Cavity wall Beads For Coastal Area Dongegal

kittykat41

Hi Everyone

I was going to get cavity beads put in the walls of house before plastering, the house was built about 15 years ago and has the 60mm white insulated sheets in the cavity

I was all for getting the cavity pumped but have been told by a friend its a bad idea as you could get cold spots in the walls and is not advisable near the coast with driving rain

Is this the correct advice ?

muffler

The suppliers should give you a copy of the Agreement Certificate regarding the product that is issued by the national standards authority and it will clearly state if the beads can be used in an exposed location. Read this document in advance of doing any works.

kittykat41

Thats good advice

The gap available in the cavity is around 40mm, would this be OK for the people to add the beads?

I'm afraid of making the wrong choice

muffler

40mm is fine for pumping beads. But do check the certification for whatever type of bead is proposed. For example this is the Agrement Cert for Kingspan EcoBead. Have a look at the bottom of page 7 and you will see it can be used in exposed areas.

eoinzy2000

Pumping beads and filling the cavity has proven to be a bad idea. The outer leaf will always remain wet and your paint will not adhere to this wet masonry if you ever want to re paint. You'd be better to internally dry line. If you're not worried about paint externally and potential freeze /thaw issues of a constantly wet outer leaf, over the benefits of additional cavity insulation, then go for it. Just remember it's called a cavity for a reason.....

MicktheMan

https://www.boards.ie/discussion/comment/119741740#Comment_119741740

Would be interested in reading the "proof" that it is a bad idea to pump beads into a cavity.

muffler

https://www.boards.ie/discussion/comment/119741740#Comment_119741740

So having the cavities pumped will result in the outer leaf being permanently wet? Where did you get that from? I posted a link to show that pumping cavities with a particular product has been tested and approved by the National Standards Authority of Ireland so perhaps you can post a link to an official source that backs up your claim.

Lumen

This BRE report is relevant.

Post_Installation_Performance_of_Cavity_Wall__External_Wall_Insulation.pdf

eoinzy2000

The water that gets into the blocks remains. There is no cavity to vent and dry the outer leaf. Many houses that I deal with have issues with outside painting. It's a simple fact that blocks retain water. The air flow in cavity drys it out. Even in modern full fill cavity board, they retain a ventilated cavity to dry out outer leaf. It's not a 'where I get that from', it's logical fact that most people don't consider and companies selling you bead definitely don't inform you of.

Musefan

Hi. I live in a very exposed area that experiences driving rain. I had booked to have the walls pumped and a surveyor from the company came out and gave the green light for it. I started to look into the process more and discovered certain stone properties aren’t recommended for cavity wall installation, my own included. When I went back to the company, they then did their own research into it and agreed that they couldn’t go ahead with the beads. It could have been a very very costly mistake. If your property has any stone walls, maybe look into whether the cavity can be pumped or not.

jackboy

https://www.boards.ie/discussion/comment/119746036#Comment_119746036

Regarding your link, does it not say you must have impervious cladding on your outer wall if using those beads in exposed locations? It does read like you must prevent all water entering the outer leaf.

Lumen

https://www.boards.ie/discussion/comment/119747252#Comment_119747252

In your experience, do solid concrete walls (single leaf block or shuttered concrete) suffer the same issues?

If not, why not? Do they dry out to the inside of the house? Or does the heating coming through (from lack of insulation on the inside) cause the water to be driven out?

This isn't a trick question, I'm interested.

muffler

https://www.boards.ie/discussion/comment/119747252#Comment_119747252

There would be individual houses here and there that have been poorly plastered where beads wouldn't be recommended but the vast majority of houses are fine. A cavity does not dry the outer leaf. It was never designed for that purpose and it certainly doesn't do what you claim. I've heard better theories discussed at the bar counter on a Saturday night.

10-10-20

https://www.boards.ie/discussion/comment/119747266#Comment_119747266

Interesting. Can you share the specific stone properties which aren't desirable with pumped insulation?

10-10-20

https://www.boards.ie/discussion/comment/119747252#Comment_119747252

Questions from the peanut gallery, if I may. When you say that "many houses that you deal with have issues with outside painting", are you in a field of work where you would be more exposed to such houses? ie defect remediation, etc? Any particular side of the country?

I don't disagree that blocks retain moisture, but I do also agree that the external finish is supposed to repel this and I'm trying to find the middle-ground between multiple levels of field experience whom are contributing to this discussion.

Like at the end of the day we have all encountered a wall which "doesn't take paint well", and it's very easy to look back in hindsight and apportion the blame to the painter/paint/weather/surface, but if there is further insight to this I'd be very interested to hear both sides of the debate.

Musefan

Hallmark stone. Roadstone confirmed at the time it was not suitable.

eoinzy2000

Common enough knowledge at this stage. It's really a debate between choosing the benefits of extra cavity insulation over the inconvenience created in relation to decorative repair. May also be implications if block strengths are low and you get a particularly hard winter. Filling cavities is relatively new, and it seems the downsides are becoming apparent in recent times.

Yes, the most apparent cases are in the most exposed locations, but all inland. Does not mean less exposed buildings are unaffected

eoinzy2000

Well, I'd call call a cavity just that, until you fill it with material and no longer becomes a cavity. Additional measures are required to deal with this alteration. Weatherproof cladding makes sense

muffler

https://www.boards.ie/discussion/comment/119748320#Comment_119748320

You have an opinion which you are entitled to but you are really just giving bad advice here due to your complete lack of knowledge and grasp of building construction and science.

Lumen

https://www.boards.ie/discussion/comment/119747146#Comment_119747146

This is also very interesting, particularly the bits about Scottish building regs and pressure moderation.

https://dampchat.wordpress.com/design-out-moisture-problems-in-new-cavity-walls-by-not-using-full-fill-insulation/

eoinzy2000

Jaysus muffler. Getting a bit personal there. I assure you I know a bit about it and am sharing observations and recent evidence. By your reaction you seem to have a vested interest in these products?

eoinzy2000

Muffler, a cavity is "an unfilled space within a mass especially : a hollowed-out space". When you fill this void completely and don't deal with the after effects of this process, then I'm afraid it is your own lack of understanding of building construction and science is being exposed. There were also several proponents of the "it's entirely freeze/thaw effects" of the recent defective block problem that put up this personal attack to IEI members statements that the problems were much more extensive. I am informing the OP that I have witnessed and have evidence of problems from filling the cavities in multiple buildings. You revert to personal attack in light of some statements says a lot more about your judgement and your poor attempts to discredit legitimate observation. I have two clients that are currently pricing removing the bead and dry lining internally to counteract this problem. A torture of a process.

OP, I would be wary of advices from people with a clear vested interest in such systems.

mickdw

Not a great fan of pumping myself due to the moisture transfer possibilities. That said, it is multiples ahead of cavity boards in terms of insulation benefit. Now this is not picked up in the theory but imo much of the benefit of cavity boards is lost due to difficulty of proper install.

With a 60mm board in an existing 100mm cavity, it's likely that the free space is alot less than 40mm in some areas. You could be looking at 25mm remaining cavity. Pumping this imo is not going to be satisfactory and to be honest the man on the gun doing the work might be the difference between a shambles and a somewhat satisfactory job.

eoinzy2000

https://www.boards.ie/discussion/comment/119747836#Comment_119747836

Chartered Consulting Engineer with in excess of 30 years experience operating in the North West in residential/commercial/industrial. This wet outer leaf issue is well known now with builders throughout the North West. Unsure of anywhere else. I know several contractors that now point blank refuse to use pumped bead in any new developments as they are fully aware of this problem. Many builders will just do it and get paid, and that's fair enough, but they should be informing clients that they'll have a warmer house, but a wet outer leaf. It's a particular issue in new houses. It's still common to dry line internally AND pump cavity full of bead. Paint never stays. Not as big a problem in older house as there are multiple layers of paint present and presents some form of a barrier to the moisture.

Lumen

https://www.boards.ie/discussion/comment/119749474#Comment_119749474

I don't see the moisture transferring across the beads, they're specifically designed to prevent that.

The argument here seems to be that the necessary effect of reducing air movement within the cavity and in/out of the cavity prevents the outer leaf drying in the very specific condition of pressure driven rain ingress.

tbh though I don't see why that can't be solved with appropriate coating solutions or even a rainscreen. The technology exists to apply coatings to steel pipelines underwater, and yet we can't get paint to stick to a wall?

And there are breathable waterproof coating solutions for porous brick and stone walls.

mickdw

https://www.boards.ie/discussion/comment/119749527#Comment_119749527

The theory i suppose is that the resin forms a unit and water does not penetrate but from my experience, it does cause issues of transfer around ties.

Lumen

https://www.boards.ie/discussion/comment/119749573#Comment_119749573

Is that definitely transfer or condensation on the inner leaf due to the tie acting as a cold bridge?

I ask because condensation would not be an issue where external insulation has been applied to complement the cavity fill.

eoinzy2000

https://www.boards.ie/discussion/comment/119749527#Comment_119749527

Exactly. The costs associated with the weatherproof render/ weatherproof seal is off putting too, but people should be made aware of this requirement. The full fill HD insulation designed for cavities mightn't seem so dear then when compared with these additional costs required to weatherproof.

Lumen

https://www.boards.ie/discussion/comment/119749609#Comment_119749609

Are you suggesting that full fill "HD" (EPS?) suffers fewer problems with retained moisture in the outer leaf under exposed conditions, compared with bonded bead?

eoinzy2000

https://www.mdoshea.ie/xtratherm-125mm-fullfill-cavity-wall-insulation-bale

full fill is misnamed!! Eg. 125mm in a 150 cavity, 25mm cavity still there between o/s insulation and inside outer leaf

mickdw

https://www.boards.ie/discussion/comment/119750694#Comment_119750694

That's a disaster if the feedback I've heard is anything to go on. Multiple reports of good blocklayers complaining about spreading cavity as in practice it doesn't sit anywhere near as well the theory would suggest.