Measurement Tolerances: Design vs Build

[Gaf]

Wasn’t sure where best to post this.

 

Are there generally accepted measurement tolerances for the finished build in comparison to the design?

 

Our construction drawings have our finished concrete floor to ceiling at 255cm. Build has it at 247cm. I know, not exactly a huge amount. Only reason I checked was when I walked in to the rooms the ceilings ‘felt’ low. 

[joe90]

  On 29/12/2024 at 09:03, Gaf said:

concrete floor to ceiling at 255cm. Build has it at 247cm

Expand  

I would find that unacceptable, about 4 inches (in old money) 

[DevilDamo]

It is common for dimensions to fluctuate during the construction process but near on to 100mm is quite a lot. Why have the builders gone in lower? Any structural or significantly increased costs in doing so? How does that affect the other floor(s)?

[saveasteading]

  On 29/12/2024 at 09:03, Gaf said:

 

Are there generally accepted measurement tolerances 

 

Our construction drawings have our finished concrete floor to ceiling at 255cm. Build has it at 247cm. I know, not exactly a huge amount

Expand  

Yes that is huge. 

I wonder if this has 'happened' because they used 2.4m studs without thought. Then 2.4m plasterboard fitted too.

Or deliberately because it's easier and cheaper.

A high ceiling has quite a cost effect, in stud, boarding and possibly structurally.

And the stairs need an extra step.

You should insist on it being corrected or get a discount.

 

[Redbeard]

Is this a whole house or an extension? A slight hiccup on a one-room single-storey extension might be understandable (though not very, to be honest) but a bit more critical on a whole house. I think I'd be a bit fed up with 10mm. 

  On 29/12/2024 at 11:06, saveasteading said:

Yes that is huge. 

Expand  

 

Agree wholeheartedly.

[Gaf]

  On 29/12/2024 at 10:37, DevilDamo said:

It is common for dimensions to fluctuate during the construction process but near on to 100mm is quite a lot. Why have the builders gone in lower? Any structural or significantly increased costs in doing so? How does that affect the other floor(s)?

Expand  

 

At the moment I’ve no idea why this was done. The first floor is concrete slab and I was so focused on the ground floor I never checked the upper floor to ceiling height.

 

  On 29/12/2024 at 11:06, saveasteading said:

Yes that is huge. 

I wonder if this has 'happened' because they used 2.4m studs without thought. Then 2.4m plasterboard fitted too.

Or deliberately because it's easier and cheaper.

A high ceiling has quite a cost effect, in stud, boarding and possibly structurally.

And the stairs need an extra step.

You should insist on it being corrected or get a discount.

 

Expand  

 

The first floor is concrete slabs and (from Googling) they’re using the metal MF Ceiling Stud system.

 

Yeah a couple of things have cropped up that I have to get corrected, this is another on the list. 🫠

 

  On 29/12/2024 at 11:51, Redbeard said:

Is this a whole house or an extension? A slight hiccup on a one-room single-storey extension might be understandable (though not very, to be honest) but a bit more critical on a whole house. I think I'd be a bit fed up with 10mm. 

 

Agree wholeheartedly.

Expand  

 

It’s this 247cm height across the whole downstairs area >100m2.

 

Edited December 29, 2024 by Gaf

[ProDave]

  On 29/12/2024 at 12:22, Gaf said:

The first floor is concrete slabs and (from Googling) they’re using the metal MF Ceiling Stud system.

Expand  

so is your "wrong" ceiling height measured from the floor to the underside of the concrete first floor?  Or measured from the floor to the suspended MF ceiling?

[saveasteading]

  On 29/12/2024 at 12:22, Gaf said:

first floor is concrete slabs

Expand  

OK. So ignore my stud and plasterboard theory. They've simply got it wrong. Perhaps measured to the plank and forgot the ceiling.

It's tricky to fix these ceilings with a small gap.

 

Of course don't get legal unnecessarily. But a judge or arbitrator would award you the cost difference, and nothing or little for the amenity. 

So the area of walls, plus the stair cost difference.

[Gaf]

  On 29/12/2024 at 12:30, ProDave said:

so is your "wrong" ceiling height measured from the floor to the underside of the concrete first floor?  Or measured from the floor to the suspended MF ceiling?

Expand  

 

It’s the measurement from the finished concrete floor to the plasterboard that has been installed onto to the MF ceiling. So bat the skim coat to go on, it’s the floor to finished ceiling height.

 

 

Edited December 29, 2024 by Gaf

[ProDave]

  On 29/12/2024 at 14:04, Gaf said:

 

It’s the measurement from the finished concrete floor to the plasterboard that has been installed onto to the MF ceiling. So bat the skim coat to go on, it’s the floor to finished ceiling height.

 

 

Expand  

So is there scope to reduce the drop of the MF ceiling to get closer to what you want?

[Gaf]

  On 29/12/2024 at 14:11, ProDave said:

So is there scope to reduce the drop of the MF ceiling to get closer to what you want?

Expand  

 Current service void. I didn’t measure it but looks like plenty of scope.

 

 

[joe90]

That’s a big service void IMO.

[ProDave]

You are on a hiding to nothing if you try getting the ceiling concrete first floor raised, but there looks to be scope to reduce the depth of the service void by raising the MF ceiling frame.  Just work out how much you need in the service void (mvhr ducts, drain runs etc) then get them to raise it as much as possible.  That really is the only viable compromise they are likely to agree with.

[Gaf]

  On 29/12/2024 at 14:23, ProDave said:

You are on a hiding to nothing if you try getting the ceiling concrete first floor raised, but there looks to be scope to reduce the depth of the service void by raising the MF ceiling frame.  Just work out how much you need in the service void (mvhr ducts, drain runs etc) then get them to raise it as much as possible.  That really is the only viable compromise they are likely to agree with.

Expand  

 

Oh yeah I know there’s no chance in hell the concrete slabs are moving at this stage (whole house structure is done, roof tiled, external rendered). Scope there for the MF ceiling by the looks.

[saveasteading]

Is there a main contractor who brought in a ceiling fitter and didn't tell them  the spec?

Is it absolutely clear what clear height you required? Some drawings can be vague on such things.

It looks as if they had room to get this right but didn't think or know about your spec.

[DevilDamo]

If there is scope to reduce the void (making sure you accommodate any services), then that’ll be your best route. Even if it’s 50mm.

[Gaf]

  On 29/12/2024 at 16:03, saveasteading said:

Is there a main contractor who brought in a ceiling fitter and didn't tell them  the spec?

Is it absolutely clear what clear height you required? Some drawings can be vague on such things.

It looks as if they had room to get this right but didn't think or know about your spec.

Expand  

That does seem possible alright. Attached is one example of a cross section on our construction drawings. Each cross-section construction drawing includes the 255 measurement.

 

Edited December 29, 2024 by Gaf

[joe90]

Yes 2550 to ceiling but no dimension to under concrete floor? The contractor needs asking why?

[Gaf]

  On 29/12/2024 at 18:15, joe90 said:

Yes 2550 to ceiling but no dimension to under concrete floor? The contractor needs asking why?

Expand  

I just clipped the previous image.

[Gaf]

  On 29/12/2024 at 18:15, joe90 said:

Yes 2550 to ceiling but no dimension to under concrete floor? The contractor needs asking why?

Expand  

Sorry I may be misreading your question, is it that it looked like the drawings didnt have the depth of the floor makeup? 

[joe90]

  On 29/12/2024 at 18:26, Gaf said:

Sorry I may be misreading your question, is it that it looked like the drawings didnt have the depth of the floor makeup? 

Expand  

No I was just questioning how the builder knew where to put the upstairs concrete floor? Is that too low? Therefore lower ceiling ground floor. However you did specify lower room height which they got wrong. 

[DevilDamo]

  On 29/12/2024 at 19:21, joe90 said:

how the builder knew where to put the upstairs concrete floor?

Expand  

One would only assume they added up the dimensions (3m) and subtracted the depth of the first floor finishes from a specification.

[joe90]

Whatever we/they assumed it’s wrong. As said above the only practicsl solution is to reduce the service void as much as possible but I still think the builder needs to be asked how this mistake was made.

Edited December 29, 2024 by joe90

[Gaf]

  On 29/12/2024 at 19:46, DevilDamo said:

One would only assume they added up the dimensions (3m) and subtracted the depth of the first floor finishes from a specification.

Expand  

 

  On 29/12/2024 at 20:22, joe90 said:

Whatever we/they assumed it’s wrong. As said above the only practicsl solution is to reduce the service void as much as possible but I still think the builder needs to be asked how this mistake was made.

Expand  

 

Full cross section if it sheds any more light on how the measurements could have been missed.

 

Im not a builder but I reckon there isn’t much missing from this to cause the ceilings measurements on the final build to be too low.

 

Edited December 29, 2024 by Gaf

[joe90]

  On 29/12/2024 at 20:28, Gaf said:

Im not a builder but I reckon there isn’t much missing from this to cause the ceilings measurements on the final build to be too low.

Expand  

Quite, builder made a mistake, how he made that mistake is not relevant, you have proof in your drawings. You need (IMO) to point this out to them/him/her. Practically the only solution/compromise is reduce the service void rather than knock a concrete floor out. As a matter of interest what is the height of the upper floor? Is that one accurate?