We are about to buy an older property where there is excessive moisture in the external walls (solid masonry). We are planning on stripping off the modern plaster and re-plastering in lime. I did wonder though, due to the solid walls, if building control might insist on us insulating the walls. We are planning on stripping back all ground floor rooms, externall walls to ceiling height. The house is not listed. I guess if we are obliged to add insulation then that will lead us to dry lining. Does anyone have any experience of this? I guess we need to ensure that ventilation is intruduced to stop rot behind the new walls. Interested in your thoughts/experiences. Thanks.
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Dry lining and building control
- Thread starter Impy
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skier-hughes
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What you don't tell them won't hurt them........ if you do it well and in keeping with the age of the building, "it was already there when we bought it gov" would be my answer.
Our neighbours have been forced to insulate and dry line their house by building control. It will make their rooms smaller and destroys some of the character of the house which they are understandably not too happy about. On the other hand, their house used to cost £1500 to £2000 per year to heat badly while our slightly larger but insulated house will cost around £350.
My understanding though is that building control are interested in the total energy required to heat the house rather than any individual element. This means that you can potentially get around a poorly insulated item by over insulating elsewhere or by installing a more efficient heat source such as a heat pump (though these are not recommended with a poorly insulated house). Walls though are such a large element that it would be difficult to over insulate elsewhere to compensate.
My understanding though is that building control are interested in the total energy required to heat the house rather than any individual element. This means that you can potentially get around a poorly insulated item by over insulating elsewhere or by installing a more efficient heat source such as a heat pump (though these are not recommended with a poorly insulated house). Walls though are such a large element that it would be difficult to over insulate elsewhere to compensate.
worms
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I'm afraid I am with MdB and Building Control, if it is all coming off anyway, what a great opportunity to improve the thermal efficiency. If you don't want to use modern materials you can always insulate with a "green" alternative and lath & plaster over it.
Penners
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Why would Building Control be interested? All you're doing is repairing some dodgy plaster - no need for them to be involved. I suggest you do whatever is best for yourself and the house.Impy said:We are about to buy an older property where there is excessive moisture in the external walls (solid masonry). We are planning on stripping off the modern plaster and re-plastering in lime. I did wonder though, due to the solid walls, if building control might insist on us insulating the walls.
Some good advice in other posts above.
If Building Control spot that you are refurbishing more than something like 25% of your walls then they insist that it is all done to the current standards. Our neighbours didn't have any plans to get BC involved at all but they did a site visit and decided that our neighbours had to do what they told them. I'm not sure of the exact rules involved and I guess there is different leeway with different BC staff so YMMW.
Before you start ripping the plaster off the walls etc. do a good long search on here for the word 'damp'. There are any number of reasons why a building surveyor may have put in the report that the property is riddled with rising damp when in fact it is possible to rectify the problem without ripping the plaster off the walls.
If you are renewing more than 25% of a wall/roof you are "renewing the thermal element" and are obliged to bring it up to meet Part L1B of the 2006 Building regulations. Which in practice means you will need to insulate the wall.
http://www.planningportal.gov.uk/uploads/br/BR_PDF_ADL1B_2006.pdf
(I'm told by my building friends that the regs will change again next year and they will be ever more stringent on thermal efficiency.)
This doesn't mean you must dry line, you can use breathable insulation and wall boards/lath and plaster etc. on the inside or if you prefer you can insulate externally and render. BUT sheepswool (for example) will need 3x as much depth to provide the same insulation value as kingspan/isotherm/celotex boards so if you insulate internally you will need to think about floor space.
There are guidelines that mean you don't have to lose more than 5% of room space or if you can prove that the insulation cost won't 'pay back' in savings in a certain period you can reduce the need - you will have an uphill struggle with Building Control on this.
If you are doing significant work to the house you can take a 'whole house assessment' (usually using a methodology called SAP done by a professional) which calculates the overall energy efficiency of the house as it is, as it will be built and a notional house of the same size and design in which all the elements meet the individual regulations. If you can get a professional to show that your work will consume less power than the same size building which complies then BC can approve works on some parts which don't meet the regulations i.e. solid walls. You can't simply trade a 1" of roof insulation for a new single glazed window (AFAIK).
In our case we wanted to restore a large vinery and integrate it with the house. The vinery would be more than 25% of the new living space and would therefore not be permitted under standard rules even if everything else was done to regs. However by specifying top quality double glazing, and heavily insulating the walls and roof in the newly renovated sections installing a heat pump to replace and oil boiler and adding a woodburner as secondary heating we were able to prove the whole house would consume less power than the oil fired fully compliant equivalent extension.
Most of the house is double glazed but has uninsulated solid walls. In the newly renovated sections we have battened then insulated the walls over the battens, leaving an air gap to allow the wall to breathe slightly internally. The roof was insulated between the rafters and over the rafters to create a 'warm roof' to avoid lowering a low ceiling inside.
If you insulate the walls internally or externally you will change the thickness of the wall which means new window reveals, window boards and/or cills perhaps door frames, changes to cornices etc. so take your time and do your sums. That kind of work is fiddly and done badly will ruin the look of the house.
FINALLY as some who bought with their heart not their head and without any previous renovation experience. Get some quotes on the renovation before you exchange contracts. I foolishly thought £50K/6 months would cover everything we needed to do. I've spent more than 3 times that much, it took 2 years planning and a year (so far) to do the work. If I'd had more advice from a RICS surveyor with conservation experience or a conservation savy architect or builder with period property experience then we could have negotiated the price down by a lot and might not have bought at all.
Good luck!
If you are renewing more than 25% of a wall/roof you are "renewing the thermal element" and are obliged to bring it up to meet Part L1B of the 2006 Building regulations. Which in practice means you will need to insulate the wall.
http://www.planningportal.gov.uk/uploads/br/BR_PDF_ADL1B_2006.pdf
(I'm told by my building friends that the regs will change again next year and they will be ever more stringent on thermal efficiency.)
This doesn't mean you must dry line, you can use breathable insulation and wall boards/lath and plaster etc. on the inside or if you prefer you can insulate externally and render. BUT sheepswool (for example) will need 3x as much depth to provide the same insulation value as kingspan/isotherm/celotex boards so if you insulate internally you will need to think about floor space.
There are guidelines that mean you don't have to lose more than 5% of room space or if you can prove that the insulation cost won't 'pay back' in savings in a certain period you can reduce the need - you will have an uphill struggle with Building Control on this.
If you are doing significant work to the house you can take a 'whole house assessment' (usually using a methodology called SAP done by a professional) which calculates the overall energy efficiency of the house as it is, as it will be built and a notional house of the same size and design in which all the elements meet the individual regulations. If you can get a professional to show that your work will consume less power than the same size building which complies then BC can approve works on some parts which don't meet the regulations i.e. solid walls. You can't simply trade a 1" of roof insulation for a new single glazed window (AFAIK).
In our case we wanted to restore a large vinery and integrate it with the house. The vinery would be more than 25% of the new living space and would therefore not be permitted under standard rules even if everything else was done to regs. However by specifying top quality double glazing, and heavily insulating the walls and roof in the newly renovated sections installing a heat pump to replace and oil boiler and adding a woodburner as secondary heating we were able to prove the whole house would consume less power than the oil fired fully compliant equivalent extension.
Most of the house is double glazed but has uninsulated solid walls. In the newly renovated sections we have battened then insulated the walls over the battens, leaving an air gap to allow the wall to breathe slightly internally. The roof was insulated between the rafters and over the rafters to create a 'warm roof' to avoid lowering a low ceiling inside.
If you insulate the walls internally or externally you will change the thickness of the wall which means new window reveals, window boards and/or cills perhaps door frames, changes to cornices etc. so take your time and do your sums. That kind of work is fiddly and done badly will ruin the look of the house.
FINALLY as some who bought with their heart not their head and without any previous renovation experience. Get some quotes on the renovation before you exchange contracts. I foolishly thought £50K/6 months would cover everything we needed to do. I've spent more than 3 times that much, it took 2 years planning and a year (so far) to do the work. If I'd had more advice from a RICS surveyor with conservation experience or a conservation savy architect or builder with period property experience then we could have negotiated the price down by a lot and might not have bought at all.
Good luck!
Schoolmarm
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I would completely leave the walls alone until building control has signed you off for the other jobs.
I am interested in this question myself (see below for context). There is something called hemcrete which contains lime (breathable), and hemp for insulating properties. I am assuming that it wouldn't be terribly cheap, but then using sympathetic and environmentally friendly materials which also give modern-ish insulation efficiency is unlikely to be the cheapest option. I also assume one would need to apply a slightly thicker overall layer than for normal lime plaster (circa 2cm? or maybe less, and then plaster on top). On the lime technology website they advertise the product as having being used by Marianne Suhr (SPAB lecturer, on telly etc) on her property. Apparently you can't apply it like lime plaster which is a shame, although I gather that you can also buy hemp-lime plasters which can be trowelled on (I think 'Hempire' may be one of these, but their website is a bit vague on what the insulation value actually is).
So this sort of thing might be of interest to you as an option. Don't know if anyone on this forum has previous experience of, or views on, using hemcrete or hemp-lime plaster.
Context - The back wall in our cottage had lime plaster which was so damp it was literally dropping off the wall in big chunks. Since taking various steps to address damp (mainly removing the immersion heater upstairs which had been leaking for at least a year in an empty house) the wall has dried out (except for some damp right at the base relating to drainage issues outside still to sort out). We now have an exposed stone wall at the back waiting to eventually be plastered in some way (I am not keen on dryboarding partly because have ripped out huge amounts of the dryboarding that was there before and very rotten). The slightly annoying thing is that everyone comes around and says what a lovely stone wall, you must leave it uncovered... I personally am not mad keen on the exposed stone wall thing, and the winters around here get pretty cold and windy so I need all the help I can get.
So this sort of thing might be of interest to you as an option. Don't know if anyone on this forum has previous experience of, or views on, using hemcrete or hemp-lime plaster.
Context - The back wall in our cottage had lime plaster which was so damp it was literally dropping off the wall in big chunks. Since taking various steps to address damp (mainly removing the immersion heater upstairs which had been leaking for at least a year in an empty house) the wall has dried out (except for some damp right at the base relating to drainage issues outside still to sort out). We now have an exposed stone wall at the back waiting to eventually be plastered in some way (I am not keen on dryboarding partly because have ripped out huge amounts of the dryboarding that was there before and very rotten). The slightly annoying thing is that everyone comes around and says what a lovely stone wall, you must leave it uncovered... I personally am not mad keen on the exposed stone wall thing, and the winters around here get pretty cold and windy so I need all the help I can get.
skier-hughes
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We had haired lime for bottom coat, haired lime mixed with hemp for second caot to help with insulating and then a finish coat.
The haired lime was bought ready mixed, but the hemp came in a compressed bale and was mixed on site.
The haired lime was bought ready mixed, but the hemp came in a compressed bale and was mixed on site.
Schoolmarm
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skier-hughes said:We had haired lime for bottom coat, haired lime mixed with hemp for second caot to help with insulating and then a finish coat.
The haired lime was bought ready mixed, but the hemp came in a compressed bale and was mixed on site.
Hmmm interesting.
Flyfisher
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Yes, that was my first thought also.Schoolmarm said:I would completely leave the walls alone until building control has signed you off for the other jobs.
I don't have any figures to hand so I could be way out but my feeling is that the thickness of any breathable insulation method would have to be considerably (x3??) thicker than Celotex which may cause problems for small rooms. I could be completely wrong on this.
As I said earlier I would speak to some professionals about the 'damp', you may not need to replaster at all (not damp proofers or general house valuers).
The insulative properties of hemp in lime plaster are not going to come close to expanded foam with foil, thickness for thickness.
Celotex/isotherm/kingspan are about 3 times as efficient centimeter for centimeter than mineral wool loft insulation. Sheeps wool is (IIRC) about the same capacity as mineral wool. As it's the air in the 'wool' in both cases that is the primary insulator then a solid mix of hair and plaster is going to have less air/more solid and therefore transmit more heat from the warm room to the cold outside.
IIRC A solid wall has a U value (the speed of heat transfer) of around 2W/m2K, to meet 2006 regs you would need to reduce that to at least 0.7W/m2K (page 25 of the link above). If meeting that won't pay for itself in 15 years then you can downgrade to a level that will, but you may not "simply not do it" because you don't want to. (Listed building concerns aside).
In context my lined walls needed 50mm of Isotherm to meet regs. We put in 25mm between battens then 50mm backed onto plasterboard over the top to meet our whole house calcs with some spare.
You could try http://www.greenbuildingforum.co.uk/newforum/ for more information on lime/hemp etc. breathability and thermal efficiency.
FWIW I think you will cause yourself a lot trouble by trying to 'complete the work' and get building control to sign off with damp walls. Building Control Officers are professionals and will take one look at you 'completed work' and know what you're going to do. You would probably have to do all your second fix electrics again when you rip the plaster off the wall which will cost you a great deal of time and money assuming the damp hasn't already done damage to the boxes etc. If you successfully got around the regs you will have a room which is (more) expensive to heat and probably less comfortable to be in. I wouldn't recommend that approach and I'm perturbed that Listed Building Consent is considered holy on here but building control is considered to be an avoidable inconvenience. In the case of one wall in a house I would, but if you're doing a whole house renovation I would work out how to do it properly. In your position I would speak to some architects/surveyors/builders before you decide what to do.
The insulative properties of hemp in lime plaster are not going to come close to expanded foam with foil, thickness for thickness.
Celotex/isotherm/kingspan are about 3 times as efficient centimeter for centimeter than mineral wool loft insulation. Sheeps wool is (IIRC) about the same capacity as mineral wool. As it's the air in the 'wool' in both cases that is the primary insulator then a solid mix of hair and plaster is going to have less air/more solid and therefore transmit more heat from the warm room to the cold outside.
IIRC A solid wall has a U value (the speed of heat transfer) of around 2W/m2K, to meet 2006 regs you would need to reduce that to at least 0.7W/m2K (page 25 of the link above). If meeting that won't pay for itself in 15 years then you can downgrade to a level that will, but you may not "simply not do it" because you don't want to. (Listed building concerns aside).
In context my lined walls needed 50mm of Isotherm to meet regs. We put in 25mm between battens then 50mm backed onto plasterboard over the top to meet our whole house calcs with some spare.
You could try http://www.greenbuildingforum.co.uk/newforum/ for more information on lime/hemp etc. breathability and thermal efficiency.
FWIW I think you will cause yourself a lot trouble by trying to 'complete the work' and get building control to sign off with damp walls. Building Control Officers are professionals and will take one look at you 'completed work' and know what you're going to do. You would probably have to do all your second fix electrics again when you rip the plaster off the wall which will cost you a great deal of time and money assuming the damp hasn't already done damage to the boxes etc. If you successfully got around the regs you will have a room which is (more) expensive to heat and probably less comfortable to be in. I wouldn't recommend that approach and I'm perturbed that Listed Building Consent is considered holy on here but building control is considered to be an avoidable inconvenience. In the case of one wall in a house I would, but if you're doing a whole house renovation I would work out how to do it properly. In your position I would speak to some architects/surveyors/builders before you decide what to do.
hoppy
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Sadly, this would not be an option.... you still need a completion certificate when ALL works are completeImpy said:Leaving the walls until the other work has been signed off sounds like a good idea. We were hoping to get all the messy jobs done at once but I suppose if we can sequence the work to follow straight on that would be OK.
Define "ALL works are complete" in reference to most of the properties people are working on here. 5 year plans turning into 20 years are all too common.hoppy said:... you still need a completion certificate when ALL works are complete
You might all be interested to know that I called Building Control at the local council yesterday about the house we are buying. In the last 10-20 years the following work has been done on the property:
- roof stripped and re-covered
- ground floor opened up, with RSJ inserted
- single storey attached outbuildings converted in to an extension.
I suspected that none of this work had building control approval/sign-off. This was confirmed when I spoke to Building Control yesterday. They did not seem at all concerned and the person I spoke to told me that they only have a 2 year enforcement period after works were done and after that they would not do anything. As far as he was concerned if my surveyor was happy (which he was) then they were happy. Reassuring for us as I now know that we are not going to be liable for work carried out by the previous owner. I did get the person's name so I can quote them back later if necessary! We are going to do some upgrading of work that was done e.g. improving the roof insulation etc as I do not think what is there is adequate. For us it is important that the sale goes through quickly and smoothly and we are accepting of the fact that we are going to have to do some remedial work to ensure that work already done is up to scratch.
- roof stripped and re-covered
- ground floor opened up, with RSJ inserted
- single storey attached outbuildings converted in to an extension.
I suspected that none of this work had building control approval/sign-off. This was confirmed when I spoke to Building Control yesterday. They did not seem at all concerned and the person I spoke to told me that they only have a 2 year enforcement period after works were done and after that they would not do anything. As far as he was concerned if my surveyor was happy (which he was) then they were happy. Reassuring for us as I now know that we are not going to be liable for work carried out by the previous owner. I did get the person's name so I can quote them back later if necessary! We are going to do some upgrading of work that was done e.g. improving the roof insulation etc as I do not think what is there is adequate. For us it is important that the sale goes through quickly and smoothly and we are accepting of the fact that we are going to have to do some remedial work to ensure that work already done is up to scratch.