Brick and Block walls - 9 Mistakes in masonry to avoid
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- Опубліковано 1 чер 2024
- I show the most common brickwork and masonry builders mistakes and shortcuts, along with the standard excuses, ….why they’re easy to avoid yet difficult to fix.
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0:00 intro - mistakes I have made
1:22 mortar droppings (snots) in cavity - cold bridging - brickwork
2:33 PIR insulation - substitute brands - affects U value - Kingspan v Celotex
4:08 No cavity vents in brickwork
4:40 10mm cavity spaces
5:00 No weepholes
5:22 No stop ends to DPC
5:36 Demolitions - using strong boys instead of needles
5:58 Padstones and correct cover - engineering brick
6:20 Eliminating movement - Shims and dry packing
6:55 No Cavity trays in critical junctions - Навчання та стиль
As a bricklayer, I can honestly say, every single point you made is valid and relevant, great video.
As an architect he’s bang on.
Can say as a mason in Canada many of these are absolutely correct. Some of the terminology is different for sure but the principles are the same. I’d venture that most bricklaying apprenticeships discuss the importance of weeping holes very early on in the course as they are fundamental.
I’m also suprisef that anyone would argue about ventilating cavity walls, there HAS to be an air gap, it’s even in the name “CAVITY” wall. Only in very rare instances have I seen or heard of the cavity being filled and in those cases it is for a specific reason making it the exception and not the rule.
Thanks a lot for the feedback. Much appreciated.
really useful video, keep up the good work
I have recently found an increasing number of builders getting the hump whenever you are trying to do these checks especially with regards to insulation and ventilation.
This video provides a lot more confidence to home owners to ensure home owners persist in asking these questions. Thank you.
My understanding of the ventilated cavity requirement is it only applies to timber frame with a brick/block outer skin, not brick and block. Weepholes are required, as you stated, to drain the cavity over obstructions but I am not aware of a requirement for them to be provided for ventilation. Can you confirm otherwise?
Great question. In the UK, it’s only a regulatory requirement for timber frame, to ventilate the cavity. I think that’s because of the breather membrane , not present in masonry inner leafs. There may be other reasons, the risk of rot to the timber at dew points. That doesn’t change the fact that all cavities should always be ventilated, including all masonry. The aim is to dissipate residual moisture at its source, not allow it to make its way down to the nearest weep hole on the inside of outer leaf. We’ve just demolished a masonry wall gable for a customer, it had no windows in, so the only weep holes were along the base of the 2 storey wall. The cavity was sodden. The insulation bats were done for, they had been wet for so long. The inside face of the wall was cold. The question you should be asking here is….why are all cavity walls not required to ventilated as a matter of course…why would you not do it? And yet…some seem resistant to it. Why??? Thanks a lot for the comment.
Thanks 🙏
Any alternatives to a cavity wall?
Yh, a solid wall insulated either inside or outside
with regards to the bridging in a cavity wall, I've seen builders using insulation which touches both inner and outer wall - i think it's called rockwool. does this not bridge outer and inner wall?
No
@@azza1793not so sure I’ve taken bricks out because of damp issues and often find blocked cavities bridging over the dpc but also find very often soaking wet insulation in cavities , I’m all for insulating cavities with kingsman/ cellotex fixed to the inside skin using 75 or even 100 mm thick but for gods sake leave a cavity after between that
If not please tell me why not
Insulation has a significantly lower thermal conductivity value than air, so while anything that conducts heat is a bridge (insulators are just very very bad at conducting), air is more conductive and therefore a worse bridge than insulation
@@Seqhael but presumably air doesn't allow water to cross from the outer leaf to the inner leaf? but this insulation must do that as it's stuffed in touching both inner and outer wall. I thought this was the reason they now say not to spray foam in the cavity.
@@samirpersonal5499It’s not just any insulation. It has to be full fill cavity batts insulation. So it’s designed specifically for this application.
So if cavity is meant to be vented why is full fill insulation recommended on some jobs?
I explained that in the video. And I’ve never known it to be “recommended” by anyone. It’s used as a last resort where a cavity cannot be used or incorporated, perhaps due to space .
7.02 I agree should happen but you stated thermal, a damptray won't stop thermal bridge
I’m not looking at the timestamp so don’t know specifically wish you’re referring to, but we use composite insulated DPCs, which definitely do help with cold bridging. I’ll add in additional bats on the dry side where I see it necessary .
@@build-better-things retro fitting damptrays. you use an insulated dpc for this? That product I have never seen please share
just started watching, am almost 2 minutes in and as much as I appreciate what your trying to do I feel scare mongering is what will happen. First off with PIR its water proof and by nature has to fitted before both skins are built ( its a bricklayers nightmare) IE any snots will not effect the internal skin. I bet I have more to say
PIR is definitely not waterproof. Snots affect the inner skin and the PIR by bridging the cavity. Scaremongering??? What?????
Aren't building regs meant to check for these types of issues?
Not sure exactly which points you’re referring to, but, a lot of these things can’t be checked as they are immediately covered up. But regardless, it’s a common misconception to believe that the council’s building officers carry out any form of quality control. All they’re doing is checking for compliance. You should be factoring in your own form of supervision and quality control for your builds.
@@build-better-things I've experienced builders rushing to cover walls up with plasterboard only to discover lots of air behind a "wall" that I needed to hang a kitchen unit to. I think its best just to let them do the roof carpentry and masonry bits for a shell which you can see and nothing else. Let other trades do the boarding and floors.
P.S. I would not let a general builder do skylights, let proper roofers do it.
@@build-better-things I recently saw a video from a popular building channel where they were using stormdry on the brickwork over the extension roof abutment instead of providing a cavity tray, and this was suggested to them by the Building Control Officer!
As a building surveyor, I totally agree with you, a cavity tray is vital for long term protection of the building.
No, building inspector only checks at a set number of points during the build such as foundations then once you reach wall plate height. They are not there to inspect the entirety of your construction
@@azza1793 It seems the only choice we have is to learn how this is meant to be done ourselves because we can't trust the people who present themselves as experts to do it. I know of great builders but they are nearly always unavailable or too expensive so we're left with the ones that can do a terrible job, or something passable if you're lucky. I found myself having to explain the current building regs for wall to roof joint insulation continuity. I'm a software guy I really don't want to know this stuff. Its the wild west out there and I have to learn and enforce these requirements to protect myself. I've had to just accept incomplete work that I will complete myself later just to get a shell started.
Rome wasn't built in a day, took two days.
lets look at your detail at 5.09. you show a damp tray over a lintel. No insulation causing a cold spot!
You’ve left a number of weird gotcha comments so far about the video, some of which I’ve responded to. This one is so naive that I’ll leave you to enjoy your time.
surely you can substitute different PIR boards but NOT substitute PIR for Phenolic insulation (e.g. K108). K108 is twice the price of PIR so can see why builders would substitute.
Yes exactly, assuming each PIR has the same lamda value. The point I was trying to make was that you wouldn’t know to look out for that v PIR, they look very similar. I’ve spotted it a few times recently since the new requirement to achieve a 0.18 u-value, at the same time to avoid super thick walls. One of the ways is to use Kooltherm, unless you go for a 10mm cavity, which I don’t recommend. So the temptation is now there for builders to substitute, if they think they can get away with it because it’s a more expensive product. (but you get lots of value from the extra expense). The point of the vid is to flag the issue. If I didn’t make that clear, apologies.
@@build-better-things having just self built a house (literally), I’m acutely aware of the difference and the cost! was just trying to clarify the difference. I used 75mm K108 and 50mm clear cavity. I don’t like full cavity insulation of any type.
I hope the self build was worth it. Thanks for your comments
@@build-better-things scratched an itch, but wouldn’t do it again!
Where have you got this idea about vented cavity?
That’s like saying…where have you got this idea about putting a roof on your walls?
@@build-better-things
Idiot
stop ends? where else is the water going? down the inside of the outer skin as it is every where else in this building.
No, that’s lazy and poor workmanship . You want the moisture dissipation to be controlled. You want it to be going out the weep holes, not travelling down the cavity. It’s not always possible, but that’s the goal.
As well-intentioned as this video was intended, it was painful to watch/listen to some of the items.
The brand doesn't matter for insulation, the technology does: Kingspan phenolic boards are "better" than PIR (0.018 vs 0.022 u-values respectively). If the design says Kingspan PIR, you can use any PIR brand as I have seen all of the ones readily available have the same stated characteristics.
The rest, very difficult to assess for a end user to be honest and even good builders would walk waalk off if questioned every step of the way.
Also steel does not always need to be on padstones, depends in the calculations (bigger spans and bigger steels with more stories on top will.most likely have padstones) but a single storey extension with a 4m steel might just have a dense block either side or some engineering bricks. If there are supposed to ve padstones they will 100% be in your engineers drawings and on the steel beam's calculations.
You suggest that “good builders should walk off if questioned“. That made me laugh out loud, it’s so silly, and it’s obvious you’ve never put at risk your own cash to build anything substantial with contractors. To your other comments, leaving aside your pedantic and condescending tone, the aim of the video is to warn homeowners of common shortcuts and errors to look out for. For example, substituting lower lamda boards because they’re cheaper. Are you suggesting these 9 points are not things to look out for…?
You are right, good luck questioning any builder at every step and although it’s the customer’s money and their right to question things etc it will not stand with a builder if you are looking over their shoulder every 5mins questioning their work. Also try telling a builder to remove how ever many course of bricks due to snots being inside the cavity 🤣🤣🤣 i’m not disagreeing with the poster but after 30 yrs working as a carpenter/building surveyor i know this will not stand and you will be told go away in not such a pleasant manner. Looking at his response response to your comment comment it’s clear that he has have never worked a day in his life on a building site and his view is purely that of the home owner spending their money which is not wrong but in REALITY no building will stand being questioned like this