Alan Ambrose

We had an estimation module in engineering school that asked us to do critical calcs in our head and come out with approximate answers. This allowed a very valuable sanity check on the fancier version of the calcs using accurate numbers. If the results differed by more than, say +- 50% you had a big problem. So, saying that, I just had some augur piling done. There's generally a fixed cost for design / mobilisation (i.e. getting off our arses) / testing etc and a variable cost per pile or metre, but sometimes the sales person might trade one against the other for window dressing. I was quoted £1.29K per pile / £92 per metre for 350mm diameter 14m piles and only a couple of £K for design etc. I was also responsible for the muckaway. Let me guess that you'll have 20 off 8m piles (who knows without seeing your soil investigation or knowing how heavy your house is going to be). That's £15K plus some fixed costs and the muckaway, say £20K. I'll guess that the ring beam will cost about the same as simple strip founds. So plus £20K for pile support. Sure, maybe you'll need 12m piles or longer and the cost will scale roughly linearly - nobody knows because you have not provided any info besides 'soft clay'. I bet a couple of local piling companies will be interested enough to give you a ballpark. To get an accurate quote number you need: A soil investigation with load bearing numbers and a sense of groundwater height. SE calcs of your house loads and a rough slab/founds design. The piling co will then do a pile design with a 3x safety factor and give you a reasonably firm quote. On consistent soft clay you shouldn't find anything too unexpected unless you suspect mine workings, archaeology, underground lake etc. A local BCO might give you an opinion on that too. This is what the interesting page(s) of the SI look(s) like. The N=xx result is what you're after and gives you an indication of the load bearing capacity. The SI may even give you a feel for what reasonable piling might look like, but the piling company will want to refine that calc.

@markc - Thanks, do you have any thoughts / recommendations re good fillers? Are there any goodonea that work in stopping driven rain / critters but allow OK ventilation?

@LaChab would you mind expanding a bit as that’s all v interesting. What is an umbrella guy? Who did you use for instance? Was it hard to find an ‘MCS guy’ who was happy to do just commissioning? Did they do the final plumbing and electrical stuff or just switch it on, test & verify?

For a set task by any trade, I am increasingly asking myself ‘what can go wrong here’ and ‘what is most important to get right’. It’s amazing how you can often predict what the f. ups will be in advance. Then make sure you’re around for that part and be firm and unapologetic. A good trade will like that you’re double checking. Listen to all the ‘we normally do it this way’ lines, decide whether you agree and, if not, explain politely why you want it done.a different way. Check in with your trades a lot at first, then less as you trust them.

>>> I can't think of any way to measure this accurately myself Err, a cheap rotating laser maybe? >>> I'm guessing this sort of thing is non-negotiable? Maybe not, get the person from the water company on site - the guys on the ground are often more realistic that the ‘rules’ say.

Isn’t it great when you’re surprised on the upside with someone’s work? Out of maybe 5 external contractors I’ve used, excluding trades, 1 has been great, 1 has been OK, and 3 have been varying levels of bollocks.

>>> How complex is the roof? Very simple, house is a rectangle with dual pitch roof. It does have some veluxes and an SVP and a coupla vents coming through it.

p.s. are any of the supplier's panels better quality or are they much of a muchness?

I know this is not a common roof treatment here on 't 'ub, but we're planning to do one of these roofs shortly. I've watched a bunch of YouTube videos (of course) and am finding a bit of variation. Most are US or Australian videos so maybe part of that is due to the local weather. I've these questions: + I'm seeing eaves overhang from 25 up to 75mm. I'm thinking 50mm for our site, but am interested in anyone else's experience. + I'm seeing some quite complex examples of folded ends to the flashings - presumably for water resistance and aesthetics. Seems to me a trade off between how well you can do the hand folding (most don't do a great job) and just having cut edges. Anyone do this? + I'm seeing some use of foam closures at the eaves & ridge but not universally. Seems to me a trade-off between water resistance & ventilation. Any thoughts? + I'm seeing some use of 'Z-flashings' - sometimes under the ridge flashing instead of foam strips, sometimes along the eaves. Can't really see the benefit? On a quote I got from Cladco they added Z flashings ... but then they also added gloves, a measuring tape and a kitchen sink ... OK maybe not the last one.

I wonder whether you can grind and then fill the grinding marks. Car body filler comes to mind, although it’s a long time since I used that

Thanks for that. BTW your install looks v neat.

Not sure that Mike's example leaps off the page, but it's a lot better than zilch. I'm planning on labelling the end of the cables with a shrink wrap labeller, which should help a lot - ever found a misc T&E and wondered where it ends up?.

I'm wondering whether modulating the speed down, if that's possible, will make it quieter?

@Beelbeebub - I know this is a while ago, but I'm planning something similar, but portrait-style. Can I ask - did you use long rails, and if so which ones? The go to, Renusol, seems to advocate their short rails for profile roof.

If were me, I might replace any v dodgy wood like for like and maybe consider a coat of Bedec barn paint. Maybe I’m biased as we’re just about to clad our place with oak featheredge. What’s your overall objective - aesthetics? Better insulation? Reduced maintenance?

I don’t think there’s that much difference. About the same U-value, both have basic fire retardant. Mostly installed by the same crews with the same equipment. We went wood fibre, from memory slightly more expensive. Mainly because ‘wood’ rather than ‘paper’ - the wood fibre resembles the stuff that mdf is made of. The installation for both needs to be done well. I’ll write up our unfortunate experience and some recommendations when I get some time.

@-rick- you couldn't achieve the same with MVHR or wouldn't it have enough throughput?

I remember working in a very air-condition building in Bahrain. I used to open the windows to warm the place up. Luckily we could. Sometimes, I think, you just want to control the temperature rather than living in a isolated machine-controlled cocoon. Maybe you're cooking Xmas dinner for the family and want to stop it getting too stifling. Yeah open the windows but you would like to stop heating the place too.

Is there an advantage to putting an intermediate thin-ish insulation layer under UFH screed in a PH-style house? We have 300mm XPS with a 150mm slab on top and we plan to have 100m screed with UFH. But I’m wondering whether, say, a 30mm insulation layer and then 70mm screed would provide a shorter time constant for more rapid heating & cooling. I know some peeps subscribe to always heating to 20/21 degrees and cooling to 25 degrees 24/365 using the slab as a big heat reservoir. But that assumes you never want to change the temperature any, and if ever you do, then it’s going to take days i.e. a v long time-constant.

re: Cascamite Fairly obvious when you think about it, but proper structural glues have proper datasheets with glue strength under tension, shear etc. All the consumer glues just say 'super-strong' or some other unquantified nonsense. Having said all that, I can't see strength numbers for Cascamite. Strict prep, thickness, temperatures, application methods etc if you want to get the manufacturer's results. Worth bearing in mind that a lot of reactions are exponential with temperature and you can cheat the weather a bit by maybe using a fridge or a bucket of hot water. Also watch for peel strength when handling - may be not so strong even if the shear strength looks good in situ. Fill your boots

Thanks John

Err, CVC was what Nick recommended. @JohnMo interesting on your use of co2 monitor, I expect I'll need to do similar. Is it possible to post your link again for the eBay sensor - it just gives me 'error page'. BTW CVC quoted an extra £190 for the humidity sensor, which makes the total about £680 more than the Zehnder unit. I'd love to see what's in the sensor - I bet there's less than £10 of parts there. I've got the unfortunately named SHT35 humidity sensor in other parts of the build - the chip is about £6.

Curious - I can't think why it's ok for hot feeds but not for recirculating.

Ah interesting, I hadn't clocked the bit about the humidity sensor - a bit dumb that it wouldn't have. BTW cheapest places I could find were TradeSparky for the Zehnder and CVC for the Brink. This thing? https://www.ventilationland.co.uk/en_GB/p/brink-excellent-rv-humidity-sensor/5791/ Seems expensive. I was planning boost in the bathrooms and kitchen and maybe a co2 sensor in our bedroom as I think my other half is very sensitive to this - she wants the bedroom window open all year round - even in minus degrees.

Congrats, looks v tidy. >>> My understanding is that a female port (where a rubber seal and seat for that seal is absent) requires the mating male to be tapered thread (BSPT) and wrapped with thread sealer to make the joint I don't think that's right. My understanding is not to mix parallel and tapered unless you need a temporary bodge. I think most threads used in residential are parallel. Both parallel and tapered will need good thread sealer and I've used some cheap parts in the past that needed a bunch of thread sealer to work. That's all consistent with the instructions you quoted which said, in effect, 'don't use tapered parts here'.