putting up a banner saying, "come and see the quality of a non show-house here".

I hate seeing less than 40mm below / above the mesh. 

[saveasteading]

55 minutes ago, sisturix said:

I do like gadgets though

Good. To test your laser set it at one wall and take readings adjacent and as far away as you can. Then move it to a central position and do it again, to the same 2 points. The level difference should be the same. This is because the laser should be projecting horizontally but they sometimes go out, and so the error cancels out with equal distances.

[sisturix]

6 minutes ago, saveasteading said:

If I had personally laid that slab so badly, or managed it badly, and it was my house, and it was definitely the only problem, then  I would relevel it with screed  because that will suffice. 2 people 1 day and disruption of course.

If it was for a client I would redo it or discuss the screeding option with them.

I guess that is the part I'm really interested to find out. What type of screed would you use for that 0 to ~30mm depth, or would you increase level everywhere by a minimum of x mm.

I imagine redo-ing it required breaking up reinforced concrete, and I imagine that's very difficult but doable?

Probably the only catastrophic outcome would be the beams sagging over the limit, in which case I really don't know what can be done 🏗️

[saveasteading]

15 minutes ago, saveasteading said:

Your gentle threats

I helped some locals on a different but recurring matter. The housing association were horrible throughout, but eventually gave way when they knew this was not going to be fobbed off. BUT they were desperate to get the owners/tenants to sign a confidentially agreement. ie they had no interest in sorting it for others. Others 'found out'. 

Edited yesterday at 13:57 by saveasteading

[saveasteading]

1 minute ago, sisturix said:

redo-ing it required breaking up reinforced concrete

No you would leave it be. Others will advise on the material but is is standard stuff.

 

2 minutes ago, sisturix said:

the beams sagging over the limit,

They won't be sagging. 

If you jump up and down in the middle of the room do you feel movement? No? The eps would have to compress before the beams bounced. 10mm average of screed is only 10kg/m2  10 bags of sugar every m2.

[-rick-]

21 minutes ago, saveasteading said:

The existing slab that is intended to be 75mm  thick may only be 75mm - 27mm thick = 48mm in places.

 

My mental maths says this could be even thinner. B&B flooring usually has a small crest in the middle due to the prestress. If laid with blocks then some of that will come out, but with EPS theres not much weight to take it out. So if the crown is 10mm over the room and now the depression is 27mm, you could potentially have a thickness of less than 40mm.

 

@sisturix suggested that self levelling might have been used in the past to correct earlier defects. If so, then the thickness of the slab might be worse, or this is evidence that something moved since it was done.

 

What would be the impact if one of the prestressed beams wasn't bedded at the ends properly and one end failed during the concrete pour? Is the slab with reinforcements sufficient to not care? The skirting board being all over the place and levels around the edge of the room being off doesn't seem great.

 

Having said that if the floor feels solid jumping up and down on it, it probably is.

 

[saveasteading]

1 hour ago, -rick- said:

could be even thinner

True. The beams I have used were pretty straight because there were  wires at top and bottom, but some curve or wobble is inevitable. Plus there are changes at joints in the eps.

Anyway we don't want to worry @sisturix unnecessarily. Nobody is going to fall through eps let alone with thin screed over it

 

Even if the lvt is out of warranty the floor can't be levelled without replacing it. So they can pay.

 

Or you could agree to tiling if you fancy it, as one contractor could sort it.

 

To pick up another worry. If a beam had moved then there would be dips and big cracks near that point. It's unlikely.

[sisturix]

Thank you @saveasteading @-rick- @Nickfromwales! Feels like the consensus on cause is very poorly laid concrete, and the solution would be to do a new pour to bring it up to flat (with whatever compound fits in this case). After that I guess I can do UFH on top of it. 

And a choice between forcing my patience with developer / NHBC and potentially getting it paid for or at least not invalidating warranty vs implementing it myself.

The only "non-destructive" solution I came across to solve it would be Fermacell Dry Levelling Compound (granules) + fermacell Therm25 boards for the UFH (gypsum) + another gypsum board on top. Sounds good in theory, but it's super expensive, and it will force changes to entrance door and staircase. I guess always good to have a plan B.

[saveasteading]

6 hours ago, sisturix said:

plan B.

The ufh can be within the screed so it's just more screed rather than adding  boards.

@Nickfromwales or @ a.n.other may know how to fix pipes down to screed.

You can stick or screw down straps that pipes click into, or the egg-box-like stuff.

 

Stroppy me would get it all paid by the developer OR you take money because you don't trust them.

[-rick-]

8 minutes ago, sisturix said:

Feels like the consensus on cause is very poorly laid concrete, and the solution would be to do a new pour to bring it up to flat (with whatever compound fits in this case).

 I think that's broadly right. For me personally though, for the few hundred quid it would cost I'd still favour getting an SE in to look around and see if they can see anything of concern (not just this particular floor given the other issues you've had). Obviously if the SE has concerns a more detailed investigation would cost more but a first visit look around won't be too pricey.

[saveasteading]

25 minutes ago, -rick- said:

I'd still favour getting an SE in to look around and see if they can see anything of concern (not just this particular floor)

Me too. I'd do it free if you were near. Because it can be an informal assessment without a formal report.

'Can't possibly commit or comment without full drawings and perhaps some tests , but I haven't seen anything obvious' sort of thing.

If they do have concerns then it could escalate of course.

 

You should be aware of course that all of us on here are in that boat... we don't know what we don't know.

[sisturix]

44 minutes ago, saveasteading said:

The ufh can be within the screed so it's just more screed rather than adding  boards.

I think my concern was to have broadly the same level over the pipes, but I suppose if I fix those to screed I could find a way to have pipes at roughly the same level to the final floor surface! This would indeed simplify things a lot, since I won't have a concern about minimum level for screed over the current high points.

[sisturix]

16 minutes ago, saveasteading said:

Me too. I'd do it free if you were near. Because it can be an informal assessment without a formal report.

 

Really appreciate it! I will try to get a SE to do an assessment, and post the conclusions here.