Forerunners to modern day Damp Proof Membrane.

Discussion in 'Builders' Talk' started by glob@l, Sep 16, 2018.

  1. glob@l

    glob@l Active Member

    An old (150 years minimum) stone built house has had a red brick built (75mm cavity) lean-too extension added with a grey roughcast, a concrete floor and an inside toilet. Any dates not mentioned are unknown. I know some houses in the village didn't have inside toilets until the early 1960's.

    When did builders start using sheet damp proof membrane under concrete floors in Scotland and what was It's forerunner if anything?
  2. stuart44

    stuart44 Active Member

    Don't know about Scotland, but England and Wales had the Regs in the mid 60's. Before that parquet floors were often laid in hot tar which probably acted as a DPM as well. Asphalt has also been used for floors.
    Jord86 likes this.
  3. sospan

    sospan Well-Known Member

    A lot of buildings down here in Wales used to have tar, lead or slate as a DPC then there was this tar paper but it wasn't until the 1920's it became more common. Although I have seen more modern properties built without it.

    Membranes weren't introduced until the 60's and even then they were a rare. I remember in the late 60's cutting up large brewery hop bags to use as a DPM for my uncle when he was changing wooden floors to concrete. Hops still remind me of walking home smelling like I had been in the pub all day
    Jord86 and KIAB like this.
  4. glob@l

    glob@l Active Member

    There must be something stopping the damp or it would surely show.
  5. sospan

    sospan Well-Known Member

    Ten of thousands of house across the UK were built without any form of damp proof barrier. Many only have rammed earth with paving slabs or weak blinding of concrete on top. Conditions, then were different more air flow, less central heating.
  6. Richard_

    Richard_ Active Member

    As Sospan says, many houses have no DPC with rammed earth floors.

    Back to topic, if you can't see any damp is there a problem? Or are you just curious?

    Have a closer look at the walls on the outside. You might see something at the bottom below the roughcast. Probably slate for the original house. The extension might have bitumen paper (between wars) or plastic DPC (60's onwards).

    Ps - My latest refurb is a 1920's terrace with bitumen paper DPC in the walls. However the old scullery had a modern concrete floor. An elderly neighbour who has lived there all his life told me the old floor was a step down and most people infilled with concrete. So your extension might be old with a newer floor with a modern DPM. A concrete floor would be unusual in a pre-war house, they'd normally be quarry tiled or flagstones - IMHO
    Last edited: Sep 17, 2018

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