Damp or a leak?

doctor40

I am looking for some thoughts on this issue that seems to have everyone scratching their heads. 

The little front hall in the house has a wet area on the concrete floor. To the left of the photo is a bathroom which is hardly ever used. The bath is run about twice a year. The toilet is used by visitors once or twice a week. To the right of the photo is the front door. Above the photo is a bedroom. 

There was a wet area in 2022. A plumber came and checked the bathroom, no issues. Another plumber came last week and found a seal that needed resealed under the bath. I wasn't convinced that was the issue as the bath isn't used. That plumber also lifted floor in the bathroom to access under the bath and it's all looking dry. He then lifted a hatch in the bedroom to look at the pipes running into the bathroom, the mains comes in from outdoors almost where that wet area is, but he said it was dry too. 

A damp proofing company came at the very start and felt it was a leak. The plumber now wonders if it's damp. The house was built in 1849 but does have a damp proof course....I don't know the details though. 

So the first photo is the floor in 2022, and the second is from yesterday...there are some new wet patches. When the plumber left last week the bits circled in red weren't there. The funny bit of concrete is where the previous plumber took some out, but stopped as he said the concrete a couple of inches down was dry underneath. Everyone is confused! 

Given there's a new wet area appeared in the last two days is that note likely to be a leak? Or is it hard to tell? I did have heat in in the hall for the first time in ages. 

Any advice would be great...thank you 

Doozergirl

It's really not possible to say with just those photos.  

Are those floors original to the house?  They look like concrete to me, which would be a later addition.  It could be moisture coming up from the ground and finding the path of least resistance in the join between two types of floor. 

Old houses would normally just breath across the whole floor, but if you have concrete, particularly with a DPM underneath you get a larger amount of moisture pushing up in smaller areas around the damp resistant materials. 

I've seen it in houses where there is a damp issue elsewhere (a massively breached DPC by building a high level patio) that was allowing water to track under the house and find its way up an internal wall.  

 I'd expect the concrete to stay dry if you chipped into it, so that doesn't say much.  

benson1980

Do you know where the waste pipes run?

What did the plumber do last week- is that activity linked (i.e. did he run the bath)

Is there a waste pipe buried under the concrete. A leak detection company might be your best bet and if it is a leak it also might be covered under your insurance.

FrankRizzo

Do you think the pipes to the bathroom are in the concrete?

I would be inclined to believe the damp proof company - I'm basing that on gut feeling. They see this stuff all the time and experts in what they do. The plumbers would not know unless they know for sure the pipes dont run through the concrete. You can use a FLIR camera which would tell you for sure if there was a leeking pipe set in the concrete - if i was a plumber I would have this device

Unprotected copper pipes can corrode over time in concrete.

ThisIsWeird

I thought it was concrete too, but one plumber seemingly checked where the mains pipe came through in that area, and proclaimed it dry - how could he see? "...the mains comes in from outdoors almost where that wet area is, but he said it was dry too." Could it be chipboard? But, if so, the obvious thing is to lift it!

BlueVeranda

So, a new wet area appeared in the last two days.

Have you had rain in the last week? Or used that bathroom since the plumber left? Have you had the heating on (first time in a while maybe)?

Could the bathroom to the left be a red herring - what's to the right of the photo?

doctor40

benson1980 said:

Do you know where the waste pipes run?

What did the plumber do last week- is that activity linked (i.e. did he run the bath)

Is there a waste pipe buried under the concrete. A leak detection company might be your best bet and if it is a leak it also might be covered under your insurance.

The waste pipes run at the back of the house. So the opposite direction from the wet area.
The plumber did run the bath to detect the leak.

I don't think there is a waste pipe under the concrete. The plumber last week got access to the space under the concrete floor by lifting the bedroom floor....which is adjacent....he then declared the area was dry.

doctor40

FrankRizzo said:

Do you think the pipes to the bathroom are in the concrete?

I would be inclined to believe the damp proof company - I'm basing that on gut feeling. They see this stuff all the time and experts in what they do. The plumbers would not know unless they know for sure the pipes dont run through the concrete. You can use a FLIR camera which would tell you for sure if there was a leeking pipe set in the concrete - if i was a plumber I would have this device

Unprotected copper pipes can corrode over time in concrete.

The plumber last week said he saw the pipes and they are all OK....not in concrete. I'm not sure if he used a camera or naked eye....he does have a camera 

doctor40

ThisIsWeird said:

I thought it was concrete too, but one plumber seemingly checked where the mains pipe came through in that area, and proclaimed it dry - how could he see? "...the mains comes in from outdoors almost where that wet area is, but he said it was dry too." Could it be chipboard? But, if so, the obvious thing is to lift it!

It is concrete. The plumber lifted the bedroom floor which is chipboard and see the area under the concrete from there.

doctor40

BlueVeranda said:

So, a new wet area appeared in the last two days.

Have you had rain in the last week? Or used that bathroom since the plumber left? Have you had the heating on (first time in a while maybe)?

Could the bathroom to the left be a red herring - what's to the right of the photo?

No rain in last week. No use of the bathroom. I do wonder if the bath leak and the wet Hall floor are two separate issues. The bathroom floor was wet once right at the start and has never been wet again...if it was dampness in there it would have been wet again over the last year.

The concrete floor wet area may be unrelated. The front door is to the right of the wet area. It's dry. I check that whenever it rains. 

benson1980

doctor40 said:

BlueVeranda said:

So, a new wet area appeared in the last two days.

Have you had rain in the last week? Or used that bathroom since the plumber left? Have you had the heating on (first time in a while maybe)?

Could the bathroom to the left be a red herring - what's to the right of the photo?

No rain in last week. No use of the bathroom. I do wonder if the bath leak and the wet Hall floor are two separate issues. The bathroom floor was wet once right at the start and has never been wet again...if it was dampness in there it would have been wet again over the last year.

The concrete floor wet area may be unrelated. The front door is to the right of the wet area. It's dry. I check that whenever it rains. 

Central heating pipes? You did mention the heating was on. Is it a sealed system/any pressure loss?