Construction tolerances - window built to wrong size

[lek28]

We are in the process of renovating a Grade II listed early Victorian house, and the builders have put in a window that is the wrong size.

There was previously a small window on the ground floor outrigger (approx 46cm x 70cm), and permission was granted to enlarge this to match another window on the second floor. The planning application specifically described "Replacing the window in the ground floor closet wing with a new window to match the existing window on the 2nd floor above to enhance the symmetry of the outrigger"

On the plans on which planning permission and listed building consent were granted (both the proposed plans and demolition plans), the new GF window was drawn in proportion to the second floor window as intended.

The second floor window is 59cm x 127cm. However, the window that was actually installed is only 46cm x 110cm. 

 

What seems to have happened is that on the 'as existing' plans (done by the D&B company), the GF window was drawn out of proportion so that it was the same width as the second floor window, so in the demolition overlay it only looks like the window needs to be lengthened rather than made wider. The D&B company's argument is that the window was never intended to be made wider and that they have made the window longer and any variations are just rounding errors. 

I know that there is always some acceptable level of variation versus plans, but is there a potential (credible) argument that this level of variation might be acceptable based on generally accepted construction standards? (The length is off by 13% or 17cm and the width is off by 22% or 13cm.) We have a JCR homeowners contract if that’s relevant.

Thanks in advance for any thoughts/advice!

 

Edited August 13, 2020 by lek28

[joe90]

I think that is unacceptable, one reason to make sure any project management is spot on. Not sure how you stand tho.

[the_r_sole]

is there a drawing which shows the existing and the proposed window, I can't understand how it could be confused to not widening the window if it's to match a wider window. 

As you say you have a contract (JCT) then there must be documents forming the contract, specifications/drawings etc? 

[lek28]

1 hour ago, the_r_sole said:

is there a drawing which shows the existing and the proposed window, I can't understand how it could be confused to not widening the window if it's to match a wider window. 

As you say you have a contract (JCT) then there must be documents forming the contract, specifications/drawings etc? 

 

Yes, there were Stage 4A and 4B drawings, but these were actually identical to what was submitted to planning. The only incremental piece of (non-)information was a "Proposed Window Schedule." However, here the window was put down as S/O "As Existing" and Type as "Refurb", which was clearly an error since they did install a new window.... We never the saw the actual construction drawings where the new window with the wrong dimensions might have been included (by the D&B company). 

 

 

[lek28]

2 hours ago, joe90 said:

I think that is unacceptable, one reason to make sure any project management is spot on. Not sure how you stand tho.

 

For sure on the project management piece! 

 

Is there an accepted threshold for variances that I could point to in arguing that the window is not to spec and needs to be remedied? 

[joe90]

 

11 minutes ago, lek28 said:

We never the saw the actual construction drawings where the new window with the wrong dimensions might have been included (by the D&B company). 

so “d@b” did not follow what the planners specified ,!!

[the_r_sole]

who produced the window schedule, it's a bit of an usual arrangement to have the jct homeowners contract to do a D&B contract...

The thing that worries me is that if the schedule forms part of the contract then you will have difficulty getting it sorted, even if they haven't built what's on the schedule, the right thing wasn't on the schedule either!

Did you have planning permission and building regs approval before starting work? and did the contractor do all those?

[Bored Shopper]

From our experience, builders do not refer to drawings / visuals as often as you'd like them to.

We've had issues with wrongly positioned windows etc, ended up nailing post-it notes to critical areas saying "IMPORTANT! this should be xxx and xxx, refer to drawing or call us". This worked.

[lek28]

24 minutes ago, joe90 said:

 

so “d@b” did not follow what the planners specified ,!!

 

Exactly... Although their argument is they made the window longer and in a matching style to the second floor one and that the drawings/plans they did were not intended to be that accurate. 

 

 

[lek28]

17 minutes ago, the_r_sole said:

who produced the window schedule, it's a bit of an usual arrangement to have the jct homeowners contract to do a D&B contract...

The thing that worries me is that if the schedule forms part of the contract then you will have difficulty getting it sorted, even if they haven't built what's on the schedule, the right thing wasn't on the schedule either!

Did you have planning permission and building regs approval before starting work? and did the contractor do all those?

We used a design and build company who has done everything including the initial 'as existing' drawings, planning applications, detailed design drawings (including window schedule), project management and construction. (We have an independent QS to keep them honest and used a separate structural engineer.) We did get planning permission before starting and have had an independent building regs firm along the way to confirm compliance. 

 

We only realised the contractual bit after the fact, but what we actually signed was a RIBA architect appointment letter, JCT homeowners contract and side letter tying it all together. 

[joe90]

1 hour ago, lek28 said:

the drawings/plans they did were not intended to be that accurate. 

ha, I know you cannot scale from a drawing (accurately) but they should have dimensions. So this company did everything?. Did you pass to them the planning permission you got? Did it include.......

 

4 hours ago, lek28 said:

Replacing the window in the ground floor closet wing with a new window to match the existing window on the 2nd floor above to enhance the symmetry of the outrigger"

if so I would get the planners out to complain to “d@b” that they have not abided by the planning application.

[lek28]

1 hour ago, joe90 said:

ha, I know you cannot scale from a drawing (accurately) but they should have dimensions. So this company did everything?. Did you pass to them the planning permission you got? Did it include.......

 

Yes, they even did the planning application themselves!

[joe90]

6 minutes ago, lek28 said:

Yes, they even did the planning application themselves!

then they have no excuse for not knowing what the planners specified (get the planners on your side and get them round ?)

[Temp]

4 hours ago, lek28 said:

 

Is there an accepted threshold for variances that I could point to in arguing that the window is not to spec and needs to be remedied? 

 

Typically you measure the opening and subtract 10mm (5mm each side and top and bottom) to allow for manufacturing tolerances. But the issue isn't a manufacturing tolerance issue but a spec issue.

 

7 hours ago, lek28 said:

The planning application specifically described "Replacing the window in the ground floor closet wing with a new window to match the existing window on the 2nd floor above to enhance the symmetry of the outrigger"

 

In no way can 46 x 110 be said to "match" 59 x 127.  

 

When you have one window above another, as you do here,  the Architecturally  "right" thing would normally be to match the width. The height normally being less critical. Its common to have higher ceilings and windows on some floors ...

 

 

If the windows are side by side then the height would normally be the thing to match.

 

PS  no thats not my house.

Edited August 13, 2020 by Temp

[Simplysimon]

1 hour ago, Temp said:

 

Typically you measure the opening and subtract 10mm (5mm each side and top and bottom) to allow for manufacturing tolerances. But the issue isn't a manufacturing tolerance issue but a spec issue.

 

 

In no way can 46 x 110 be said to "match" 59 x 127.  

 

When you have one window above another, as you do here,  the Architecturally  "right" thing would normally be to match the width. The height normally being less critical. Its common to have higher ceilings and windows on some floors ...

 

 

If the windows are side by side then the height would normally be the thing to match.

 

PS  no thats not my house

his is off left, just out of shot ?

[lek28]

15 hours ago, Temp said:

Typically you measure the opening and subtract 10mm (5mm each side and top and bottom) to allow for manufacturing tolerances. But the issue isn't a manufacturing tolerance issue but a spec issue.

 

In no way can 46 x 110 be said to "match" 59 x 127.  

 

When you have one window above another, as you do here,  the Architecturally  "right" thing would normally be to match the width. The height normally being less critical. Its common to have higher ceilings and windows on some floors ..

 

Super helpful, thanks!!