Understanding possible damp problems/causes in new flat

We have just moved into a flat and some potential damp issues have come to light from:

- Our own inspection

- The initial home buyer report

- A survey by a damp contractor

As far as I can tell the damp contractor offered no reason as to the causes (other than a failed DPC). Surprise, surprise, none of the suggested work remedies the causes of the supposed damp. Their work would involve DPC injection, replastering, CDM tanking, etc...

However what I would really appreciate is any advice regarding what the genuine causes are and how I can remedy them. Here's a summary of the possible problem areas. I=92ve included some photos and a summary of what I think the possible causes are - which of course may be completely incorrect.

** Rear Left of property ** Some of the plaster is blown here on the rear wall and on the 3rd party wall. There is no smell of damp in the room. There is external evidence of rising damp - salty deposits on the brickwork - see photo below Damp contractor said there were high meter readings here (I realise a meter reading doesn't equate to damp) See photo:
formatting link
* Possible Causes * The original DPC has previously been judged (correctly/incorrectly) to have failed and a new chemically injected DPC has been added. This is not below the level of the internal floor. The pebble filled trough has a biggish gap in the corner which may be allowing water to penetrate. The two drainage pipes from the trough were very difficult to access from inside the trough - it seemed that they were covered in very hardened sand.

  • Possible Remedies * Clear entrances to the copper drainage pipes - done. Fix up damaged mortar. Paint a liquid bitumen DPM around edge of trough? Line the trough with a water proof sheet?

** Rear Right of Property ** Some of the plaster is blown on both sides of the internal wall =96 nothing major. There is no smell of damp in the room The damp contractor noted high meter readings, claiming there was "Lateral Penetrating Damp" See photos:
formatting link
and
formatting link
* Possible Causes * The diagonal section of the guttering had originally fallen out of place meaning water was discharging directly onto the flat roof, I have put this back (although it needs fixing properly in the middle as it=92s sagging, which is probably why it fell down in the first place) The flashing is made of the same material as the flat roof rather than lead. The drainage pipes in the pebble filled trough seem a little too high to be effective, they are at least a centimetre above the base of the trough. The raised platform at the back of the property could be bridging the DPC to the lower rear bedroom?

  • Possible Remedies * Relocate the copper drainage pipes slightly lower Paint a liquid bitumen DPM around edge of trough Line the trough with a waterproof sheet?

Are there any causes which I have incorrectly identified ?

Any help/advice/criticism would be gratefully received.

Charlie

Reply to
Charlie
Loading thread data ...

Without being there and having a good look round - I'm guessing - but:

Fixing the obvious gutter leak was an excellent first move - be sure to deal with any other obviously "wrong" things with the drainage like that promptly.

The guttering and downpipes arrangements around the property looks "complicated". It could be that other parts can't cope with heavy rainfall, and tend to spill over sometimes. I would look to modify the drainage to ensure everything flow freely and has lots of capacity, and nothing leaks. Also check "where" it drains to - probe with a hosepipe - soakaways or public drainage? Does it all work - no blockages or poor flows?

The brickwork around the pebble filled troughs is obviously newer than the original brickwork - and the levels inside look like they correspond to half way up the walls inside.

I would dig out the contents (simple, but hard work!), and maybe remove those new walls as well. Reason being - your house was probably built correctly in the first place - but later modifications (may) have "broken" it.

All damp problems usually come down to either ill-considered modifications, or lack of maintenance.

Good design allows everything to drain freely - including run-off from walls, away from the building - and for the residue to be windswept and dry quickly. That new brickwork trough looks suspicious to me in that respect.

The damp tester is an idiot. They usually are. They all usually say "failed DPC" as well. He wants to sell you a proprietary damp treatment - rather than fix the underlying cause. A similar idiot has already tried injection treatment - and clearly hasn't fixed the problem.

Common causes are - penetrating (e.g. a heap of stuff outside that bridges the dampcourse or your downpipes), leaks (water/sewage pipes), condensation (poor ventilation), and rising (least common).

Reply to
dom

First thought that went through my head when I saw the marks on the wall a pebbled filled enclosure was "that isn't draining". Think I clear everything out of that make sure the drains are clear and that no water can remains standing in it anywhere. Then put back the pebbles making sure that the drains don't get blocked.

The broken down spout (guttering is the trough that runs along the edge of the roof) wouldn't help. I'd check the conditionof the flat roof particularly along the wall. Our flat roof was torched on and also has the felt material bent up a parapet wall. This was torched on but the stiffness of the felt and thermal cycling has pulled it away leaving a gaping chasm to let in rain, snow etc...

Pebble trough, as the other one. Make sure it fully drains.

On the 3rd phot a couple of the injection holes haven't been filled.

I see lots of washing in the lower room, condensation might be the cause of some of the damp.

Reply to
Dave Liquorice

formatting link

As the others have said, but I'd also be looking *very* closely at what's lining the pebble beds. If they're not draining properly, the bed will fill with water, and if the waterproof lining on the wall of the flat is defective, it's like having a pool outside the wall. Take the pebbles out, take off as much of the original lining as you can, make good all the mortar joints in the area, and use bituminous damp proofing to seal the brickwork up to about 100mm above the level of the pebbles, then apply something to protect the bitumen. If you do it right, you could replace the pebble beds with small ponds with good results, apart from the possibility of the occasional drowned child. I'd guess it's a problem of quite long standing, as an attempt to cure it has been made by injecting a chemical DPC through the mortar filled holes in the bricks. Above the floor level, too.....

Is it clay soil? Weather related movement could have caused the damage shown in the first picture. I can also see the very degraded remains of what could have been the original damp proofing put in when the raised beds were added.

Reply to
John Williamson

Dave,

Thanks for your post, I agree with what you say, only a couple of points.

To be honest it looks OK, the material is neatly tucked in and the cement all present and correct

Yes agreed - I will fill those in

Well spotted :-) We've just moved in so I'm not sure this is was the original cause

Thanks again for your comments

Charlie

Reply to
Charlie

Dom,

Good idea I'll also check when we next have a heavy downpour to what's going on.

Yes it is newer

I had a horrible feeling someone might say that. That's going to be a simple but big job, presumably I'll need to replace the steps down to the garden as well?

Thanks for all the rest of your comments - I really appreciate them. They make a lot of sense.

Charlie

Reply to
Charlie

probably

The steps look orginal with the two walls built onto them. Some of the paving making up the steps looks a bit broken/uneven. I think you only have to remove the side walls down to the steps and the two front ones. Then worry about what is filling up most of the space in those troughs, if the drain pipes are at the top of that fill.

Some form of rails each side might be useful addition. It looks like quite drop from the steps to ground level.

Reply to
Dave Liquorice

It looks to be an old building without a cavity wall. Has it has had double glazing fitted without trickle ventilators? Single brick walls have poor insulation and are inherently damp. They rely upon a lot of air changes to prevent internal damp showing. Fitting double glazing (especially with no ventilation at all) or even new well fitting windows stops adequate ventilation in the building and also moves the cold spots in rooms from the windows (where they used to be) to the walls.

Before looking outside make sure the problem isn't actually the far more common one of condensation.

Reply to
Peter Parry

Must first say I am not an expert in any of this but purely from looking at your pic:-

  1. Where you have indicated "Holes in mortar", I notice the vertical join between the two walls has been heavily re-pointed.
2.Look like re-pointing finished at top of second visible course of bricks.

  1. The damp seems to worse at the left hand side and tapers toward the RHS - ending at the bottom of that ventilator panel.

  2. A guess is that this whole area was filled with gravel, which has now been removed.

  1. The two walls in view are not in line horizontally with each other above the 7th course of bricks.

6.The LHS side wall seem (in the pic) to be leaning away from the RHS wall. This would explain the gap that has possiby opened up between them - (and has then been filled with mortar).

Sorry if this is tosh - is just how it looks to me.

Reply to
dave

Yes, evidence of damp near ground level is not evidence of rising damp. In the overwhelming majority of cases its one of the other causes, such as condensation or splash.

DPC failure is unlikely to have anything to do with anything. Almost all houses built with no dpc functioned jsut fine, dpcs are more backup devices than functionally necessary.

A big container full of wet material against the all is jsut asking for trouble. Thre are various other possible causes that I dont know whether they'd apply here, its just not possible to look around and check it all out remotely.

NT

Reply to
NT

Agreed, it looks like I've got swimming pools leaking into my house :-)

This seems like a straightforward solution

Agreed - probably the previous owner had a damp contractor in when he bought the place and they told him he needed an injected DPC

Yes you are right you can see this one of the photos quite clearly.

Thanks for all your advice

Reply to
Charlie

Agreed, I'll fix this up as per John Williamson's suggestions

Reply to
Charlie

Agreed, I'll fix this up as per John Williamson's suggestions

Reply to
Charlie

Agreed, it looks like I've got swimming pools leaking into my house :-)

This seems like a straightforward solution

Agreed - probably the previous owner had a damp contractor in when he bought the place and they told him he needed an injected DPC

Yes you are right you can see this one of the photos quite clearly. Thanks for all your advice

Reply to
Charlie

HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.