# Slight dimension change in planning drawings



## house (24 Feb 2010)

I have recently being granted planning and now wish to employ an engineer/architect to sign off the construction of my home. 

I wish to increase the cavity and increase the thickness of internal leaf of the external wall from 100mm to 150mm,  in turn this will increase the overall width of the house by 260mm, 

Will my new engineer enforce the original plans or are slight dimension changes acceptable?

This is a house in the country with plenty of space to the next property.

Thanks


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## onq (24 Feb 2010)

Ask your new engineer.

Who designed your house and lodged the application?

ONQ.


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## RKQ (24 Feb 2010)

This is a very interesting question and I'd be interested in peoples views.
On one hand planning permission is based on Gross Floor Area, which will not change if you increase the cavity width, however the roof ridge height _might_ increase, depending on the wallplate detail.

Personally, it could be argued that a total increase of 260mm is not a huge increase especially when it is done to improve heat retention, BER and Building Reg compliance. The structure could be in substancial compliance with planning permission.

Ask your Certifier and maybe ask your Planning Department for their opinion.


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## DBK100 (24 Feb 2010)

house said:


> Will my new engineer enforce the original plans or are slight dimension changes acceptable??  This is a house in the country with plenty of space to the next property. Thanks



If he is black & white about it he might say that your approved drawings are annotated with dimensions (- those of the external envelope & from the external faces to the site's boundaries -) and those dimensions govern exactly what you have permission for.

If he is pragmatic he might say that 260mm added to the main dimensions of a house is not a significant addition and he therefore might take the view that the slightly enlarged structure is in "_substantial compliance_".
"Substantial compliance" being the key words normally employed in an Architect's Certificate of Compliance.

That will come down to the particular individual's opinion.
Just ask the person you intend to engage.


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## house (25 Feb 2010)

another option i was thinking of was to go ahead with the slightly larger dimenison and then apply for retention planning? 

i will ask my engineer but i dont think i will be asking my planning offier (very unhelpful)

to answer onq we designed the house ourselves, i come from a construction background, and i got a freind to draw it up - the house currently meets building regs, i just was to better insulate!


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## xeresod (25 Feb 2010)

You could reduce the internal dimensions instead.


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## house (26 Feb 2010)

xeresod - thats thinking outside the box !! or inside in this case!! 

the first engineer i spoke to was unable to shed any light on the matter needless to say i told him not to bother quoting! 

what do you think of the retention planning permission route if there was a "problem"


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## Superman (26 Feb 2010)

house said:


> what do you think of the retention planning permission route if there was a "problem"


If there is a problem, this would be your only route possible.  

If your location is quite rural, then there is unlikely to be any problem and I would expect your engineer to run with it.  Being realistic, would 260mm extra affect the development of the area? 

If you wanted to be sure to be sure then contact the Planning Dept.


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## onq (27 Feb 2010)

house said:


> another option i was thinking of was to go ahead with the slightly larger dimenison and then apply for retention planning?
> 
> i will ask my engineer but i dont think i will be asking my planning offier (very unhelpful)
> 
> to answer onq we designed the house ourselves, i come from a construction background, and i got a freind to draw it up - the house currently meets building regs, i just was to better insulate!



If you're not formally trained to interpret the building regulations - and your late change to the cavity suggests this may be the case - how can you give that assurance?
I know plenty of people from a construction background who haven't a clue about the current Part L requirements, never mind Part F.

You would be wise to have the entire design checked before proceeding to site by someone competent to interpret ALL the building regulations, not just Part A Structure, the Engineer's speciality.

I also strongly urge you to agree any variation to permitted drawings with the local authority before you commence, because if the planner is as difficult as you've suggested, he could strictly interpret your permission and half work while you get retention permission.

Did you not see that programme on recently about the house being delayed 5 months due to planning "paperwork"?
Measure twice, cut once and stick to what you're good at 

[broken link removed]

All advice on AAM is remote from the situation and cannot be relied upon as a defence or support - in and of itself - should legal action be taken.
Competent persons should be asked to advise in Real Life with rights to inspect and issue reports on the matters at hand.
My best advice is that you should retain a competent building professional to advise you on these matters.


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