Take the U-Value of a wall

joejoem

I have single glazed alluminium windows in the house which I'm planning on replaceing, but Im not sure if they are the only reason I am loosing heat so fast. The house is from the 50's so I think I could be loosing heat through the wall.

I would like to find out

If the walls are cavity walls? (so I can use warmm fill)

If not, what the U-Value of the walls are, so I can decide weather to dry line them or not.

Thanks

Viking House

When you fill cavities it is difficult to avoid air pockets around the windows and doors which will cause cold bridging.
If your house is from the 50's it is probably not insulated.
First thing I would recommend is to put one foot of insulation in your attic.
A foot of Rockwool will keep your house warmer for longer than a foot of Glasswool because of Decrement Delay.
If you dryline, the place where the inner walls meet the external walls acts as a coldbridge, you will lose a lot of heat from there.

Technically it is wrong to dryline as the condensation builds up at the dew-point between the insulation and the wall and leads to dampness and mould.

The best way to insulate your walls is to insulate externally with rigid Granitewool and replaster directly onto that. 50mm of insulation outside will give the same benefit as 100mm inside.

Here are the details of a test done at of all the different wall systems in Oakridge Laboratories in Ireland. External insulation is 84% better for Thermal Efficiency than any other Irish system.
http://www.greenspan.ie/samples/OakridgeReport.pdf

Oh yes, fill a bin bag with rockwool and stuff it up your chimney when its not in use.
An open chimney is like a window with broken glass, its a hole in your house.

Gordon Gekko

Oh yes, fill a bin bag with rockwool and stuff it up your chimney when its not in use.
An open chimney is like a window with broken glass, its a hole in your house.

I thought you weren't supposed to fully block a chimney, even when never used, because it is needed for air circulation in the house? Blocking a chimney can lead to condensation and thus damp in the chimney flue, causing damp patches and mould on internal surfaces of the flue.

Viking House

I blocked two chimneys in my house and there are no damp patches.
Try it, if you have a problem take the bag back out.

patrido

Viking House wrote:

Technically it is wrong to dryline as the condensation builds up at the dew-point between the insulation and the wall and leads to dampness and mould.

this is incorrect. if the building regulations and manufacturers instructions are followed there will be no condensation. vapour from inside cannot reach the due point.

Viking House wrote:

An open chimney is like a window with broken glass, its a hole in your house.

this is a wild exaggeration. on a SAP rating, a chimney rates equivalent to 4 wall vents or intermittent fans. i.e. 40 cubic metres of air per hour. not ideal but it's nothing in comparison to a broken window.

the most recent SAP rating I have completed is a 2800 sq ft house with a SAP rating of 93 (A rated) and it has 2 open fires. your vested interest is clouding your judgement.

joejoem

Viking House wrote:

The best way to insulate your walls is to insulate externally with rigid Granitewool and replaster directly onto that. 50mm of insulation outside will give the same benefit as 100mm inside.

Here are the details of a test done at of all the different wall systems in Oakridge Laboratories in Ireland. External insulation is 84% better for Thermal Efficiency than any other Irish system.
http://www.greenspan.ie/samples/OakridgeReport.pdf

Hi, thanks! I much prefer the idea of insulating externally and not wasting floor space! Have you any more details on this? I didnt know it was possible!


In fact I can only find two websites that mention it, nothing about cost or availability.

Viking House

Hi Joejoem

Here is my link, I am still working on this page.
http://www.viking-house.net/external-insulation-and-cladding
Click on this Paroc link for more info, all U-values are Scandinavian as used values so add 0.06 to get Irish equivalent. http://www.paroc.com/channels/com/building+insulation/solutions/default.asp

We charge €75/m2 for this system.

Hi Patrido

I take your points and well made, I am learning about a new way of building which I think is the way we will all build in 10 years time. A few years ago I also swore by the Homebond manual.
But I don't have any vested interest on whether you block up your chimney or not.
All I know is that 95% of chimneys in Scandinavia come with a valve fitted which they close when the chimney is not in use, I asked why and I was told that when there is an airflow over the chimney it causes low pressure in the chimney like an aeroplane wing, and it sucks 75% of the room heat out the chimney. I was told that every builder in Scandinavia knows this.
It costs about €900 to heat a 2500 sq.ft house there. In Ireland it costs 3 times that in a much better climate.
The first three things they are recommended to do in Finland to reduce the heating costs are, 1. insulate the attic 2. insulate externally 3. install a chimney valve.

I am still learning so can you please explain to me what SAP figures are?
Is it some sort of energy audit using wind blower or Thermal imaging?
What is an A rating?

As regards drylining, the cold comes too far into the house with this system, its like wearing a jumper inside your skin, its the wrong way round, this system is only used here and in England. In the Oakridge trial the same thickness of external insulation was over 90% more efficient than drylining.
I take your point about the Condensation when you use a Vapour Barrier on the inside, you are right.
I will ask my Scandinavian guy more about this tomorrow and if I find anything more I will post it.

Eurorunner

I am still learning so can you please explain to me what SAP figures are?

SAP stands for Standard Assessment Procedure (for Energy Rating of Dwellings)

All I know is that 95% of chimneys in Scandinavia come with a valve fitted which they close when the chimney is not in use, I asked why and I was told that when there is an airflow over the chimney it causes low pressure in the chimney like an aeroplane wing, and it sucks 75% of the room heat out the chimney. I was told that every builder in Scandinavia knows this.

I'm fairly new to this subject area but there seems to be a difference between 'having a valve fitted' and 'stuffing up a chimney with rockwool'. My understanding is that the 'valve' is never 100% shut - and allows a reduced airflow.

smashey

SAP stands for Standard Assessment Procedure.

This is the method devised and currently being built into building regulations
to ensure that dwelling houses are constructed to standards which ensure that the building uses energy in an efficient manner. It is a measure of a building’s overall energy efficiency and takes into account the following-:
Insulation, Heating System, Ventilation, Solar Gain, and also the Fuel Costs(
Oil is relatively cheap whereas Electricity is more expensive).

Viking House

Hi Patrido

Would you mind posting the details of the (A rated 93) house you tested?
What type of build was it? Timberframe or Partial fill cavity wall or other?
Was it a tested rating based on a Wind blower test and Thermal imaging or a calculated rating based on thickness of insulation?

Viking House

Eurorunner wrote:

I'm fairly new to this subject area but there seems to be a difference between 'having a valve fitted' and 'stuffing up a chimney with rockwool'. My understanding is that the 'valve' is never 100% shut - and allows a reduced airflow.

The Scandinavian chimney valves are 100% closed when they are closed, they even have a heat resistant seal to make them airtight.
You never get damp patches in the chimney because the chimney is open to the outside air above the valve, and open to the inside air below the valve.

Because of this airflow you will never get dampness in your chimney when you stuff it with a binbag full of Rockwool to stop the draught.

If your chimney is built properly it will have a layer of insulation around the flew, this will stop the cold air inside your chimney causing condensation on your chimney breast.

rooferPete

Hi,

I have never worked in Scandanavia but I have worked on a lot of 1950's Irish houses and assorted commercial buildings.

I have yet to find one 1950's chimney with insulation around the flue, although I have worked on some without a flue that were built even in 60's.

I have also came across chimney's that looked perfect outside and were not intentionally blocked at the fireplace but still had stains on the chimney breast caused by birds nests in the flues.

The chances are the walls of a 1950's house are not cavity, but easy to check by drilling a hole about 150mm deep.

.

rooferPete

Attention of Viking House,

Sincere apologies regarding my reference to not having worked in Scandinavia.

I had not visited your web site until now I can assure there was nothing personal intended.

Sincerest Apologies for any offence or mis-understanding.

Peter.

Viking House

Do you cross batten the lats on your roofs Pete?

rooferPete

Hi Viking House,

We used to but not as often as I would have liked, cost was usually the issue.

I expect with the demands for high insulation in houses today counter battons will become more popular as it is a great way of providing decent ventilation in the roof space.

As usual Ireland was way behind other countries providing through flow ventilation and breather membranes.

I used both in the UK back in the 80's while we were doing almost identical work in Dublin using Blizzard felt and if I wanted the customer to think I was completely crazy mention eave to ridge ventilation.

.

Viking House

Excellent! Where do you get the kits for that?

rooferPete

Hi,

We didn't use kits for counter battons it is just hard work, it can help if you use 2m lengths for the bottom laths just make sure to break the joints and measure up the rafter first, "Murphy's Law" if you have a continueous joint on the first lath up the rafter your cross lath will certainly land on the joint.

If you are referring to the ventilation systems I recommend Richmond Building Products, www.richmondbp.com.

.

Viking House

No the Ventilation systems, we always cross batton anyway.
We bought a roof kit for a house in Wicklow from Richmond, I thought they were a bit pricey.

By the way, we use 50mm latex impregnated softboards on top of the rafters instead of a breather membrane, you don't need a membrane on the outside of the roof or a vapour barrier internally with this system and it increases the U-value of the roof considerably by eleminating cold bridgeing. Its very fast and you can leave the roof exposed for 6 months without slating.

aka_Ciaran

Hi Viking,

Your external insulation product looks interesting..could you give us a ball park figure what a typical 3 bed semi migh cost (abt 1100 sq ft house)?
Also hasd a look at your website...one quick thing I would say is that navigation/table of contents are nearly always along the left hand side as opposed to the right.

Cheers,
Ciaran.

Viking House

Hi aka_Ciaran

Our price for supply and fit of Granite wool external insulation with a fibreglass mesh supported mineral plaster is €75 per m2+ vat.
I think your house has about 100m2 of external walls.

Two things you have to think about first .
Do you have enough overhang on your roof?
Will your neighbours mind if the insulation sticks out 2 inches where both houses meet?

First I would put a foot of insulation in my attic because the payback is quicker then I would put in double glazing and only then would I insulate externally.

Do you think the website would look better if the navigation was to the left?

Victor

Viking House wrote:

First thing I would recommend is to put one foot of insulation in your attic.

Well, before I'd do that, I'd make sure there was proper ventilation and vapour barriers. Otherwise you end up with a rotted roof.

Technically it is wrong to dryline as the condensation builds up at the dew-point between the insulation and the wall and leads to dampness and mould.

Hell no. Are you technical or in sales? That sort of jibberish comes across as hocus-pocus sales talk. Proper ventilation and proper vapour barriers will prevent condensation.

The best way to insulate your walls is to insulate externally with rigid Granitewool and replaster directly onto that.

How does that work with planning permission?

Oh yes, fill a bin bag with rockwool and stuff it up your chimney when its not in use. An open chimney is like a window with broken glass, its a hole in your house.

And remember to remove it if having a fire.

Viking House

Hi Victor

Are you an advocate of drylining, partial fill cavity insulation and letting all the heat escape up the chimney? These archaic building practises were scrapped in Scandinavia and mainland Europe 50 years ago.

And of course I recommend to put a vapour barrier on the warm side of insulation. But in most cases the vapour barriers are not installed properly and the moisture gets through anyway. Check out the Wind Blower test data. How many times on site have you seen vapour barriers done correctly?

When you dryline 15% of the surface area of the wall is un-insulated where the floors/ceilings and internal walls meet the outside wall. The ground floor slab, the middle floor and the area between the bedroom ceiling and the roof.

We are a building company and it doesn't make any financial difference to us whether a client wants us to dryline or insulate externally.
We don't sell any of the products on our website, we just use them.
We like to use the best possible materials and systems to get the best possible results.

aka_Ciaran

Viking House wrote:

First I would put a foot of insulation in my attic because the payback is quicker then I would put in double glazing and only then would I insulate externally.

Do you think the website would look better if the navigation was to the left?

Hi Viking,

Yea I think I need to get my attic insulated first and I'm also getting quotes for new double glazed windows, so I suppose I'll see how things stand after that.

As for your website probably 90% of all sites have navigation/menu on the left...it's probably become standard at this stage. My natural instinct is to move my mouse towards the left when navigating, and a menu on the right seems out of kilter. Just my opinion for what it's worth

Cheers,
Ciaran.

Viking House

Hi Pete

We bought a load of slates from Richmond and they miscalculated the amount and we had to go back for an extra pallet of slates at extra cost.
Did you ever have this problem from them?

Maud

Hi Viking

Do you find the Poroton blocks easy to work with? We are thinking of using them for our extension.

rooferPete

Hi Viking,

I never had a problem with team at Richmond but then again I do my own quantities and always allow 10% for waste when using natural slate.

.

Viking House

Maud wrote:

Hi Viking

Do you find the Poroton blocks easy to work with? We are thinking of using them for our extension.

Its important to get the first row level and after that its quite easy.