Redundant drain and damp

[tobydog]

Ever since we moved in we have had a problem with damp in our side utility. You can't see it inside but you can definitely smell it. The bricks in one corner on the outside are damp but there was no obvious reason why. I recently started taking the bitumen coating off the wall thinking that it might help and I realised that the single skin wall only goes 2 brick courses into the ground at most. In the first picture below you can just about see the brick plinth below the power cable. I have poked around directly under the plinth and there is nothing else supporting it.

At first I thought that ground/rain water was finding its way easily under the plinth until I came across the bottom of a redundant downpipe. The odd thing it that this downpipe is 5" diameter compared to the functioning standard downpipe at the other end. The redundant pipe was full of earth but just 6" in the soil became very soggy. I've traced the angle of the pipe back to a main drain in the drive. For some reason we have another in-line inspection hatch in the drive which is a single drain with a bend. I would have thought the main drain cover would have had to come off off when the extension was done in 2010 but it looks well sealed down. The builders tapped into the existing waste pipe from the house so maybe they didn't open it.

I think that this main drain will have a redundant pipe heading from the side utility that backs up with water if it is overloaded and that this pipe must have a leak somewhere. Does this make sense?

Dumb question alert as I've not worked on drains before. Is there any reason why I can't lift the main drain cover and check? Are the airtight? If I get in, is there a way of capping off the link from inside the inspection chamber?

Thanks

 

[Lime]

tobydog, the first rule of thumb with drains is don't assume anything.
It is quite common for rainwater drains to have a separate system/s not connected to the foul sewer system but sometimes not.
Alternatively each rainwater downpipe may have a separate run off somewhere.
The drain inspection cover appears to be metal (?) and may be held in place by small screws (2 usually) and will be stuck in place with mud/dirt around it's perimeter.

When you look down the open pipe in the picture, where does the bend in the pipe (in the ground) suggest the pipe is flowing?

Are the marks on the cement render damp?
If so the damp is very high up the wall. I suggest you inspect the guttering when it is pouring with rain to see if there is a leak.

 

[tobydog]

Lime - thanks for the feedback. The marks on the wall in question are actually shadows from trees. The wall is damp though in that corner at least up to the bell-drip which is above inside floor level. I've not noticed any problems with the gutter before, and the outhouse lean-to roof is fairly small, but I'll take a look tonight. I'll also check to see if there's an incline to the gutter to see if water is collecting at the wrong end and leaking. This part is directly over the area in question, however, the area is always wet even if is hasn't rained for some time.

The knuckle on the old pipe in the ground aims directly at the inspection hatch. I don't hold out much hope for unscrewing any screws that might be there given how encrusted the whole thing is. The actual working downpipe for this roof (at the other end) appears to head off in the opposite direction towards the main sewer but there are no more inspection hatches anywhere. There is also a sink and toilet in the outhouse but, again, I don't know where these head to. Lifting the old hatch is a must.

As a side issue, the room next to the outhouse was the old kitchen. The water main still rises in the floor but I have no idea what direction it comes from. I'll need to check with Anglia Water. I don't suspect a leaky mains but it's another box that probably needs ticking.

By the way, any ideas why there might be a 5" pipe there in the first place?

 

[Lime]

The 5" pipe suggests a make-shift drain rather than a professional addition to your 4" domestic system.
(It isn't a round gulley/drain with its top removed is it? .. just an idea)
Is the pipe open so that you can smell what is at the other end? Often the give-away for a pipe connected to a sewage/soil system is the smell that comes out of it.

The inspection hole cover may be difficult to remove. Circular ones are always more difficult than oblong.
I assume that the edge of the cover is held within the brown plastic collar of the inspection chamber.
Sometimes (sometimes, not always!!!) it is easier to dig around the top part of the inspection cover to reveal the joint/connection (similar to a pipe connection but bigger) that connects to the lower section. However much will depend on how deep inspection hole is.

With regard to the water pipe.
It is not unusual for a small leak to cause the type of damp you have. Leap pipes can be damaged very easily.
To test for a leak you need to use a listening stick.
http://www.google.co.uk/search?q=listening+stick&rls=com.microsoft:en-GB:IE-Address&tbm=isch&tbo=u&source=univ&sa=X&ei=MDTdUcbgKOaO7Abr_oGYAg&ved=0CC8QsAQ&biw=1584&bih=723

A broom handle should do if it is solid wood.
Even tiny leaks will make a hiss when the pipe is listened to.
The nearer you are to the leak the louder it will be.
Make sure everything is off in the house and elsewhere so that the hiss doesn't get drowned out with the noise of rushing water.

 

[Keithj]

I would suggest you need to be able to open that drain cover. Old, rusted-on ones can be "fun", but a pressure washer, WD40 and a hefty screwdriver will often make them see things your way.

Once it's open, you can squirt a hosepipe down that open pipe and see if the water goes through that inspection chamber. If it rushes happily past, then you know something. If it doesn't, you know something else...

We found an open pipe end like that under a slab by the back door of the church. It was a metal pipe (plastic probably hadn't been invented then) but it went to a soakaway some distance across the churchyard, and proved very useful for dealing with one of our "damp and soggy" problems.

 

[tobydog]

The 5" pipe suggests a make-shift drain rather than a professional addition to your 4" domestic system.
(It isn't a round gulley/drain with its top removed is it? .. just an idea)
Is the pipe open so that you can smell what is at the other end? Often the give-away for a pipe connected to a sewage/soil system is the smell that comes out of it.

There is no evidence that it's been used, or is suitable, for anything. Very strange. It's also clogged with mud in the knuckle part you can see so no smells coming out.

With regard to the water pipe.
It is not unusual for a small leak to cause the type of damp you have. Leap pipes can be damaged very easily.
To test for a leak you need to use a listening stick.
http://www.google.co.uk/search?q=listening+stick&rls=com.microsoft:en-GB:IE-Address&tbm=isch&tbo=u&source=univ&sa=X&ei=MDTdUcbgKOaO7Abr_oGYAg&ved=0CC8QsAQ&biw=1584&bih=723

A broom handle should do if it is solid wood.
Even tiny leaks will make a hiss when the pipe is listened to.
The nearer you are to the leak the louder it will be.
Make sure everything is off in the house and elsewhere so that the hiss doesn't get drowned out with the noise of rushing water.

The water meter is at the end of the drive so that's presumably where the main runs. Of course it would probably be foolish to assume the feed to the house went in a straight line :roll: I will check the drain and the guttering bits first.

I would suggest you need to be able to open that drain cover. Old, rusted-on ones can be "fun", but a pressure washer, WD40 and a hefty screwdriver will often make them see things your way.

Once it's open, you can squirt a hosepipe down that open pipe and see if the water goes through that inspection chamber. If it rushes happily past, then you know something. If it doesn't, you know something else....

From experience, when I try and make things in and around the house see it my way, they end up broken, usually through frustration. Of course that doesn't apply to Mrs. T where everything in and around the house see's it her way. That's the answer, she can lift the lid.

 

[tobydog]

Well, despite being bitten to pieces by knats, I played around with the drains again tonight. The main round cover in the first picture was held in place with cement but no screws so it came away okay. You can see that it heads directly for the corner of the outhouse where the pipe in question sits. If you look at the second picture it shows the inline inspection housing that comes from the round drain. I flushed them through and it flowed fine. They are not lined up so there must be at least two joints somewhere between the two.

I managed to clean the mud out of the pipe in question because it only sat in the knuckle where it would have fallen in. Reaching in, it ran fairly shallow. I ran some water through it to see if it was joined up to the main flow but nothing came out. In fact it started to fill up and not drain away.

One thing I hadn't noticed before, as you will see from the third picture, is that the gutter isn't quite long enough for the roof. I sprayed the roof and whilst the water from the flat part of the tiles channels into the gutter, the tile groove where they normally hook up acts like a mini rill. It dropped right into the damp area in question. I've never noticed it dripping before. Ingoring the bitumen on the bricks, you can see the dark corner compared to the other end which is dry. The gutter comes up short there as well but there's no gully. It's hard to believe that such a small overlap might cause so much constant damp. I'll fit a new full gutter shortly and see if this make a difference over the summer. If not then it's driveway up time in the autumn to check the joints.

Thanks for the help.

 

[Keithj]

That "gutter too short for the roof" thing is exactly what caused the damp problem in our church that goes back as far as PCC records! Our gap was a bit bigger than yours (but not a lot bigger). The amount of mastic and plaster and paint and who knows what else expended on the damp (and smelly) corner is scary. Then along came a "proper" builder who looked up rather than down, and the real problem was identified.

"Rising damp" was the previous diagnosis - we all know what that is, don't we!

The builder fitted a "full length" gutter early this year (or was it late last year?). He removed all the crumbling plaster from the wall inside, and the cement, and the mastic, and the Snowcem, and the umpteen layers of "waterproof paint" and let the wall structure dry out before lime plastering it again. The lime has dried and carbonated well, but there's still a damp area on the corner pillar: he reckons there's 200 years of water in that pillar, slowly working its way out.

He cited the bottled water "filtered for a thousand years through the chalk hills of <wherever>..." (but with a best-before date a few months away - that water must have popped out of the spring just in time!).

The churchwardens won't let me pencil in the outline of the damp patch to see how it's shrinking, so I have to keep taking photographs. But shrinking it is.

 

[tobydog]

Hopefully our house will behave just like your church and recover nicely. I honestly can't tell how long that gap has been there but I would suggest it's at least 20-25 years from when the cement render went on. We've been there 4 years and the less than 2" shortfall just didn't register. What with the lower wall being covered in bitumen, the ground being covered in stones, and the apparent dripping stopping quite quickly when the rain stopped, the evidence didn't jump out. I'll look up more in future :roll: .

 

[MatthewC]

We've been there 4 years and the less than 2" shortfall just didn't register. What with the lower wall being covered in bitumen, the ground being covered in stones, and the apparent dripping stopping quite quickly when the rain stopped, the evidence didn't jump out. I'll look up more in future :roll: .

And presumably the dripping from the short gutter is the reason why the wall was covered with bitumen some years ago?

Well done for finding the cause rather than getting misled by the symptom. Another period property maxim is proved again!

 

[Penners]

And presumably the dripping from the short gutter is the reason why the wall was covered with bitumen some years ago?

That certainly seems likely. The bit of roof that the gutter misses doesn't look like much, but consider how long it's been like that, and how much water will have overshot the gutter end as a consequence! The resulting damp problem has been exacerbated because the wall was sealed with bitumen, so once the moisture had got into the wall, it couldn't get out again.

 

[tobydog]

All offers to help me get the bitumen off would be gratefully accepted. I've been using Strippers 510 but I'm reluctant to use a hot water pressure washer as suggested (but which I don't actually have anyway). The problem is that under the bitumen the wall is smeared with cement in places so it's coming off the clean bricks but not the cement. Not got much to do so a few bricks at a time. The wall is already starting to dry out where I've bug out the wet soil.

 

[DJH]

A little bit of lead tucked up under the end tile diverting the water into the gutter would take the pressure from you Toby to be taking down the gutter during this dry weather. We wouldn't want it to rain the minute you take it down do we... :lol:

Doug

 

[Penners]

The problem is that under the bitumen the wall is smeared with cement in places so it's coming off the clean bricks but not the cement.

Can you hack the cement off, bringing the bitumen with it? You'll need to get both of them off anyway.

 

[Flyfisher]

Hopefully our house will behave just like your church and recover nicely. I honestly can't tell how long that gap has been there but I would suggest it's at least 20-25 years from when the cement render went on. We've been there 4 years and the less than 2" shortfall just didn't register. What with the lower wall being covered in bitumen, the ground being covered in stones, and the apparent dripping stopping quite quickly when the rain stopped, the evidence didn't jump out. I'll look up more in future :roll: .

When I was repairing our roof, I would regularly walk around the scaffolding in the pouring rain to see what was happening and it was very instructive to see how much water could spill onto walls because of the slightest fault with guttering and flashing etc, and also how how a relatively tiny change could make such a huge difference.

Since then I regularly walk around the house in the pouring rain to verify that all is well, especially in the warmer months, and I'd recommend the practice to anyone.

 

[Lime]

Hopefully our house will behave just like your church and recover nicely. I honestly can't tell how long that gap has been there but I would suggest it's at least 20-25 years from when the cement render went on. We've been there 4 years and the less than 2" shortfall just didn't register. What with the lower wall being covered in bitumen, the ground being covered in stones, and the apparent dripping stopping quite quickly when the rain stopped, the evidence didn't jump out. I'll look up more in future :roll: .

When I was repairing our roof, I would regularly walk around the scaffolding in the pouring rain to see what was happening and it was very instructive to see how much water could spill onto walls because of the slightest fault with guttering and flashing etc, and also how how a relatively tiny change could make such a huge difference.

Since then I regularly walk around the house in the pouring rain to verify that all is well, especially in the warmer months, and I'd recommend the practice to anyone.

I walk around my house and sheds at least 4 times a year doing just that, looking to see where the rain is going, checking gutters etc.
Gutters can get blocked up very easily and unless you look in a downpour you will never notice the flood down the wall.

Next time it is realy raining hard, don't waste your time, get out there and inspect!