Do we need to amend our planning permission; builder says yes, architect says no!

[Whyismycatanasshat]

We were granted planning permission last year to extend the rear of my (rented out) house adding a kitchen and utility space.
a bit of backstory…
The current tenants are wonderful and have been in the property for years and are delighted to be gaining a larger kitchen and utility room where the previous owner to me had a shoddy car port that covered half the rear window and we ripped out due to it being unsafe (tenants where in situ then and glad to see it gone as they were worried about it collapsing as well as blocking light.
I see this property as my retirement fund so have no issues developing it.

The builder started last week; my tenants have asked if they could have an outside tap and plug added to the build (they offered to pay, I said no, we’d happily cover this cost - good tenants are hard to find and I have no issue adding this for them) and my builder has told me and them that it can’t be done, we’d need to change the planning permission. My architect/building consultant is adamant it’s not necessary and they can just have it added! The builder has also said we can’t have the water inlet or outlet fitted for the washing machine or a vent for a tumble drier put in the utility because it’s not on the plans…

Is my builder being difficult or is he right? He came highly recommended and the work of his we’ve seen are a great standard!
Thanks!

I suspect your builder does not mean planning permission but rather building regulations permission.
Dicc DD you apply to your council to have building regs? Or are you using an external company

Ring the Council planning office and quickly ask them, they should tell you there and then if you need to do anything more

It has zero to do with planning permission
Electrics have to be linked up by a 'competent person' and that is it as far as any regulations exist - no need for any permission for any of that

If you have an architect managing this project, just ask for the change to be made and leave it up to them.

None of those things if done separately would need planning permission so I don’t see why this would be the case?

Thanks everyone.
The plot thickens in that, I’ve spoken to the builder again (the house is not where we live) and he’s adamant the planning permission must be amended for the building regs. The architect disagrees. I can’t get through to the council! I’ve sent them an email but the auto response says allow 10 working days for a reply.

I will tell my tenants that if the builder won’t do these things, the handyman I use will and we’ll sort it out that way. I text the handyman and he said “no problem!” to any of the jobs the builder won’t do.

I hope I’ve not chosen the wrong builder.

Planner here - assuming it's not a listed building and you don't live in a Conservation Area, the planners will not be interested in an extra tap or plug nor water inlets/outlets.

There may be implications under building regs, but you do not need to amend your planning permission.

@Whyismycatanasshat
These are not planning issues. Ask Architect about building regs but unlikely. We put in both electrics and tap when we did a few amendments. No one cares.

@Seeline Thank you for confirming all of my research. It’s a 1960s built, former council house so absolutely nothing of any interest about it; other than mine is one of the few without the extension I’m having done, or similar, added already.

@TizerorFizz the Architect assured me the building regs are also unaffected, he laughingly said I’ve chosen a builder who can’t be wrong.

@Whyismycatanasshat
They are useful additions though. Plus electric car charger. We just added that too. Plus a swimming pool. That didn’t need planning either.

@TizerorFizz I’d not thought of an electric vehicle point; great idea.
Swimming pool might be a waste in the North East of England though!