craig1410
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| posted on 28/12/08 at 03:46 PM |
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Home Insulation - Best bang for buck on modern house?
Hi,
Looking to improve our home insulation and wondered where best to start to get the best savings with quickest payback. Our house is a 5 bedroom
detached house built in 2000/2001 in central Scotland (Kilmarnock). It is of brick and block construction with breeze-block inner and brick outer
leaves. Windows are wooden framed double glazed. Heating is gas central heating with microbore distribution to room radiators.
My initial thoughts were to add a 200mm layer of loft insulation to the existing 70-100mm layer but I've just seen some figures which suggest I
will only save £30 per year and given that it will cost £210 for 50 sq m of "space blankets" from B&Q to cover the unfloored section
of my loft this is a 7 year payback which is not what I was hoping for.
My next thoughts are to improve draft proofing as there are a few gaps under skirting boards and around doors and windows that I could fill but this
is more difficult to measure in terms of cost/benefit and will be time consuming.
I hope to change the windows for UPVC in a few years but can't afford it just now.
I'm not keen on cavity wall insulation as I believe the cavity is there for a reason and don't plan to bridge it. There is foil backed
rockwool insulation between plasterboard and breeze block anyway so the walls shouldn't be too bad.
Anyway - any thoughts as to whether it is worth doing my loft or fixing draughts or anything else which might help keep the gas bills down? By the way
my current gas consumption is around 26000 kwh per year which costs around £900 per year... 
Cheers,
Craig.
[Edited on 28/12/2008 by craig1410]
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blakep82
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| posted on 28/12/08 at 03:53 PM |
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I'm no expert, but i'd say go with cavity wall insulation. the cavity in the wall is there to give an air gap, this means (as i
understand) if its cold outside, and warmer inside the house, the air gap in the wall has to cool down before the air inside the house is cooled.
cavity wall insulation puts extra barriers and extra layers, so instead of 1 air gap, you get thousands of them, means it takes even longer to
transfer the heat. just like your loft, and loft insulation.
you say the cavity is there for a reason, as i see it, cavity wall insulation was invented for a reason too.
it is rather cold outside today though, isn't it?
just read the edit bits, yeah, stopping draughts will make a huge difference though!
[Edited on 28/12/08 by blakep82]
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David Jenkins
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| posted on 28/12/08 at 03:55 PM |
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In my house, 3 things made the biggest difference:
1. Fixing the draughts - the biggest thing being a second door in the hallway to act as an air-lock when going in and out.
2. Loft insulation. A lot of heat goes out that way.
3. Cavity wall insulation - I know you don't like the idea, but it made a huge difference to my house. Previously my house was always warm
enough, until the cold winds blew. Then the house would chill down very fast. Now it doesn't chill anywhere near as fast.
The double glazing didn't make such a difference, apart from fixing all the draughts.
Talking about cavity wall insulation - in new houses they have to build in insulation by law these days, usually in the form of foam blocks in the
cavity. Can't be all bad! 
[Edited on 28/12/08 by David Jenkins]
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JonBowden
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| posted on 28/12/08 at 04:10 PM |
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Wood framed double glazing is pretty good if it has proper seals. I read specifications recently that suggested it was better than uPVC (I think due
to the lack of internal metal surround). I definitely wouldn't want to change good newish windows.
Jon
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craig1410
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| posted on 28/12/08 at 04:19 PM |
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Hi,
Thanks for your suggestions - much appreciated.
My objections to cavity wall insulation are more to do with concerns about dampness traversing the cavity from the outer leaf to the inner leaf. This
is a heavily debated issue and there are many advocates of cavity insulation and many who frown upon it. I have read the arguments and counter
arguments at length and my own conclusion is that I prefer to retain the cavity at least until my NHBC warranty is up to avoid any potential
complications should a warranty claim be necessary (I hope it isn't mind...)
If, on the other hand I owned an older house then I would be more inclined to go for cavity insulation but I think it is still too early to determine
whether using it in a modern house is going to cause dampness issues or not. To counter Blake's argument that cavity wall insulation is there
for a reason, I would say it is there to make the manufacturers money and to help the government meet its targets for CO2 reduction - neither of these
goals means that it is the best thing for my house... 
On the subject of draughts, I have just noticed that my windows have a draught exclusion seal between the frame and the bit that opens and this is
compressed to the point where it doesn't really seal any more. I wonder if I can replace this stuff with new or supplemental sealing strip? I
think that would make quite a difference.
Cheers,
Craig.
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craig1410
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| posted on 28/12/08 at 04:21 PM |
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quote:
Originally posted by JonBowden
Wood framed double glazing is pretty good if it has proper seals. I read specifications recently that suggested it was better than uPVC (I think due
to the lack of internal metal surround). I definitely wouldn't want to change good newish windows.
Yeah, I was just talking about that in my other reply - do you know if I can get replacement seals as mine are compressed. I don't think they
would pass the everest feather test if you remember it from their adverts...
Cheers,
Craig.
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MikeR
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| posted on 28/12/08 at 04:35 PM |
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over the last year i've had my cavity walls insulated and done the attic. The house is a lot warmer.
My dad has done the same - except being my dad he's seriously exceeded the reconmendations. His house now has the problem that its too warm at
times. Brother has turned off the radiator in his room if he turns the pc on. i did the same when i turned the xbox on in my room.
Biggest thing stopping my house being as warm as my parents is drafts - which is what i'll work on over the next year.
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smart51
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| posted on 28/12/08 at 04:40 PM |
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Cavity wall insulation is cheap, especially if you get a grant, which we did a couple of years back. I think we only paid £75 for the job.
B&Q have started to sell thin loft insulation. It looks like plasticised foil coated bubble wrap. 6mm thickness of it has the insulating
properties of 65mm of polystyrene (1.4 M K/W). A couple of layers of that under your loft boards would help.
Double glazing is expensive. You could replace your sealed units with K glass ones if you wanted to improve them. It would save on replacing the
frames. If you want cheap, just make sure the frames are sealed to the walls properly.
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JoelP
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| posted on 28/12/08 at 05:07 PM |
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ive just climbed down from my loft now!
B&Q had an offer on loft insulation, i got 100mm stuff, and 56 square meters was about £60 (it was half price). Im putting double layers in over
the existing scrawny stuff. No need to get the bagged stuff, ive been tearing it all day and its not at all itchy!
Drafts is the number one thing to sort. Either expanding foam, decorators caulk or strips of whatever sort.
Its a shame that your house, being so new, wasnt built better. Its always harder to sort later. But you defiantely want something in the cavity
insulating it. This will be a significant factor in your house if there is nothing in there. 100mm kingspan is nice if you're building a new
wall, or thermal blocks, but for existing walls you just have to do what you can. You wont have a problem with damp IMHO.
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coozer
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| posted on 28/12/08 at 05:27 PM |
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When I extended into my loft I lined the rafters with 100mm Kingspan. The difference is amazing. The rads upstairs are turned off as the heat rising
from downstairs keeps the loft really comfy and warm.
Would recommend it everywhere, under the floor, in the walls, above your head....
Current building regs recommend 10" of Rockwool in an 'open' loft. 4" of Kingspan is warmer
1972 V8 Jago
1980 Z750
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Howlor
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| posted on 28/12/08 at 05:30 PM |
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I got a load (36 rolls) of the Knauf space blankets from B&Q on Xmas Eve. They had them half price and 2 for 1 and if you spent more than £50 you
got another 15% off. This offer finishes tomorrow though. This makes the 200mm space blanket only £2.55.
Steve
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blakep82
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| posted on 28/12/08 at 05:34 PM |
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quote:
Originally posted by craig1410
Blake's argument that cavity wall insulation is there for a reason, I would say it is there to make the manufacturers money and to help the
government meet its targets for CO2 reduction - neither of these goals means that it is the best thing for my house...
true enough. and yes, its maybe not as great as manufacturers would claim, but i suppose that goes for everything. no toothpaste manufacturer would
say 'buy our toothpaste! its not the best. its alright... but it tastes nice!'
as for the governament reducing co2 targets, well thats reducing the gas consumption for central heating, which is what you're looking to do
________________________
IVA manual link http://www.businesslink.gov.uk/bdotg/action/detail?type=RESOURCES&itemId=1081997083
don't write OT on a new thread title, you're creating the topic, everything you write is very much ON topic!
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JoelP
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| posted on 28/12/08 at 07:04 PM |
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someone worked out that if you had one metre of insulation in your walls, and equivilent elsewhere, you wouldnt need central heating at all.
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dinosaurjuice
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| posted on 28/12/08 at 07:27 PM |
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this is what my friends in the trade recommend:
1. stop cold air getting in - and hot air getting out. £1 shop draught excluders are the ultimate bang for buck
2. heat rises - loft insulation next, anything from 10 inches of rockwall, 100mm of kingspan, or 50mm of lambswool/fibre stuff.
3. cavity insulation - injecting polystyrene balls is cheap. just make sure you dont want a conservatory or extension in the near future, they will
fall out (funny to watch)
4. good quality curtains. cheaper than double glazing.
5. heat source - insulate hot water pipes and tank. install a more efficient boiler.
Will
edit: if your house has a porch, USE IT!!! only open one door at a time to avoid loosing heat. avoid using backdoor if possible.
[Edited on 28/12/08 by dinosaurjuice]
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delboy
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| posted on 28/12/08 at 07:40 PM |
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First, and in answer to your question about best bang for your buck, the introduction of additional glass or mineral wool fibre roll or batts to the
roof void will give a good improvement for a modest outlay.
Secondly, if you want to improve matters further, and assuming that you have a suspended timber floor and sufficent space between the underside of the
floor joists and the solum, you could install insulation to the floor, staple netlon ( it looks like strawberry netting) to the underside of the floor
joists and place more glass or mineral wool between each joist. At the date your house was built and assuming it got Building Warrant before the build
date, it wouldn't have needed floor insulation, so an easy improvement is available here.
The cavity wall insulation insn't as bad as you think, the cavity is not to provide a pocket of insulated air, it's basically to stop
driven rain going from the outer side of the wall to the inner. That's why wall ties have drips on them so any water that passes throuth the
outer leaf and onto the tie drips of and down the cavity before it runs to the inner leaf blockwork. Cavity wall insulation installed by an approved
installer using a product tested by BBA or similar will provide a big insulation improvement for a small outlay. The products used today are usually
closed cell insulants to stop moisture migration across the filled cavity. I would say from both a personal and professional perpspective that done
properly the introduction of cavity wall insulation is fine.
There are a few other things to consider, as others have said, introducing draught strips etc will help, you obviously in the future intend to change
windows and doors, choose a low e glass with an inert gas filling for your windows, some glazing will give as low as a 1.1 U value. Finally, how
efficent is your boiler, a boiler installed in a house from the early ninety's will be of poor efficency compared to current condensing combi
boilers with TRV controls etc to all your rads. It's worth thinking about a change to your boiler, it's approaching 20 years old and is
probably going to give you trouble soon anyway. If you want any more specific advice re what I've said drop me a U2U and I'll get in
touch.
If you introduce more insualtion and make the house more air tight please ensure that you have good ventilation above the insulation in the roof space
and below the floor as interstitial condensation could become a problem other wise.
Derek
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craig1410
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| posted on 28/12/08 at 08:04 PM |
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quote:
Originally posted by delboy
It's worth thinking about a change to your boiler, it's approaching 20 years old and is probably going to give you trouble soon anyway.
Hi Derek,
Thanks for what appears to be some solid advice. Just one small correction - my house was built in 2000/2001 not 20 years ago so hopefully my boiler
will be okay for a few more years. I'm hoping to get it maintained in the next few weeks and it's a corgi registered friend who is doing
it so I'm sure he will give mea nudge when it's ready for replacement.
Also, thanks for confirming what I understood about cavity walls. I was aware that the outer leaf is not designed to be 100% water tight and this is
why I am not keen on cavity wall insulation. I respect your opinion that "done correctly by an approved installer" it should be fine but
there are so many cowboys around that finding a good installer isn't so easy. Even if you do find one there is conflicting advice/evidence about
whether to use glued together poly beeds or rockwool or PU foam. Then you can get issues with cold spots due to poorly distributed insulation and
perhaps even condensation issues due to moving the cold-warm interface. I'm going to pass on cavity insulation for now I think. Maybe I'll
rethink later when I've covered everything else. By the way I have concrete floors downstairs but I've no idea if they are insulated or
not. Would they be insulated below the concrete or above it? I don't have a suspended floor - it is concrete then underlay then carpet.
Maybe TRV's for my radiators should be my next purchase? Do these make much difference to energy consumption? I've got them fitted in the
larger rooms but not in the smaller rooms.
I took the first step tonight by nipping down to B&Q for some rubber p-section window seals. These come in 10 or 20 meter packets for about £5.50
or £11 respectively. I have fitted it to the window in my computer room to see if it makes any difference. I've also taped up the vent above the
window as it can be very draughty even when closed. I'd rather just open a window if I need fresh air. Typical though, there is hardly a breath
of wind tonight so I can't tell if it has helped to stop the draughts or not...
Thanks again to all,
Craig.
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maartenromijn
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| posted on 28/12/08 at 08:32 PM |
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I bet the best bang for your buck is foil-backing your radiators.
However for a more structural insulation I would succesively put on the whole package. Loft or roof insulation, cavity insultation, floor insulation,
etc.
Now is the time to get started. Products are relatively cheap, and when the recession is over, energy prices will go sky-high.
BLOG: http://thunderroad-super7.blogspot.com/
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trextr7monkey
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| posted on 28/12/08 at 09:56 PM |
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Like Joel we have gone for the cheap deals on loft insulation at B and Q and put in 51 rolls the other weekend- depending on your energy costs it
should be less than 7 years before it pays its way if you buy it economically, we are on the dreaded bulk LPG here so didn't hesitate.
As your house is relatively new it should be built to a half decent standard so savings may not be so dramatic,
BTW what sort of central heating controller do you have - is it 7 days and zoned?
http://www.flickr.com/photos/14016102@N00/ (cut and paste this dodgey link)
Our most recent pics are here:
http://s129.photobucket.com/albums/p211/trextr7monkey/
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craig1410
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| posted on 28/12/08 at 10:02 PM |
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quote:
Originally posted by trextr7monkey
Like Joel we have gone for the cheap deals on loft insulation at B and Q and put in 51 rolls the other weekend- depending on your energy costs it
should be less than 7 years before it pays its way if you buy it economically, we are on the dreaded bulk LPG here so didn't hesitate.
As your house is relatively new it should be built to a half decent standard so savings may not be so dramatic,
BTW what sort of central heating controller do you have - is it 7 days and zoned?
It's interesting you mentioned the central heating controller as I was wondering if it is worth changing it.
Ours is a simple, off, on, once, twice type controller with a split between hot water and heating. There is only a single thermostat in the downstairs
hall. I'd love to have an all-singing, all-dancing controller with room temperature feedback but I'm not sure that I would actually save
anything (quite the reverse probably...) I've not looked into it though - do you know what is involved both from a cost, savings and DIY point
of view? I am an electronics engineering graduate by the way so I'm happy enough to do any fitting as long as it is straightforward enough.
I do find that every time I switch the heating to timed mode (ie. on in the morning and evening) my wife tends to switch it back to on all the time
mode at the weekend and it doesn't then get switched back. When on all the time it depends completely on the thermostat to switch it off again
which probably isn't very efficient.
Cheers,
Craig.
[Edited on 28/12/2008 by craig1410]
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delboy
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| posted on 29/12/08 at 11:10 PM |
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Sorry, Craig, when I was answering your post I thought it had said built in 1990/91. To answer your question re floors, it could have insulation below
the concrete floor slab. However, some builders, usually the big ones used an allowance in the Building Regs to trade off building elements. In other
words they put no insulation in the floor and used heat loss calculations to show that even with no floor insulation that the house still met
standards due to slightly less glass or slightly more wall insulation than a house designed to the minimum for each element would have acheived. The
Building Regs in force in the late 90's and early 2000 were easy to manipulate in this manner. It's not so easy now. Basically what
you're doing is going to help, but lots of small improvements will collectively make a difference. Eventually you will get to a point where you
need to think about cavity wall insulation and new windows etc. Either that or go build a new house with insulation designed beyond those prescribed
by the Buidling Regs. Just for info our current political masters want us to achieve zero carbon by 2050, so it looks like new houses in the future
will have to have lots more insulation than at present.
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craig1410
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| posted on 29/12/08 at 11:42 PM |
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No worries, forgive me if I'm not surprised that there are ways around the regs...
For info, the house was built by Barratt and is of the "Ascot" variety. The build quality is pretty bad, certainly from an internal fit
and finish point of view. Also, the plumbing had to be redone twice due to lead contamination and the standard of plumbing is absolutely awful, as is
the standard of joinery and plasterboarding. I'm a keen amateur and I could have easily put both the plumbers and the joiners to shame with my
own skills!
The brickwork looks pretty good so I can work on the internals over the next few years and bring it up to standard.
Cheers,
Craig.
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