Insulate a few rooms in the gaf. Advice

garlad

Hi, moved in to an old house 18 months ago. Wasnt until last winter that we noticed a few of the rooms got much colder than other rooms during the winter. These rooms are playroom (converted garage), and 2 bedrooms built over the garage. The garage had hollow block walls (bricks with 2 holes), so I am guessing we dont have insulation.
Had a guy out who quoted us for pumping foam stuff to fill the hollow blocks, but heard that this is a waste of time. Best ways would be too fit new plaster boards internally on the external walls, or else do a big external job.
Anyone any advise?

rooferPete

Hi,

From your description of the wall it sounds like a 9" cavity block, we researched an American system SPF slow rising foam and it wouldn't fill the cavities much to the suppliers surprise.

There are arguments for the outside system which I'll leave to Viking House, dry lining the inside can be done in stages, use a good insulation and mechanically fix to the walls, skim the plaster slab it will make a huge difference.

The disadvantage to dry lining is you will lose up to 50 mm (2") off the room, that said I like it because I know it works.

.

smashey

The man is back.

Ignore the pumped foam, a lot of money with very poor results. Dry-lining is the way to go here.

I should just have copied rooferPete's post.:D

Viking House

By drylining your house with polyurethane backed plasterboard you are only insulating 90% of the wall because you are not insulating where the internal walls and floors meet the outside walls. Lining the inside of your house with non-breathable Kingspan moves the condensation line of the wall internally to the point where the insulation meets the wall. This is the point where you get mould and fungus growth that is causing a lot of our health problems.
Scandinavian building regulations state "If at all possible insulate on the outside preferably with a breathable insulation, if it is impossible to insulate on the outside only then consider drylining".
Two inches of insulation externally gives the same effect as four inches internally.
Here is some independent research:
http://www.greenspan.ie/index.php?content=content&id_section=11&id_category=12&id_content=50&id_menu=2

Did you enjoy the school hols Pete?

garlad

Thanks for the info guys, really appreciate it.
I rang greenspan, who are now awaiting a drawing of my wall so they can give me a quote.
Should I sit down for that?

sas

garlad wrote:

Thanks for the info guys, really appreciate it.
I rang greenspan, who are now awaiting a drawing of my wall so they can give me a quote.
Should I sit down for that?

To quote the email response they sent me about Dryvit

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Approximate cost for Dryvit External Insulation would be €40 - €50 sq/m for material depending on thickness used.

The installation costs would be approximately €60 sq/m.

All prices are subject to vat labour @ 13% and Materials @ 21%
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Hope this helps.

SAS

garlad

sas,
Thanks for that. More expensive than I thought.
By my calculations I would be looking at 8-10K for my side wall !!!

oneillk

I would opt for the kingspan thermawall (insulated backed plasterboard) inside. This beats the tradtional dry lining because you dont not have any battons bridging accross.

Viking House says, 'Two inches of insulation externally gives the same effect as four inches internally'.

Im not an expert but i dont see how this is possible in this case, ie, first of all you have to heat the 9" cavity blocks, then all the air spaces in the blocks befor the heat hits the insulation. By this time surely some of the heat will have transferred to other parts of the house via the block wall and air cavities leading to loss of energy.
I know that the majority of the heat will be released at a later stage back into the room but i think for this situation the internal dry lining is enough and insulation externally is over the top. I do not have any problems with the method viking house has suggested, just i think this solution should be used as an overall solution, for an entire builidng and not just part of a building.

Correct me if im wrong, just mt opinion.

cheers

Viking House

oneillk wrote:

I would opt for the kingspan thermawall (insulated backed plasterboard) inside. This beats the tradtional dry lining because you dont not have any battons bridging accross.

Viking House says, 'Two inches of insulation externally gives the same effect as four inches internally'.

Im not an expert but i dont see how this is possible in this case, ie, first of all you have to heat the 9" cavity blocks, then all the air spaces in the blocks befor the heat hits the insulation. By this time surely some of the heat will have transferred to other parts of the house via the block wall and air cavities leading to loss of energy.
I know that the majority of the heat will be released at a later stage back into the room but i think for this situation the internal dry lining is enough and insulation externally is over the top. I do not have any problems with the method viking house has suggested, just i think this solution should be used as an overall solution, for an entire builidng and not just part of a building.

Correct me if im wrong, just mt opinion.

cheers

Hi Oneillk

Many people use the Kingspan backed plasterboard in Ireland but why are we using the technologies that have been scrapped in Europe over 20 years ago.
By all means try it but remove it in 1 years time and see how much mould has grown between the insulation and the wall.
Lining your house with Polyeurethene is like putting your head inside a plastic bag. http://www.viking-house.net/why-breath-easy

The reason that 2 inches outside is as good as 4 inches inside is because it changes the thermodynamics of the wall and the wall becomes a hot wall instead of a cold wall. It also eliminates cold bridging completly. The greenspan trial prooves this as the same levels of insulation were used in all wall types with big differences in the results.
Our price for external insulation with Granitewool is €75 plus vat but we are not looking for work as we are far too busy.

A lot of people think External insulation is a bit excessive for this problem, I don't agree, if a job is worth doing it is worth doing right. Only time will tell!!!

Only consider outside insulation when you have 10 inches of insulation in your attic and have double glazing.

Mellor

A quick question Viking house, I'm not getting into the internal verus external debate. There pros and cons of both, and im still undecided.

For this paticular job where he wishes to only insulate certains poor areas of the house. How does external insulation deal with an insulated area (such as garage) and an uninsulated area (such as front of house) that are on the same wall.

rooferPete

Hi Mellor,

I have no doubt Viking House can answer that himself but I am interested in external insulation as well so I might try answering and he can correct me or expand on my answer if that's ok ?

From what little I understand of external insulation I would presume if the garage section is insulated it will stop what I think would be a cold bridge from forming at the joint and travelling up the wall behind the system similar to rising damp ?

Personally I don't like the insulation attached to the plaster board, my choice would be a foil faced board facing into the room and a foil back plaster board fixed through the insulation breaking the joints.

The foil will provide two services, one is to reflect the heat back into the room and the second is it will act as a vapour check substantially reducing the chance of a dew point in the insulation.

Dry lining while not the perfect answer in a retrofit due to existing stud walls and floors in place as pointed out by Viking House, it does show a remarkable difference in the heat level of the rooms where it is used.

.

Viking House

Lets say Irish people wore their sweaters outside their raincoats for the last 50 years and Paddy went to Canada where the weather was much colder and saw the people there doing a crazy thing "they wore their raincoats outside their sweaters". How long is it going to take Paddy to change everybody's opinion?

We have the corporate power of Kingspan, CRH and Homebond all pushing in the same direction leading to damp, cold construction.
Polyeurethene and Concrete are frowned upon in colder climates as building materials.

A wise old Dutchman once told me "you can't save everybody"

Mellor

rooferPete wrote:

From what little I understand of external insulation I would presume if the garage section is insulated it will stop what I think would be a cold bridge from forming at the joint and travelling up the wall behind the system similar to rising damp ?

I was actually refering to the appearance of the wall and not the effectiveness. I dont agree with Polyeurethene as an internal insulation.
But I was wondering what would happen at the junction where insulated area meets regular wall. What would it look like were the garage has an extra 50mm of insulation on it. There would be a change in surface.
I an just asking because I think the whole wall should be done, and i am not sure if im right.
Its a little hard to explain the area i am on about. Might be easier to consider the same problem in two semi detached houses. One owner want s to external insulate his house, the neighbour doesnt, what happens at the junction of the houses. Is there any point in doing a job like this.

Viking House

rooferPete wrote:

my choice would be a foil faced board facing into the room and a foil back plaster board fixed through the insulation breaking the joints.

The foil will provide two services, one is to reflect the heat back into the room and the second is it will act as a vapour check substantially reducing the chance of a dew point in the insulation.

Dry lining while not the perfect answer in a retrofit due to existing stud walls and floors in place as pointed out by Viking House, it does show a remarkable difference in the heat level of the rooms where it is used..

Lets say the heated air in your room is like the air in a ballon, you have two forces working in the room, the first is the high pressure inside and the low pressure outside pushing the heated moist air outwards, the second force of nature is the need for hot air to go towards cold, the same way as hot air rises.
The fact that your room looses heat means that hot moist air always gets into your walls meeting the cold outside air, we can slow this down but it is impossible to stop.
When you use foilbacked plasterboard Pete the warm moist air is escaping through the joints where there is no foil and where the electrician puts the sockets and lights and radiator pipes.
It is a lot better than no foil but definately not as good as a Vapour check.

Viking House

Mellor wrote:

I was actually refering to the appearance of the wall and not the effectiveness. I dont agree with Polyeurethene as an internal insulation.
But I was wondering what would happen at the junction where insulated area meets regular wall. What would it look like were the garage has an extra 50mm of insulation on it. There would be a change in surface.
I an just asking because I think the whole wall should be done, and i am not sure if im right.
Its a little hard to explain the area i am on about. Might be easier to consider the same problem in two semi detached houses. One owner want s to external insulate his house, the neighbour doesnt, what happens at the junction of the houses. Is there any point in doing a job like this.

Hi Mellor

You are correct, there are problems with outside insulation like the semi-detached problem you mentioned above, window cills, is there is enough cover around the windows to take insulation in the reveals and is there enough overhang in your roof?

So we mostly use this system for new builds as it is much easier.