MarkyP

the lime screed looks good. What sort of mix did you use and what was your approach to installing it?

I'd be inclined to hold onto the lot but I'm a bit of a tool hoarder and am still up to my eyes in 2nd fix so doing loads of DIY. I would say even if you aren't massively inclined to do DIY you should at least hang onto the basic stuff. Even simple DIY will want a corded drill, a cordless drill and an impact driver. Perhaps a cordless circular or jig saw. Maybe, just maybe an oscillating saw if you have one for that fiddly little cut you'll need to do in 5 years. You will have odd little jobs to do over the years that you'd otherwise put off or never do for want of a tool. It's sunk cost now, and if you really think there's no resale value (I dont know much about titan but could you get at least 30% back on eBay given they must be like new?) then you could either freecycle them or just tuck them away in case the DIY urge comes back, storage permitting. I know some DIY'ers who use cheap brands and find them great value. I guess for self builders, considering whether you might keep the tool or sell on at the end is a factor. Good quality, well cared for gear will be easy to re-sell but professionals will shy away from cheaper stuff. All my cordless gear is Makita and my corded stuff tends to be Bosch blue. Not cheap but I've looked after them and could sell on, but actually I've really enjoyed the DIY and the grand or so I spent on additional tools has saved me tens of thousands in saved labour.

thanks all. I did last night look a bit more closely at spares and yes it seems they aren't as abundant and two local plant servicing companies don't cover bobcat which is perhaps a sign. The tracks aren't cheap, crikey, £600+ per side! With VAT, new tracks, and perhaps a few bushes and pins, and a service it's suddenly not looking so cheap and into the price bracket for a much newer machine. The ground here is good, well drained on a chalk slope so doesn't get churned up too much but am looking at rubber tracked over wheels or metal. Not much woodland, lots of trees around scrub around the boundaries so think a glazed cab will be OK, but not fussed either way. @Vijay how close are you to being done with your machine? Want to sell it?

here's the vid clip of it running

I'm toying with the idea of buying a digger. All the ground work for our main project is done but we have a large plot (about 3.5 acres) which is very overgrown in places, some derelict outbuildings to demolish and loads and loads and loads of landscaping to do (the site was neglected for decades prior to our ownership). I keep thinking that getting the plot into shape would be so much easier with a digger of my own rather than trying to plan work and hire in a driver and machine. We are also planning to build a holiday cabin (subject to planning consent) which will need ground works. We're here for the long haul and so I think that eventually a machine will pay for itself and having it around will allow me to do stuff that I might otherwise never bother with. I did read somewhere someone saying when you have a machine it makes all sorts of jobs so much easier. Just last week when I spent all afternoon digging out the stump of a dead apple tree, would have taken 5 mins with a digger. And the ability to hire attachments like post knockers and flail heads is appealing for my plot. I'd be interested in any thoughts on what to look for. I started looking at a few sub £5k machines but they were really old and tatty and rattled everywhere and I wonder if £10k might be a more sensible budget. It's a lot of cash though and bit worried about buying a lemon. I'm on the look for a 2.5t or 3t machine, I have the space to keep it and think it will be that much more capable than a smaller machine, and I don't have access or transport worries that might make a smaller machine a better compromise for a builder taking it to and from sites. But anything half decent at this operating weight seems to be around around £12k+. Seen a few possibles at £8 - £10k. a cheaper example I'm considering going to view is this one https://www.sjhallplant.com/mini-midi-diggers/id-2001-bobcat-328 it looks clean but I think this dealer has a paint shop so I expect it's had a blow over. They claim it was farm owner, hence the low hours. The tracks look pretty far gone and it rattles a bit in the video. But does play in the pins and bushes really matter for a DIY'er for occasional use? I'm sure privately a similar machine would be much less and via a dealer there is VAT to pay. Obviously not knowing how to operate a machine yet makes it all the harder to go and inspect as well.

I would imagine quality control is a challenge nightmare on these large sites. Agency supplied workers, all sourced at the lowest possible rate and trades here today and gone tomorrow so no continuity or sense of a team. I believe work is typically paid on a volume rather than time basis, so placing emphasis on getting as much done as quickly as possible. I realised as I negotiated various headaches in my traditional blockwork/cavity walled project that trying to do it to a consistent standard at scale would be a nightmare. I think the answer must be to absolutely minimise site work when assembling the superstructure and pivot to a prefabricated timber systems produced in a factory/quality controlled environment and assembled on site.

this story brought back some bad memories. We had a bit of a issue with mortar strength, the blocklayer was very busy and I ended up with a young inexperienced bunch on site without much supervision. I was concerned that they just weren't using enough cement based on fag packet ratios of ton bags and bags of cement. My engineer was on site and pointed out that the mortar looked very sandy, and a few pokes found it very weak in places. He did some calcs based on material consumption and worked out worst case there were patches of mortar at somewhere between 7 and 9 parts sand to each part cement. the situation wasn't helped by very hot weather and them just letting the blockwork bake in the sun (one young lad had no idea that mortar cured by action with water rather than just drying out!). Anyway, we caught the problem early, a few sections were rebuilt, the labourer was given a lesson in counting buckets of sand into the mixer and from then on wet sheets were hung over the blocks to stop the mortar drying too quickly. It was a bloody stressful business and ofcourse the block layer thought it was all nonsense and insistend they were using 5 and 1 throughout, but the bare facts were irrefutable when we showed calculations for material usage, plus the fact you could poke a screwdriver through the mortar in places. The engineer was pragmatic through , didn't insist on it all coming down as it was 1.5 storey so small elevations and was to be rendered so weakness in the joints in terms of weathering was less a concern. Surprisingly the compressive strength of mortar is still very much adequate even at 9 parts sand, I think the issue is the integrity and weather resistance where in facing brickwork, it would simply wash away and fail in freeze/thaw situations. I was very unhappy for a while but our extension is still standing, another one of many hard lessons learnt along the way in my project.

TPOs typically come with a fairly hefty penalty. From memory £20k for interfering with a tree under order. We had a house purchase some years back which was complicated by a TPO. At the last moment the solicitor called me and told me he'd found a TPO on a large cypress in the rear garden. Funny, I thought, there weren't any trees in the garden. Went for a look a found a large stump. Turns out liability is transferable with title, so if we'd bought the house, we'd have assumed liability for absence of said tree should the LA decided to act. We had to shop the sellers in and tell the LA that they'd illegally felled the tree. Luckily the LA decided to let it go and removed the TPO and the purchase went ahead.

as an aside, I find that a can of compressed air is super handy for blowing the drilling dust out of pilot holes for concrete screws and thunderbolts. Saves having to over drill to account for the dust compacting at the bottom of the hole as you drive the fixing home. In fact they are handy for clearing dust and swarf form hard to reach places, I've used a few during my project.

Thunderbolts apply very little or no expansion pressure as driven in, the thread is really very slight, only marginally bigger than the pilot hole. I think they'd be OK even with aerated blocks (though I would pause for thought with those as you only have to look at them a bit funny and they crack which is why I used lightweight aggregate blocks)

If we're talking abut fixing a ledger beam I would go for something beefier than concrete screws. I used M10 thunderbolts to fix a ledger beam to a blockwork wall. It supports floor joists in a stairwell, the thunderbolts work really well, rock solid and easy to use. Pilot hole in both beam and blocks, and then drive them in with a socket. I used washers to stop the head being driven into the beam.

I recall the PVC sheath of electrical cables and EPS should not come into contact, is there any issue with MLCP pipe work contacting EPS? I have a small sub-floor void where my UFH manifold presents and would like to fill it with EPS beads, is there any concern with a reaction between polystyrene and the (I think) polyethylene pipework? I could wrap the pipes in a cloth tape prior but it will be a faff and would rather not bother..

you cant get a sulphur stat?!

ah, I'm not familiar with the Larsen approach, my comment was in relation to insulation boards fixed to wall and rendered over.

there isn't one and typically one isn't required.

they should come and have a look at mine! I think there is a general issue with quality control in large scale schemes where social housing is modernised. I read a surveyor report about issues with EWI seen across multiple installations, it was grim reading but I took some comfort in that the problems were all a result of installation practice and attention to detail, and in some cases product selection. In retrofit you are going to encounter all sorts of potential headaches - meter boxes, flue penetrations, stuff fixed to walls, things abutting or close the walls which would need to be moved or create cold bridges, lack of eaves or verge overhang - the horror surveys show terrible corner cutting in the approach to these. And then more problems in addition with poor installation of the boards, fixings and render finishes. I guess when you win a contract for an EWI scheme for a large number of homes, finding the skilled labour is very hard, impossible even. I wouldn't let this put anyone off EWI of their own home, but research carefully good practice and ensure the contractor is skilled and understands the system and its application.

I've been looking vent-axia sentinel units which seem to offer a good degree of scope for speed control and boost either at the unit via a humidity sensor, from a wired or wireless controller, or via other external triggers such as light switches. I guess what I'm getting at is why have a boost switch at all if unit or duct installed sensors can trigger boost at a programmed threshold for humidity?

I'm planning an MVHR DIY installation in the months ahead, I'm in the process of insulating and flooring the loft conversion at the moment and thinking about what cables I might need to run for controls or switches to the ground floor rooms before the new chipboard floor goes down. It seems the main thing is boost activation when a "wet" room is in use. What is the best approach here? A manual boost switch on the wall? Have boost activated by the light being turned on (in bathrooms)? Or use no switches and instead employ a humidistat in the MVHR unit to trigger boost when humidity reaches a certain level? I like the idea of the latter assuming it would work reliably.

I think you are right, it could well become a sticking point if a buyer or solicitor decided they didn't like the look of it. I think you'd have to use a single supplier for the whole system and convince them you were competent and had installed it properly. I sourced components from various places, installed the insulation myself, and also found my own renderer but my EWI was largely based on Baumit's ETICS system (I sourced my own EPS and some of the beads). I didn't ask if I could have a warranty but expect the answer would have been no. They did give excellent technical support and visited site. with regard to components, read system supplier documentation. There is also an industry body who publish a best practice document with installation details. Most suppliers follow the same approach which has been evolved in mainland Europe for years. I based my EWI on Baumit and largely followed their technical installation guidance. After lots of research I found they offered systems incorporating what is considered best practice in all aspects. For example, recessed rather than surface mounted fixings, and frame seal beads around windows, rather than just rendering up to them. But most systems are basically the same and I don't think installation principles would vary greatly if you compared the main system suppliers. EWI has been covered in enormous depth over the years on the green building forum so without wishing to divert people away from this great resource, there is a wealth of insightful discussion there which is worth a read for anyone seriously considering EWI.

I'm sure it something that a solicitor might pick up on if it's mentioned in the survey or by the buyer. The thing is the warranty itself is largely worthless. I looked at this topic and discussed with system providers. "yes, of course, we provide a manufacturer warranty in case of system failure should you use an approved installer". But the thing is the system never fails, the installation does. I know someone who runs a training centre and covers EWI and knows the industry well. If there is an issue, the system provider will inspect, even drilling cores to assess the build up and will find one of the many issues of installation. Boards with large gaps which were filled with render (can lead to differential drying rates of the render during wet/drying cycles and a grid pattern forming. Other problems such as fixings left too near the surface, inadequate detailing around reveals allowing water ingress, render too thick or too thin, mesh not applied, expansion beads not used as specified, the list goes on. At this point the installer becomes liable, and your redress is via the installer (if they are still in business) So there's a possibility the solicitor would ask for an indemnity to insure the perceived risk should the EWI not be covered by a warranty. You'd possibly have to educate your buyers. My EWI was done to a very good standard, there aren't any problems and nor do I expect any. In fact it addressed two big issues with the house. The first was condensation mould in the corners of some rooms. And the second was wind driven rain on a very exposed south west elevation getting across the narrow cavity and tracking over a lintel to the inner leaf, causing significant damp issues. The EWI has fixed both of these problems by providing a very robust rain proof skin and raising the temp of the internal walls so they never reach dew point. But, yes, I suppose there's a risk buyers may be put off if they don't understand the work and associate it with bad things they have heard about CWI. EWI is subject to building control. Mine was inspected at various stages and signed off.

no, I don't think so. The warranties are completely worthless in any case. I don't have a warranty, my EWI is fine.

I would assume worst case and work on the basis of 9 inch solid walls. graphite EPS is the way to go, better R-value than rockwool. And I agree with @gravelld , rockwool below DPC I think would be a bad idea, not sure I saw any systems which specified it. I reckon it would not like getting damp and would hold water in damp conditions which EPS would not. I remember the wool batts i left out in the rain, went all soggy and took weeks to dry. EPS needed a whack to knock of the water off and wipe and was dry, didn't seem to absorb or hold water to any degree. I think the retrofit standard in EWI work is 90mm or 100mm enhanced EPS to give a BC acceptable u-value of 0.3 over 9 inch solid walls ( you would need thicker wool to achieve the same). But it's relatively cheap to go thicker with the EPS if you can. Where it gets fiddly is at the eaves and gables if the roof doesn't overhang sufficiently to allow the walls to be built out. Also there's a point where the window reveals start to get really deep which might affect visibility and light. I re-roofed so fitted new gable rafters and extended out to allow for the thicker gable walls, and my eaves overhang was already sufficient to allow the EWI.

I don't doubt given enough heat and exposure to fire my EWI would eventually burn. But it's a single storey, the EPS is to the side rather than over any windows, the soffits would be more at risk. By the time my EPS was exposed to enough heat and fire the house would have to be well and truly alight internally. But the video does highlight the risk of very large vertical expanses of EWI or cladding as a major risk factor in the spread of fire. Worth noting the video appears to have been edited, it's rather unclear just how quickly the fire spread. I haven't seen any birds pecking my EWI so far ?

I don't think it would result in a fire. The EPS would perhaps burn locally where exposed but would struggle to burn behind the render and form the necessary "chimney" required for a facade fire to really get going. I think most facade fires are where there's exposed flammable material (e.g. timber cladding) or where there is a cladding with ventilated void over flammable material creating a chimney effect which we know from recent history lethal once it gets going. I sleep very well at night with my rendered EPS EWI, I think there's negligible fire risk over the previous rendered blockwork. The most likely scenario (still very remote) is that the fire would be started inside the house, this would have to burn through a window and through the render and form a chimney. I think by that point the fire service might have put it out, or the rest of the house would be so ablaze that the EPS would make no difference.

You can get mineral wool batt and woodfibre board insulation systems with lime renders over, all marketed for situations where a highly vapour open buildup is required. Not sure the reality of the problems they resolve though and at the same time they are more expensive and less insulating than EPS. And EPS is breathable to a good extent (open cell) in any case. Likewise standard cementitious basecoats.