Insulation specs

iplogger1 · 18-02-2006 11:25AM #1

I'm looking over the plans we submitted (drawn up in conjunction with our site engineering company) for a block construction house in the West (250sq mtr, 2690sq feet dwelling area).

For insulation they have a section to state the building will comply
with building regs, 1997,etc.

Here is the double dutch (I need to be educated about insulation basically)

Insulation in accordance with U-value (W/M2K)
Wall Insulation - 0.27
Pitched root/loft - 0.20
Attic - 016
Flat roof 0.22
Soffit 0.25
Floor insulation - 0.25
Semi Exposed Floor - 0.25
Semi Exposed Wall - 0.27

Can someone decipher this for me ? I'll be talking to the engineer early next week. Can someone give me a guide to where this insulation could be improved. Perhaps this is just a statement of minimum or slightly above minimum insulation requirements for a block constructed house. I'm clueless on this. It also says 300mm blockwork cavity wall on one of the cross section views of the house.

thanks in advance

~ipl

patrido · 27-02-2006 02:43PM

uvalues are expressed in W/M2K, and they basically tell you how much heat (in Watts) is lost for every square meter and every degree of temperature difference between outside and inside. the lower the figure the better (i.e. the less heat that is lost from the house).

the figures you quoted are the minimum specs for a new build as per the current building regulations. despite being the "minimum", this is actually a very high level of insulation.

if you have extra money to spend, then spending it on insulation is usually a good idea. however...

purely in terms of the cost of insulation, putting in 10% more insulation will cost 10% more, and will retain 10% more heat. but, because the regs are now so high, putting in more than the current building regs, usually means an increase in the construction costs.

for example, if you want to decrease the uvalue of the walls, you'll probably need a bigger cavity, which means wider foundations, bigger wall ties, different cavity closers, and a deeper soffit. OR, you can use a thermal liner on the inside of the external walls, which reduces your effective floor area. either way, your cost per sq foot goes up.

similarly, if you want more pitch roof insulation, you'll need deeper rafters to hold it. so the cost benefit of extra insulation is no longer proportional. now, that does not mean it's not a good idea, or good value for money. it just means that as you put in more insulation, the cost rises exponentially.

iplogger1 · 27-02-2006 04:14PM

Padrido,

Thanks v. much for clarifying the whole issue of min. insulation standards
and the cost factors in terms of increasing beyond this level.

Someone else who I know in passing told me that in his house build they added a dry-line slab on all external walls in the inside. Does this refer to that same "thermal lining" possibility you mentioned regarding a better U value for wall insulation (as opposed to widening the cavity and expanding foundation width, wall ties,etc)? I'm just trying to align terminology here. I've a feeling it is the same approach just named differently.

This chap also had some reflective foil backed insulation added to ceilings to reflect heat downward. Do you know anything about the effectiveness of that as a method of boosting ceiling insulation ?

~ipl

patrido · 27-02-2006 04:48PM

yes i'm talking about the same thing.

do a search in the archives for "actis" or "xfoil" or "foil insulation" in this forum, for lots of opinion on these. there is little hard evidence or independent certification to back up the manufacturers claims on these products... but that does not necessarily mean they are not true.

Viking House · 31-05-2006 03:47PM

Hi iplogger

Please note that the U-values quoted by Irish insulation wholesalers for drylining and partial fill cavity walls are laboratory figures and not "as used" figures.

When you dryline 10-12% of the wall in not insulated and you move the "Dew point" of the wall towards the inside which is technically wrong.
With partial fill cavity insulation, in 90% of cases you get "Thermal Looping" reducing the effect of the insulation by half.

Lining a house with petrochemical insulation backed plasterboard is like sticking your head inside a plastic bag. Almost 20% of the population of Europe now have symptoms of asthma, 50 years ago it was 5%.

If you want a warm house use warm building materials and let it breathe.

Maud · 24-06-2006 10:17AM

Has anybody here used the Actis foil insulation and what are their heating cost reductions?

Salmon · 24-06-2006 12:04PM

Just wondering about this myself!

My plans call for a 100mm cavity with 60mm (U 0.27 Kingspan insulation) or a 150mm cavity with 100-150mm insulation.
I was wondering if i would be better increasing the cavity width, or keeping the 100mm cavity and slabbing the external walls on the inside with this insulated slab mentioned above?

Anyone got any suggestions?

Mellor · 24-06-2006 12:09PM

I'd recommend going for 60mm insulation and 100mm cavity, and getting extra proformance from an upgraded insulation. Such as the newer phenolic resin based board from kingspan

24-06-2006 12:40PM

Does anyone here know how good the rockwool/fibreglass backed plasterboard is??
It's also suppose to be a good sound supressor.

It looked like a good idea ,and very very heavy.

Salmon · 24-06-2006 12:44PM

Any idea how much this stuff costs mellor? Is it much more expensive than the standard kingspan?

Viking House · 24-06-2006 01:55PM

Sorry for sounding like a parrot but putting insulation in the cavity doesn't work because of Thermal Looping.
Its like buying a new Mercedes and when you go to collect it they give you a Lada for the same money.
Drylining only covers 90% of the wall.
Petrochemical insulations are rarely used in Scandinavia because they let the cold in quickly and hold onto heat very badly when compared to other options..

Xtend · 24-06-2006 05:16PM

Viking House wrote:

Sorry for sounding like a parrot but putting insulation in the cavity doesn't work because of Thermal Looping.
Its like buying a new Mercedes and when you go to collect it they give you a Lada for the same money.
Drylining only covers 90% of the wall.
Petrochemical insulations are rarely used in Scandinavia because they let the cold in quickly and hold onto heat very badly when compared to other options..

Hi Viking House,
I am thinking of renovating an end-of-terrace house built of cavity blocks (built 1960). Outside of house has a roughcast finish. I was considering drylining the inside of external walls with Kingspan or similar.
What would you suggest is the best solution for insulation?

Viking House · 25-06-2006 10:33PM

Hi I would recommend external insulation and plaster directly onto the insulation.
My Scandinavian colleagues say to insulate externally if at all possible, if it's impossible to insulate externally only then insulate internally.

Do-more · 26-06-2006 10:16PM

Sorry folks if I am straying a little off topic, but hopefully it is of benefit to others also.

Viking House I have been having a look at you website and am most impressed with what you do. One question though, I don't see any mention of ventilation systems. Do you use heat recovery ventilation or what do you reccommend?

sunnysoutheast · 27-06-2006 06:13PM

On the advice of our heating suppliers we decided to upspec. the insulation with 50mm extra kingspan under the UFH, foil-backed polyiso on external walls and kingspan in the rafters in the roof. we didn't go for the wider walls/foundations.

we're also planning to install HRV, both to retain expensive heat and to improve air quality, so I'd be interested in any experiences people have on that. Seems that there's a range of performances you can expect from these systems.

Viking House · 28-06-2006 12:19AM

Hi, I have to add a page on HRV I think it is really important, we have it on the detailed specs we send to customers for new builds.
I totally agree with HRV and it should be specified on all new builds.
We are also trying to get some customers we are renovating for to install it as part or an eco package.
It cuts down a lot on heating bills.
It eliminates mould in bathrooms and kitchens by extracting the damp air.
Delivers fresh filtered warm air to the occupants.
I think an important tool in cutting down the incidence of asthma.

What prices are you guys paying for a HRV kit?

I have been studying recently the natural ventilation chimneys that they put in most Polish houses.
I have a few photos of this system but I don't know how to post them.
It seems a lot better than putting vents in the walls that let in a lot of air on windy cold days and not so much on warm clammy days when it is needed the most.

Do-more · 28-06-2006 07:28AM

Viking House wrote:

What prices are you guys paying for a HRV kit?

I have been considering a Stiebel Eltron LWZ161 from this Guy http://www.heatpumps.co.uk/vent.htm The last time I priced it, it was about €1200 + vat seems like good value but a little undersized for my 2500sq ft.
Ducting etc. extra.

Viking House · 28-06-2006 09:00AM

Thanks for that
It looks like it can handle a 3500ft house easily.
And the price looks good also.

I saw this article today in Construct Ireland.

http://www.constructireland.ie/articles/0204hrv.php

sunnysoutheast · 28-06-2006 01:36PM

we're being quoted approx. 9k inc. VAT fully installed, I think for Vent-Axia kit

the unit for EUR1200 + VAT therefore looks good value, are you planning to install it yourself?

sunnysoutheast · 28-06-2006 01:36PM

oh, yeah, house is c.4500 sq.ft.

Do-more · 28-06-2006 05:42PM

Viking House wrote:

Thanks for that
It looks like it can handle a 3500ft house easily.
And the price looks good also.

Correct me if I'm wrong, but it says that it can handle 450m3 at 0.5 changes /hr so by my calculations it will hadle 450/2.4 = 187.5m2

or am I missing something?

Viking House · 30-06-2006 02:23PM

My mistake, I thought it was squared not cubed.

Vinneyboy · 30-06-2006 03:30PM

I've been quoted €5,500 for a hrv system from a company in northern ireland, how does that sound for a new house 2500sq ft storey and half?

Do-more · 30-06-2006 08:53PM

Vinneyboy wrote:

I've been quoted €5,500 for a hrv system from a company in northern ireland, how does that sound for a new house 2500sq ft storey and half?

Depends what you are getting for your money Vinney. The better systems are infact a small air to air heatpump and will be more efficent at recovering heat. Some are only passive heat exchangers with much lower efficencies. Do you know the make and model they are supplying?

Pocari Sweat · 30-06-2006 11:19PM

Viking, can you quote me for a passive / zero loss house with all the extras.

Triple glazing, HRV, under 0.1 loss on walls and ceilings etc. I have a budget of about 200K. Can traditional oak beam construction be incorporated into a passive house? Obviously this would put the price up a bit.

Viking House · 01-07-2006 06:17PM

Hi Pocari

What size is your house?
Do you have plans that you can send me?

Insulation specs

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