Water under my bungalow

youth_leader

I'm not having much luck finding out why there is so much water under my bungalow. 

I've bought a 1926 Ordnance Survey map, and there isn't any sign of a burn.  I've contacted the descendent of the original land buyer/builder, who still runs a building company, unfortunately his Uncle's records were lost when he died.  I've also written to he person that sold him the land in 1938.  Drainage and Water searches didn't show anything.

Would a structural engineer be able to help do you think? Or should I just have the floors replaced and have drains put in?

Bendy_House

What is your actual issue? Do you have a suspended floor with a void underneath? Is this water causing damage? Does it 'flow' from one point to another, or 'pool'?
And... sixmilliondollarquestion...can you USE it? Eg dig a sump and put a pump there to haul it up?

Rosa_Damascena

Is the water current or a legacy?

I had something similar last year and it apparently dated back to a major flood in the 1950s! Resolved by digging down by over 1ft across the whole area - c16" x 13" - and laying an impermeable base. Its was a big job and not a cheap one.

youth_leader

I feel a bit embarrassed Bendy_House, I have posted before and can't find it. 

I have a suspended floor with a void underneath in two bedrooms. The third bedroom and bathroom have half a concrete floor from an extension. The lounge/kitchen extension is fully concrete. 

The previous owner had the timber floors ripped out in two bedrooms, the hallway and bathroom because of woodworm, timbers replaced with chipboard.  The chipboard in these areas is black with mould.  The damp/timber surveyor cut a hole and said the joists are wet, but luckily not rotten.

The remaining bedroom timber floorboards weren't replaced, and has wet/dry rot and woodworm. The underlay is black with mould.

FreeBear

Bendy_House said: And... sixmilliondollarquestion...can you USE it? Eg dig a sump and put a pump there to haul it up?

I think I'd dig a sump and pump as much of the water out as possible. Wait to see if it comes back, and if it does, start looking for other solutions.

Bendy_House

youth_leader said:

The previous owner had the timber floors ripped out in two bedrooms, the hallway and bathroom because of woodworm, timbers replaced with chipboard.  The chipboard in these areas is black with mould.  The damp/timber surveyor cut a hole and said the joists are wet, but luckily not rotten.

Just how wet it the foundation void? When you look down, what do you see? Are there enough vents?

In theory, provided the joists and floorboards are above a DPC, and there is enough through-ventilation, the timber should be fine even if the actual ground is soaking.

youth_leader

The foundation void 'solum' concrete feels wet - I can only touch a small area where the surveyor broke the floorboard.  The joist he touched in the other room was also wet.  There are many plastic vents and they are all clear. When I looked under the floor I can't see any obvious 'pools' of water.  

I don't know if there is through ventilation from the back of the 2002 concrete floored extension to the void, the surveyor said they would investigate once the floors are up.

Neighbours who have lived here all of their lives said as children they played on this field and called it the 'muddy hill'.  I did try and find out about the water table, without success.

I'm trying to find the source as I'm nervous of spending the £11K (disclaimer in the quote saying it could be more depending on what they find) having the floors replaced with timber,  and having to do it all again in four or five years. 

Bendy_House

youth_leader said:

The foundation void 'solum' concrete feels wet - I can only touch a small area where the surveyor broke the floorboard.  The joist he touched in the other room was also wet.  There are many plastic vents and they are all clear. When I looked under the floor I can't see any obvious 'pools' of water.  

I don't know if there is through ventilation from the back of the 2002 concrete floored extension to the void, the surveyor said they would investigate once the floors are up.

Neighbours who have lived here all of their lives said as children they played on this field and called it the 'muddy hill'.  I did try and find out about the water table, without success.

I'm trying to find the source as I'm nervous of spending the £11K (disclaimer in the quote saying it could be more depending on what they find) having the floors replaced with timber,  and having to do it all again in four or five years. 

I think I can safely say it ain't because it's chipboard and it ain't because it's timber floorboards. So replacing one with t'other won't sort anything.

A very possible cause is that some original vents have been blocked off by the addition of solid concrete floors - the usual remedy is for ducting to be laid from the original vents and laid in the concrete to continue that venting to the remaining void.

If this was an issue of 'rising' damp or a failed DPC, then only the areas where the joists make contact with the sleeper walls would be affected. The fact that other parts of the joists are also damp, parts which aren't in contact with anything (other than air), suggests strongly to me that this is simply a case of lack of ventilation.

Do you have a plan of your house? If not, could you sketch one? On this, shade in all the concrete floors, and then mark out the location of the existing vent bricks. Once other thing you'll need to know, but prob won't until some flooring comes up, is whether there are adequate venting gaps in the sleeper walls.

Damp on the found'n ground should just not cause an issue like this.

youth_leader

Thank you so much Bendy_House I will do the sketch for tomorrow, I have a meeting tonight.   

stuart45

On a more modern house the oversite concrete has to be higher than the external ground level. If it's not possible, a drainage system has to be in place. 
The water table can be higher at certain times of the year, so it can be low when you check. 
Are you at the bottom of a hill?
Had the moisture content of the timbers been checked?
Is replacing the floors with concrete a possibility?

youth_leader

Hello again, I've marked the air vents on the diagram. Concrete floor areas shown with scored lines, the actual kitchen floor is tiled. The concrete floored extension was built in 2002, retrospective permission granted in 2007. 

I found out nine months after purchase that previous owner had floors replaced in both left hand bedrooms, bathroom and hallway in 2016 for woodworm.

My side of the road is higher than the houses opposite which were built in the early 30's, my bungalow is 1938.  My drive slopes downwards to the road, no road drain nearby. My semi detached neighbour doesn't have a problem with wet.  My garden at the back is raised.

I've just heard from the original 1897 landowner's archivist, with an extract from the OS map, and there wasn't a burn here.  I was wondering, if it had been unnamed, if it had been redirected.

I can only wonder if the field drains just aren't efficient, or are blocked. A new estate was built behind the bungalow several years ago and apparently people there complain their gardens are very wet. 

I think I just have to wait until all the floors are up.

The damp/timber surveyor didn't give me a moisture reading for the timbers @stuart45 - he just put his machine on the carpet and said it was 96.  We could only cut a small hole in the chipboard and he just put his hand down to test the joists, black and slimy but not rotten.  His company don't do concrete floors.

I had hoped to go concrete, but the surveyor I've engaged to supervise this work for me has advised me that a concrete floor will be triple the cost and disruptive.  

Thank you for all of your helpful comments and suggestions.