Are some snots and caps a problem on the inside of a new brick wall?

[Iceverge]

1 hour ago, Bounce said:

They have agreed to rectify it from tomorrow. I think they are potentially going to take the blocks (inner skin) down and relay them, with the insulation attached properly. Do you think this possible? 

 

 

 

No is my firm answer. It's real life here I'm afraid and Like I say, I've never seen it done correctly before. I think you'll repeat the mistake but just slightly less bad as the rigid board system in the wall is fundamentally flawed. 

 

Get yourself down to a BM's and buy some 100mm wool cavity batts. You can get to a K value of 0.032 W/mK but you're gaining very little over the ones at 0.035 or 0.036 for the extra spend. 

 

 

 

Something like this would be fine. 

 

 

 

 

 

 

[Iceverge]

Alternatively you may be able to remove the existing boards without taking the walls completely down and use EPS bonded beads injected into the wall instead. 

 

I know the builders did a sloppy job but you have some responsibility for QCing the situation too. 

 

In this light the overall cheapest and most workable solution is in your interest as much as the builders. 

 

Any wider pics of the built wall will help us all determine how most satisfactorily to proceed. 

 

Like I say, please post any further pics of the plans, most specifically the sectional drawings to help us help you for the rest of the project . 

 

 

 

 

 

 

[saveasteading]

Blocks down, keep the ties in place, break off snots and remove,  repoint the brick inner face.

Hand the bricky a picture of how it should be.

build block with insulation.

 

Does that mean that the insulation is tight to the blockwork and a gap to the brick?

[Bounce]

48 minutes ago, Iceverge said:

Alternatively you may be able to remove the existing boards without taking the walls completely down and use EPS bonded beads injected into the wall instead. 

 

I know the builders did a sloppy job but you have some responsibility for QCing the situation too. 

 

In this light the overall cheapest and most workable solution is in your interest as much as the builders. 

 

Any wider pics of the built wall will help us all determine how most satisfactorily to proceed. 

 

Like I say, please post any further pics of the plans, most specifically the sectional drawings to help us help you for the rest of the project . 

 

 

 

 

 

 

Do you mean photos like this? 

 

I will try upload sectional drawings too. 

 

[Bounce]

Just now, Bounce said:

Do you mean photos like this? 

 

I will try upload sectional drawings too. 

 

[Iceverge]

Spot on. 

 

Right here's my proposal. 

 

Pull out the boards, done carefully they can be reused elsewhere. Like I've said a billion times they can't be done properly in the wall. You may need to dismantle some of the wall but probably not all of it. 

 

Build your walls as an empty cavity.  Ensure the cavity is kept clean and bricks correctly pointed. Best way to do this is slide in a 100mm board at a few opening's to catch the snots. With a squirty hose give the ties a quick rinse at the end of every day. At the end of the build pull out the 100mm cavity boards. 

 

Use EPS blown beads to fill later on. Your theoretical U value will drop from about 0.22 to 0.33 but as you won't get any thermal looping ( wind blowing around the board) your real world performance will be better. 

 

You can reuse the wall boards in the floor so no extra cost. In fact you'll save money on the construction as EPS beads are quite economic. (About €120/m³ plus Vat in Ireland) 

 

 

[Roger440]

Iceverge is spot on here. Its what id be doing in this situation.

 

Out in the real world, without exceptional levels of detailing, this can never work.

 

Ive seen a coule of videos by builders showing, proudly, that they have fitted this stuff. And whilst not as poor as this effort, its clear to anyone that the air will get behind the insulation.

 

Sadly, the BCO, nor anyone else except the OP, has any vested interest in the thermal performance of the completed building. So long as the boxes are ticked, thats all that matters.

[Bounce]

2 hours ago, Iceverge said:

Spot on. 

 

Right here's my proposal. 

 

Pull out the boards, done carefully they can be reused elsewhere. Like I've said a billion times they can't be done properly in the wall. You may need to dismantle some of the wall but probably not all of it. 

 

Build your walls as an empty cavity.  Ensure the cavity is kept clean and bricks correctly pointed. Best way to do this is slide in a 100mm board at a few opening's to catch the snots. With a squirty hose give the ties a quick rinse at the end of every day. At the end of the build pull out the 100mm cavity boards. 

 

Use EPS blown beads to fill later on. Your theoretical U value will drop from about 0.22 to 0.33 but as you won't get any thermal looping ( wind blowing around the board) your real world performance will be better. 

 

You can reuse the wall boards in the floor so no extra cost. In fact you'll save money on the construction as EPS beads are quite economic. (About €120/m³ plus Vat in Ireland) 

 

 

Thanks appreciate that info.. 

 

In regards to saving money, they are supplying all the materials etc, so any additional costs for this, will be paid for by them, I just want to make sure it's all done correctly. 

[Canski]

My opinion as a bricklayer who cares about insulation 😂😂

what they have done is awful. That insulation needs the joints taping and then clipping back hard against the blockwork. This can only be done with the blockwork built first.

 

I would let them ( as they have agreed to do) take the blockwork down and rebuild with full fill cavity bats. You will be left with a load of waste insulation for the skip but that is the best place for it. The cost of this waste insulation should be deducted from their payment. Any bricky worth his salt should know how it is fitted and if not should have researched it before the crash bang whallop. They won’t be able to tape the joints with the brickwork up. It is possible to use the existing insulation  without taping and get it tight against the blockwork but you would have to stand there and watch them. 

[crispy_wafer]

If you take the approach above, i'd pile up the PIR and sell it, facebook marketplace, someone will have it, and you'll get some money back.  Couple or 3 boards for £20 or so, I found people are fitting it into sheds, and allsorts when I sold a load of offcuts over autumn/winter last year..

[Canski]

7 hours ago, crispy_wafer said:

If you take the approach above, i'd pile up the PIR and sell it, facebook marketplace, someone will have it, and you'll get some money back.  Couple or 3 boards for £20 or so, I found people are fitting it into sheds, and allsorts when I sold a load of offcuts over autumn/winter last year..

 

Good advice and well worth a try. Personally I wouldn't even use it in a shed 🙂

[Mr Punter]

On 11/03/2025 at 20:55, Iceverge said:

Either start from scratch or use a closed cell foam like Walltite or Technitherm to completely fill the residual cavity

 

I would not recommend any spray foam insulation.  It could be a disaster for insurance, mortgage or resale purposes.  I doubt these even have current BBA certificates.

[Iceverge]

1 hour ago, Mr Punter said:

 

I would not recommend any spray foam insulation.  It could be a disaster for insurance, mortgage or resale purposes.  I doubt these even have current BBA certificates.

As with everything the devil is in the detail. Using closed cell foam to encase timber is the most common cause of decay etc. Unfortunately with the exception of the 'hub the entire industry is full of morons who can't see nuance or indeed understand any science. 

 

They both had BBA certs in the past, i don't know if they've expired or just were withdrawn for another reason. In a masonry wall it's quite safe, especially alongside PIR as it'll only be bonded to one face of blockwork avoiding any shrinkage cracking that you get with full fill foam in wide cavities. 

 

 

 

 

[Mr Punter]

3 hours ago, Iceverge said:

They both had BBA certs in the past, i don't know if they've expired or just were withdrawn for another reason. In a masonry wall it's quite safe, especially alongside PIR as it'll only be bonded to one face of blockwork avoiding any shrinkage cracking that you get with full fill foam in wide cavities. 

 

The point is it could make the property unsaleable.  I agree that badly fitted pir boards are hopeless.  The EPS beads and cavity batts are non contentious. 

[Roger440]

5 hours ago, Iceverge said:

As with everything the devil is in the detail. Using closed cell foam to encase timber is the most common cause of decay etc. Unfortunately with the exception of the 'hub the entire industry is full of morons who can't see nuance or indeed understand any science. 

 

 

Its worse than that though isnt it.

 

It seems that most cant understand that if the air on the outside of the insulation can get behind/go round the insulation, its not insulation any more!

 

If you cant grasp that, then as you say, they are morons. OP's brick layers included.

[saveasteading]

49 minutes ago, Roger440 said:

cant grasp that, then as you say, they are morons.

That's rather extreme.  I can't lay bricks well, most bricklayers don't understand structure or insulation.

 

What annoys me is when they are too arrogant, or just dim, to do what they are told.

[Nickfromwales]

51 minutes ago, Roger440 said:

Its worse than that though isnt it.

 

It seems that most cant understand that if the air on the outside of the insulation can get behind/go round the insulation, its not insulation any more!

 

If you cant grasp that, then as you say, they are morons. OP's brick layers included.

There are an alarming number of dwellings that have had EPS EWI applied, that are now displaying huge amounts of damp and mould growth on the interior surfaces of the external walls, literally stopping at the party wall. This is down to rain getting in at the top, or air convection (aka thermal tenting) happening from the bottom to the top, with the moisture then being harboured by it condensing and then being trapped with nowhere else to go than into the fabric of the house.

 

Do this properly or receive the consequences!

[Nickfromwales]

8 minutes ago, saveasteading said:

That's rather extreme

I disagree wholeheartedly, sorry!!!!

 

 

That is a bag of shite, and even Stevie Wonder would agree.

[Canski]

2 hours ago, Nickfromwales said:

I disagree wholeheartedly, sorry!!!!

 

 

That is a bag of shite, and even Stevie Wonder would agree.

I'm sure Stevie wonder could improve on that after 10 pints on a Friday but ....

 

This is my bugbear with T & G insulation. This type is not so bad but that Xtratherm plastic faced crap boils my piss. Ok the bats need to be fixed tight against the walls which isn't difficult. I can't understand why anyone has a problem doing this. Then come the problems with the ties going over the tongue. I cut a slit in the insulation for the tie to keep the insulation boards tight to each other (top to bottom) but as you can see from this photo the ties have 'drips' on them so the slit needs to be oversize in depth to accommodate the tie. This means that you often need to cut a slit in the next row of boards. NHBC correctly state that cavity ties should fall towards the outside so the brickwork skin should be slightly lower than the blockwork skin which makes it even more difficult. Sometimes you have a 10 mm air gap in which you need to fix your retaining clips which can measure 10 mm in thickness leaving no room for play. Of course you then need to be careful removing snots from the back of the facework and God help you if you are 2 courses up from the tie and catch a clip and send it falling down the cavity. Bear in mind also that sometimes the clips are not really tight on the ties and get pushed back by the often warped bats of insulation.

 

The only way to use this is by building the blockwork first and letting it set properly before fixing the insulation tight against the blockwork then taping it remembering to slit your tape at the tie position then clipping it hoping that the clips are not cheap shit internet clips.  I therefore charge an extra £5 per m2 over full fill for this insulation if I have to do it. I don't work on them but a lot of the guys on 'house factories' don't get a penny for it as it is 'included in their rates' It is no surprise that they cut corners and get so used to cutting corners that they don't know any different.

 

It is of course possible to do a great job but T&G is not a user friendly product. Full fill or blown cavities any day for me.

 

 

[Roger440]

20 hours ago, saveasteading said:

That's rather extreme.  I can't lay bricks well, most bricklayers don't understand structure or insulation.

 

What annoys me is when they are too arrogant, or just dim, to do what they are told.

 

I dont think it is.

 

These same people, on a cold winters night, wouldnt leave their front door open, and then wonder why its cold!

 

The concept is that simple. I cant imagine there are many people so dim as to be unable to grasp this. Bone idle, disinterested etc, possibly.

[saveasteading]

2 hours ago, Roger440 said:

I dont think it is.

I've checked, and the word seems to be  less offensive than I thought, or than it used to be.