Help With Damp Proff Course On Old House

Discussion in 'Builders' Talk' started by AutoFreak, Apr 16, 2016.


Is DPC cream a good idea ?

  1. Yes

    0 vote(s)
  2. No

  3. Only in certain cases

    0 vote(s)
  1. AutoFreak

    AutoFreak New Member

    Hi there folks. I'll try and put as much detail as I can with the hope of it helping....

    I live in a mid terraced 1960 built house and have always had problems with damp on the front wall of the house. I eventually took the step of taking the plaster back to the brick and pulled the floor up to see how bad the problem is. I have found that the air brick is flush with the exterior ground level and by the look of it, water has been coming through the vent and has even soaked a few floor supports. My plan is to dig out the ground level and put a French drain in to help with that problem. While I have been looking at it, I have noticed that there is a few bits of broken black tile that look like they have been in the wall at some stage and also a felt like material that is all disintegrating. I am going to get a guy in to tank the walls and then also fit insulated plasterboard for heat as my house is always freezing and I thought that I would kill 2 birds with one stone.
    My questions are this.....

    1 - Am I correct in doing the French drain system to lower the ground level ?
    2 - Is the slate and felt the DPC which is breaking down ?
    3 - Should I install a DPC using the cream that is available while I am down this far whether I need to or not ?

    I really appreciate any help that I get
  2. KBJ

    KBJ Active Member

    I suspect, from what you have written, that because the airbrick is level with the ground outside (unusual), that the outside ground level has been raised since the house was built. This is the most common cause of damp in cases such as this as the DPC is effectively below ground, rather defeating its purpose. The drains are a good idea, but they won't do the job on their own if the ground level is too high. I understand that the modern damp-proofing creams are quite good where the DPC has broken up, but you might be interested to learn that the DPC is unusual in most other countries. Even in Holland. The Dutch find it quite amusing that we put a layer of plastic/bitumen between two layers of already waterproof cement.
    Last edited: Apr 16, 2016
    AutoFreak likes this.
  3. AutoFreak

    AutoFreak New Member

    Thank you for the reply. My idea was to lower the ground level down and then fit the French drains with the theory of driving the water away from the wall as much as possible. I have heard mixed reports about the DPC cream but thought it might be a good idea to do it while I have the wall stripped as an extra precaution?
    KBJ likes this.
  4. chris.t101

    chris.t101 New Member

    Lowering ground level to 150 below floor level is a good start - if possible. Digging a 100mm wide channel and filling with shingle (French drain) as an extra measure if 150 not possible. It should be a cavity wall, so have the cavities cleared of debris- a bit fiddly but well worth it as they are usually filled with builders rubbish bridging The damp proof course. Make sure the vent is clear and provide a periscope vent externally if the shingle would otherwise cover it. This may cure the problem but the wall could take 3 months to fully dry out. I would opt for a studded membrane on the wall finished with dot and dabbed plasterboard or if you want to insulate, treated battens fixed through standard dpc roll, with insulated plasterboard fixed over, with skim coat. DPC in injection is a waste of time in my opinion! Ensure joists not rotten, reboard with moisture resistant chipboard enduring it's not laid tight to the masonry.
    AutoFreak likes this.
  5. KIAB

    KIAB Super Member

    Once you clear air vent,you good airflow through front vent & out rear vent(s) (plenty of ventilation) & lower ground, let the place throughly dry out first, before any other course of action.

    Have a look at 'Dry Rods', very effective damp treatment system, if you decide you still have a damp issue, very simple to install.:)
    AutoFreak likes this.

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