Insulation (or NOT!) ideas for an old house

Timmyboy

Folks, hoping that I can receive some comments, recommendations or opinions here on thoughts and considerations that I am having in regard to the insulation of an old house.

The house is a two storey (really actually a storey and 3/4 type house as the upstairs ceiling also has sloping upper side parts formed by extended rafters from the roof coming down to the main external walls on either side) and is constructed of mass concrete in a single leaf.

The building has now been gutted and structural repairs and roofing repairs completed.

The structure is generally dry and also there is no appreciable rot or damage from woodworm to the timbers that support the first floor and roof.

I am now at a critical point of having to make a decision with regard to insulation.

Fundamentally I have concerns that doing either an external insulation or internal dry lining insulation solution is going to create more trouble than it's worth in the long term by being a possible jeopardy to my health and to the health of the building.

I am considering doing a basic type of dry-lining by battening with walls with 2 x 2's (i.e. 44mm x 44mm (what a rip off:mad:)) timbers and then facing the cavity formed by those timbers with new plasterboard to be taped and double skimmed.

I have considered the provision of let's say insulated dry lining (i.e. plasterboard backed with an insulation layer) but right now I don't want to do this as I don't like the idea of putting plastic material that may be outgassing chemicals in the future.

So the idea is now to see if its possible to simply put some form of glass fibre or rock fibre material or another type of suitable insulation into the gaps between the battens.

Suitable to me means, mostly of natural content, i.e. metal, rock or timber etc. but not plastic; and that it be breathable and able to allow moisture to migrate through it and away to ventilation.


Any considerations or thoughts or comments on the above much appreciated.:)

Carlow52

I would suggest you google for " breaking the dry-ling mould" and read the material by a Mr Little.

The building has now been gutted

Can u be more specific please on the current stated of 'guttedness' or lack thereof?

Timmyboy

Thanks for the information Carlow52. I will do some searching on that Mr Little information in the next short while.


To answer your question, by gutted I mean the following:

The ceilings of the ground floor were made of some thin type wood board in panels about 4' x 6' with little mouldings running along the grooves. These have been removed from the ceilings to expose the joists

The ceilings on the first floor were painted 3" or thereabouts tongue and grooved boards nailed to the underside of the first floor ceiling joists and extended rafters.

The walls of the kitchn had been lined previously. This consisted of some 2" x 1/2" battens which had been steel nailed to the mass concrete walls. The some beauty board (i.e. a wood finish type veneer thin boarding) had been affixed to those battens securing them to the wall.

This lining system was also in use on two of the upstairs (3 in total) bedrooms.

All of the above described ceilings and linings have been removed leaving bare walls and roof structure exposed. Also have tried to remove old paint on walls that were peeling or separating from those walls.

The walls of some rooms appear to have been plastered with concrete plaster. Other walls had some type of lime plaster in various states of disrepair. The degraded lime plaster has been hacked down and removed.

Carlow52

Gutted yes! Just like Dunkies programs, it will be all done after the ad break starting now:D

What is the ground floor comprised of?

Do you think it has a damp proof course fitted?

The use of lime is an interesting item as it is more breathable.

Are u 100% certain they walls are concrete?

If there is no dpc and lime has been used then you cant use the stuff used in more modern houses..
Google hemp and lime

Timmyboy

Thanks again Carlow52. I read through that information from Mr. Little and it was good stuff.

I picked up that it appears to indicate the importance of avoiding risks due to interstitial condensation and that some form of appropriate, modern, analysis should be completed in order to take account of the possibility of condensation occurance that might result.
I also thought the section with reference to historic buildings, mine is one of those (built in 1939 I think) was useful.

I'm not sure that I have the experience to run one of the programs that were mentioned such as WUFI efficitvely so I'm going to be a little more basic and try to describe the solution that I'm thinking about right now.

Working from the Ouside In:
Plaster Coat
Mas Concrete Wall
Batten with 44mm x 44mm timber
Fill with 2" Rock Fibre insulation
(Pipe work for radiators and cabling for electrics will also be packed into this 44mm x 44mm space between the battens as required)
Foil Backed Plasterboard
Double Skim and Tape
Paint.

On ground floo level the ceiling joists will also have plasterboard and double skim below them with the plasterboard of the ceiling butting up to the plasterboard rising vertically at the external walls.

I intend right now on leaving the rock fibre cavity formed by the battens open below the ceiling joists so that any trapped moisture here can ventilate upward to the first floor area through the joists and the first floor floor boards.

Similar external wall specification to be used for the first floor but I do have an idea of lining the extended rafters with some 30mm phenolic type insulated plaster board (42.5mm overall thickness) below the extended rafters. The space between the extended rafters to be left unfilled to continue to allow eaves ventilation to clear any damp that may develop.

I'll see if I can investigate downloading a trial copy of WUFI and giving it a shot!;)

More after the break....:D

Timmyboy

Ooops, sorry that I didn't answer your questions, answers now below:


What is the ground floor comprised of?
The ground floor is currently a cork lino upon a concrete base. Not sure of the thickness but I guess about 2"

Do you think it has a damp proof course fitted?
I do think that there is a form of damp-proof fitted, to both the walls and the floor. I'm guessing some form of bitumen tar or some such from the technologies of the 1930's.
I've no proof that there is a fitting of such a course but the walls and floor do have a general dry nature to them, even given the exposure of the building to the wind driven rain coming onto the building and its site located on a hillside.


Are u 100% certain they walls are concrete?
As certain as I can be but I'd rarely give a 100% on anything.
The walls are visible unpainted and unplastered behind the kitchen cabinets that have also been removed.
Here it can be seen the courses of the mouldings of the different layers of concrete that was poured to form the wall. The shuttering lines are visible and apparent in layers.
The visual appearance of the material tells me that it's concrete. Also it can be seen that in certain cases the mix may not have been as consistent as I would have hoped it would have been.:rolleyes:


If there is no dpc and lime has been used then you cant use the stuff used in more modern houses..
Google hemp and lime
That's a good point about the lime but all factors at the moment, including that the external walls appear to me to be plastered with concrete plaster rather than lime render (where they have been plastered) points me to think that lime may have been used for only the interior surfaces for some other reason?

BryanF

hi timmyboy,
you've a lot going on here:) and i may need to re-read:) so apologies if you've covered this already

roof:

1. your roof is freshly slated?
2. was a breathable felt used?
3. if not is there vents at eaves or vented roof slates
4. ie do you intend to insulated from above or below

walls

1. mass concrete is not really the best structure to make 'breathable'
2. however, i commend you on wanting to use of natural insulations and materials. what Carlow is suggesting by pointing you to Little's studies is that: internally dry-lining (over a certain thickness, probably the amount you have existing) will cause interstitial condensation problems on the inner surface of the mass concrete wall. this can be limited by use of a Vapour barrier but ultimately insulating externally would be a better solution. not least because its deals with floor junctions etc more comprehensibly
3. External wall insulation(EWI does not have to be EPS or PIR plastered painted. for instance it could hemp of timber rigid batts with a rain-screen cladding of mineral-board plaster painted or you could go with hemplime.. there are many options..

windows:

• the quality
• and how you fit your windows is important
• do consider the materials of your wins..

ventilation

• much of the above will limit the amount of ventilation and air- movement, so you need to think about either wall or window vents & some or alot of mechanical ventilation depending on your strategy
• is there dampness? mould? stale air in the house?
• are you sure there is no asbestos etc in any of the existing materials ???

thermal bridging

• in an old house its diffiult to detail and insulate every inch of surface, but it worth attempting or at least considering..

building regulation

• please note that your are obliged to consider current building regulations and you should either get reading or get an arch/ arch tech to advise you
• /BuildingStandards/
• technical guidance documents
• also see here re passive house retro-fit standard
• and see the seai's website

re wufi:your a brave man, it will take you some time.. quiet a bit of time:)

muffler

BryanF wrote: »

also see here re passive house retro-fit standard

I think that's the same link you have posted several times but it never works...well, not for me anyhow

Timmyboy

hanks Bryan F for your inputs and helps here. Very much appreciated. I'll add some commentary to your feedbacks below:



roof:

1. your roof is freshly slated? I hadn't covered this Bryan so I'll fill in here. There were what appeared to be original Valential Slates on the roof. Generally the most of these were in good condition. One of the chimneys of the house (there is one on each gable) was structurally damaged and this was cut down to foundation during late Summer and re-built in early Autumn. When this had been completed action was taken to repair some damaged slates here and there with natural slates that were a reasonable match for the original (smoother and not as thick but of the same dimension and near enough the colour). This work didn't go as smoothly as I had planned and the builders were damaging and breaking more slates than they were fixing so I actually had to show and tell the builders to get off the roof as they were not paying enough attention and generally just making a mess of good work rather than making bad things better. I was upset by this as they had done a good job with the chimney structure....
2. was a breathable felt used?
   No and not now either. There was a lime motar render used upon the backside of the slates. This was repaired (I must check if this work actually has been completed:cool:) with more of the same where it had broken away in places. I guess that the lime mortar was the breathable felt of the old days.
3. if not is there vents at eaves or vented roof slates
   Yes, there were vents (in actual effect gaps below the slates along the eaves at both sides of the house - Looking down along the extended rafters to the walls you could see slots of light outside coming through and feel a small blow of air).
   Additionally to this due to damage to a number of the ridge tiles, the rige tiles in total have been replaces with a ventilated ridge to supplement the eaves ventilation.
4. ie do you intend to insulated from above or below
   I'm not quite sure that I exactly understand your input here but this is what the plan is regarding roof insulation. It is planned to keep the attic area as a cold attic that will not be used for habitation but only for the purposes of water tanks and for small storage (e.g. christmas tree, empty boxes and suitcases.
   The general idea is to provide a small level of breathable, natural material (or more natural as I can cost effectively afford).
   So this leads me to the following solution: 4" of rock fibre type insulation between the horizontal attic joists and foil backed insulated plasterboard below the attic joists, combined with 30mm or 40mm of phenolic type insulation board + 1/2" plasterboard below the extended rafters which will remain clear and open between adjacent rafters so as to preserve the ventilation pathway from eaves through into the cold space of the attic. Plastic moulding barriers are to be used to keep clear the spaces between the extended rafters from being intruded by the rock fibre insulation from the joints getting moved into those regions.

walls

1. mass concrete is not really the best structure to make 'breathable'
   You got that right!:D
2. however, i commend you on wanting to use of natural insulations and materials. what Carlow is suggesting by pointing you to Little's studies is that: internally dry-lining (over a certain thickness, probably the amount you have existing) will cause interstitial condensation problems on the inner surface of the mass concrete wall. this can be limited by use of a Vapour barrier but ultimately insulating externally would be a better solution. not least because its deals with floor junctions etc more comprehensibly
   Good feedback here Bryan, thanks again. Just to be clear though that currently there is no insulation. i.e. Nada, Nothing. Basically just the mass concrete walls.
   The detail that I had given previously is essentially just about as much as I want to go because I don't want to cause or bring about the jeopardy of interstitial condensation that could damage my health or the health of the buidling through mould growth, and/or mould growth and rot of the structural timbers (floor joists, attic/roofing timbers).
3. External wall insulation(EWI does not have to be EPS or PIR plastered painted. for instance it could hemp of timber rigid batts with a rain-screen cladding of mineral-board plaster painted or you could go with hemplime.. there are many options..
   I've seen the hemp lime and I kind of like it but I am concerned about its durability and ease of mainteance and given what I've seen with some of the lime plastered walls on the interior where they had degraded to powder in places I think I must pass on lime for now even though I do genuninely appreciate it's breathable and anti-fungal properties.
   I'm leaning for the minimal approach internal dry lining methodology and keeping the cavity top breathable and somewhat heated (by having the radiator pipes in there) since it allows me to hide the electrics also and the piping for the radiators. It also allows me to achieve a regular interior surface finish.

windows:

• the quality
  Currently there are aluminium double glaze units installed along with aluminium doors front and rear. I'm a fan of aluminium even though it acts as a super duper cold bridge.
  I like its durability and damage resistance and prefer it as a more natural material than PVC type window units.
  For this reason the window specification is planned to be Thermally Broken double glazed new aluminium windows. I have this opportunity to replace them as part of the renovations of the house so I'm probably going to do this.
  The windows are generally sound but various of the top opening sections are currently showing interior condensation as if the seals of those parts have failed and allowed moisture to enter of the years. I guess that they were fitted about 25 years ago judging by their appearance.
• and how you fit your windows is important
  Totally. I want the replacement windows to be fitted super sealed and only to allow the controllable ventilation that is to be designed into them to be the the only ventilation at the windows. Certainly I don't want cold air from the outside getting into the cavity of the dry lining. So as such, the windows are to be both foam and tape sealted and to be proven to be not leaking by pressure testing the house if I can maage that...:rolleyes:
• do consider the materials of your wins..
  I do know that my choice of Aluminium rather than PVC is more heart than head based. The head is strong but Aluminium windows have only failed me once whereas I've had various issues with PVC windows over the years. For this reason the Thermally Broken Aluminium windows seem to be winning it for me.
  
  One final items on the windows is that the guys who designed this house, like so many of the older houses really knew how to size and locate the windows. They have the base of the openings at about 2' above ground rising to 6'4" above ground. Grand tall windows and decently wide as well. Originally these would have been the old style weighted sash windows. I'm not sure that I really want sash style window but I am thinkiing about this too but ultimately I will probably go for a split in the middle as per the Sash Windows but with a more typical Casement type openign arrangement.
  
  The sides of the windows are to be enlargened so as to allow a fitting of 25mm phenolic +12.5mm plasterboard reveals around the window openings and to also display a 35mm frame dimension.
  
  These final details to be agreed with the supplier before purchase.

ventilation

• much of the above will limit the amount of ventilation and air- movement, so you need to think about either wall or window vents & some or alot of mechanical ventilation depending on your strategy
  Totally. Great stuff there Bryan.
  The plan is as follows:
  
  a. Some of the windows are to have built in pre-installed horizontal slot window ventilators.
  These are the two windows (front and rear) of the kitchen, the window to the Bathroom, the side window to the Scullery, the window to the Bathroom Lobby, the upstairs window to the stairway landing.
  b. Two mechanical through the wall ventilators to be installed. One to the kitchen to ventilate from the hob vent to the outside and One to be installed to ventilate from the Bathroom (both the Kitchen and Bathroom ventilators are be on timers that keep them going for 15 minutes after fan/cooker operation or lights on in bathroom.
• is there dampness? mould? stale air in the house?
  No . It was one of the better houses of its time I believe and built in a good way by a family who were returning from America during the end of the Great Depression.
• are you sure there is no asbestos etc in any of the existing materials ???
  Generally sure overall.
  Not really seen any signs of it. The main worry has been that paints used in the house would have been lead based paints and I've thus far removed any of those paints that were loose and would scrape off easily.

thermal bridging

• in an old house its diffiult to detail and insulate every inch of surface, but it worth attempting or at least considering.
  Agreed. Going to do this as much as possible in 3 stages.
  Ground Floor Walls, First Floor Walls, First Floor Ceiling

building regulation

• please note that your are obliged to consider current building regulations and you should either get reading or get an arch/ arch tech to advise you
  Good advice.
  Will do as much as is feasilble and practicalbe and in keeping with the regulations while bearing in mind the benefits that the Building Regulations have for Existing Buildings that this is that was built prior to the Building Regulations being implemented.
  There are space limitations within the house and it's relatively compact (about 100m2 in total for a 3 bedroom one bathroom house)
• /BuildingStandards/
• technical guidance documents
• also see here re passive house retro-fit standard
• and see the seai's website
  Thanks for that link on the Passive House Retrofit Guide. I'll do a bit of looking at that tomorrow morning.

re wufi:your a brave man, it will take you some time.. quiet a bit of time
Brilliant!

BryanF

muffler wrote: »

I think that's the same link you have posted several times but it never works...well, not for me anyhow

i never have any problem:o here's the other link to it

http://passivehouseacademy.com/downloads/Retrofit-Passive-House-Guidlines.pdf

BryanF

timmyboy

walls: if it was me, I'd be going external insulation, doing windows reveals etc externally, also externally below ground floor level

roof: replace the phenolic for wood fibre board or if you can drop the ceiling by 1-200mm on the slope to add more insulation then use the mineral wool batts. also consider a Vapour barrier behind plasterboard. on the flat see if you can stretch to 400mm of mineral wool.

ventilation: see the regs + get a RH sensor.

thermal bridging much easier to achieve from the outside

muffler

BryanF wrote: »

i never have any problem:o here's the other link to it

http://passivehouseacademy.com/downloads/Retrofit-Passive-House-Guidlines.pdf

That one works fine. The first one may have something to do with the browser settings or add ons.

Just to explain that it wasnt really myself I was thinking about. If the link wasnt working for me it may not have been working for some others also.

Timmyboy

Thanks to everyone who's contributed information.

It's now final decision time and currently it appears that I will be going for a phenolic type insulation product! :rolleyes:

I'm not overjoyed about this but here are my reasons.

The house is small enough at about 100m2 and if I use the more natural insulations e.g. the wood-fibre board then to achieve similar U-value performance I'll be generally looking at about twice the thickness (not including for battens etc.)

One of the external walls, that which includes a chimney is effectively exposed to severe wind driven rain and is presently a little damp. I believe though I am not entirely certain that this dampness is due to the cracked chimney and that the chimney concrete had been fairly damaged leading to a situation where the chimney had become a sponge and was soaking in water from above and keeping it inside.

Anyway, to cut a long story short I am concerned that dampness of one form or other on this and possibly other external walls may lead to rot of a timber based insulation product.

So now here are my current ideas and I'm very open to criticism of thes and would actually appreciate any further comments.

External walls:
To be battened with 50mm x 35mm treated battens with a DPC layer behind those battens on the external wall side.
Then over the battens to place a layer of 45mm thick phenolic insulation board and with 12.5mm plasterboard over the top of this. (Where in the Kitchen there is to be Kitchen Cabinets and Shelvings fitted a layer of 18mm marine plyboard will be used between the plasterboard and the phenolic insulation).

Reveals and internal walls that come off external walls (there are two of these at the front hall as well as two at a back lobby) are to have dabbed and mechanically fixed (mushroom head fixers) 25mm thick phenolic insulation with 12.5mm plasterboard on top coming back in for at least 1m or the depth of the reveals which ever is greater.


My calculations indicate that this gives me a U-Value for external walls of 0.40 W/m2K. Hardly an amazing result but a significant improvement over the 2.86 W/m2K that the existing wall appears to provide.

Also, the overall thickness of the wall, allowing for a 3mm double coat of skim plaster comes in at 95.5mm, i.e. just under the 4 inches and due to the size of the house I don't think that I want to loose much more space.

The 0.40W/m2K I know does not meet current building regulatoins but given the existing building nature and the small size of the building I believe that this is an appropriate solution to demonstrate satisfication to the try to do a sensible improvement without an extreme detriment of space.

Any ideas to steer me onto a better pathway are very much appreciated;)

BryanF

as you've stated your U-value doesn't meet current regs , by my reading of table 5, you need to be at >0.35w/m2k

regarding your decision to go with non breathable insulation, may i suggest you install a few humidity sensors in a couple of the existing damp areas, this will allow you to assess over time if moisture problems are occurring. also regarding your Mechanical extracts, why not get ones that are RH sensitive instead of timed..
I still think going with a good EWI system would be best, have a look at this case study on where EWI was used on a similar aged structure

is this to be your home or is it for sale? have you considered doing a energy calculation - BER or preferably phpp?

Timmyboy

Thanks BryanF for your inputs, much appreciated.

Actually, on review of your information, I respectfully suggest that we may both have been misreading Table 5.

Looking at Table 5 again from Part L of the Building Regulations, it might appear that from Column 3, which relates to Material Alterations or Material Change of Use, then the 0.35 requirement actually relates to "Roofs" whereas a value of 0.60 is applicable for "Walls". Do I have this correct this time.

So, then I must now re-look at the breathable insulation solution.:rolleyes:

Looking first though at a phenolic type of insulation solution now tells me that I can achieve regulations comfortably and achieve a 0.49 U-value using 35mm phenolic insulation with 12.5mm on top.
This would give a total thickness = 35(battens and air gap)+35(phenolic insulation)+(12.5 plasterboard)+3 (skim plastercoat) = 86mm.

Now looking at the wood fibre board breathable option:
Say I use a 60mm thickness panel atop of 35mm battens and then having 5mm of breathable plaster over the top.
This would give me a U-value I calculate at 0.59.

I need to do more thinking.
I think.:rolleyes:

BryanF

Timmyboy wrote: »

Thanks BryanF for your inputs, much appreciated.

Actually, on review of your information, I respectfully suggest that we may both have been misreading Table 5.

Looking at Table 5 again from Part L of the Building Regulations, it might appear that from Column 3, which relates to Material Alterations or Material Change of Use, then the 0.35 requirement actually relates to "Roofs" whereas a value of 0.60 is applicable for "Walls". Do I have this correct this time.

So, then I must now re-look at the breathable insulation solution.:rolleyes:

Looking first though at a phenolic type of insulation solution now tells me that I can achieve regulations comfortably and achieve a 0.49 U-value using 35mm phenolic insulation with 12.5mm on top.
This would give a total thickness = 35(battens and air gap)+35(phenolic insulation)+(12.5 plasterboard)+3 (skim plastercoat) = 86mm.

Now looking at the wood fibre board breathable option:
Say I use a 60mm thickness panel atop of 35mm battens and then having 5mm of breathable plaster over the top.
This would give me a U-value I calculate at 0.59.

I need to do more thinking.
I think.:rolleyes:

Acceptable levels of thermal
insulation for each of the plane elements of
the building are specified in terms of average
area-weighted U-value (Um) in Tables 1 and
5 for each fabric element type for extensions
(Table 1, Column 2) and for material
alterations and material changes of use
(Table 5, Column 2). These values can be
relaxed for individual elements or parts of
elements where considered necessary for
design or construction reasons. Maximum
acceptable values for such elements or parts
of elements are specified in Column 3 of their
respective Tables 1 or 5. Where this
relaxation is availed of, the average area weighted
values given in the Tables continue
to apply and compensatory insulation
measures may be necessary for other
elements or parts of elements of that type to
ensure that these are met.

TGD L 2011

I would take it that: column 2 and not 3 are to be followed in this case, as in: use the 'average area-weighted U-value' instead of assessing every 'individual element', which i take to mean every junction and thermal bridge.. it then goes on to say that if these values are not achieved, you need to compensate elsewhere..

Timmyboy

Thansk BryanF.

I think that you got it right about the interpretation of Table 5. Thanks for putting me on the right track.

On further investigation however I did find that on Page 3 of the 2011 Part L Building Regulations document that there is a detail describing "Transitional Arrangements".

I understand that this will apply in my case as my works commenced and have taken place before 30 November 2011, so that means that Technical Guidance Document L - Conservation of Fuel and Energy – Dwellings
(2008 Edition) is still the relevant document in my case.

Then that means that the Table 5 of the 2008 Builidng Reulations is applicable.

Then this (see page 3 and page 28) would imply that the 0.60 W/m2K standard is acceptable for walls where Material Alterations or Change of Use is occurring.

So I'm going to aim for a value of 0.60 or somewhat better but I doubt much better than 0.40 due to lack of floor space in the dweling.

Timmyboy

I am still undecided but really it's necessary for me to make a decision rather than continuing to sit on the bowl so as to speak.

I've got a few concerns with the so called breathable options as I'm not quite convinced that it's quite the ultimate solution that it is being made out to be.

Building Description
The building is of mass concrete construction and is about 70 years of age (built in the late 1930s).
The walls are relatively dry aside from the wall that is on the side where the chimney was cracked (the chimney has subsequently been rebuilt). This wall is still damp but I believe that the dampness is due to embedded rain that was soaking down from the top and had been sitting inside of the fairly porous concrete (that was probably damaged by smoke acids and fire damage).
The ground floor walls are approximately 325mm thick and then the upstairs walls are 250mm thick approximately. There is a ledge of 75mm on each side upon which are sitting the first floor joists.


Potential Insulation Options
1. No insulation to be installed.
Effectively the plan would be to batten the wall to provide a service cavaity and then overlay that with plasterboard. No fibres or no insulation of any sort to be installed into that cavity (of about 35mm batten thickness). U-value of 1.89W/m2K

2. Conventional Dry Lining
Batten the walls with 55mm battens then apply 45mm phenolic foam insulation and 12.5mm plasterboard to achieve a U-Value of 0.34W/m2K

3. Breathable Wood Fibre Dry Lining
Fix 60mm wood Fibre Board Dry Lining directly to the mass concrete walls. Then apply 35mm battens to the outside with 12.5mm plasteboard then 3mm skim finish to achieve a U-value of 0.49


Concerns and Issues
Breathability appears to have certain opportunities to cause problems as much as to fix them.

A. Imagine the situation that the kitchen room becomes highly vapour laden due to a combination of cooking and persons walking in from outside with wet-clothes and wet shoes. Ventilator is running and fresh air is coming in but nevertheless does not the moisture in the air migrate through the breathable food fibre progressively until eventually near the interface with the concrete wall it condenses and this leads to a build up of wet there?

B. If there is a build up of wet there due to condensation, how also about some wet perhaps being there due to the existing concrete being a single layer only and maybe allowing in rain driven moisture from the outside?

C. Should the interior of the breathable wall (what about underneath of the existing first floor joists) be treated so as to prevent the concrete from breathing? Or should it be kept breathable too?

D. What type of detailing is going to be required around the first floor joists to prevent that concrete in this area being exposed. Would it be acceptable to cut slots into the wood fibre board so that the board could be dropped down around the joists from above at first floor level? Would these slots need to be sealed and if so with what type of product? A breathable product?

E. Is a vapour barrier required? If so why? Won't that prevent not only moisture from the room getting to the breathable insulation and to the cold point where it might condense but also won't it actually prevent the material breathing out back into the room when the room eventually goes dry?

F. Has anyone actually used wood-fibre type insulation or perhaps a hemp lime plaster etc. to help insulation of a single solid wall (either rubble stone/mass concrete/ashlar etc.)?



The more I read the more troubled I become about any form of insulation being added but I do think that I will gain a very definite improvement in comfort and livability by bringing the U-value from near 2.0 to one quarter of that....

BryanF

Tim,

1. from what you have said, your current mass concrete walls are more like 3w/m2k
2. ok
3. ok, why the battens though if not included above?

2 or 3 seem ok but as we discussed before imo you would be better off with some form of external insulation.

re your queries
A,B: that why you use a Vapour barrier but really that's why dry-lining may not be an ideal solution (some of the wood fibre boards act as a VB or to put it another way is an air-tight layer but allows for absorption of moisture and release of moisture)
B: moisture from the outside? well then definitely externally insulate
C: mass concrete doesn't breathe, concrete blocks allow some air_infiltration but concrete if poured correctly is practically water proof. the first floor joist areas where warm air is hitting cold external walls and may form condensation. also known as thermal bridges. these are going to be where internal walls meet external + the floors + windows etc.
D,E: as a remedial solution cutting the wood fibre boards around the joists would work, using an air-tightness tape/caulk would help here also. the VB is about stopping moisture laden air getting to the cold structure.
E: yes thats why i suggested 'breathable' insulation that will allow a certain amount in and out. that why i prefer the wood fibre as it can to quote one manufacturer

hygroscopic nature of ** woodfibre insulation allows for the rapid absorption of moisture when internal humidity is high. The moisture can in turn be released quickly when internal conditions are too dry

**I have no connection to this or any other product
F: yes

Timmyboy wrote: »

The more I read the more troubled I become about any form of insulation being added

your a prime example of where some form of External wall insulation would suit best

but I do think that I will gain a very definite improvement in comfort and livability by bringing the U-value from near 2.0 to one quarter of that....

there you go, 1/10 or more!

Timmyboy

Thanks again BrianF for your comments and inputs which are very much appreciated.

If I can just for the moment deal here with the External Insulation Idea.
I've got three quotations (or abouts) from three different contractors. Prices that I have received are between about 11,000 and something around 18,000. Admittedly these prices would have to be firmed out. I've got nothing in writing at the moment from the contractors but anyway it gave me thoughts.
These prices would include fittment of the insulatoin and finishing of its surface with the relevant treatment.

Generally I'd be all over External Insulation (provided that the price was more in the 10K range) provided that I was convinced that any of the 3 no. of contractors had a proper solution for the insulation around the eaves detail of the roof. From what I've heard from the I just wasn't convinced that any of them really came with a definitive solution about how to deal with the eaves cold bridge.

They were more of picking up on what I was telling them and giving that back to me rather than really being forward coming with their solutions for the problem. I wasn't impressed.

There's like a concrete moulded eaves detail, like a 3" x 3" beam that rungs along the outside/top of the side external walls of the house. Then the slates run over about 1" beyond this.

Anyhow my concern would be that there would be no good solution to providing insulation continuity around the top of the concrete walls/wall plate/rafter ends.
Also, this external insulation seems quite expensive.

I can't see an easy solution (and I have looked at the solutions in the Approved details on the environ.ie website) but I'm really still poorly convinced. None of the contractors, nice lads and all that they all were, actually really convinced me about how they would treat this situation.

External insulation does appear to have many advantages. I give you that but I can see major roof work required to provide proper detailing of continuity of insulation around the eaves of the roof and also at the place where the gables have barges...More time to think again about external insulation.

Timmyboy

After reading more information last night I do now feel that a better approach is a type of breathable interior dry-lining insulation.

I must call a group of agents on Monday and try to gather details on costing for wood-fibre board insulation (60mm) and also for any special breathable vapour membrane (I'm guessing a paper type might be appropraite????) that they will recommend and for any special surface plasters and platers that may be necessary behind the wood fibre board

Any sugestions from anyone on a build up that might be appropriate?

Timmyboy

BryanF wrote: »

Tim,

1. from what you have said, your current mass concrete walls are more like 3w/m2k
2. ok
3. ok, why the battens though if not included above?

2 or 3 seem ok but as we discussed before imo you would be better off with some form of external insulation.

Just getting back on some of your contributions that I had not taken account of:

1. Yes, you're right, my calculations show that the current external wall has a U-value of 2.86 W/m2K.
2. I'm presently tending more away from the phenolic type foam insulation towards a breathable internal solution.
3. The reason why battens would be used in this way (i.e. on the inside of the inulation rather than on the outside) is that it would allow the service cavity to be immediately beneath the plasterboard while allowing maintenance (with no holes for passage of service connections) through the wall. There might be just one single location where I would place battens both behind as well as in front of the wood fibre board and that would be in the location of the south westerly facing wall - I believe that this wall, which was the wall that included the cracked chimney is wet only because of the crack of the chimney, however to be sure and since the wall is still damp I may need to batten it if I can't get it to dry out before work on the dry-lining commences.

I see where you are coming from in terms of the external insulation but I'm not for it at the moment because of concerns of detailing around the eaves. One of the contractor for external insulation is looking into this and would be due to come back to me next week. His was also the highest quote (nearly 18,000!)

Still undecided by tending towards breathable intennal insulation


Any recommendations on the details of the wall build up?

BryanF

Timmyboy wrote: »

1. I see where you are coming from in terms of the external insulation but I'm not for it at the moment because of concerns of detailing around the eaves. One of the contractor for external insulation is looking into this and would be due to come back to me next week. His was also the highest quote (nearly 18,000!)
2. Still undecided by tending towards breathable intennal insulation Any recommendations on the details of the wall build up?

tim,

1. i appreciate these systems aren't cheap but there is a solution to each every issue - for instance with EWI at eaves: the last few rows of slates can be raised and insualtion installed to meet/overlap with the roof insualtion. this argument you make where your leaning towards dry-lining can only be about cost, as the thermal bridges, reduced U-value, loss of space and reduced insulation rap of internal insulation makes some form of external insulation the best solution in your situation of mass concrete walls.why are you expecting a contractor to come up with these solutions. you get an arch to specify the best solution and then tender it to several contractors for their best price
2. this is it now, I think your main problem here is you need to get some professional help in to look at your actual situation and assess the best solution, anyway here goes

• wood-fibre board (upto 100mm), with good VB/Airtight tape then depending on your requirements a silicate type plasterboard, with correct plaster & paint.
• or (upto 150mm) hemp, sheepwool, even mineral wool between studs with VB taped and sealed with plaster as above
• or external insulate with rigid mineral wool with base/prime & mineral finish minimum (100mm but if your at it, you could do 200mm..)
• or replace the EWI plaster painted finish for rain screen cladding, while its an even more expensive option it means you have different components to fixed/change/replace by the next generation

re your other posts



- paper breather membrane ????

- EWI and your 10g budget - don't bother doing it if your not going to get it done right. I would say allow 100-130m2sq (that the MINIMUM) for a good job, not including eaves and plinth overlaps

Timmyboy

Thanks again BryanF for your inputs that are very useful.

Just briefly here on 3 things.
1. Cost of the external Wall insulation. Roughly speaking the house has a gan external wall area to be treated of some150m2. So then I'm now looking at some 15,000 Euros to 20,000 Euros by your estimations. Not even mentioning anyting to do with the roof modifications. I'm going to be conservative here and put those down at 5,000.
So all in all about 20K to 25K to do external wall insulation. I could just about cope with that but then I'd still have to spend about another 5K to 8K to finish the interior. I certainly will save on about 5m2 or so of interio space. Whic is very valuable (say if I put the house value down at 200K then that's 2K per m2 and so 10K for the loss of space! So net cost of the external wall is now at about 15K

BUT

The dry-lining is really going to match this cost and if I can cope with cold-bridging details by using the breathable dry-lining then I still come out ahead.

2. Architects. Yes I'd love to hire an architect and I may still do this. At the moment I was to test to see if the installers are capable and knowledgeable themselves per their manufacturers details.

3. Cost. Overall. It's all down to this right now and I'm very concerned that EWI is proving to be really not cost effecttive as it should be.

BryanF

have you allowed for the €3,600 seai grant in your EWI calcs?

RenoAl

I too am renovate an old house in Monkstown, Edwardian. I had done a lot of research on drylining as external insulation is prohibitively expensive for the size of the house and the red brick frontage. I am drawn towards an aerogel insulation solution because of all its advantages.
Does anybody have experience with this product? Where can it be purchased in Ireland/Northern Ireland/UK? Any idea of the cost involved, I read that it was about £25 per m2 has the price changed?

BryanF

pm sent