saveasteading

Glad you asked. SE is a specialised branch of being a Civil Engineer. So they may actually be CE but few know what that is. How often do we see ," ask your CE" in these pages? The SE has probably done a degree in Civil Engineering, then chosen to veer towards structures. Many practices do all CE fields including structural. So a CE can do structures and drainage, and roads and bridges and dams, but tends to let an SE do serious structural stuff, esp if complex. Therefore there is no concern.

Such a common problem, and water simply pours through the air brickinto the house. I think you know the solution. Break it all out, use even textured stone to hold rain until it soaks away. Gully down the middle and slab to a slope. Finished level well below any air bricks and dpc.

Agreed. You will have to at some stage so best now. As you will have a thick slab anyway, a raft should be the answer. Then the whole building can rise and fall seasonally. They can also test the ground, look at the topography and ' take a view'. As nobody will be sleeping in the buildings the risk to life is negligible.

Klargester is the best known brand and so tends to be specified for convenience. I much prefer air bubble tanks to moving wheels. I wouldn't worry about changing the model at this stage though. However, the planners should be looking at the location, even sending your plan out for consultation. Therefore I would tell your SE that it is not your land ( or won't be) and get the drawing changed. Most importantly it may affect how it ultimately drains. Then they will also deal with building proximity. There are digesters designed to be less deep, which can help near buildings.

Interesting. The water drains away but without taking cement with it, ie the blocks act like a filter? That could still leave more water in the mix than the theoretical optimum, but perhaps that doesn't matter as it is filling voids, not the entire structure. Entirely for my curiosity, could you theoretically be laying blocks, with another person mixing concrete on site and following behind? None of the excitement of whether it will hold when the big pour goes in.

Presumably they specify a plasticiser additive and a small aggregate mix. This provides very much better strength quality than added water. When you have the 6 course constraint, does this result in lots of small deliveries of concrete?

Nice to see the completed job, esp when a success. I'm assuming the fibres helped to stop it slumping. I once used the wrong bag for filling a hole in a wall. Self levelling screed wasn't great for this, but worked eventually with sand added and when it gave up on slumping. Is it worth filling the web space with timber so that the stairs can be fixed in wherever they touch? Also an attachment point for any boxing or trimming.

More info on this please. What are the issues? Presumably the water goes away eventually. Where to?

But I wouldn't. Amateur builders like me make lots of mistakes in cutting, and wood is very forgiving (and an extra piece is easy to find). Also, normal domestic tools suffice. Metal has advantages, but with professional builders.

That's fine. With render I can see that is an advantage. Its just that, with the systems I looked at, it always ended up a much higher quote than the marketing had implied. Also I seem to recall that it wasn't great for large rooms, but others on here know more as they have done it.

Welcome. Good advice above. When using ufh there are other advantages: warm feet make us feel good, so the air temperature ( air heated from the floor) can be lower than the norm (tell people it is 20°t though.) So the air isn't so warm and there is energy less wastage when doors are opened. I don't agree about the single zone, as some rooms can be cooler. As @ProDave says, upstairs bedrooms may not need heating at all. As all your space heating is from the floor, this needs lots of insulation, not forgetting horizontally to the outer walls. No carpets, or get special ones that let heat through. Ceramic tiles are best. Because of the CoP, the rating of the air source heat pump (ASHP) is the output, and the electric supply is 1/4 or 1/5 of that, hence a normal mains supply is enough. Structure....what would you like? Then it can be made to work. I could never get ICF to work out commercially, but many swear by them and I can see the attraction for DIY.

T beams are used close together to support an increased load, so I'd expect to see these are under walls or stair or some such. In which case you would not put insulation at that point.

These blocks should knock out upwards easily. There is just a skim of cement slurry by the looks if it. The first block in any row may have to be smashed down. After that I would expect them to come out whole. Then polystyrene or pir placed in between the t beams. They are not terribly strong so I am wondering whether you should first lay some thin board. OR, instead of normal screed, perhaps add steel mesh. I also wonder if a thin layer of insulation can be placed over the whole floor before the screed, to provide z thermal break over the beams. 20mm pir, 60mm screed.??

Half / double doesn't seem right. Best check their input?

Too much information. Are you allowed to refuse to detail the objections because there is so little information? Politely of course.

The walls have to be structural, and may be thicker than the norm to support the long span. Then there is no point on doubling up the joists...the SE and supplier will advise the spec. NB.. if the optimum centres don't suit plasterboard sizes, it would be best to ignore that, buy the best value joists, (for example 350 cc) and counterbatten for the ceiling.

In very approximate terms, loads spread at 45° from the lowest point of the footings. So from a 1m deep foundation it spreads out another m by the time it is 1m away from the wall. If your tank is 2m deep or less, then the load flies under it. If over 2m deep then they clash. This is theory and the bco would be entitled to proof that all was OK, which it probably is, because the pressure has spread so far as not to matter.

Personal or practical...?. I would never have an internal gutter. If they block, the water runs down the wall , at best. When not blocked, the rain runs down pipes somewhere inside your building. Making a noise, breaking the insulation layer, and someday blocking or leaking. And for what? External gutters and pipes will also save you £50/m at a guess. There are attractive ones.

My feeling is that the extra steel beam and supports woyld exceed the saving on joists, and complicate construction . This based on a project I did using fabricated joists to clients surprise. Not a lot in it, and it would need calculating both ways......but then your SE rightly has another fee. Whoever told you that trusses might be better, get them to sketch it so it us clear what they meant. In doing so they will likely change their mind anyway. If not, we may see a great idea.

2 issues I can think of. If the tank is not sealed, where does the effluent go, and does it undermine the garage? Do the foundation loads from the building pass through the tank?

From memory the osb web versions give more options for non standard joists like yours, so are a bit cheaper. Metal for standard spans. But with fluctuating osb prices it needs checking. An off the wall suggestion, esp if you have an SE, is to consider plating the ceiling in plywood, which might allow reductions in joist constituents, and be less deep.

Are we to assume that the walls and upper floor are built and can't be raised? Any access space under the b and b floor to fix insulation beneath it?

8.1m is a very long clear span. Ecojoists or similar by another name will just do it but will be deep and expensive. Trusses rely on filling the space with lighter weight diagonals, but they fill the space and you lose the rooms. What your drawing shows looks optimum to me. Expensive but optimum.i

A garage is designed very differently to any occupied, heated building. It is likely to need strengthening, insulation and an improved door. All building regulations issues. Perfectly doable, but a thorough job is required.

That matters. You probably have a good relationship with the sales staff too. Can you ask them how other prices are moving ?