Iceverge Posted February 28 Posted February 28 11 minutes ago, lizzieuk1 said: The last build we did we used 90mm kingspan (think porsche boxster in your walls just to pay for the tape!) as tighter site needed to avoid large cavity, along with lightweight 100mm blocks we achieved good u values Kingspan rep gets a nice holiday once more. 😵💫 Those boards are £62/m2 plus waste plus fitting for a U value of 0.018. Rigid boards in walls are a rubbish plan. Mineral wool batts or EPS beads every time. 6 times cheaper and twice as good. A 200mm cavity with full fill mineral wool batts for the same U value is £11/m² and almost zero waste. No thermal looping unlike those stupid boards too. Lightweight blocks are a con too. Add almost zero to the insulation value and are far harder to fix and plaster to and cost 3 times as much as normal blocks. Fair enough with ICF, if your mind is set. Why woodcrete and not EPS?
lizzieuk1 Posted February 28 Author Posted February 28 20 minutes ago, Iceverge said: Kingspan rep gets a nice holiday once more. 😵💫 Those boards are £62/m2 plus waste plus fitting for a U value of 0.018. Rigid boards in walls are a rubbish plan. Mineral wool batts or EPS beads every time. 6 times cheaper and twice as good. A 200mm cavity with full fill mineral wool batts for the same U value is £11/m² and almost zero waste. No thermal looping unlike those stupid boards too. Lightweight blocks are a con too. Add almost zero to the insulation value and are far harder to fix and plaster to and cost 3 times as much as normal blocks. Fair enough with ICF, if your mind is set. Why woodcrete and not EPS? Indeed, lesson learnt! You don't know what you don't know eh! Woodcrete really because, amongst other things, we don't want lots of eps on the internal walls. This is our forever home and, we feel, trying to fix anything to the walls going forward will be a right pain. Our old house had battened out plasterboard walls and was near impossible to drill through to get anything like solid fixings in. Yes, we can fix ply for kitchens etc, that's fine on day 1 but on say day 500, we may want to fix other things and will have no ply in place and no idea where the ties are to fix to! We also like it has no need for props and, iyswim, the blocks feel like blocks.
Iceverge Posted February 28 Posted February 28 15 minutes ago, lizzieuk1 said: Our old house had battened out plasterboard walls and was near impossible to drill through to get anything like solid fixings in. Lightweight blocks are pants for fixings. Are you not facing the same issue with having to batten out and plasterboard as per @Nickfromwales difficulty in chasing woodcrete above. Out of interest what did @JohnMoand @ToughButterCup do for services? Chasing or a service cavity?
JohnMo Posted February 28 Posted February 28 9 minutes ago, Iceverge said: service cavity? OSB foam glued to parge coat.used to attach pipes and the top channel for all wiring. 50mm battens used on walls and ceiling. 2
lizzieuk1 Posted February 28 Author Posted February 28 51 minutes ago, Iceverge said: Lightweight blocks are pants for fixings. Yes indeed, but, our old house wasn't the new build we did with the lightweight blocks (that was a 2 house 'project' which was sold on). The old house was a 1980s build so solid block rather than lightweight, still a nightmare to fix to with the big void to span. 54 minutes ago, Iceverge said: Are you not facing the same issue with having to batten out and plasterboard as per @Nickfromwales difficulty in chasing woodcrete above. Realising that we may the same issue! But, hoping there may be a way around it, dot n dab could work but obv still issue with services. I think we need to get some blocks and 'have a go' at surface chasing 😬
Iceverge Posted February 28 Posted February 28 I assume with EPS ICF it's just a hot knife for services and then plasterboard straight to the EPS? How do you stick the plasterboard? Is it screw to the ICF webs or glue it on? How do you fix to it? Is it a matter of drilling through to the concrete core? @Jenki @Nickfromwales @FM2015 or any other ICF aficionados. 2 hours ago, lizzieuk1 said: think we need to get some blocks and 'have a go' at surface chasing 😬 Yes please do. Live experiments are always appreciated.
Nickfromwales Posted February 28 Posted February 28 3 hours ago, lizzieuk1 said: I think we need to get some blocks and 'have a go' at surface chasing 😬 Remember to fill it with concrete first, and let it cure, or you'll just smash straight through the woodcrete. 45 minutes ago, Iceverge said: Yes please do. Live experiments are always appreciated. .....*Shiver goes down spine..... 46 minutes ago, Iceverge said: I assume with EPS ICF it's just a hot knife for services and then plasterboard straight to the EPS? How do you stick the plasterboard? Is it screw to the ICF webs or glue it on? How do you fix to it? Is it a matter of drilling through to the concrete core? @Jenki @Nickfromwales @FM2015 or any other ICF aficionados. Depends on the EPS block type / manufacturer. Nudura for eg have thick plastic / nylon(?) bands running vertically every 405mm (imperial, damn Canadians!) set a few mm into the face of the block for fixings.
Nickfromwales Posted February 28 Posted February 28 5 hours ago, lizzieuk1 said: Hubby thinks he may just parge externally as well as we build up, we'll see how that pans out! Waste of time and money. Focus all efforts on the interior surface plz!! 1
lizzieuk1 Posted February 28 Author Posted February 28 1 hour ago, Nickfromwales said: Shiver goes down spine 🤣 that made me chuckle! OH is pretty good with the old power tools, should be a fun experiment! 1 hour ago, Nickfromwales said: Waste of time and money. Focus all efforts on the interior surface plz!! I guess the only positive could be to even out the surface for brick slips 🤔 though we may put an external insulated slip board on, in which case, as you say, likely pointless
Nickfromwales Posted March 1 Posted March 1 12 hours ago, lizzieuk1 said: 🤣 that made me chuckle! OH is pretty good with the old power tools, should be a fun experiment! I guess the only positive could be to even out the surface for brick slips 🤔 though we may put an external insulated slip board on, in which case, as you say, likely pointless Clients who used Velox had a builder and they ended up rendering with a particular cementitious product before installing cement boards and then brick slips. Took at least 2 coats of that product to get anywhere near good enough to put the boards on, and they’d tried and failed at going straight onto the product with the slips, hence the introduction of a 9mm board. IIRC the boards were dabbed on with that product, which was much like a tile adhesive, and it took a LOT of time and a LOT of money to do. Ironically they chose a very distressed brick and it ended up looking hugely non uniform anyways 🤷♂️. If you think you’ll brick slip onto woodcrete think again, so probably a very good idea to fit an insulated tile backer board and slip to that. Just remember it’ll need to have been installed in a way that doesn’t allow airflow behind the boards, or that will cause huge issues with airflow and moisture ingress into that void. It’ll also completely negate the benefit of the insulation effect from the boards; the air gaps would actually make the wall far worse overall. Also, you’ll need to work out the fixing schedule and kg/m2 mechanical load capacity, so the boards don’t just break off the wall with the weight of the slips, adhesive, and pointing mortar. Likely you’ll need to dot n dab these to get flat and plumb, and then when the dabs are dry you drill through and fix at those points. The way I do that is to pre-drill the boards with a 4mm drill bit on the face, then apply the dabs on the reverse to line up with each drill hole (manufacturers will give guidelines for the frequency / distance apart for placement of fixings) and then you know when you screw back through you’re on a dab. Yes, it’s a total PITA. “Enjoy!”. Q: How much of the external facades will be boarded and brick slipped? It may be better to move the airtight layer to the external skin at this point, worth exploring as you could maybe kill a few birds with one stone. Anyone here know of a reason this wouldn’t be possible, assuming the woodcrete was left raw / exposed on the interior and moisture (any) could travel inwards? Would require some quality detailing at the head / foot / openings, but doable perhaps, and could save time and money. Just a lot of work vs EPS……not for me, not after being on these types of builds. Does the manufacturer state a max permissible (dimensional) tolerance for the finished / delivered block?
lizzieuk1 Posted March 1 Author Posted March 1 14 minutes ago, Nickfromwales said: How much of the external facades will be boarded and brick slipped? All of them!
Nickfromwales Posted March 1 Posted March 1 5 minutes ago, lizzieuk1 said: All of them! Ok, then maybe time to ask the collective here if it’s possible to migrate the airtight layer to the exterior and save some time & dosh. ”People, Activate!”. There. I have awoken the gods, now we just sit back and watch the magic happen. Or I get another stupid idea shot to shit. 1
Iceverge Posted March 1 Posted March 1 The wonderful world of bricks is something I know nothing about but am I missing something: Bricks price onlines = 64p Brick slips = £1. Why would this not be a much cheaper and more durable option?
lizzieuk1 Posted March 1 Author Posted March 1 3 minutes ago, Iceverge said: Why would this not be a much cheaper and more durable option? Could be an option, not what we'd originally intended as obv adds another separate layer to the wall construction. We were also hoping to install the slips ourselves but not sure we'd be up for building a whole brick skin.
lizzieuk1 Posted March 1 Author Posted March 1 29 minutes ago, Nickfromwales said: If you think you’ll brick slip onto woodcrete think again, so probably a very good idea to fit an insulated tile backer board and slip to that. Just remember it’ll need to have been installed in a way that doesn’t allow airflow behind the boards, or that will cause huge issues with airflow and moisture ingress into that void. It’ll also completely negate the benefit of the insulation effect from the boards; the air gaps would actually make the wall far worse overall. I'm wondering if we just fix a slip board without insulation whether we could then level them out as we installed. Not sure if moisture behind those would create an issue 🤔 if there are drain holes or something at the bottom. If not maybe we make sure we seal all round them.
Nickfromwales Posted March 1 Posted March 1 10 minutes ago, Iceverge said: The wonderful world of bricks is something I know nothing about but am I missing something: Bricks price onlines = 64p Brick slips = £1. Why would this not be a much cheaper and more durable option? You’d need to extend the entire foundation?! 9 minutes ago, lizzieuk1 said: Could be an option, not what we'd originally intended as obv adds another separate layer to the wall construction. We were also hoping to install the slips ourselves but not sure we'd be up for building a whole brick skin. Brick slips attach to the structure. It would be a lot more money to increase the footprint of the foundation for that option and the walls would be enormously thick (380mm block + cavity + bricks)? Your window sills would be resting on next doors dining table.
JohnMo Posted March 1 Posted March 1 (edited) Sorry you are all over thinking this. Durisol blocks have a slight taper to allow them to be removed from moulds. But it is slight. The wall when complete will be vertical and straight. Apply flexible external tile adhesive and just apply slips. We did stone slips with zero issues direct to block. By the time you have completed it the wall will be mostly airtight. The issue is the DPC area, but this acts as a drain should any moisture het behind the slips. Forgot to mention the securing tabs on the slips, I use copper nail but can also be screwed directly to blocks Edited March 1 by JohnMo
Nickfromwales Posted March 1 Posted March 1 6 minutes ago, lizzieuk1 said: I'm wondering if we just fix a slip board without insulation whether we could then level them out as we installed. Not sure if moisture behind those would create an issue 🤔 if there are drain holes or something at the bottom. If not maybe we make sure we seal all round them. Ah……”no”. Those is what the aforementioned builders attempted to do, and they were very good guys; methodical and meticulous in their workmanship but also good at solving issues pragmatically (albeit issues unidentified by the pathetic architect and then left to the builder to resolve, and the client to then have to pay huge amounts to overcome, and repeat) and they gave up and switched to ‘dubbing’ the walls and levelling with 8’ 10 and 12’ straight edges, prior to then installing the backer boards. I’d not seen the slip boards before, but I assume they need a constant and regular structure to fix against do the brick slips don’t all ‘kick’; eg I doubt you can dab / level these “as we go”. The beauty of coming on Buildhub at this stage is to get yourself in check, so happy days. Forewarned is forearmed, and so on 1
Iceverge Posted March 1 Posted March 1 Just now, Nickfromwales said: Ok, then maybe time to ask the collective here if it’s possible to migrate the airtight layer to the exterior and save some time & dosh. ”People, Activate!”. There. I have awoken the gods, now we just sit back and watch the magic happen. Or I get another stupid idea shot to shit. Of course you could. The diffusion scaremongers will along shortly to theorise us to death about how structures need to "breath" outwards no doubt . This completely forgets thehuge relative disparity in magnitudes of diffusion driven moisture and moisture carried by air leaks. It's often hundreds of times more. It's like worrying about a drip in the ceiling of your pleasure yacht when there's a hole in the hull as big as a my boot. An immaculate Airtightness layer can go anywhere in the wall and it'll work fine The OPs plans are quite straightforward though. No silly unbuildable details. An external AT layer without a rain screen cavity is asking a lot around penetrations though. Your sealing will be doing the job of weather tightness and Airtightness and will submitted to drying and wetting, high and low temps. If I was to do an external a/t layer I would at least have it behind a rain screen, preferably some insulation too to keep it dry and temperature stable. 1 1
Nickfromwales Posted March 1 Posted March 1 4 minutes ago, JohnMo said: Sorry you are all over thinking this. Durisol blocks have a slight taper to allow them to be removed from moulds. But it is slight. The wall when complete will be vertical and straight. Apply flexible external tile adhesive and just apply slips. We did stone slips with zero issues direct to block. By the time you have completed it the wall will be mostly airtight. The issue is the DPC area, but this acts as a drain should any moisture het behind the slips. Good to hear yours was that level to just ‘tile’ straight to it with the slips. The Isotex and Velox builds defo didn’t allow for this, nowhere near. I guess this is a warning to remain vigilant at the time it matters most, as some may just steam through the construction and not realise how impactful even a 10mm undulation will be downstream.
JohnMo Posted March 1 Posted March 1 @lizzieuk1 I would do the maths on additional external insulation is it worth the expense and head ache? Moving from 0.14 to 0.12? 1
JohnMo Posted March 1 Posted March 1 Photo for clarity on what an unfinished wall looks like. This internal but exterior the same 1
JohnMo Posted March 1 Posted March 1 Just found the long external wall - about 15m long and 2.5m tall. 1 1
lizzieuk1 Posted March 1 Author Posted March 1 21 minutes ago, Nickfromwales said: Your window sills would be resting on next doors dining table. Gosh I'd hope not, they're 1/4 mile away 🤣 1
lizzieuk1 Posted March 1 Author Posted March 1 19 minutes ago, JohnMo said: Sorry you are all over thinking this. Durisol blocks have a slight taper to allow them to be removed from moulds. But it is slight. The wall when complete will be vertical and straight. Apply flexible external tile adhesive and just apply slips. We did stone slips with zero issues direct to block. By the time you have completed it the wall will be mostly airtight. The issue is the DPC area, but this acts as a drain should any moisture het behind the slips. Forgot to mention the securing tabs on the slips, I use copper nail but can also be screwed directly to blocks Thanks JohnMo, that makes me feel far better! This is what we're hoping to achieve so really glad you have successfully done the same.
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