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    • CommentAuthorSpaceTofu
    • CommentTimeFeb 16th 2017 edited
    HI all,

    have been reading so much good material on this board; now we finally own a house so decided to sign up!

    We own a mid-terrace Victorian house. I was busy pulling a wire at the other end of the office room, located at the first floor of the extension bit (potentially built in the 60s?) on the back. This extension is facing a downward road which is, on windy days, creating a funnel for the cold air hitting the exterior wall.
    This blurred picture hopefully give an idea of the situation:

    The wall with the window sill and exposed wires is the wall facing an open environment.
    Especially now that the floorboards are removed, I can definitely feel a stream of chiller air coming through from that window wall, seemingly much sever than anything coming from the wall pictured on the right. As you can see joists are running perpendicular to the concerning wall.
    If I stick my head in the hole and look to the right, I can see some grey material (I couldn't guess what was it) which is potentially shielding the external wall

    If I take a peek at the underside of the concerning wall, the situation is different: the floorboard slide into a gap between the above skirting board/wall and the below joist and hit directly onto a wall of red bricks, which are supposedly the same red bricks of the exterior wall (which in turn is rendered with pebble dash)

    Having a look at the underside on the left, just the usual mess of rubble and some wires / pipes at the very end.

    I hope my words and pictures were descriptive enough.

    My goal is to try and reduce the draught of cold air coming from the concerning wall which in turn will eventually sift through the floorboards (there has been carpet up until now).

    I am reading that, better than trying and insulate the space between joists, it is always best to first try and seal the wall where the draught is coming from.
    How would you action this, seeing the very tight space? Airtight tape? Insulation foam?
    Ideally I really would like to intervene only in that tiny space where the draught is coming from, right where the floorboard slides in (as seen in the third picture)

    Secondly. Is it generally agreed on that under upstairs floorboard I shouldn't be worried too much about condensation appearing?

    Thirdly, if I were to instead lift up the whole floor assuming that the only way to bring a remedy here is to insulate the whole floor, would it be silly to think about UFH to also help counteracting the cold draught?

    Thank you so much
    • CommentAuthortony
    • CommentTimeFeb 16th 2017
    some info here, http://readinguk.org/draughtbusters/going-further/first-floor-void/

    you are one of millions but the majority are unaware of the problem, basically wind comes in through the blocks, mortar beds and round and over joist ends in the floor void from the cavity
    • CommentTimeFeb 16th 2017
    Posted By: SpaceTofuAs you can see joists are running perpendicular to the concerning wall.

    It would help if you posted an image that you had brightened so we could see it, or turn the flash on and take another photo!

    As far as I can see, the joists run parallel to the wall, not perpendicular to it? So the info on Tony's page won't really help much.

    Is it a solid wall, or one of the early cavity walls? How is the wall plastered? Is it wet plaster on the bricks or has plasterboard been added at some time? If there is plasterboard then the wind could be getting in anywhere, especially around the window.

    It looks to me as if the endmost joist is tight against the inside of the bricks. If so, it's not just the gap where the floorboards are that you need to worry about but also the part behind the joist. By far the most straightforward solution is to add EWI. If that is not possible, then you probably need to lift the floor and remove the end joist, then plaster behind it, add some internal insulation and put the joist back in a new position.

    You don't need to worry about condensation under the first floor, unless you have a kitchen or bathroom that is kept at a very high humidity most of the time for some reason. Modern houses have insulation under the first floor but that is to reduce noise transmission. You definitely do not want to insulate under the floor but leave the joist exposed to the brick wall. It will rot.
    • CommentAuthorSpaceTofu
    • CommentTimeFeb 16th 2017
    Thank you Tony and Djh for your comments.

    Indeed the joists are running parallel to the concerning wall; I prepared the post yesterday night when I was not in the best of shape!

    Really interesting inputs. I can try to get some more decent pictures, however I would like to show these pictures I have taken this morning, from the outside. It looks suspicious to me.
    As you can see we have a small single floor extension jotting out, which was added some decades after the extension in examination.
    I am now concerned about that gap that sits below the pebbledash render, running through the whole span of the concerning wall

    I looked at other neighbours' and it definitely doesn't look like that.
    It looks to me as indeed the wind is channeled into there and then it goes eventually under the floorboard; I am not saying that there is an actual gap, but it looks like the depth of material is very thin.
    Here is a close-up and a high-exposure close-up too

    I think the cold wind gets into that slit and therefore I am thinking of actually using some insulating foam in there. (or else? suggestions?)

    As with regards to your questions Djh, I am not sure of all of the answers, I am pretty much a novice at all of this stuff.
    I have the feeling it is one of the early cavity walls, as if I stick my hand well inside under the wall I can feel a bit of a narrow cavity.
    The wall is plastered with pebbledash on the outside and "normal" (lime?) on the inside.
    You mean adding EWI into the slit I tried to picture? Because I then am afraid it is no option, unless I were to trim the end of the floorboards to gain a bit of space
    • CommentAuthortony
    • CommentTimeFeb 16th 2017
    If there is a cavity with draughts in it then they will be coming in beside the edge joist and blowing through any holes or notches, under the skirting etc.
    • CommentTimeFeb 16th 2017
    Don't worry about being a novice. All it means is that it will take a little while to gather all the information and make a good plan.

    I think a plan drawing would help, and/or some external views of the whole house so we can picture where everything is.

    I'm no expert but I suspect the 'slit' you are seeing is just a fold in the render stop supporting the bottom of the pebbledash. In any case it is outside the brick wall so shouldn't be a problem.

    When I said EWI, I meant insulating the walls externally, either over the top of the pebbledash or removing the pebbledash first.
    • CommentAuthorpeacebabe68
    • CommentTimeMar 14th 2017 edited
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