Cutting back bottom of exterior render

Discussion in 'Getting Started FAQ' started by Jlen, Jul 2, 2019.

  1. Jlen

    Jlen New Member

    Hey everyone,

    I'm the upper ground floor and lower ground floor of a 4 story Georgian seafront building.

    I've got a very damp lower ground floor. The exterior is rendered and i'm pretty sure its trapping water in the walls and just driving it in.

    The render goes right down to the ground outside. I've attached some images. My builder is suggesting cutting 100mm of it away at the bottom to let it breath. Good shout?

    Also, not location of air bricks. What are these for? Ones painted closed and another one is just not there! Both are at exactly ground level. Has the ground level been raised? (see images)

    Also, the concrete blocks and slab that junction with the exterior wall are driving loads of damp into the room the other side. Its all in the same location as the corner of the room. (see first image and internal image)

    Thanks for any advice.

    Jlen
     

    Attached Files:

  2. KIAB

    KIAB Super Member

    Does makes sense to trim render back, but I first sort the air bricks clear them out back & front of house to get a good air flow from front to back of house, ( presume floors are suspended).

    Once you have a good air flow & ventilation (so important under a suspended floor,other wise you can get moisture/damp issues,mould,dry/wet rot) you might find your damp problem will clear up & go,might take a few months, but summer is here,which will speed things up drying the place out.
     
  3. Jlen

    Jlen New Member

    Thanks KIAB,

    The lower ground floor (behind those air bricks) is just a slab (the floor is also a bit damp). The upper ground floor is indeed a suspended floor.


     
  4. ajohn

    ajohn Screwfix Select

    Our house isn't as old as this but one side of the property did have a suspended timber floor. 1911. Rot, woodworm of what ever got in so ripped out and a slab poured to replace it.. No dpm but damp hasn't been a problem. If it was we would have to tank it or rip it up and replace it. Done a long time ago before we moved in.

    Don't know what type of damp proof course they used on georgian houses but would suspect the same as ours - blue brick. That means that some will come up the walls via the mortar and can cause damp proofing people to go down the injected damp proof course and remove plaster etc route. That's what happened when my wife's house was sold even though she had been there long enough to know that there wasn't any problems even though tarmac bridged the damp proof cause for a short length on the outside of the lounge wall. I've always wondered about ripping off plaster if the injected dpc is any good.

    Render shouldn't bridge blue brick but a bit is ok so depends on what is under the render really. Understand that masonary paint should be micro porous to allow the walls to breath but that wall butting against your internal corner looks like bad news to me - unless it does have some sort of damp proofing. Blue brick maybe ? What paint is on the walls might matter as well.

    John
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  5. KIAB

    KIAB Super Member

    As floor is apparantly solid, then trim back the render,out of intrest what is all the brickwork in 1st photo, can't help with keeping wall dry.
     
  6. ajohn

    ajohn Screwfix Select

    ;) Whoops - a bit of bridging blue brick is ok - I mean render just over part of the top course. That's how ours has been for rather a long time and it hasn't caused any problems.

    John
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