What ground level clearance for DPC?

Discussion in 'Builders' Talk' started by CosRush, Nov 28, 2009.

  1. CosRush

    CosRush New Member

    I have a problem with damp in my bungalow.

    One wall which runs the entire length of the bungalow (living room and our bedroom) has damp on the wall inside.
    It has caused wall paper to flake off, skirting to become soaked and the wall is damp to touch.
    On the outside there are white powderery deposits on th bricks just above the ground but below the dpc.
    The ground level is only about 100mm from the dpc.

    Plus in the bedroom there is also 2x dark patches on the ceiling right in the corner and just away from the corner slightly that are both blackened.

    This bungalow was built around 1970.

    I also have damp coming in around a back door which is a new extension.
    We had the builder back not long afterwards since the brand new carpet just inside the door was getting wet.
    The door frame and wall next to it have also become black with mould (which I have just cleaned off).

    The builder said the ground level was possibly too high outside the door and hence why the water was getting in through the bricks (???).

    I dug it out about a 8" but still we get some mould around the door frame and a damp carpet.

    Can anybody please confirem about the ground height and also offer any suggestions as to what I could check or test?
  2. Mr GrimNasty

    Mr GrimNasty Active Member

    Minimum 2 bricks below DPC.

    Possibly you have lots of different issues - I'm sure others will have advice?

    Have you got cavity wall insulation? What type, when installed, where is your house situated - is it exposed - coastal/hilly etc.
  3. CosRush

    CosRush New Member

    I do have cavity wall insulation. The previous owners were pensioners and therefore got it via some grant for little or no cost.

    No idea who did it though, or just how long ago it was done but its probably at least 10 years ago.

    My bungalow is nowhere near the coast, and is not exposed either. apart from the front I have other bungalows both sides and behind.

    we have soakaways as well. I wonder if it could be anything do with them.....
  4. CosRush

    CosRush New Member

    Sorry, I forgot to say 'thanks for the reply' :)
  5. Mr GrimNasty

    Mr GrimNasty Active Member

    Cavity wall insulation can cause problems with damp - especially if you are in an exposed or wet position, but also if your external brickwork is porous, or your cavities are full of rubble (less likely on your age of house).

    Is the worst wall facing the prevailing wind - if not, probably not the insulation at fault?

    The only way to find out is to pick one of the dampest areas and do an autopsy - take a brick out or whatever, and examine the insulation for wet. God knows how you get it all out if that is the problem!

    Also if uninsulated voids have been left that could encourage condensation in those 'cold' spots.

    Any damp near the top corners of rooms in a bungalow is likely to be condensation at a cold spot near eaves or damp from a roof or gutter problem I would guess.

    Check your gutters and pipes aren't overflowing/leaking anyway. No leaky drains? Window frames well sealed? Get in the loft and check for leaks/rafters for damp - low down especially?

    As well as ensuring the ground level is low enough below DPC, ensuring rain can't splash back up from the ground with gravel might help a bit.
  6. s.bury

    s.bury Member

    In addition to advice given - check your paths, drives, awns dont drain back towards the house!! You could consider rendering the property to waterproof and insulate the 40 year old bricks.

    Are the rooms warm, heated, ventilated etc? Often people switch rads off in spare rooms, shut all the doors for days, never open the window....

    I have this render on my house- superb http://www.netweber.co.uk/

  7. CosRush

    CosRush New Member

    Thanks again for the replies.

    I had considered the rendering before, but I presume it would be a case of applying to the council?

    None of the properties on my estate have rendering, and they entire estate was built by the same building company, thereofre all properties are similar in construction with only brick colours being different.

    I do plan to dig out the path that runs alongside the longest wall where we have damp.

    I would like to drop the entire garden height down as well ( as the main part of the garden is about 18" higher than my back door and my patio doors) but I suspect this would cost a small fortune.
  8. Mr GrimNasty

    Mr GrimNasty Active Member

    If you could cut back a path width and put in a ~2ft retaining wall it might help - you'd probably be best off directing any run-off from the path/trench to a main sewer (if they'll let you).

    There must be quite a bit of hydraulic pressure if the land is higher than the house - you might have genuine rising damp on that wall?

    Whatever if you have the wool type insulation it sounds like it is going to be sopping wet, it will probably take years to dry out on it's own.
  9. s.bury

    s.bury Member

    I think you'll find its hydrostatic pressue forcing water into the building. You'll need a decent space between the garden and the house to act as a sump and drain soakaway. This all depends on the soil type, aspect, slope and the building.

    Get in touch with a local reliable experienced builder for advice.

    Rendering can fall under PDR - permitted development rights but contact your local council planners.

    You are not looking at mega bucks! - fella with a digger at £130/ day shifts a lot of muck away!
  10. Big Jumbo

    Big Jumbo New Member

    Before getting too far into remedial work, check that the gutters are clear and working properly and not allowing water to run down the walls when it rains.

    Look at the roof and make sure all tiles are in place. If water gets onto the felt it is possible for it to end up in the cavity.

    The dark patches in the bedroom sound more like lack of air circulation.

    Regarding the new extension, bridging from the old to the new is possible, but to the extent of a soaked carpet...sounds more like it a problem with the dpm-to-dpc joint. Do you see the floor being laid and where the dpm went in relation to the dpc?
  11. CosRush

    CosRush New Member

    Ive checked the gutters no blockages there. No rain makes it onto the walls, ive been out and looked over all of it in the pouring rain.
    I haven't as yet checked the tiles though but will do.
    I suspect the dark patches in the corner may be a result of condensation and lack of air circulation.
    I didn't see the DPC during the extension build. Could the carpet soaking be as a result of condensation that forms on the door and then runs off onto the carpet below?
    I guess I could put some kitchen roll onto something like a piece of plastic below the door frame, and then if it is coming from the door itself the water would show on the kitchen roll as the roll would be insulated from the ground by the plastic.

  12. CosRush

    CosRush New Member

    Thanks for the info.

    I will contact the council and see what they say about rendering.

    The only problem I can see at the moment with levelling the entire garden (which I would like to do) is that the higher ground is currently where my and my neighbours fences are situated. dropping the ground nearly 2 feet would mean there wouldn't be enough ground to supprt the fence posts.

  13. CosRush

    CosRush New Member

    I'd like to run something interesting past you guys.......

    I spoke to a guy yesterday who whilst not a builder is a jack of all trades. And has been in the building trade for 20+ years.

    He straight off the cuff (about the main wall) it indicates that the main wall is the coldest. And that if I were to to fit a radiator onto both of the walls i.e. one in our bedroom on that cold wall and one in the living room on that cold wall, with the pipe runs along the the top of the skirting, the heat from the rad plus the heat given out by the pipes along the skirting would probably stop the damp problems completely.

    It makes sense to me, what do you guys think?
  14. Humour Me2

    Humour Me2 New Member

    sounds a bit like nailing a hair drier above a sink with a dripping tap........... might help mask the problem

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