Cavity Wall Insulation

sharkman

Hi Guys,

We had a chap from electric Ireland around last week and they quoted €250 to pump the beaded cavity wall insulation into the front wall of the house (standard 3 bed-semi in Swords). Has anybody had this done? Do you feel it would make much of a difference? I'm a wee bit dubious as they said they can only do the front as the side of the house is dashed.

sydthebeat

sharkman wrote: »

Hi Guys,

We had a chap from electric Ireland around last week and they quoted €250 to pump the beaded cavity wall insulation into the front wall of the house (standard 3 bed-semi in Swords). Has anybody had this done? Do you feel it would make much of a difference? I'm a wee bit dubious as they said they can only do the front as the side of the house is dashed.

the side of the house being dashed has nothing got to do with the ability of the wall to be pumped or not...

gramar

I remain unconvinced that the pumped insulation can cover the whole inner surface of the cavity wall unless they put holes in every couple of square feet.

As for only doing one wall, it's like turning on the heating and opening the window.

muffler

sharkman wrote: »

Hi Guys,

We had a chap from electric Ireland around last week and they quoted €250 to pump the beaded cavity wall insulation into the front wall of the house (standard 3 bed-semi in Swords). Has anybody had this done? Do you feel it would make much of a difference? I'm a wee bit dubious as they said they can only do the front as the side of the house is dashed.

If the side is a cavity wall (and the rear) then there is no reason for them to stick to the front wall only and while every little helps you would be better getting a firm that specializes in this and get the entire house done.

Saying they cant do it because the wall is dashed is a load of bollix

sinnerboy

Standard 3 bed semis in Swords will have rendered hollow block to side and rear elevations. It is the hollow block and not the render which means that cavity fill is not practical.

It is best for the thermal envelope to be in the same plane i.e. all external , all in cavity or all internal.

You do not have a continuous cavity plane to fill. So if you cannot afford external insulation then stick to internal dry-lining. For 2 reasons do not go over board i.e. no more than 50mm insulation

1. to reduce the risk of interstitial condensation i.e condensation forming behind the insulation on the internal blockwork face
2. to minimize the loss of floorspace.

muffler

sinnerboy wrote: »

Standard 3 bed semis in Swords will have rendered hollow block to side and rear elevations. It is the hollow block and not the render which means that cavity fill is not practical.

Ah, thats a different scenario so

BryanF

gramar wrote: »

I remain unconvinced that the pumped insulation can cover the whole inner surface of the cavity wall unless they put holes in every couple of square feet.

Search for any cavity pump systems IAB cert, you'll see that holes are drilled 'every couple of square feet' !!!

muffler

BryanF wrote: »

Search for any cavity pump systems IAB cert, you'll see that holes are drilled 'every couple of square feet' !!!

I think he's probably referring to the vertical spacings

just do it

sinnerboy wrote: »

Standard 3 bed semis in Swords will have rendered hollow block to side and rear elevations.

Does this mean there is no insulation in the wall to start with? Did they comply with building regs at the time they were built?

I know of houses built like this in Newbridge Co Kildare a well.

tea and coffee

sinnerboy wrote: »

You do not have a continuous cavity plane to fill. So if you cannot afford external insulation then stick to internal dry-lining. For 2 reasons do not go over board i.e. no more than 50mm insulation

1. to reduce the risk of interstitial condensation i.e condensation forming behind the insulation on the internal blockwork face
2. to minimize the loss of floorspace.

I am interested that you say 50mm board, Sinnerboy, as builders I have been speaking to have all recommeded 82mm board. We are not short on space, but the point you raise in #1 in relation to condensation worries me. For all its faults, the one thing the house isn't at the moment is damp

sinnerboy

Dry lined external walls need some heat transmission through them to keep them dry. If you over insulate then not enough heat energy passes through the wall to drive condensation away. ALL dry lined walls will experience interstitial condensation to a greater or lesser degree. The "trick" is to minimise the occurrences and to rely on the capacity of the blockwork to absorb and disperse the moisture safely with a certain amount of heat transmission ( heat loss ) to assist.

For an answer in more than simple terms refer to this journal 50mm is found here to be about the optimum insulation thickness to minimise heat losses and condensation risks.

sinnerboy

just do it wrote: »

Does this mean there is no insulation in the wall to start with? Did they comply with building regs at the time they were built?

I know of houses built like this in Newbridge Co Kildare a well.

Sometimes , yes. We know in Ireland that regulations are always complied with

I live in a hollow block house near Swords built circa 1980. The walls were dry lined with plasterboard placed over 25mm deep timber battens. There was a time when a 25mm airspace was considered "good insulation" Throughout the 90's builders tended to use 50mm battens with 50mm fibreglass. During the early 00's this was typically increased to 75mm.

I should add that this is the inheritance of those of use who live in spec houses local to the M50. Our country cousins tend to have had built cavity wall constructions. On hollow blocks , "I wouldn't build a garden wall with them" I have been told more than once ....

And then it all changed around 2007....and some are still only waking up to that today