9 inch Hollow Block with internal Dry-lining but cold house

TheBoyConor

Fair play to you. I admire your optimism.

I find the most common word I use in emails is "outstanding". As in, "it still isn't done after telling ye 5 times" rather than, "wow great job".

leonlafrite

Hi Guys -

I have just been in the attic and it looks like the blocks have been caped with other narrower blocks see pictures, can you confirm this the case?

Interestingly the temperature in that extended part of the attic is colder then the main house (pic old vs new) does this means something that can help me find confirm the issue?

thank you for the help so far.

Calahonda52

It does not help when they are sideways or upside down
In any event they tell me nothing, what I want to know is what is happening on the far side of the wall plate in image 3.
In addition some wider angle shots would give some perspective

the_pen_turner

doesn't look like the cavity is closed under the wall plate.
what is going on with the rafter in pic 2 . is the building off square . why is there a piece added on at an angle

blackbox

It sounds like there is too much air movement between the wall and the plasterboard.
As mentioned above, the top of the wall may be an issue, but have you carefully checked the external walls for gaps or openings? Underneath the window sills is a real possibility.

You can stop the draughts internally around the switches, but if outside air is circulating behind the plasterboard, your walls are only effectively the thickness of the plasterboard.

TheBoyConor

Those blocks on the flat close off the gable cavity blocks ok but it is the wall under the wall plate that is of most interest. It looks as if there is no top course of block on flat there. If the cavity blocks have the horizontal void then that is OK. If they have vertical voids then that is a problem and there should be a block of flat course to top them off. Without that, the insides of the walls running along the top

the pen turner, it is a cavity block wall, not a cavity wall.

You would expect the temperature in the attic to be colder than inside the house. You are above the insulated envelope when you're in the attic. If the new attic has more insulation than the old attic the you would also expect the new attic to be colder than the old one.

leonlafrite

Hi TheBoyConor, What can I show you to help identify exactly what you want to see, could you point on the new pic?

Also both the extension and the original house have the same attic depth but the temperature are different by a few degrees

I uploaded wide angle pics

TheBoyConor

Those pictures are showing the gable wall but that is not what we are looking for. We need to see the side wall, right down in the very corner of the roof near the eaves. You might need to get a borescope to see the top of the wall there, or look by removing a roof tile on the eaves, or putting your hand up through the soffit.

you'd also need to see the junction between the insulated plaster slab and the ceiling from the attic side. You'd have to lift the insulation and expose the joint, both at the gable wall (easy) and at the eaves wall (difficult).

A couple of degrees difference between each part of the house could be caused by multiple things. An extension probably has a higher surface to volume ratio than the main block of the house, and possibly thermal mass. As such even with the same overall U-Value of the building envelope, the temperature will drop quicker in the extension than the main house.

Penn

leonlafrite wrote: »

Hi Guys -

I have just been in the attic and it looks like the blocks have been caped with other narrower blocks see pictures, can you confirm this the case?

Interestingly the temperature in that extended part of the attic is colder then the main house (pic old vs new) does this means something that can help me find confirm the issue?

thank you for the help so far.

In image Cap3 showing the wallplate, are you able to get your hand to the other side of the timbers and check if the cavity has been closed? It doesn't look like they've used a solid block on its flat to close the cavity there, but they may have bedded in a slate across the cavity to close it. Or even if you can stick the camera over the timber you might be able to get a photo

the_pen_turner

are there 2 layers of insulation.
are they 90 degrees to each other. the insulation doesn't look like a well installed job . is there a walk way to that tank.
the tank is not insulated
. it wouldn't surprise me that the insulation is not installed far enough into the corners . are there black spots on the eiling below at the wall to ceiling joins

what kind of ventilation is there at the eaves level and higher up the roof.

pull back the insulation at the wallplate and post a pic of that area

leonlafrite

Ok so I looked at the area from attached pic named "attic issue" and found no caps on the block in the area in red but it looks like block are capped in the area in green (gable slope) see other pics.

Problem is that it is really hard to get access to the wall plate as the roof is very low but will try later today ...

I am thinking that having someone come in and check this from the roof will be the easiest way to go - so we could then fill all the gaps with some foam, does that make sense as a first step?

the_pen_turner

is it a tiled roof or slates. whats access like to the soffit area

leonlafrite

Hi the_pen_turner

The roof it tiled and It is easy to access as far I can see. See pics
On the pic call "back extention kitchen and kid bedroom.jpg" the small roof is with slates and has no insulation and will need improvement)

Thank you

Calahonda52

IMO, that sewer pipe vent should go up beyond the gutter.
the red zone pics are part of your problem

leonlafrite

Calahonda52 wrote: »

IMO, that sewer pipe vent should go up beyond the gutter.
the red zone pics are part of your problem

I have put some foam in there now red zone holes - I hope it will not just sink into the hole - I will check in the morning.
But even if this helps I think there is more to the problem than this?

Ignore the attic for a moment; earlier you posted these pics:


https://www.boards.ie/vbulletin/attachment.php?attachmentid=513443&d=1589877336

https://www.boards.ie/vbulletin/attachment.php?attachmentid=513445&d=1589877354


Maybe I'm looking at it wrong, but what's going on there? Why is there a big gap with nothing in it? Where did you take that photo from and is there any insulation on the back of the plasterboard? To me, that looks like you have no insulation at all?

Insulation is like a thick foam of sorts, that's stuck to the back side of the plasterboard sheet. This foam should be tight to the brick work, like in this picture:

https://thorhelical.com/wp-content/uploads/2015/10/fixing-insulated-plasterboard-laminates-banner.jpg


There, to my knowledge, should not be a gap between the insulation and the block. It should be fixed directly to it.



EDIT: I'm not a builder! Just a DIY'er of sorts, so I'm always open to correction.. just to cover myself

TheBoyConor

KKV you are dead right. On a plaster dab dry lined wall there should hardly be a 10mm gap between the block wall and the slab. You certainly should not be able to get a camera or phone in there.

If what we see in that picture is indeed the gap between the slab and wall then there is something very fishy going on that needs investigating. That would not be a normal set up at all.

Calahonda52

the presence or absence of insulation is a separate issue from the obvious porosity problem, not solving the latter first will negate the value of an additional insulation work.

leonlafrite

Thank you all.

There is insulation on the plasterboard and the space in between the wall and the back of the PB is may a couple in cm only
Is this even OK ?? I would agree with KKV that it should stuck to the wall (I used a borescope to check)

Silly question probably but if I need to fix the walls porosity problem, is there any way to do this without removing the existing dry-lining?

Based on all the feedback I think the house is just not air tight in so many ways .... The blocks could be only the tip of to iceberg here ...

leonlafrite

leonlafrite wrote: »

There is insulation on the plasterboard and the space in between the wall and the back of the PB is may a couple in cm only

How is there a gap, though? Are there wooden battens fixed to the wall, and the plasterboard fixed to them?

It would definitely give a reason as to why the otherside of the wall is drafty when you remove light sockets etc. as you effectively have a cold air 'shell' around your extension.

Perhaps this is a legitimate way of doing things, but I personally can't understand why you'd do it that way.

(theoretically, though.. you still do have insulation plasterboard, so, again, in theory, your house should still be warm inside..?).

A boroscope probably has an ultra-wide angle lens that makes the gap look bigger than it actually is.. Could you give an idea on how deep the gap is?

To be honest, it might be worth your while cutting a small square out of the wall, and having a proper look in there (you can always fill it back in, just use a stanley blade to cut out a square/circle and keep the piece you've cut out, then use a bit of filler to put it back on).

It'd take a lot of the guesswork out of it. I reckon you may need someone that's a bit more clued in to have a look, though, or ask the builder that did it what the reasoning was behind doing it that way.

leonlafrite

Ok, So I looked again and there is a 1 cm gap in between blocks and insulation from PB

Total thickness from block to room side PB is 7 cm so I presume we have about 40/50 mm insulation on a 12.5 board

Pics attached

It was installed using the dot and dab method which looks widely used... BUT there should not be a draft going on (I am now convinced this is main reason for the heat loss)

Looks like I will need to find a way to stop the draft coming thru the block... sound expensive to fix...

The house gets warm very fast but the heat escapes quite quickly over a few hours, it is impossible to keep warm.

kadman

Dot and dab by its nature, was used for fast expedient method of preparing walls for finishing
with minimal input.

Dot and dab crew could fly around a room in minutes. But its method of fast fitting does not seal
either at the bottom of the plaster board sheet, or the top of the sheet.

So if you have air movement here, its either coming down from above, or up from below.

The fact that you have an unsealed low level roof area, in line with your existing first floor level,

may be worth more investigation. Air entering below the slates here, have access to the ceiling/joist level,

into the floor zone, depending on build method. And then free access to any of the dot and dab sheets

near that zone, and then onto the rest of the house.

Thermal imaging camera will yield loads of answers.

2 cents

Calahonda52

IIRC the fire regs require a fire stop top and bottom so maybe there is a bigger issue here

leonlafrite

Thermal imaging/heat loss survey is probably the way I will go in order to pin point the root cause(s) as It should allow me to pin point the fixes with the highest return on investment...

I did some math and our gas bill over last winter was 650 (November to March)
Best case we will save 25 % or about 160/year
I will need over 15 years to recover a 3 k investment (probably less as prices will go up)

This does not account for the extra comfort of a warm home :-)

kadman

Calahonda52 wrote: »

IIRC the fire regs require a fire stop top and bottom so maybe there is a bigger issue here

Little use in having regs, and no policing of the same.

Even when the government came up with the insulating homes scheme

after the 2008 crash. It was an absolute joke.

Groups of ill trained home insulators, and rule bending sign offs .

I saw my own family home half done, and wrongly fitted with roof ventilation

areas blocked.

It was a joke then, and still the same now. I spent many many years on sites

both as an architectural joiner, through to timberframe / steel detailer and

insitu concrete form designer. I've seen things to make you cry, and i dont

scare easily

Calahonda52

kadman wrote: »

Little use in having regs, and no policing of the same.

Even when the government came up with the insulating homes scheme

after the 2008 crash. It was an absolute joke.

Groups of ill trained home insulators, and rule bending sign offs .

I saw my own family home half done, and wrongly fitted with roof ventilation

areas blocked.

It was a joke then, and still the same now. I spent many many years on sites

both as an architectural joiner, through to timberframe / steel detailer and

insitu concrete form designer. I've seen things to make you cry, and i dont

scare easily

.

Not disagreeing with one letter in the above , I was pointing towards the OP perhaps having stumbled on a bigger problem

kadman

Calahonda52 wrote: »

.

Not disagreeing with one letter in the above , I was pointing towards the OP perhaps having stumbled on a bigger problem

I think we are both singing from the same hymn sheet.

Good god man, dont be telling the op that things could get worse the

more he digs:eek::D:D

leonlafrite

Hi Guys - I suppose I have to ask now but what are these fire stop top and bottom?
How can this be checked?
I know an architect was involved back when this was built but that probably count for very little....

kadman

I worked on many different sites, block, steel,timberframe.

At the time Homebonds housebuilding manual was the rulebook of the day for timberframe.

And for the dot'n'dab merchants, firestops were alien technology, so I doubt very much if

you have them.

https://passivehouseplus.ie/magazine/help-desk/fire-compartmentation-timber-framed-party-walls

A quick google will explain the purpose of fire stops. Its to stop both fire and smoke permeating through the building.

If you dont have them, it would be a pointless expensive thing to refit.

Look at all those apartments in Dublin a couple of years ago, that had no adequate fire safety fitted.

Like i said before policing and inspection for this sort of thing is a joke. Always was, and nothing will change

TheBoyConor

Things are marginally better now with the BCAR. However, it is only a modest improvement. There are still far too many "sure it'll be grand" merchants and contractors and trades only interested in doing the most convenient, handiest and cheapest thing with the mentality of get it all closed up quickly and what is out of sight is out of mind.
Until a few of the more lax assigned certifier and contractor engineers are strung up by the courts and struck off as an example, not much will change.