MortarThePoint

It doesn't drain well and I think the bottom of the trenches will be within the water table so it will be flooded one way or the other

That's comforting to hear. I'm just not really aware of what could go wrong as people normally don't have a delay at this point.

They are very open to discussion so I we will be talking things through. I expect from their side they will want to carry on and may not be able to weigh up the risks dispassionately as it's their livelihood. I need to find out how long it will take them to dig the trenches, but they are not going to be able to do the full dig and pour on the same day so there is a real risk that the government announces some form of shutdown that affects concrete deliveries an leaves us with an unstable hole to fill.

Good question. It's a fixed price job but they are a small independent company and this sort of situation hasn't arisen before so it's anyone's guess really. I have to assume that it would be my risk in the end.

I'd like to acknowledge that there are people with bigger issues, but hoped I could ask people's advice. The groundworkers are onsite as planned and progressing with prelims prior to digging foundations. I am worried that they may get in to the dig and it turns out that, due to Coronavirus restrictions, either they have to stop or their supply base stops. It strikes me as a disaster if the trenches are dug (1.5m to 1.75m depth with claymaster) and then can't be filled for a number of months. I'd really appreciate your thoughts. Should I call a halt to things now as the situation is changing rapidly and one day everything may be possible and the next nothing possible.

+1 for ProDave's response There are lots of factors to consider including nearby trees, future planting requirements, volume change potential of bearing strata and so on. Clay can be complicated by the fact that it can swell (heave) or contract (subside) depending on water levels and how thirsty nearby trees are (or were if cut down). I'm not trying to scare you, but I personally left that side of things to the pros with their experience and insurance.

Sounds sensible bissoejosh. Did you have to have verification testing done afterwards etc. I'm planning to use a specialist installer for the membrane work as then any issues with subsequent testing will be on their head rather than mine. I'd like to be an informed customer though rather than going at it without a clue, hence the thread.

It may be unusual, but we have designed a precast concrete product in for our ground floor. A bit more expensive than beam & block, but It has the following key benefits: has insulation already attached to its underside can be installed by manufacturer in a day and then ready for next stages puts the concrete of the floor inside the insulated envelope increasing the insulated thermal mass Due to some Made Ground on site and not wanting the vagaries of Ground Gas well testing, we decided to incorporate a gas membrane into the design which replaces the DPM. This gas membrane will be installed above the concrete floor and then ultimately have screed over the top. There is the option to do perimeter first and then infill, but cheaper to do all as one. What I am wondering is how I leave all this for the subsequent year or so as the rest of building works goes on. Options that spring to mind are: Just do perimeter and leave concrete slabs exposed (probably grouted), infill later Do full gas membrane and cover with full depth of screed (minimum 75mm) including underfloor heating pipes Do full gas membrane and partial cover with screed (? e.g. 30mm ?) to protect the gas membrane I expect people who have used Beam & Block and a gas membrane have faced the same quandary, so it would be great to get some pointers.

All sounds like fair game for studding on the log burner. I'll look out for screws and nails. There's a 20t machine here with selector grab which has loaded one wood skip with wood from an old barn I wouldn't want to burn already. I'm paying a flat rate for the 40yd bin and suspect I over estimated the weight it will be when full.

If I were you I would ask by email rather than over the phone. The emailed response is handy to file away.

Would you have any reservations (treatment?) on an open fireplace as a friend has one and I could offer him some?

It's what I figured. May take me a while to separate it from the OSB etc, but should keep me warm.

I have already made a 'shed' out of ply and studding ? Overflow can go raised off the ground under a tarp.

I've told the guys doing the demolition that I'd like to keep the timber from a barn which consists of studding, plywood and cladding. Plywood is always useful and they are soft stripping that so easy decision. The cladding is a bore and will get burnt (modern so I presume no nasty treatments). I think there may be OSB between the cladding and studding which will get trashed by the Selector grab and so useless. I was thinking I could keep the studding to burn on the log burner. Is this a folly, or can someone say they've burnt such on their log burner and it's a good idea? I'm wondering about a 40 yd RoRo for wood to take the studding, OSB and cladding as it could save a lot of hassle and keep the place tidier. It's difficult to know how much the skip will pack and so what weight to expect in a 40yd bin. Any thoughts?

Pretty small trees. NHBC considers the zone of influence for high water demand trees to be 1.25 times mature height so you can be surprised how far away tress can have an affect. Makes sense, I wouldn't either. The NHBC guidelines will be cautious and you're not building multiple storey habitable space.

PLOP may be a better option than GRUB: https://www.plop.at/en/bootmanagers.html A video that talks about it:

Are you installing ubuntu on a HDD in the laptop then? If booting from an HDD is an option then it's the way to go.

A left field thought could be to have a CD or DVD with GRUB on it that then supports (i.e. set to default to) USB boot. That way you can install the OS on a cheap writable USB FLASH drive. You can get some nice low profile USB sticks (64GB SanDisk Ultra Fit £8) that mean it's almost unnoticeable.

Actually, I just checked an old quote and I'm wrong. The plant insurance is owned or hired in. I would still guess it to be an expensive way to go to cover plant only though, but if you expect to get underway quickly it could well make sense.

I haven't looked at this side of things for a while, but I think most site insurance policies cover hired in plant but have a pretty small allowance for your own tools and therefore plant too. The site insurance policies are also very expensive as they cover some greater risks that probably make it a more expensive way to go.

You could build an insulated envelope inside the steel frame using cold store panels. Just a thought.

You have a double whammy as the geology is likely high volume change potential (VCP) and the trees removed are high water demand so that will maximise any resulting heave. How high were the Leylandi? If over 9m or 10m (I think) then they would be classed as mature and their full height (>=18m) would be used for any foundation calculations. What are the different strata? Don't forget to consider other nearby trees. NHBC have a foundations mobile app but I don't know if it covers raft. Chapter 4.2 of their guidelines has useful information (NHBC 2020 Chapter 4.2). I have some experience in this area as we are to build a large(ish) garage with high VCP geology (alluvium over gault clay). We can't bear on the alluvium so need to do bulk soil replacement down to 1.25m with MOT Type 1. Thankfully we should be yielding some concrete from demolition. There are some sizable trees and ex-trees near by so a raft was the best bet. Thankfully this isn't the case for the house, but the trench foundations need to be pretty deep there. I'd expect the dimensions of your workshop are consistent with a less fussy approach, but you will certainly need reinforcement and +1 for the thickening round the edges. You could (some might say should) spend a lot on geotec and structural engineering, but that's your call and I don't think I would for the likely cost of what you are proposing. Be careful of building regulations (Outbuildings vs Building Regs) but the size you are proposing (26m2) will be OK if you are >1m from the boundary or substantially non-combustible (i.e. no timber cladding). I'm no expert on any of these areas so don't take the above as gospel.

I like QCAD for doing drawings like this. You should be able to find a DXF or DWG with the symbols in that you can copy out and then it is easy to measure everything out. I you're only creating a sketch, on top of an image file then an image editor (or even PowerPoint) could work, but QCAD does allow image import as a base layer. QCAD has a freemium price model so if you are doing basic stuff it's free (or more advanced stuff before the 10 minutes after opening the software hasn't expired). I spent a while opening and closing QCAD to make use of the advanced features until I bought it for about £30.

I'm looking at using Kingspan GreenGuard under a slab floor. It will be on top of compacted hardcore (due to soil conditions) but may be suitable for what you need.

I had to replace some old 20mm chipboard and did it with 18mm on shims. Whenever I bounded down the stairs on to that floor I convinced myself I'd go though it some day. I suspect good timber floorboards would be stiffer and inspire more confidence though.