Flat roof on our/neighbours garages

[flumpybear]

Hi - we have a garage joint to our neighbours garage - both stand alone, so not attached to either house, just to each other

The roof is flat, there is a
Drainpipe outlet on their side so the roof is sloped that direction slightly.

It's not draining because something has happened on their side so it's pooling with water now encroaching into our side. Our builders (having renovation) happened to see this (the house is being renovated, garage is detached so they're not doing anything with the garage)

Builders say it's about 3 inches deep now on our side and it may bust under the strain - is this a joint problem, or is it something their side needs to sort out?

One problem is we don't get on, so want facts to make sure I approach it correctly - they don't live there so use it as a lock up and only see it every few months
Thank you

Probably a blocked drainpipe.

I'd email them and tell them you're taking remedial action. If cost is a bother to you then offer to pay half otherwise just pay it yourself.

I think it's the roof on their side is lower than the outlet pipe at the top -
There has been a problem for years with this - the neighbour before had sorted it but it's back again

Definitely not blocked, it's that it's too low to reach the exit at roof level (IYSWIM)

Our builders said 'it's their problem' but I want to be sure before we agree to pay thousands possibly towards their roof problem

Surely the guttering just needs adjusting? Why would it be thousands?

Could you ask your builder to put something in writing that you can forward to them? Keep a trail of what's said in case it all blows up (figuratively speaking). Have you much of value in your garage? I take it you have insurance?

If they aren’t living there I’d get up yourself on a ladder and have a good look around given it’s a single story flat roof.

@Herocomplex - I think it's more structural

Yes got insurance

Nothing in the garage as we've moved out whilst the work is taking place - few bits of building materials but the garage is mainly used as a conduit to the garden for the build so nothing stored in it

@BlueSkiesLies - builders, building inspector and my husband all looked already and said it needs proper attention and essentially the while roofing is at risk because this exit point is not working because of the roofing around it - without stripping it back and compromising the roof it isn't clear exactly what needs doing - but it's their roof so we can't do it

@LizzieMacQueen - yes alwaysnkeep correspondences and I have a video from the builders
Not looking forward to forwarding the info as the owners can be very nasty and very rude - they're bullies to be frank and I stand up to it and don't buckle but it's stressful dealing with them at the best of times let alone when it's not clear if jointly it needs fixing (and our build is very expensive as it is! )

Ok, that sounds a bit more complicated than just sorting out an exit point on your side.

Hope you can come to an agreement of how to proceed with your neighbours

Oh, I see. Sounds difficult!