Damp next to back door

[Movingtonumber4]

Could a badly fitted uPVC door be the explanation for these damp patches next to the door? @pigletjohn can you help?

Photos

Maybe. Stand back and take some wider pics please. Inside and out. Up to the top and sides of the doorframe and the sill, and all the way up to the roof, especially gutters, downpipes, drains, and puddles against the house.

Thanks.
Here's some more pics.

And a couple more.

have a good look at the gutter above the door during and after rain. Does it drip?

pour some water on the doorstep

does it run towards the house or away?

is that a waste pipe built into the steps?

is the kitchen floor concrete? Are there water pipes buried in it?

The pipe you can see in the steps is labelled gas.
I will check the gutter above the door. Next time it rains, and will try pouring water on the step tomorrow morning.
The kitchen floor is concrete (the rest of the house is floorboards), I don't know if there are water pipes underneath it or not.

looking at the wall side-on to the steps, above the airbrick, I can see some marks suggesting previous chemical injection. I can also see long-term moss or algae on that wall, and on the side of the steps, and on the wall near the waste pipes.

this makes me think that the water is probably in the concrete floor of the kitcjen; and since the waste pipes appear to come through the wall to the gulley, and since the concrete round the gulley does not look cracked or sunken, I think it is probably coming from a waterpipe buried in the floor. This is quite common.

There may also be limescale deposits on and around the brick steps.

Have you got a water meter, or an outside stopcock near the house boundary?

Have you got a pre-teen with sharp hearing?

There has previously been damp proof injections, yes. We bought the house in Sept. It had been rented out for a couple of years prior to that. Empty for 6 months before we moved in. The last tenant had complained of damp in the lounge - they got the damp company out to re-inject. Second viewing I pulled carpet back in there and the boards were wet. After a lot of back and forth with the owners I got them to get someone to look at the radiator and they found a leak, which was fixed. We moved in, no 'damp' in there since. Your comments on various threads on here helped me massively with that issue - so thank you!
I tried the pouring water on the doorstep thing - it flows away from the house. The gutter above the door is fine and not dripping.
We don't have a water meter. I know where the stopcock under the sink is, but what am I looking for at the property boundary?
I have an 8 year old who's hearing is probably unimpaired - I've read your 'turn off the water and listen for a hiss' technique before. Would that work if it's under the concrete?
Your under the concrete floor theory feels right - what do we do to diagnose/fix?

More photos! Prodded the wall next to the door and made a hole in the wet plasterboard... Pulled up the lino, the ply that it's on top of is sticky/wet in places, as you can see in the photo.

@Movingtonumber4

More photos! Prodded the wall next to the door and made a hole in the wet plasterboard... Pulled up the lino, the ply that it's on top of is sticky/wet in places, as you can see in the photo.

reinforces my view that there is a leak in the floor.

look for a small hatch in the pavement, or near where the front gate used to be when the house was built. It will typically be in a straight line to where the kitchen sink used to be when the house was built.

Found it. Just outside the back gate.

A person with good ears will probably detect the off/on/off change in the quiet of the night.

you can get one of these if you like, and press it to the pipe

Will have a play with turning it off and listening tonight.
If it is the mains water leaking under our concrete kitchen floor, then I assume the plan would be to re route the mains and disconnect the leaking pipe? Do I do that through the waterboard (Yorkshire water) or get a plumber or something else?

it's easier if you have one person in the kitchen listening, and another person at the external stopcock.

Yes, it is easiest to run a new pipe, all the way to the external stopcock (and preferably to the connection, meter or cock under the pavement or road). It does not have to follow the same route as the old one, it may be easier to trench under a path, or enter under the wooden floor or something rather than dig up the kitchen floor. I recommend running it in 32mm blue plastic, which is pretty sure to be bigger than your old pipe, this will give improved flow for better filling of baths and less chance that one tap will weaken when another is turned on. You need full-bore stopcocks which are bigger and more expensive than the 1/2" ones, so make sure the plumber fits them and does not scrimp. It is a hundred times more expensive to dig up and change later than to do it while the trench is open. You can take a 22mm copper pipe tee off for the cold supply, and another to go to your hot cylinder, water tank or combi boiler, and one in plastic for your outhouses or garden taps. You will be amazed and delighted at the improvement in flow. You can turn it down a bit if too strong.

Plumbers are weedy little fellows with petal soft hands, so a sturdy woman or a builder is more suitable for digging the trench. You can have it moled if necessary. A plumber can probably connect it to the incoming supply, but if it is in the road you will normally have to pay the water company or one of their approved contractors. They might do it free or at a reduced rate if you are replacing lead piping or having a water meter fitted, or if they know you have a long-term leak. If you have any lead piping, ask them to test your drinking water for lead content BEFORE you start any work.

"Blue water supply MDPE should be laid in a trench at a depth of at least 750mm (measured from the pipe crown), but no more than 1350mm, from the finished ground level and at least 350mm away from other utilities (such as gas or electricity)."

and the water co will (should) inspect to verify this before you refill the trench. You must tell them in advance.