Damp, cold bedroom wall with serious condensation problems

Discussion in 'Builders' Talk' started by Alicegal, Aug 9, 2019.

  1. b4xtr

    b4xtr Active Member

    + one for lime & horse hair
     
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  2. Alicegal

    Alicegal Member

    Thank you, that's encouraging!
     
  3. Joe the Plumber

    Joe the Plumber Active Member

    Spare a thought for the bald horse though....

    Another vote for lime plaster.
     
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  4. Alicegal

    Alicegal Member

    You guys are fantastic! Thank you so much!
     
  5. Joe the Plumber

    Joe the Plumber Active Member

    It's a lovely house, so it's nice to be able to help.
     
  6. Alicegal

    Alicegal Member

    Thank you Joe the Plumber
     
  7. Alicegal

    Alicegal Member

    Hi Mr Rusty, I'm just revisiting this thread and reading your comment again. Could I please check with you (and everyone) that I'll be doing this correctly? We will be starting at the end of the week. So... we will be building a stud wall using wood 2 x2 inches or 2x1 inches to create a cavity space against a solid stone wall. On top of that we will put insulated plasterboard (we are not filling the gaps in between the stud wall batons), then we will staple a breathable vapour membrane (have no idea which one to buy!). We are then planning to attach plywood sheets, then cladding onto the breathable membrane so our daughter can have shelves etc screwed onto the wall later without damaging the insulated plasterboard underneath. Have I got the layers in the right order? Or will I risk creating condensation elsewhere with these layers? Have I missed out anything? Many thanks!
     
  8. b4xtr

    b4xtr Active Member

    Hi, if you are applying plywood sheets you might as well forget insulated plasterboard and just,
    Fix studs - then celotex/kingspan or similar - then tape the joints or apply a vapour barrier - then apply the plywood
    Condensation happens when warm moist air hits a cold surface hence the need for a vapour barrier on the warm side.
     
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  9. Mr Rusty

    Mr Rusty Well-Known Member

    I'd forget the ply. Build a studwall about 50mm inside original wall leaving a gap which must be ventilated. Insulate between studs using pir or rockwool batts (in which case use a breathable membrane on cavity side to retain insulation). On the room side you then need a dpm. You could use a thin insulated pb which incorporates a vapour barrier or use a separate one and standard plasterboard. You can fit your shelves though the pb to the studs.

    There are different points of view on insulating old buildings. The separate stud wall doesn't change the fabric of the building and could be removed if unforeseen problems appear. The main thing i think if doing this is to ventilate the cavity. The outside wall will be even colder so you not only need to try and stop humid air getting in to the cavity but also ventilate it to protect against any that does.

    This is my own opinion. It is likely that others will have different views.
     
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  10. Alicegal

    Alicegal Member

    Thank you so much for that advice. It is very much appreciated! Could you possibly recommend a breathable membrane for the cavity side and a vapour proof membrane for the room side please? We're drowning in products and websites! There are so many! Thanks again!
     
  11. Mr Rusty

    Mr Rusty Well-Known Member

    What I am suggesting you aim for is a similar wall construction as a timber frame house like this https://www.a1timberframe.co.uk/timber-frame-design/ except as your stud wall won't be structural, you don't need the sheathing ply layer. The breathable membrane is only needed if you use rockwool -PIR insulation is virtually self supporting and can be easily retained in position. For the vapour control layer, just use a polythene vapour control product like koolpc showed in a picture earlier. Note the cavity space is ventilated.
     
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  12. Alicegal

    Alicegal Member

    Thank you, that's clearer now. I'm wondering how we should ventilate the cavity. Would you recommended installing a vent of some kind in the wall from outside? Do you think this will be tricky given that the outside wall is extremely thick old stone?

    If we used something like kingspan, do we cut the pir boards to fit them into the gaps in the stud wall?
     
  13. Mr Rusty

    Mr Rusty Well-Known Member

    I would say yes and yes BUT you are asking for a lot of detail from us for a building we have not seen. The forum is great as a guide and for ideas, but I do think you need to perhaps get a local opinion before you go ahead with anything. Perhaps ask a local building surveyor. It is slightly risky just following suggestions on a forum because there may be things that should be taken in to account that haven't been mentioned.

    The "extremely" thick old stone bothers me a bit. And I am wondering if the answer is not to insulate internally but strip that concrete render outside and let the wall breathe and dry out better. In theory a very thick wall should be a great heat sink, and once warm should stay warm. Internal insulation definitely works in some circumstances - I've done it very successfully myself several times, but.....

    The stud wall idea is at least easily reversible and is quite inexpensive so worth a try
     
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  14. Alicegal

    Alicegal Member

    Thanks for that. We did get a surveyor to look at the wall and he did suggest hacking off the render, but he wondered if it might be hiding something else. The cement is extremely thick - not just a thin render. We have a huge settlement crack in the wall which we discovered when removing the internal (blown) lime plaster (see photos). Our worry is that this crack extends to the outside as there are hairline cracks in the external cement render which follow the same direction as the ones inside. The room definitely had a big condensation problem, but there seems no sign of water ingress on the exposed internal sandstone which is a relief. We'll give the stud wall a go and see if it solves the condensation issue. Unfortunately our budget is very small, as naively we throught we'd just move in, replace the rotton windows, decorate and that would be that. We never anticipated other issues. Stupid I know, as it's an old house and we should have had this in mind when buying it. We've certainly learned a lesson! We also discovered all the floors have been eaten by woodworm. Flight holes everywhere on the exposed beams and staircase. Our surveyor never picked this up which is unbelievable. We've removed all the floorboards now too. Hoping that the half eaten joists will be ok as we have no funds to replace them. It's the house of horrors. We've had to move out and camp on my Dad's floor, as we have a little girl to look after. The house now looks like a building site. The plaster and lath ceilings are coming away and falling into the downstairs area. I wish we hadn't bought it, but we're stuck with it now and just have to do the best we can.
     

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  15. Mr Rusty

    Mr Rusty Well-Known Member

    OK. We've just finished a house project which has been completely gutted also with worm in lots of timber. Take a deep breath. Don't panic and reassess. You WILL get there in the end. There is no point putting new floorboards onto joists that are too far gone - but are they? Get a plug cutter (small core drill) and cut a plug out of the joists where there are some worm holes. If they are just in the top surface and not too many, you can spray the joists (we used N-Virobor 10) and carry on. If the joists are well wormed, then there is no choice - you will have to drop the ceiling and replace them. This is a horrible dirty job, but within the scope of DIY.

    Probably because you have removed the floorboards which provide considerable strength to the floor which is now flexing. You might as well plan to drop the ceiling if the plaster is loose, re-board it with plasterboard and have it re-skimmed. I know you don't want to hear this, but the only way to move forward is to do each step properly. It will be disruptive, dirty, but remember the most expensive part of employing someone else to do it is generally the labour - materials are not so bad (for example new floorboards for that room are probably about £150 + screws, but perhaps £3-400 of labour,) so work out what you can do yourself, and what you can't and make a plan. Reboarding a ceiling is easy if you buy a cheap plasterboard lifter (about £90 - which you will recover a good proportion of the value of on ebay afterwards). Plasterboard is cheap, and screws easily into the joists.

    Flight holes everywhere on the exposed beams and staircase. Again, you can treat the existing timber if the damage is not too bad. The staircase needs to be checked - obviously if the treads are well wormed, then they will need replacing for safety.

    It looks a lovely house from the pix, and looks very sound from the outside, so this is all do-able. I know you didn't plan it, but it might even be worth hiring a caravan to give you a bit of a bolt-hole away from the mess.

    BTW, I wouldn't get hung up on that crack. It doesn't look too serious to me - unless there are other signs of recent movement, and can be made good. Remember old buildings do move about a bit.

    If you plan to do a fair bit yourself you will need a few decent tools - there will be much advice here on what is good value. This is an opportunity to really make a nice home how you want it. I cannot pretend it won't be a fair bit of work, but take it a step/room at a time and try and keep the mess isolated to just the area being worked on.
     
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  16. Alicegal

    Alicegal Member

    Mr Rusty,

    I can't thank you enough for your words of support and encouragement. Thank you!! The stairs aren't too bad and seem fairly strong. There are 3 joists in my daughter's bedroom which are the worst (we haven't begun lifting the floor boards in the other room!). What you can see in the photos is only the top half of the joists. The other half is exposed downstairs. The beams are fairly small as it wasn't built to be a house. It was a small stable with a place upstairs for servants. See photos below. My husband put noggins in between all the joists as the floor does have a bounce. He said the screws still went in with some bite to the most eaten joists. It looks as though it is just the top halves which have been destroyed. We have a woodworm company coming in to spray both bedrooms on Wednesday (and the loft) . The loft does have some beams with lots of holes, but they don't appear compromised. The loft is incredibly shallow with only crawl spaces through huge webs. As the roof is just old slate torched onto the structural roof beams, the torching crumbles off when you even just stick your head in the loft. We didn't fancy trying to get up there amongst the insulation and loose torching etc to treat the wood. We felt so fed up, we just called a company. I know we could have done it cheaply ourselves, but it was just one more issue we didn't need. The woodworm company are going to lay 22mm weyrock down on the joists. I hope this is ok.
     
    Last edited: Sep 9, 2019
  17. Alicegal

    Alicegal Member

    Photos below...
     

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  18. Mr Rusty

    Mr Rusty Well-Known Member

    I think the joists are just about OK. You see some big notches in joists sometimes and these are not much different - not ideal but passable depending on how much is below. If it was me I would carefully square out the decay and insert a very tight piece of new wood - glued and screwed. The top of the beam is in compression when loaded so the piece needs to be very tight end to end. Personally I wouldn't use weyrock (chipboard). Wooden boards are a better job and will probably flex better than chip without squeaking and creaking which I think is a risk with chip over a bouncy floor. Also, boards are much more accessible if you need to access the ceiling void for services in the future. But, a chip flooring will work and is the most inexpensive solution. what do others think?
     
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  19. Dam0n

    Dam0n Active Member


    On a house such as your own I wouldn't dream of fitting anything other than proper floorboards. Don't cheap out on sheet material, especially chipboard. Anyone who suggests that isn't going to be used to working on older buildings. I'd steer clear.

    The joists on old buildings are much larger than new builds so what rusty suggests r.e cut +glue and screw is a good idea. You could also sister the joists and add a few noggings. Where are you based?

    Lathe and plaster is always going to feel like it's about to fall down. It wont though unless you start pulling on it. As mentioned above, pulling the floorboards probably caused it to move a bit.
     
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  20. Alicegal

    Alicegal Member


    We are in Northumberland. The surveyor suggested the 22mn weyrock as he said it would help to make the floor less bouncy apparently. It will be glued and screwed into the joists for stability. Floorboards wouldn't have stopped the bounciness he said. I obviously have no idea - I'm just trying to gather the best advice! The woodworm company has been booked for Wednesday and they have been paid to put 22mm weyrock down. I'm concerned about the weight of the weyrock on the joists. As it was a tiny stable, I think the joists might not the same as the ones they used in the houses in the 1800s. Our house is only about 28 square metres as the stable was just for 2 horses. I know you're not a fan of weyrock, but do you think weyrock might be too heavy for our puny, half eaten joists? We also have gaping holes in the room walls (which don't go through to the outside. We were thinking of wedging some rocks in them and cementing them up. The holes are about the size of two or three sandstone bricks. There are three of them in the room. One was made to put pipes through, but the hole is enormous! That one is about a foot wide and a foot deep!
     

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