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Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
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    • CommentAuthorkristeva
    • CommentTimeNov 10th 2020 edited
     
    Hello everyone,

    I purchased a house in the summer which forms part of a very old hop farm (early 1800's). I had no idea how old it was, but then again neither did the estate agents. The last incumbent lived here well into her 90's and as a consequence the house saw very little maintenance.

    So I inherited a house with damp walls, mainly due to excessively high ground levels along the perimeter (how damp the walls are /were is open to debate). The plates in the dinning room floor were entirely shot and there was a huge hole in the floor under the stairs, much of this due to failing air bricks and woodworm dining out all over the house. The electrics are stuck in the first half of the 20th century, both gas and electric meters are in the most stupid place imaginable, and the kitchen is a toxic nightmare of asbestos and lead painted brick.

    But funnily enough I really love this place, and after making a few early errors (yes, expandable foam I'm looking at you!) I feel strangely committed to doing right by this house. When I started to plan and research the subject I soon realised there was an alternative body of opinion regarding how to treat older, sold brick properties which seemed to divide modern and traditional building techniques. At first this just made everything more confusing, with no clear path to follow, so i thought I ought to reach out for some support and expertise from like-minded folk. Whilst doing my research this forum seem to pop up a lot. I'm doing this alone, apart from the odd professional here and there (BC will be happy to know I'll be going no where near the electrics), so I'll apologise in advance for any dumb questions.

    Cheers. P
      screenshot_534.jpg
  1.  
    Welcome to GBF!

    Ask away. We'll do all we can to help.
    • CommentAuthorrevor
    • CommentTimeNov 11th 2020
     
    Welcome Kristeva There are no dumb questions except the one you don't ask.
    • CommentAuthorkristeva
    • CommentTimeNov 12th 2020 edited
     
    Posted By: Nick ParsonsWelcome to GBF!

    Ask away. We'll do all we can to help.


    Posted By: revorWelcome Kristeva There are no dumb questions except the one you don't ask.


    Thanks guys

    I've sent a sample of the lime mortar used on my house to the Lime centre for matching as I need to make some basic internal repairs and also 'pack out' the window frames which had become exposed when I removed the plaster.
    I can use spare bricks to pack the larger gaps under the window ledge but can you suggest something breathable I could use other than expandable foam for the smaller gaps around the perimeter? I was thinking Steico Flex perhaps?

    I've also been considering IWI for the house as the downstairs walls are now back to brick. Everyone I know seems to be suggesting baton & Cellotex (or dot and dab) but I was thinking of something breathable like Warmshell or Steico. I know it won't be as effective as Cellotex.

    Also as I understand it some people use gypsum to plaster their internal walls in old properties and reserve the lime plaster for external walls. All of my walls were originally plastered in lime and all suffered damp on the ground floor due to high external ground and probably just age. I'm hoping I've sorted the causes by digging a french gully around the house and fixing the guttering last summer, and I also had an internal DPC (whether you believe in that or not). But I'm thinking I should really lime plaster all the walls, internal and external, despite the extra cost. Am I mad? I would happily go on a course to learn more about lime plastering if they weren't all closed due to Covid restrictions.
  2.  
    Burnt Sand Mastic for small gaps around window frames outside.

    Tanking slurry is a good solution for high external ground levels. We have used it on 2 previous properties. One was buried up to the eaves at the back (handy for getting on and off the roof!)

    Do the lime plastering yourself, its easy.

    IWI you could consider Hemcrete or similar, it's a bit laborious unless you get a company to spray it on, and you will lose about 4" all round. (edit - may not meet BRegs depending on thickness of your walls, but DECREMENT DELAY or some such mystery...)
  3.  
    My favourite 'recipe' for internal insulation of external walls (IWI) is 80 - 100mm wood-fibre board (subject to an interstitial condensation risk analysis) on a lime parge coat/lime adhesive/mechanival fixings/lime toothed coat/mesh/next base coat/optional 3rd base coat to prevent mesh 'ghosting'/ top-coat. +1 with Dominic re not quite meeting the 0.3 required by bldg regs, but do it with really good air-tightness and you won't notice the difference. Just had a tesxt from my last Wood-fibre IWI client saying what a massive difference it has made, and my front room, too, is living proof. It *feels* and *smells* lovely!
    • CommentAuthorkristeva
    • CommentTimeNov 12th 2020 edited
     
    Posted By: Dominic CooneyBurnt Sand Mastic for small gaps around window frames outside.

    Tanking slurry is a good solution for high external ground levels. We have used it on 2 previous properties. One was buried up to the eaves at the back (handy for getting on and off the roof!)

    Do the lime plastering yourself, its easy.

    IWI you could consider Hemcrete or similar, it's a bit laborious unless you get a company to spray it on, and you will lose about 4" all round. (edit - may not meet BRegs depending on thickness of your walls, but DECREMENT DELAY or some such mystery...)


    Thanks for the burnt sand mastic tip, is it used inside also? That's a new one on me, I'll see if there are any videos out there.

    I'm very curious to learn about lime plastering, is it really that easy?

    Would it be worth me finding a lime plasterer and asking if I could shadow him?
    • CommentAuthorkristeva
    • CommentTimeNov 12th 2020
     
    Posted By: Nick ParsonsMy favourite 'recipe' for internal insulation of external walls (IWI) is 80 - 100mm wood-fibre board (subject to an interstitial condensation risk analysis) on a lime parge coat/lime adhesive/mechanival fixings/lime toothed coat/mesh/next base coat/optional 3rd base coat to prevent mesh 'ghosting'/ top-coat. +1 with Dominic re not quite meeting the 0.3 required by bldg regs, but do it with really good air-tightness and you won't notice the difference. Just had a tesxt from my last Wood-fibre IWI client saying what a massive difference it has made, and my front room, too, is living proof. It *feels* and *smells* lovely!


    How do I go about getting a condensation risk assessment Nick?

    Your IWI routine sounds very similar to Warmshell / Steico systems promoted by Lime Green.

    Do you extend the wood fibre down beyond the floorboards, or is ok to sit it just above the floorboards and cover with skirting?
    • CommentAuthorkristeva
    • CommentTimeNov 12th 2020
     
    Another tricky problem I've got is I removed a flu in the kitchen and there's obviously a trail of soot down the wall which will come through any new plaster. I've been advised to coat the wall with PVA or SBR first to negate this but I'm guessing neither of those materials are breathable? It's a party wall which I wasn't planning to insulate but I'm starting think I might as well insulate as an alternative to using the PVA as the soot won't come through the wood fibre board.

    When I moved in I had an internal DPC on virtually all walls - the plaster at the bottom of most walls just fell off or came of easily. The guy left an additive to be used with the plaster to repel the salts in the wall, but before he left he suggested I look at IWI which obviously negates the use of the additive (and the guarantee lol).

    I think he was expecting me to be using gypsum and not lime, although this additive can be used with either I believe. But I wonder if you use breathable materials / plaster whether this is required at all?

    I think it was age that ultimately beat this house and the original lime plaster, at least the bottom half, succumbed. The ground its built on is of a clay sort.
    •  
      CommentAuthordjh
    • CommentTimeNov 12th 2020
     
    Posted By: kristevacan you suggest something breathable I could use other than expandable foam for the smaller gaps around the perimeter?

    Hi Paul. Don't worry too much about breathability of every little bit. Generally it's the overall average that's going to matter. The burnt sand mastic is good stuff, though. We avoided it by taking the render right up to the window and using a flexible window reveal bead with mesh to join it to the window. It's plastic so not as worthy as mastic but it is convenient.

    digging a french gully around the house

    They're usually called a French drain. The F is capital because it's a chap's name but that's just a bit of pedantry. The drain part is important though; there does need to be a route for water to escape out of the drain otherwise it may turn into a moat. Hopefully you know this and I'm embarrassing myself.
    •  
      CommentAuthorfostertom
    • CommentTimeNov 13th 2020
     
    Posted By: djhthere does need to be a route for water to escape out of the drain
    which means there has to be some kind of 'downhill' for it to be piped to - may be quite a long lead-out drain to be dug. It's no good draining it into a soakaway, unless far distant, as the water will just soak back to where it came.
  4.  
    Posted By: kristevaThanks for the burnt sand mastic tip


    We now use kiln-dried sand from any DIY store mixed with Linseed Oil. It's a bit of a faff to use and it takes a while to go hard, it may need protecting from heavy rain until it has gone hard (we had a few bits wash away, but just re-did them in better weather). Looks good too, traditional.

    Small gaps inside - expanding foam!
  5.  
    Posted By: kristevalime plastering, is it really that easy?


    I think its easier than skimming plasterboard, which I have tried, but concede to those more practised at it.

    If you have never tried any sort of plastering or rendering or used a trowel to spread anything across a wall then now is the time to have a go. Try in an inconspicuous area first (as many instructions state!)
    YouTube all sorts to do with plastering or rendering.
    If you are a practical person then you will pick it up. I quite enjoy it now.

    Green Building is about empowering individuals as well as saving energy!
  6.  
    Kristeva said:

    ''How do I go about getting a condensation risk assessment Nick?

    Your IWI routine sounds very similar to Warmshell / Steico systems promoted by Lime Green.

    Do you extend the wood fibre down beyond the floorboards, or is ok to sit it just above the floorboards and cover with skirting?''

    Your supplier should be able to do a CRA for you, but be aware that most are done according to the British Standard (Glaser) method, which is not as sophisticated as dynamic modelling software such as WUFI (Warme und feuchter something - ish, I think) which is a lot more location-specific and recognises that moisture can come from outside as well as inside. Unfortunately, AFAIK, WUFI practitioners are fairly rare. I used to get mine done ('free') by the supplier of my WF board, but mergers and take-over mean that this is no longer offered.

    I have, in the past, sat IWI on the floorboards, but would now not encourage that. Always try to get the 'joints' right. Cut back floorboards so that the wall ins meets the underfloor ins. At the top of the wall cut back the ceiling, parge coat between the joists and up to the floor above, prime and tape around joist ends with air-tightness tape, extend the insulation to just shy of the floorboards and then leave it ready to 'pick up' when you eventiually do the upstairs room.
    • CommentAuthorkristeva
    • CommentTimeNov 16th 2020
     
    Posted By: djh
    Posted By: kristevacan you suggest something breathable I could use other than expandable foam for the smaller gaps around the perimeter?

    Hi Paul. Don't worry too much about breathability of every little bit. Generally it's the overall average that's going to matter. The burnt sand mastic is good stuff, though. We avoided it by taking the render right up to the window and using a flexible window reveal bead with mesh to join it to the window. It's plastic so not as worthy as mastic but it is convenient.

    digging a french gully around the house

    They're usually called a French drain. The F is capital because it's a chap's name but that's just a bit of pedantry. The drain part is important though; there does need to be a route for water to escape out of the drain otherwise it may turn into a moat. Hopefully you know this and I'm embarrassing myself.



    Thanks djh, yes you're right, what I'm learning is a balance needs to be reached with all this. It's so difficult when there's so much information out there. I must say I couldn't find a great deal of info on burnt mastic and exactly how its used. Can I use it to fill out large gaps?

    The other issue I'm grappling with is what to do with some of the lathe and plaster ceilings. This house is a flying freehold and one of my rooms is beneath my neighbours dressing room. The ceiling in there is absolutely fine but at the very beginning I was certainly thinking of dropping it and insulating / sound proofing accordingly. Since then I've read a lot about the purpose of Lathe and plaster ceilings in old houses - breathable / moveable / decent sound proofing - and I'm loathed to trash it, and yet the thought of losing all that heat upstairs is difficult to shake off. Some even warn of cracked ceilings if replaced with plaster board. I'm now thinking maybe I could overboard it with a thin insulated plaster board the weight allows? What are your thoughts?

    My neighbour is due to sell the house soon but I'm not really up for asking if I can access the room and rip her floor up just to add some rock wool insulation.

    Yes, it's not a French drain at all and I shouldn't have referred to it as such. Its just a gully I dug as an emergency measure to take the pressure off the DPC, and I needed to insert new air bricks anyway so it made that job easier. After leaving it to dry out over the summer, whether rightly or wrongly, I applied bitumen beneath the DPC and filled with pea shingle. Its been pretty wet here over recent months and I've not noticed any issues. My plan next summer is to completely remove (lower) the path way at the front of the house and back which will hopefully negate the use of the gullies.
    • CommentAuthorkristeva
    • CommentTimeNov 16th 2020 edited
     
    Posted By: Dominic Cooney
    Posted By: kristevaThanks for the burnt sand mastic tip


    We now use kiln-dried sand from any DIY store mixed with Linseed Oil. It's a bit of a faff to use and it takes a while to go hard, it may need protecting from heavy rain until it has gone hard (we had a few bits wash away, but just re-did them in better weather). Looks good too, traditional.

    Small gaps inside - expanding foam!


    Thanks Dominic, maybe I don't feel quite like the Devil after all if I use a bit of expandable foam!! I must say I couldn't find a great deal of info about burnt mastic, but maybe I wasn't looking in the right places.
    • CommentAuthorkristeva
    • CommentTimeNov 16th 2020
     
    Posted By: Dominic Cooney
    Posted By: kristevalime plastering, is it really that easy?


    I think its easier than skimming plasterboard, which I have tried, but concede to those more practised at it.

    If you have never tried any sort of plastering or rendering or used a trowel to spread anything across a wall then now is the time to have a go. Try in an inconspicuous area first (as many instructions state!)
    YouTube all sorts to do with plastering or rendering.
    If you are a practical person then you will pick it up. I quite enjoy it now.

    Green Building is about empowering individuals as well as saving energy!


    Cheers, maybe under the stairs first? I don't know if its the infamous 'money saving' spirit of my late father coming through but I really want to have a go.
    • CommentAuthorkristeva
    • CommentTimeNov 16th 2020
     
    Posted By: Nick ParsonsKristeva said:

    ''How do I go about getting a condensation risk assessment Nick?

    Your IWI routine sounds very similar to Warmshell / Steico systems promoted by Lime Green.

    Do you extend the wood fibre down beyond the floorboards, or is ok to sit it just above the floorboards and cover with skirting?''

    Your supplier should be able to do a CRA for you, but be aware that most are done according to the British Standard (Glaser) method, which is not as sophisticated as dynamic modelling software such as WUFI (Warme und feuchter something - ish, I think) which is a lot more location-specific and recognises that moisture can come from outside as well as inside. Unfortunately, AFAIK, WUFI practitioners are fairly rare. I used to get mine done ('free') by the supplier of my WF board, but mergers and take-over mean that this is no longer offered.

    I have, in the past, sat IWI on the floorboards, but would now not encourage that. Always try to get the 'joints' right. Cut back floorboards so that the wall ins meets the underfloor ins. At the top of the wall cut back the ceiling, parge coat between the joists and up to the floor above, prime and tape around joist ends with air-tightness tape, extend the insulation to just shy of the floorboards and then leave it ready to 'pick up' when you eventiually do the upstairs room.


    Thanks Nick, really interesting and much appreciated.
    •  
      CommentAuthordjh
    • CommentTimeNov 16th 2020 edited
     
    Posted By: kristevaCan I use it to fill out large gaps?

    Not really, look at it more as like putty for sealing round windows etc. Use lime mortar or similar to fill large gaps.

    Sorry I don't know much about changing old ceilings. Others know much more.
  7.  
    Posted By: kristevaThe other issue I'm grappling with is what to do with some of the lathe and plaster ceilings. This house is a flying freehold and one of my rooms is beneath my neighbours dressing room. The ceiling in there is absolutely fine but at the very beginning I was certainly thinking of dropping it and insulating / sound proofing accordingly. Since then I've read a lot about the purpose of Lathe and plaster ceilings in old houses - breathable / moveable / decent sound proofing - and I'm loathed to trash it, and yet the thought of losing all that heat upstairs is difficult to shake off. Some even warn of cracked ceilings if replaced with plaster board. I'm now thinking maybe I could overboard it with a thin insulated plaster board the weight allows? What are your thoughts?

    Taking down lath and plaster ceilings creates an unbelievable mess and is best avoided if possible. The usual fix is to overboard with plasterboard fixed with long PB screws through to the joists. For over-boarding you should aim for at least 30mm of screw in to the joist (use coarse thread for fixing to wood). And find the joists first, mark the wall then pull a line across the new PB to ensure all the screws hit a joist.

    If you are worried about heat loss then use insulated PB or if the budget is tight then glue the ESP to the back of the PB yourself. (do the sums).

    If you have a lot of ceiling to over-board thin I can recommend using a PB lift.
    https://www.obi.hu/munkaeszkoezoek-munkagepek/lapemelo-gipszkarton-es-faforgacslapokhoz/p/4344214
    Sorry about the language - look at the picture ! I'm sure they are available to buy or hire in the UK and they really make putting PB on a ceiling an easy one man job.

    Over here no one skims PB it's all taped joints with glass fibre 50mm tape, not the paper tape.
    • CommentAuthorkristeva
    • CommentTimeNov 18th 2020
     
    Posted By: Peter_in_Hungary
    Posted By: kristevaThe other issue I'm grappling with is what to do with some of the lathe and plaster ceilings. This house is a flying freehold and one of my rooms is beneath my neighbours dressing room. The ceiling in there is absolutely fine but at the very beginning I was certainly thinking of dropping it and insulating / sound proofing accordingly. Since then I've read a lot about the purpose of Lathe and plaster ceilings in old houses - breathable / moveable / decent sound proofing - and I'm loathed to trash it, and yet the thought of losing all that heat upstairs is difficult to shake off. Some even warn of cracked ceilings if replaced with plaster board. I'm now thinking maybe I could overboard it with a thin insulated plaster board the weight allows? What are your thoughts?

    Taking down lath and plaster ceilings creates an unbelievable mess and is best avoided if possible. The usual fix is to overboard with plasterboard fixed with long PB screws through to the joists. For over-boarding you should aim for at least 30mm of screw in to the joist (use coarse thread for fixing to wood). And find the joists first, mark the wall then pull a line across the new PB to ensure all the screws hit a joist.

    If you are worried about heat loss then use insulated PB or if the budget is tight then glue the ESP to the back of the PB yourself. (do the sums).

    If you have a lot of ceiling to over-board thin I can recommend using a PB lift.
    https://www.obi.hu/munkaeszkoezoek-munkagepek/lapemelo-gipszkarton-es-faforgacslapokhoz/p/4344214
    Sorry about the language - look at the picture ! I'm sure they are available to buy or hire in the UK and they really make putting PB on a ceiling an easy one man job.

    Over here no one skims PB it's all taped joints with glass fibre 50mm tape, not the paper tape.


    Thanks Peter.

    In the end I decided to only drop my kitchen ceiling, through gritted teeth mind. Its not the mess that bothered me but more that I felt like a complete vandal. But its given me a more room and scope to fix a couple of the ceiling joists that were hacked up when they put the old hearth in upstairs. Thats one of many issues, I don't have a van to transport materials!

    Yes, I heard from a builder friend that glueing ESP to PB is a cheaper option. I'll look into it further. And my neighbour actually has a PB lift which he's offered to lend me. I've never worked with PB before though.
  8.  
    PB is easy to work with but do not over drive the screws otherwise the PB will be weak. Get a PB screw driver bit that has depth control/shield for your electric screwdriver or drill. There are several designs mostly inexpensive. I have about 3 different ones but only use one as its the one that works for me (as it happens it was the cheapest)

    The correct depth for the screws is driven below the surface of the PB but not enough to break the paper.

    If you are taking down ceilings under your flying freehold I'm not sure if fire regs. kick in. The problem is that if you start asking the authorities questions then they may start taking too much interest. If you overboard then you are not altering the existing, just adding a covering !!
    There are lots of different types of PB, normal, moisture resistant, sound insulating and fire retardant and combinations of the foregoing.
    • CommentAuthorkristeva
    • CommentTime5 days ago
     
    Posted By: Dominic Cooney
    Posted By: kristevalime plastering, is it really that easy?


    I think its easier than skimming plasterboard, which I have tried, but concede to those more practised at it.

    If you have never tried any sort of plastering or rendering or used a trowel to spread anything across a wall then now is the time to have a go. Try in an inconspicuous area first (as many instructions state!)
    YouTube all sorts to do with plastering or rendering.
    If you are a practical person then you will pick it up. I quite enjoy it now.

    Green Building is about empowering individuals as well as saving energy!


    Hi again Dominic,

    May I just ask, what Lime plaster do you use?

    Cheers

    P
  9.  
    I have used lime putty which is the easiest as it takes ages to go off, but the job then takes longer to complete.
    I have also used NHL5 powdered lime (we had some left over from the floor slab) and it goes off like cement so you have to be ready!
  10.  
    Quite fancy trying the LimeGreen stuff over plasterboard (or something similar) as I’ve never tried a lime based skim over plasterboard before. (I have only tried thistle multi-finish, inside an airing cupboard, and it was okay - I think I could get the hang of it with practice.)
  11.  
    (The lime putty and the NHL5 were mixed with sand to make the plaster)
    • CommentAuthorkristeva
    • CommentTime5 days ago
     
    Posted By: Dominic Cooney(The lime putty and the NHL5 were mixed with sand to make the plaster)


    How many coats did you apply? And have you applied it on to brick?
    • CommentAuthorkristeva
    • CommentTime5 days ago
     
    Posted By: Dominic CooneyQuite fancy trying the LimeGreen stuff over plasterboard (or something similar) as I’ve never tried a lime based skim over plasterboard before. (I have only tried thistle multi-finish, inside an airing cupboard, and it was okay - I think I could get the hang of it with practice.)


    Surely not worth it over standard plaster board? I think you can get a breathable equivalent, although most likely much more expensive.

    Yes, I think I'll start in the cupboard under my stairs lol.
  12.  
    One or two coats, most of it was over Hemcrete which I did in one coat, some was on rubble stone and some brick (chimney breasts). Some of it was sponged off to reveal the grit in the mix to get a more interesting texture, all of it over the Hemcrete was done flat & smooth - work quickly and get it on the wall, apply it as evenly as you can, then after a bit wet it with a brush and keep going over it with the trowel.

    The first wall I did in NHL5 went rock hard with trowel marks in (I think I might have left it overnight!) so I had to skim over it with a lime putty mix. That day was a bit stressful, but it got better after that.

    The person that makes no mistakes never makes anything!
  13.  
    Flat walls left and right over Hemcrete, end wall is textured over rubble stone.
      snug.JPG
   
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