building porch/external insulation

marask

(Not sure if I am posting to the right subforum)
Hi,
We are thinking to build a porch to the front of the house, within the allowed 2m2, and also to externally insulate the house. Its mid terraced house with enough space towards the street.
Would anybody be able to tell the order what should be done first, and could we apply for the SEAI grant for the insulation job?
We would prefer to externally insulate rather than fill the cavity wall.
Thanks

Rabbo

Build porch then apply external insulation to entire structure.
Yes, you should be eligible for the SEAI grant

MicktheMan

marask wrote: »

(Not sure if I am posting to the right subforum)
Hi,
We are thinking to build a porch to the front of the house, within the allowed 2m2, and also to externally insulate the house. Its mid terraced house with enough space towards the street.
Would anybody be able to tell the order what should be done first, and could we apply for the SEAI grant for the insulation job?
We would prefer to externally insulate rather than fill the cavity wall.
Thanks

Ewi is ineffective if the cavity is not pumped first.
Ewi first, then porch (as porch is generally outside the thermal envelope)
Seai require both front and back walls to be insulated to avail of the grant.

Handsandtools

No point insulate external wall without filling cavity.
build porch first, or insulate top floor than build porch and finish insulation on ground floor, depends on detail where porch joins the building. Try insulated blocks like AEROC

marask

thanks all for advice

Calahonda52

MicktheMan wrote: »

Ewi is ineffective if the cavity is not pumped first.
Ewi first, then porch (as porch is generally outside the thermal envelope)
Seai require both front and back walls to be insulated to avail of the grant.

Will seai give grant if cavity not pumped if ewi useless on unpumped cavity wall?

MicktheMan

Calahonda52 wrote: »

Will seai give grant if cavity not pumped if ewi useless on unpumped cavity wall?

There is no requirement to have the cavity pumped in order to claim the ewi grant. :mad:
So, yes.

Bigcheeze

Handsandtools wrote: »

No point insulate external wall without filling cavity.

Does same apply with a cavity block construction ?

cerastes

MicktheMan wrote: »

Ewi is ineffective if the cavity is not pumped first.
Ewi first, then porch (as porch is generally outside the thermal envelope)
Seai require both front and back walls to be insulated to avail of the grant.

How is Ewi ineffective if a cavity isn't filled? I have never heard of this mentioned before?
I'm trying to see why anyway? A pumped cavity of insulation surely only adds extra insulation, but not done surely doesn't render ewi on its own ineffective? I've never heard ewi being mentioned in conjunction with a pumped cavity before, only ever as two different possible options, are there possibly even downsides? It seems like a good way to build up the insulation layer without making changes or adding layers that decrease space available, eg down a side entrance.
What would be a standard depth of insulation added to exterior? How much does cavity pumping change the U value, given all cavity blocks are the same and the spaces of constructed cavities are generally standard?
Is this meant to mean in cavity blocks only? What about where a facade makes the other side of a cavity?, isn't there meant to be separation there?

MicktheMan

cerastes wrote: »

How is Ewi ineffective if a cavity isn't filled? I have never heard of this mentioned before?
I'm trying to see why anyway? A pumped cavity of insulation surely only adds extra insulation, but not done surely doesn't render ewi on its own ineffective? I've never heard ewi being mentioned in conjunction with a pumped cavity before, only ever as two different possible options, are there possibly even downsides? It seems like a good way to build up the insulation layer without making changes or adding layers that decrease space available, eg down a side entrance.
What would be a standard depth of insulation added to exterior? How much does cavity pumping change the U value, given all cavity blocks are the same and the spaces of constructed cavities are generally standard?
Is this meant to mean in cavity blocks only? What about where a facade makes the other side of a cavity?, isn't there meant to be separation there?

Your post is confusing, too many questions (you seem to be mixing cavity walls and cavity block walls). My comments previously were about a cavity wall.
But to answer you first question, thermal looping / bypass is the reason.

cerastes

I see, I thought you were meaning cavity walls of any kind, but I was thinking cavity block too/mostly.
As for thermal looping, doesn't adding ewi and ensuring it is fitted well limit the effects of thermal looping? Limiting the coolness on the cold side? Does that not also presume that there is some breach that air currents can move through? Probably likely but as it can't be checked.
Are there disadvantages to cavity fill in that case?re Moisture?

If cavity fill is such an advantage in that construction, would it be advantageous to fill cavity blocks, where they were intended to be covered with ewi anyway, eg some houses have cavity blocks back and sides and a cavity wall on the front where there is a facial of red bricks.
So if getting cavity fill for one space, is it worth continuing all sides? Or does the cost then outweigh the savings?

Calahonda52

Dont know about doing it in CB, the walls you describe, very accurately, as I have them , are pretty haphazard when you consider opes, lintels etc and the use of solids etc.
I think it would just cost to much and be very hit and miss.
Any money would be better spend on thicker EWI...

BryanF

If your in the trades, could you take a few days off and work for an Ewi company.. a few days ? Then assess the best approach.

MicktheMan

cerastes wrote: »

I see, I thought you were meaning cavity walls of any kind, but I was thinking cavity block too/mostly.
As for thermal looping, doesn't adding ewi and ensuring it is fitted well limit the effects of thermal looping? Limiting the coolness on the cold side? Does that not also presume that there is some breach that air currents can move through? Probably likely but as it can't be checked.
Are there disadvantages to cavity fill in that case?re Moisture?

If cavity fill is such an advantage in that construction, would it be advantageous to fill cavity blocks, where they were intended to be covered with ewi anyway, eg some houses have cavity blocks back and sides and a cavity wall on the front where there is a facial of red bricks.
So if getting cavity fill for one space, is it worth continuing all sides? Or does the cost then outweigh the savings?

The problem with any kind of ventilated cavity inside an insulation layer is that the vented cavity allows cold air to circulate and carry away the heat before the outer insulation has a chance to work.
Trying to fill cavity columns in "cavity block" walls can be problematic.
When installing ewi on any wall type, best practice is to remove the facia/soffit/gutters and make sure the wall insulation meets / overlaps the roof insulation. While this space is open, in a "cavity block" wall, the top of the (columns) wall can be inspected and holes sealed (slate bedded in mortar) where necessary. This reduces significantly the negative effects of thermal looping/bypass and allows the ewi to work. While this isn't ideal, it is a big improvement on not addressing the cavity ventilation.

Handsandtools

MicktheMan wrote: »

The problem with any kind of ventilated cavity inside an insulation layer is that the vented cavity allows cold air to circulate and carry away the heat before the outer insulation has a chance to work.
Trying to fill cavity columns in "cavity block" walls can be problematic.
When installing ewi on any wall type, best practice is to remove the facia/soffit/gutters and make sure the wall insulation meets / overlaps the roof insulation. While this space is open, in a "cavity block" wall, the top of the (columns) wall can be inspected and holes sealed (slate bedded in mortar) where necessary. This reduces significantly the negative effects of thermal looping/bypass and allows the ewi to work. While this isn't ideal, it is a big improvement on not addressing the cavity ventilation.

At last one good answer in here!

Handsandtools

Did any It in Ireland offer study of calorific or building climatology???

Outkast_IRE

Handsandtools wrote: »

Did any It in Ireland offer study of calorific or building climatology???

Not sure exactly what your asking but Building Energy Systems in CIT has building thermal dynamics as part of the course, along with psychrometrics.

cerastes

MicktheMan wrote: »

The problem with any kind of ventilated cavity inside an insulation layer is that the vented cavity allows cold air to circulate and carry away the heat before the outer insulation has a chance to work.
Trying to fill cavity columns in "cavity block" walls can be problematic.
When installing ewi on any wall type, best practice is to remove the facia/soffit/gutters and make sure the wall insulation meets / overlaps the roof insulation. While this space is open, in a "cavity block" wall, the top of the (columns) wall can be inspected and holes sealed (slate bedded in mortar) where necessary. This reduces significantly the negative effects of thermal looping/bypass and allows the ewi to work. While this isn't ideal, it is a big improvement on not addressing the cavity ventilation.

Hmm, I see, its got to depend on the construction of the cavity then, I wasn't even considering ventilation of a cavity space, there is no ventilation or open spaces at the bottom of the cavity which is on a base of a concrete floored newer house. The wall is on the front of the house I'm referring to, the rest are cavity blocks I'm sure, and the top I'm fairly sure is covered in a layer of blocks? I'll have to confirm that but its above the level of the soffit in the attic space as I recal, if so no ventilation of could occur.

Can any problem occur from capping cavities which didn't start that way? Or was it just a cost saving measure or something no one bothered with as was not a requirement?