gambo

It's late 80s house build, I think, by David wilson. This has ducting is not the worse I've seen during the renovation. The other end is probably around the water meter 12m from this place and around 4m from the fron of the house, although I can't see it due to an amount of mess/soil around the meter. I spent 1hr digging and removing the soil just to be able to turn off water. If the condensation is from either some sort of leak (would need to be very small if the meter doesn't move when turned off) or rain/soil then isn't it better to let it escape by not pushing the pipe insulation to deep? If I put pipe insulation that doesn't go inside the hole than that covered pipe doesn't attract condensation and it just sits and breath on the pipe inside the hole.

Yes, unfortunately there is no leak at stopcock. I've checked it in number of ways. I can feel and smell damp further down and it smells like when you are inside bristol-bath two tunnels path.

I've now removed rockwool mineral wool from the hole and the pipe insulation from mdpe. The mineral wool is wet at the bottom. Not very wet but enough to assume that it may get quite wet if left for longer. I know it's breathable but will this not cause an issue if it attracts condensation quicker than it breaths? I wonder if just leaving it open is more sensible. I can cover the pipe partially as the whole and angle of the pipe doesn't allow to push it all the way to the ducting.

But mineral wool will slow down the process of transferring moisture from one side to another, correct? Will this not cause an issue long term (build up of moisture at the bottom side)? My other thread was going to be about usage of the foil below mineral wool in the loft but I guess I would need a very well specified mvhr to avoid build up of moisture beneath the foil.

@andyscotland wow! That's a great explanation!! Thank you! I'll keep it wrapped (did it a few days ago) a bit longer and will unwrap it just before covering with units to see where and how much if condensation is there, and will give an update.

It's not difficul to graspz but i see gaps in what some suggest. I don't see how filling the hole with mineral wool can be any better than covering it with foil+ PIR. Im trying to understand the whole process of forming the condensation to make sure Im bit causing bigger issue later on.

Iim more than happy to give you my postcode but it's a rabbit hole with lots of other issues waiting for a separate threads. Anyway, I do have pipe insulation just don't understand what I'm gaining by installing it. If I read your answer correctly, each side of the tile has its own reason for moisture so I can't cover it up but by covering the pipe with insulation I'm moving it further up to the next cold spot (stopcock)?

But if it's from the house then it should not penetrate the foil easily or at least I should have moisture on top of the foil too, but the foil is dry.

duct and pipe is buried in the ground/concrete. It has some very low temperature comparing to temp of the house. The duct ends in the hole and the pipe goes out of the hole. I have no idea where the humid air comes from but assuming it comes from somewhere deeper I don't understand why insulating the final run of the pipe would improve it.

I don't mind OTT just but i like if i can remove something easily. Putting foil first and gluing the PIR with expending foam is a good idea. Are you saying that because the hole now has a higher temperature by being warmed up it pulls the air/moisture up? But once i isolate it to keep it at lower temp it will be fine?

How is it different from covering it with foil and not allowing the air to move both ways? Alternatively I was thinking about putting 75mm PIR on top of the pipe (with a groove for the pipe) to keep the hole colder. Yes, there is a ducting but it ends under the tiles.

@JohnMo @Nickfromwales I've done the plumbing myself so may not be perfect but I do have another ball valve further up which is easily accessible. I did it to avoid doing 90 degree mdpe bend and run it on the wall (I dont want to loose space by having the pipe running through the middle of cabinet. My view is that if I insulate the pipe with pipe insulation it will not go to deep, so the sweating can still occur before the insulation (deeper in the hole). If I stuff rockwool will it not get very wet overtime?

Due to the shape of the run it's difficult to put pipe insulation. Lets say I fit a sleeve up to the duct will this not move the condensation to bottom of cabinet or before the insulation? Why covering it is bad? I get that in general condensation shouldn't be covered but right now it feels like it's going wrong way round, ie from cold to warm area. Stopcock at the moment is planned to be under the unit to gain space in cabinet. I could reroute to run on the wall behind the unit.

Just pipe and the duct to run the pipe through. its late 80s house with concrete + 40-50mm of screed + Ditra matt. Water meter is on the other side of the house (8-10m from the kitchen).

The pipe goes from the meter to the house and exits through this gap. I could probably put a bit of sleeve insulation from kitchen side but this would likely be a very short piece only. I don't really understand what this issue is. Is it the concrete/screed "breathing", a leak or a hole somewhere?