saveasteading

It seems to be an old-fashioned septic and settlement tank, which will do 90% of the work, followed by the filter chamber. That should work nicely £3,800 inc vat for a 10 person is not a bargain. The downsides? The outlet appears to be 2m deep or so, which will limit options and add to drain cost. OR it has a pump, so the avoidance of mechanics is lost. If anyone was to put bleach or wash out paint brushes etc into the drains, , I think it wold cause more damage in this than in an air mixed tank.....but that's just a feeling. If it gets heavy use on occasions will it cope? I think so as the solids stay in tank 1. How do you change the filter medium bags? will they still be available in 10 years? Maybe they could be washed out.

I don't know the product but am interested enough that i will look into it for future reference. Have they explained their logic? I wouldn't (ahem) poh-pooh it until checked out. It is all using natural bugs to eat the poo. one method adds air bubbles to keep it moving and oxygenated. the other i assume uses the principle of enormous areas of surface for it to cling to while eaten. That logic is good. for many (15+) years I dispensed with oil interceptors on car parks and instead used natural drainage through lots of gravel. It worked really well and has next to no maintenance or running cost. The analogy is quite close.

It was once the default and became the term for a digester. like having a Hoover. Their marketing and technical advice helped a lot too. But that was a long time ago, It is rather a bad habit to use the term generically these days. I can only assume that an professional using the term without a model number etc, isn't up to speed.

All talking stud I think. Nobody talking blocks ot any word like that. You've made me think though. A metal stud wall might be so weak that it crushes under any load from the floor above and doesn't transfer it to the screed and the insulation supporting it. That doesn't seem proper though as there then wouldn't be a seal at the head.

Whether you could is dealt with above. Whether you should? It is taking a risk regarding approvals and any changes during construction. It will be a 2m to3m deep hole so it's maybe better to wait, and a bigger digger can hoist in the tank and hold it safely while you shovel gravel around. PLUS it might be in the way, if you are tight for working space, and damaging it would be awful. That goes for the pipes too, as you will surely be driving machines around the building.

End of commercial life caravans on 'holiday' sites are cheap as long as you don't mind a lot of cleaning and putting up with the shabbyness. I drove past such a site yesterday and there were a dozen roadside for sale. The wheels on most are for tax avoidance purposes and not for towing, so make sure they include delivery. We have one that was included with the sale whuch we use as office. The farm worker occupants had clearly been clean and proud people, but there was 20 years of muck and mice in the hidden areas.

Practically....if you lay the ufh clear of the wall position then you can drill and screw into it. I took to the new breed of Fischer plugs, but have reverted to hit-fix for sole plates...it's so easy to drill and fit in one operation. As often, well known brands often work best. Engineering-wise. The load of the wall is simply its dead weight, so negligible BUT if the stud is tight to the floor above then it will take load from it, and the screed on insulation won't be strong enough. So leave the wall short at the top with a flexible infill. Of course it still needs fixing, so use screwed brackets to the joists to let it displace.

That looks tall and heavy. How did you get it in position? That ladder also looks very high and precarious...I used to do that but no longer.

They should ask for the connection details. You need it anyway. It doesn't work as drawn, and saying on the drawing that it doesn't work as shown is a cop-out.

@JamesP it's almost a shame to hide that frame behind boards. Did you prefab any of that? I'd bought 2 lots of 4 x 2 (excuse the shorthand. One lot was dressed as carcassing, the other sawn and tanalised for shuttering. The latter was cheaper and seemed better quality, so I will note the advice on finished dimensions.

Tempting as it is to premake panels on the floor or bench (the structural ones with osb) it wastes a lot of doubled up timber. So studwork must be the way and use a simple hopup for fixing boards. Probably worth buying or hiring a self feed screw gun. A lot of pre-thought needed too, on osb or plasterboard sizes if therd will be lits of cutting and cursing. I've watched stud wall specialists, metal and wood, working with ease and speed, but not thought this size thing through before. I have moaned at the amount of stud cutting waste but they, of course, are doing what suits them. A new stud or board every time whereas we on BH will find an offcut to use whenever we can. I still need to know the best method for constructing the stud. A sole plate is essential levelled. There won't be any floor above to connect to. Studs flop all over until the header goes on. We will have a builder doing this, but not one with this expertise.

Im shocked I don't know this. I've been knocking up a simple enclosure for a site toilet that will become a garage toilet, on an existing slab. 4 x 2 stud in 2.4m lengths. then osb facings. When i make it with a base and head plate , and verticals, I end up with a panel that is 2.4 + 0.05 = 0.05 + 2.5m high then onto that goes a 2.4m board that doesn't reach the ends. this is an increased issue if the frame is erected on a sole plate. I've got gaps. It seems a nonsense to cut the ends off standard studs. The same will apply with plasterboard except that it is available 2.5m long......but not so competitively priced perhaps. Are there any tricks?

Your thoughts on crack control if we don't want shutters or slicing of the cured surface. Crack inducers? Or with all that mesh it is microscopic. Clearly no worries about the pipes failing when they stretch that tiny bit.

Neither. I would do option 3. btw, I only mentioned slabs 175th as what a factory needs. A house doesn't need that. So shave off another 50mm at 100m2, 5m3 @£150. for 250mm it is 12m3. but muck away, shutters, and the mesh spec. Rain or frost damage or delay. Risk of damage to sticking out, loose ends of ufh pipes? What was your method for fixing the ufh? tie to the mesh? In the factory I mentioned, the building was enclosed and the slab was poured 'indoors'.

pods have differing peas. 2 varieties of pea perhaps. Forget the fire analogy , I only meant a quick change, not the amount and controllability of heat. Not usually in my experience. . Scratches, machine marks, mortar splashes. But I'm more used to bigger projects than houses, with steels etc. on and off the floor, and mewps running around. Perhaps different if its very very closely supervised. otoh, with a house, it seems that most builders can't get the slab remotely level, and they are too small for the specialist contractors. so the second chance with the screed comes to the rescue. still sweating their arses off on the Wednesday, Doesn't that show that the heat in the slab was then wasted, and it would take 3 days to warm up again? Bottom line....I have never priced or built a new house with a raft. so it is a hunch. and of course I am interested in he all rounder's view. But I was an Estimator for years and the hunch is usually about right. Worth £5k to £10k in my mind. That can be wiped out by consultants fees or a builder with a proven system not wanting to change processes.

Now I don't understand that I'm afraid. Sounds a mechanical thing, not to do with the heatsink. Why should it not be good that a screed reacts quickly when the weather changes. It's like 'let's light the fire' evenings.. It is fundamental I think, that you should not need an exceptionally heavy duty factory spec floor for a house, then build it on pir or eps. But I am interested. Do you think it isn't that expensive all things considered? I also like that the first slab can be run on and bricks dropped on it, and scuffed, knowing it will be covered.

OK. I have seen heave once. I think clay heave is assumed too often but I don't know your ground conditions. Clay heaves when it was dry and gets wet. If the whole area is rising and falling then it doesn't matter. Under a 15x9 slab will it be much drier or wetter than the surroundings? If you had conventional footings at 1m deep then they won't budge, and the slab will be on fairly standard ground. OR refer to another discussion on here about beam and block. No heave.

I posted this in error in another discussion on the same subject. and have mixed the 2 up I think. No time to review so here it is again. My thoughts. questions first. Where is the floor insulation? Is the ground levelish and good bearing capacity? Assuming the ground is good, I would lay harcore and 150mm slab. 175 maybe . Crack control mesh is all that is needed. This suffices in warehouses and commercial vehicle garages so is ok for your sofa. Lay PIR on that with ufh on top, then screed in 60mm poured or hand laid. If you need more capacity for internal loadbearing walls then it can either have a thickening in the slab, or a trench footing, as the ground dictates. I think rafts are specified too often. I really don't like structural slabs on top of insulation. Now some other points. 85m3 isn't much and I will stab at it being about 8m x 10m. I'd have to check but this is close to not needing any contraction joints for a finished surface. But with a screed over it that is irrelevant because the slab will crack well before the rest of the work, and will not reflect through the screed. Even as a finished surface this cracking would be trivial. With careful mix control (absolutely don't allow extra water added on site) and fibre additive (£30 or so) any cracking will be microscopic. Cracks would be tiny and many. The UFH pipes will likely debond at cracks but are also well capable of stretching the 1/10th mm required. I did put UFH into a 175mm slab once, as the client's specific requirement. (It was a factory and this was the area where people stood to do craftmanship stuff.) It had anti-crack mesh in the floor, and the UFH pipes were fixed on top of it. Shrinkage joints were either the old fashioned method of pouring alternate long strips, or crack inducers built in....I can't remember. So there was no cutting into the slab afterwards. More mesh reduces crack width if necessary, which it wasn't in this case. I guess the shrinkage cracks were about 1mm. It went well and worked welI. I heard no more about it so it must have been ok. I had a further job for them so it's not as if we lost touch either. It was an uninsulated for various reasons I won't divert into. btw I've done 200,000 m2 of slabs and never more than 175mm when ground bearing. So there are choices. Even the best SEs don't know all the ins and outs of costings (it isn't just the slab but the walls, the insulation , UFH , access to site)......That needs a close collaboration between contractors and consultants. The biggest and best contractors will know, if they have an SE inhouse, or have developed a standard method. But that will cost you in either overheads or conservative design. Small contractors may well know, but that is rare, and with some, the less they know, the more they think they know. BUT perhaps they and your SE together can optimise this. If there is a reason against my suggested method, then please say.

I may have mixed up 2 current discussions! take what is relevant.

My thoughts. questions first. Where is the floor insulation? Is the ground levelish and good bearing capacity? Assuming the ground is good, I would lay harcore and 150mm slab. 175 maybe . Crack control mesh is all that is needed. This suffices in warehouses and commercial vehicle garages so is ok for your sofa. Lay PIR on that with ufh on top, then screed in 60mm poured or hand laid. If you need more capacity for internal loadbearing walls then it can either have a thickening in the slab, or a trench footing, as the ground dictates. I think rafts are specified too often. I really don't like structural slabs on top of insulation. Now some other points. 85m3 isn't much and I will stab at it being about 8m x 10m. I'd have to check but this is close to not needing any contraction joints for a finished surface. But with a screed over it that is irrelevant because the slab will crack well before the rest of the work, and will not reflect through the screed. Even as a finished surface this cracking would be trivial. With careful mix control (absolutely don't allow extra water added on site) and fibre additive (£30 or so) any cracking will be microscopic. Cracks would be tiny and many. The UFH pipes will likely debond at cracks but are also well capable of stretching the 1/10th mm required. I did put UFH into a 175mm slab once, as the client's specific requirement. (It was a factory and this was the area where people stood to do craftmanship stuff.) It had anti-crack mesh in the floor, and the UFH pipes were fixed on top of it. Shrinkage joints were either the old fashioned method of pouring alternate long strips, or crack inducers built in....I can't remember. So there was no cutting into the slab afterwards. More mesh reduces crack width if necessary, which it wasn't in this case. I guess the shrinkage cracks were about 1mm. It went well and worked welI. I heard no more about it so it must have been ok. I had a further job for them so it's not as if we lost touch either. It was an uninsulated for various reasons I won't divert into. btw I've done 200,000 m2 of slabs and never more than 175mm when ground bearing. So there are choices. Even the best SEs don't know all the ins and outs of costings (it isn't just the slab but the walls, the insulation , UFH , access to site)......That needs a close collaboration between contractors and consultants. The biggest and best contractors will know, if they have an SE inhouse, or have developed a standard method. But that will cost you in either overheads or conservative design. Small contractors may well know, but that is rare, and with some, the less they know, the more they think they know. BUT perhaps they and your SE together can optimise this. If there is a reason against my suggested method, then please say.

Everybody is right here....my pennyworth tomorrow.

Deflection is shown on the design tables so is predictable. In reality I've never felt a b&b floor bounce even in the raw state. A screed is often part of the design. Even adding a grout brushed into the joints makes an improvement.

Pir between joists I favour half pir and half mineral wool. The thinner pir can be cut more accurately and the wool is squeezed in and completes the seal. Doesn't expanding foam shrink too?

OK to summarise my thoughts. I have often used, and would again use, B and B. This has been as the ground floor on sports halls where the ground sloped and a ground bearing slab was not my preference. It jumps gaps between sleeper walls, is as solid as we choose to specify it (no bounce), and won't rot. In one case, the access to a big hall was so awful that b&b allowed for manual handling if the worst of the winter prevented lorries from getting near. The floors are strong and hard enough even before screeding to support cherry pickers...with great care. Timber will not allow that. Also used on the first floor on office blocks and classrooms and similar areas. These are big spans and the loading is quite high, and timber would have been rather deep. But it is becoming a close thing between b and b , or steel joists, or timber I joists. Plus there is the density for sound absorption, especially if there are different occupiers and they shouldn't be aware of the neighbours. For a house I would always consider b&b, but would compare it to the other options. Even the house dimensions or room arrangement could swing the decision.

Show it to your builder perhaps. Some of these guys are strong and don't mind the weather....and that is about it for suitability. Maybe with knowledge he will improve.