How sloped is too sloped?

newparent77

My parents have recently had an extension built, flooring laid etc. It looks great, but when I was in there in felt like there was a slight slope towards one of the walls - nothing major but noticeable I thought. I laid a 60cm spirit level and it is out, with the bubble lying as in the photo below. I don't think my parents are that bothered really so it's not a disaster, but it got me wondering, how tolerant would you be of a floor where, at its worst, the bubble of a spirit level was slightly touching one of the lines?

Section62

newparent77 said:

...I laid a 60cm spirit level and it is out, with the bubble lying as in the photo below. I don't think my parents are that bothered really so it's not a disaster, but it got me wondering, how tolerant would you be of a floor where, at its worst, the bubble of a spirit level was slightly touching one of the lines?

Did you check the spirit level for accuracy?  I.e. turn it through 180 degrees and see if it gives you the same result?

Different types of spirit level have different sensitivities, so one kind could show 'level' whilst another on the exact same surface could have the bubble off the scale.

It is also virtually impossible to get surfaces exactly level, so the norm would be to specify in terms of a difference of no more than 'x' mm in a distance of 'y'.  If not specified in the contract, industry norms could be applied to determine whether the quality of the workmanship was appropriate in the circumstances.

Alderbank

The NHBC standard for new homes is

• level within a 3mm deviation per 1m for floors up to 6m across (measured at the furthest points across the full width of the floor)

• a maximum of 20mm out of level for floors over 6m across

• flat within a ±5mm deviation, measured using a 2m straight edge with equal offsets.

Allowing for parallax your bubble looks to be within the two lines. I would not be too concerned about that.

I notice what looks like laminate flooring? For laminate, level as in no undulations is as important as level as in no slope. The tolerance for laminate flooring is often <4mm per metre hence the NHBC standard of 3mm. Larger undulations would not be absorbed by the underlay and the floor would feel springy underfoot.

stuart45

NHBC standards for floors are 3mm in a metre, in a 6 metre or less width.
20mm max overall if it's more than 6 metres.
Have you reversed the level to check it's accuracy?

newparent77

Thanks all! Level seems to be accurate, or at least consistent anyway. The bubble is slightly over one of the lines (the one on the right) but then when you move it along it does go a bit more central, this is just where it is at its worst.

The flooring is LVT - I think the subfloor was screeded before installation, it feels solid enough, no obvious bumps or anything like that.

Obviously without a 2m level it might be hard to properly find out how out it is. As mentioned, no-one else seems too bothered by it, it just got me thinking!

stuart45

The shorter the level, the less accurate it will be. If you have a straight edge it can work will a smaller level. 
With a 2 metre straight edge the max dip is 5mm.

EssexExile

We have floors much worse than that, you get used to it.

diystarter7

Hi OP

From what others have said here and what yuo said re your parents, please just let them enjoy the extension. You too can enjoy it and as you said it looks "great."

Unless there is a major problem, let it slip.

I'm a bit like you, have an eye for things that are not bang on, but you will get used to it.

Good luck

GDB2222

You really need to hold one end of the level up, so that the bubble is central. Then measure the gap at the raised end.

newparent77

Thanks everyone who responded to this. For those interested, I had completely forgotten that I had a self-levelling laser level at the back of the shed so out of interest dug it out.

I set it up at the highest point and pointed it to the other wall, where I feel like I can feel the slope. Let it self level and then measured the height of the laser mark right in front of the level, and then where it projected onto the opposite wall.

Over a span of about 3.36m, it appears to be about 22mm lower on one side - way over the recommended 3mm per metre from the NHBC (which I assume means the drop should be no more than about 10mm?).

Anyway, it isn't my extension and parents don't seem to mind so I haven't said anything. Just a bit gutted on their behalf that it seems way over!

Please let me know if there's any flaws in my methodology here. Anyway, photo below of the laser against the run of the slope, which I think demonstrates it better.

Alderbank

My 30-year-old nephew recently sold the house he had lived in since birth and asked me to give it a 'once over'.
He was very surprised when I showed him a similar slope in the dining room, which he had never noticed in 30 years.
Since parents don't mind, I wouldn't worry.