Squelching Under Floor After Rain

[b0ng0]

The Problem

I've got an issue whereby water is getting into my house whenever there is moderate-heavy rain. This is a new build from 2015. Current theory is that water is getting trapped between either the DPC and flooring or DPC and concrete underneath.

I suspect it is coming in via the front door area, but there is no visual evidence of water ingress anywhere. However, walking around there is a very audible sloshing under the floors. But the flooring itself (including carpets) is bone dry.

The builder is not very helpful as warranty period is passed so I'm on my own. No signs of damage anywhere that would clearly point to ingress and only occurs during periods of rain (so think that rules out pipe issues). 

The Pictures

The construction of the flooring is (bottom up):

• Concrete
  Plastic Membrane
  Plywood
  Laminate (glued down)

I've tried to make a schematic below of where the water can be heard in the house. I believe it enters at the front and then is channeling/pooling at low points. The heavier the rain, the further into the house the sloshing can be heard and then drains away after a few dry days. The garage which is at a lower level is bone dry.

I've investigated for cracks, poor/broken sealant, any way the water can get in but can't find any. I removed the lock-blocks at the threshold and concrete is still intact with no obvious damage or cracks. Front path is level.

If I move aside some of the gravel at the side, there is the DPC visible. Not sure if this is a possible entry point for water?

The garage (white door on left) which is at a lower level than the front door is completely dry, even during heavy rain. There is no pooling of surface water anywhere. Everything is very level (build to wheelchair standards).

 

 

[Mr Punter]

If you bought from a developer it is common to have a 10 year structural warranty and this should be covered.

 

No mention of insulation in your build-up.  Do you know where it is?

 

The DPC looks like it is below ground level.  It should be 150mm above.

 

I suspect that there are a few defects at play here, not least  that to achieve the "wheelchair standard", the finished external ground levels may have been built up with no attention paid to damp and water ingress.

 

Can you take up a section of floor so you can see what layer the water is getting to?  Maybe under the stairs?

[ProDave]

I would start by lowering the ground level adjacent to the house, if you can't lower the whole garden, dig a trench cluse to the house at a lower level and make a feature of it with decorative gravel for instance.  If nothing else it will give you an indication of high water table (if it fills up and does not drain away)

 

Ideally you would cut back the paving leading to the front door and fit a drainage channel there to again try and keep water away from the front wall of the house.

 

And do the same on the paved area leading to the garage, stop the paving a bit away from the side wall of the house and a drainage channel to keep water away from the side wall.

[saveasteading]

@ProDave suggestions are the most likely. But my gut feeling here is that lots is wrong. Sorry.

If you can give more details then we can all help more.

5 years warranty may be irrelevant if the whole thing isn't done to normal standards.

 

You say new build, but was this a one off, or a development?

You say builder, but is this a local builder or a major developer?

[jamieled]

The way you describe the problem suggests the quantity of water must be quite significant - you could only get 'sloshing' noises if there's some movement/flow, and a reasonable volume of water. While there may be some defects, I'd struggle to believe the problem is with the areas you highlight in the photo. A higher water table might explain it, so the idea to dig a small investigation trench seems a good one.

 

Have you checked to make sure it's not related to a problem with the downpipes - either a poor joint or misdirected gully?

[Temp]

3 hours ago, b0ng0 said:

walking around there is a very audible sloshing under the floors

Is it only when you move about or can you hear it when standing still? 

 

I think I would check that rainwater down pipes take water away to a soakaway the correct distance from the house (or a drain) and not just into the ground too close. 

[Kelvin]

If it’s sloshing but nothing is obviously wet then it’s underneath the plastic membrane which suggests the membrane is sealed at the perimeter. Otherwise you expect more obvious signs of things being wet. Is it possible the DPM has failed and water is coming up from underneath? I was surprised at how much groundwater water seeped into my steel wells for example, easily a few litres per day into two the wells (both inside the house whereas the perimeter well stayed dry) 

[b0ng0]

3 hours ago, Mr Punter said:

If you bought from a developer it is common to have a 10 year structural warranty and this should be covered.

 

No mention of insulation in your build-up.  Do you know where it is?

 

The DPC looks like it is below ground level.  It should be 150mm above.

 

I suspect that there are a few defects at play here, not least  that to achieve the "wheelchair standard", the finished external ground levels may have been built up with no attention paid to damp and water ingress.

 

Can you take up a section of floor so you can see what layer the water is getting to?  Maybe under the stairs?

Tried NHBC but they said without visual water damage they wouldn't cover anything. 

 

The wheelchair accessible part of the path is just a gravelly substrate with lock-block on top.

 

Not sure about insulation. Can't take up flooring easily as it is glued to underlying plywood with some water-tight adhesive (it's Amtico Spacia or soemthing like that).

 

2 hours ago, ProDave said:

I would start by lowering the ground level adjacent to the house, if you can't lower the whole garden, dig a trench cluse to the house at a lower level and make a feature of it with decorative gravel for instance.  If nothing else it will give you an indication of high water table (if it fills up and does not drain away)

 

Ideally you would cut back the paving leading to the front door and fit a drainage channel there to again try and keep water away from the front wall of the house.

 

And do the same on the paved area leading to the garage, stop the paving a bit away from the side wall of the house and a drainage channel to keep water away from the side wall.

Probably not obvious from the photos, but there are drainage channels around the house already filled with gravel, show no signs of filling up. I will try to dig down a bit deeper and see if water is pooling.

2 hours ago, saveasteading said:

@ProDave suggestions are the most likely. But my gut feeling here is that lots is wrong. Sorry.

If you can give more details then we can all help more.

5 years warranty may be irrelevant if the whole thing isn't done to normal standards.

 

You say new build, but was this a one off, or a development?

You say builder, but is this a local builder or a major developer?

New build by Cala Homes, they have done hundreds of copy/paste designs in my area in the last years and are still actively building. Have asked a few neighbours but none so far seem to have the issue. Issue started to occur after 5 years of the house being built.

40 minutes ago, jamieled said:

The way you describe the problem suggests the quantity of water must be quite significant - you could only get 'sloshing' noises if there's some movement/flow, and a reasonable volume of water. While there may be some defects, I'd struggle to believe the problem is with the areas you highlight in the photo. A higher water table might explain it, so the idea to dig a small investigation trench seems a good one.

 

Have you checked to make sure it's not related to a problem with the downpipes - either a poor joint or misdirected gully?

Sloshing is only when walking around/putting pressure on an area of the floor (e.g. rocking from foot to foot to create pressure difference).

 

Not sure how I would investigate if it's an issue with downpipes? Any suggestions?

24 minutes ago, Temp said:

Is it only when you move about or can you hear it when standing still? 

 

I think I would check that rainwater down pipes take water away to a soakaway the correct distance from the house (or a drain) and not just into the ground too close. 

Only when moving about. Issue started to occur after 5 years of the house being built.

9 minutes ago, Kelvin said:

If it’s sloshing but nothing is obviously wet then it’s underneath the plastic membrane which suggests the membrane is sealed at the perimeter. Otherwise you expect more obvious signs of things being wet. Is it possible the DPM has failed and water is coming up from underneath? I was surprised at how much groundwater water seeped into my steel wells for example, easily a few litres per day into two the wells (both inside the house whereas the perimeter well stayed dry) 

That was my thought, given everything is still dry. Maybe DPC is chanelling from outside onto the DPM? No idea how I could check if DPM has failed short of digging a hole in my house!

 

 

[ProDave]

That's a good idea about checking the rainwater drains.  In a fry spell when the problem does not show, try running a hose down one of the rainwater drains at the front for a good length of time and see if that induces the problem.

[Temp]

8 hours ago, b0ng0 said:

Only when moving about. Issue started to occur after 5 years of the house being built.

 

I've never heard of a concrete floor moving enough to cause audible squelching from underneath it. 

 

I wonder if there is an issue with the insulation under it becoming waterlogged?

[Kelvin]

It must be water trapped between the concrete slab and plastic membrane. But then where does it go if it only happens when it rains and there no obvious signs of wet in the house. 
 

 

[Redbeard]

Question from Left Field...

 

Do you have proof that the floor is insulated, as of course it should be?

 

It still does not make great sense since, if it wasn't, the condensation would be on the *top-side *, not the underside, of the plastic, but I am trying to play Devil's advocate so that you ensure that all the variables, however unlikely, have been considered.

[Sparrowhawk]

8 hours ago, Temp said:

 

I've never heard of a concrete floor moving enough to cause audible squelching from underneath it.

My thought too. If you can hear it as you move, how much flex are you feeling in the floor?

 

Between the plywood and laminate won't there be a layer of particle board or similar, which would be a place that could be wet and make an audible sound?

 

 

[saveasteading]

18 hours ago, b0ng0 said:

drainage channels around the house already filled with gravel, show no signs of filling up. I will try to dig

Can you measure the height difference between the gravel and internal floor? It's easiest to do this at an opening window.

[Redbeard]

14 hours ago, Temp said:

 

I've never heard of a concrete floor moving enough to cause audible squelching from underneath it.

...and Sparrowhawk replied: My thought too. If you can hear it as you move, how much flex are you feeling in the floor?

 

As per the OP's description 

 

The construction of the flooring is (bottom up):

• Concrete
  Plastic Membrane
  Plywood
  Laminate (glued down)

The 'squidge' appears to be occurring between the concrete and the plastic immediately on top of it. I don't think there is any suggestion that the concrete is moving.

[saveasteading]

Speculating...

 

By Cala's builders

 

Hardcore

Blinding

Dpm

Screed 

Insulation board

Screed

 

By the flooring contractor.

 

Another dpm for some reason

Plywood for some reason

Floor cover.

 

This suggests that the concrete floor was rough and damp.

Normally a floor contractor would use latex to level, but this one has put plastic then plywood.

 

Unfortunately most developers resist all claims as they have lots uf funds.  But perhaps if thd LA got involved on your side...

[b0ng0]

On 12/10/2023 at 00:03, Temp said:

 

I've never heard of a concrete floor moving enough to cause audible squelching from underneath it. 

 

I wonder if there is an issue with the insulation under it becoming waterlogged?

Sorry for delay in replies, have been out for work.

 

I do not recall seeing any insultation. We had an extension put on the rear of the house a few years ago and so I was able to see the flooring. I wish I'd taken photos but from memory there wasn't any foam type insulation.

On 12/10/2023 at 08:29, Kelvin said:

It must be water trapped between the concrete slab and plastic membrane. But then where does it go if it only happens when it rains and there no obvious signs of wet in the house. 
 

 

That would seem to be the obvious answer, but not sure why it only occurs mainly at the front door/living room. Whatever way the water is getting in, it can clearly take the same route to exit the house.

On 12/10/2023 at 08:46, Redbeard said:

Question from Left Field...

 

Do you have proof that the floor is insulated, as of course it should be?

 

It still does not make great sense since, if it wasn't, the condensation would be on the *top-side *, not the underside, of the plastic, but I am trying to play Devil's advocate so that you ensure that all the variables, however unlikely, have been considered.

I don't and I don't remember seeing any insulation. I went to their sales office nearby but they said - conveniently - that they've changed the way they lay floors and the original site managers are no longer around.

On 12/10/2023 at 08:55, Sparrowhawk said:

My thought too. If you can hear it as you move, how much flex are you feeling in the floor?

 

Between the plywood and laminate won't there be a layer of particle board or similar, which would be a place that could be wet and make an audible sound?

 

 

Basically no flex, although I do feel that since this has happened a few times in the past 2 years the floor in the lounge feels a bit like whatever is under the carpet is maybe a tiny bit warped?

 

When I saw the flooring contractors laying the floor they put screed down, then cut plywood to go over the top of that. Then basically glue the laminate down (a quick check on youtube for "laying amtico spacia" seems like that is normal?).

On 12/10/2023 at 09:29, saveasteading said:

Can you measure the height difference between the gravel and internal floor? It's easiest to do this at an opening window.

If I move away the gravel I eventually get down to some hard concrete type material (not smooth, but "chunky"). Probably about a foot.

On 12/10/2023 at 14:18, Redbeard said:

14 hours ago, Temp said:

 

I've never heard of a concrete floor moving enough to cause audible squelching from underneath it.

...and Sparrowhawk replied: My thought too. If you can hear it as you move, how much flex are you feeling in the floor?

 

As per the OP's description 

 

The construction of the flooring is (bottom up):

• Concrete
  Plastic Membrane
  Plywood
  Laminate (glued down)

The 'squidge' appears to be occurring between the concrete and the plastic immediately on top of it. I don't think there is any suggestion that the concrete is moving.

I agree. Also, the squidging noise doesn't occur at the walls, its always either in the centre of the room or hall/front door entrance. That could just be where it's pooling however.

On 12/10/2023 at 14:34, saveasteading said:

Speculating...

 

By Cala's builders

 

Hardcore

Blinding

Dpm

Screed 

Insulation board

Screed

 

By the flooring contractor.

 

Another dpm for some reason

Plywood for some reason

Floor cover.

 

This suggests that the concrete floor was rough and damp.

Normally a floor contractor would use latex to level, but this one has put plastic then plywood.

 

Unfortunately most developers resist all claims as they have lots uf funds.  But perhaps if thd LA got involved on your side...

I may have the plastic under the plywood wrong actually. We had the same original contractor install flooring in our extension a few years ago and they used screed to level off then just put plywood and flooring down.

 

What is the LA, I'm not familiar with that? Trying NHBC again, but first step is always asking for photos of any damage. Unfortunately(?) in my case it's based on sound rather than visuals.

 

Really appreciating all the good suggestions here.

[saveasteading]

Others know better than I, but I think nhbc only warrant the 'structure' viz..is it going to fall down? Even then they gong seem to be greatly helpful.

 

They do have building standards though, including damp and insulation 

 

There has to be insulation. If not, then it is not  fit for purpose.

 

There are drawings. If they can't find them, then their designers and building inspectors could find them if they try.  They are fobbing you off.

 

Apologies. LA is local authority. They probably weren't the building inspector, but they are responsible for residents welfare. A wet house is unsafe. 

Try your Councillor. They may be able to get a building inspector along.

 

Cala obv don't care much about you or their houses once sold. They may consider they have a reputation to defend.

[b0ng0]

I do have building plans from an extension we had built (which doesn't have the water issue) and they tried to keep the flooring design the same as the house.

It consists of (top to bottom)
 

• Laminate flooring
  22mm Chipboard
  50mm Recitcel Eurothane (insulation)
  125mm concrete slab with 1 layer A193 mesh top 30mm cover
  100mm Recitcel Eurothane (insulation)
  1200 gauge DPM
  50mm sand blinding
  Foundations
   

If the rest of the house is the same as the extension then I feel like the water must be in the concrete slab and/or 100mm insulation. So either DPM has a hole in it, or water is getting in over the top.

I have checked the drains leading away from the property, all water levels way below ground level. Checked the downpipes and all look in tact and leading away from the property. I feel like it really doesn't need much rain to start hearing it so it must have a pretty direct path in.

Not sure if water could be getting in between the walls? In that case I would expect to see water damage on the walls?

[saveasteading]

It takes very little water to create your problem. My guess is a gap in the vertical dpm outside the concrete slab. These are often done very casually. 

 

How near the outside wall is the worst bit?

[Andehh]

Have you FORMALLY asked NHBC?  If not... Would be a shame if one corner was to suddenly get damp in the inside which could be connected to it? Which would(?) trigger their investigation into the subfloor.

 

Just hide the watering can...

 

(Probably £1000 excess, so research that first)