saveasteading

6 person is about £1,700 + vat, from marsh, delivered. Fibreglass and very tidy. Discuss any tech stuff with Marsh but orders are through any bm. 4 person obv should be less. Yes, air bubbles preferred to anything mechanical. There is an extra shallow one but costs more.

Not on clay surely? Perhaps if on silt. 4m would be usual in clay. But yes, changing the foundation type so dramatically is likely to cause trouble.

House prices to fall 8%? The developers will be slowing down until they can ensure their normal 30% profits. That will affect labour and materials, but it normally takes many months for the reality to show in quotes.

Just a bit more to add to Gus' excellent explanation. There is nothing magic about 450mm depth, probably originally foot and a half, but it is a good guide to how deep frost will go in the uk. Frost and freezing causes changes to the ground as explained. If you were in an area that gets especially cold or for long periods then the frost can creep deeper. My own house was built from timber in the 1920s. It has 2 bricks above dpc, then 2 below on 150 concrete. So not remotely 450mm. The house moves up and down seasonally, mostly through clay shrinkage, causing doors to stick. But it is still standing, even the brick chimneys. I have often designed buildings with 450 or 500 deep edge strips where they are not structural. It works nicely with 2 blocks, and keeps the strip and internal slab safe from frost. Hence also 450 or so depth for water pipes.

Or leave the chimney in place and find a use for it. A floral display perhaps, or storage. We only fitted the gallows bracket because the wall was already gone, and the chimney propped on the joists. These houses work using the chimney as a major part of the structure and a ventilator. Doing a proper job will be disruptive and expensive. Who knows what the next wave of buyers will think. Perhaps they will value the chimney or fear that it has been removed.

With no offending trees you don't need to go deep, so piling should be unecessary (it is expensive). It might be worth incorporating the existing piles but it will depend on type of pile, the beam of slab design, and positioning. Good fun for your SE.

I analysed the quants /estimate commissioned by one of our tradesmen , who readily offered that it 'looked a bit high'. Though skilfully enough prepared, there was doubling up and lots of waste allowance. That waste could have been real with a cavalier joiner. You could also argue that there are always omissions and unknowns, so it works out. In real life we worked out a price thst worked for us and him. One element of the work is costing a third of the original estimate.....which happens to equal my own forecast. Tip...it is easy to get bogged down in detail. Stand back and have your own stab at the total cost of any element. How long will it take? Rule of thumb is 40/40/20 % for labour, plant and materials. Then add oncosts and profits esp if using a bigger company.

If the tree was there when the house was built then it needed footings of over 2m, or piles.

I don't agree. Get it right as it is your house. Then the bco will agree anyway. Oaks at 35m have no effect. Hawthorns have very little effect.

TS discount is stated as 5%. Even then, there always seem to be conditions when I have asked. Maybe they have local promotions. For me they are handy for availability but many prices are high/ opportunist. Ditto / more so at SF

This seems over complex. 4 layers of vapour barrier of different types whereas one out and one in should do. Plywood on the frame will make it very much stronger, laterally and vertically, so that is a great idea. I'm not a fan of foil insulation if there are other options. 6" between the studs as shown is a good start. Then some non- conducting liner over the studs. What external facing have you in mind?

You might find there is less waste that way too. Too easy to pick up a nice new coil every time. Then there Is the other sort of 'wastage'. I only supplied cable once as it was obvious a lot was stolen: not nec by the electrician.

You are allowed to trade off insulation in the floor against the walls and roof. Not the best idea if you have UFH*, but worth thinking about if the depth us critical. * esp when the floor has cold air under it.

How far to the oaks?

I like TLC too, although not nationwide. Longer lengths too I think.

The effects of a willow or oak are much the same as both grow to about 24m and take up huge amounts of water, and clay shrinks. The foundations would be designed for the mature height. Apart from the shrinkage in summer, another issue us that a large tree looks out of place and grows lopsided if very close to a building. Also sheds leaves and sticks, perhaps into the gutter. The main benefit is obvious, that trees are a good thing. But also, If to the south of the building they shade and cool in the summer but allow light in winter. A willow on clay will need foundations about 2.5m deep. Not the end of the world. If it does / they do fall over suddenly then you need a wet winter and spring for the ground to recover IF there are roots to the house. Ignoring this can cause immediate heave of the foundations.

No. Once cut down, its effect on the ground will continue, as the ground becomes wet and the ground expands. Unless you can leave it a season to stabilise. Don't assume that the BCO understands this. It will be your problem, not theirs. I once had a bco walk round the site with me looking at founds. He had no comments about the differing depths , sometimes quite deep when close to large trees. On gentle questioning it became clear that he was unaware of the subject. But what are your ground conditions? Clay/rock/gravel/ an old landfill???

The problem is with big, deciduous trees on shrinkable ground such as clay. They drink the water in summer, the clay shrinks, and the building moves. Then is winter the tree is dormant and the ground expands again. The solution is deeper footings or piles, which you have. For a willow/oak etc on clay, the effect is up to 24m from the footings. At that distance a 0,9m deep footing may need to be 1m (approx from memory). But very near to the building it may require 4m deep foundations. If there is a stream between, or rock beneath, or multiple other variables' then this doesn't apply. It is important so check it out. NHBC is the easiest resource (online) for the guidelines, using the BS graphs for "Building Near Trees"

Make sure that the capping is good for a few decades. I suggest making sure the construction is agreed, and also getting a photo to confirm. Assuming you are not going up to inspect. I don't know how to cap of a chimney. Rainproof but ventilated....somehow.

Just be sensible and polite to the council and they will be the same to you. I would send an email to bc saying what you have said here about just waiting for results, drinking bottled water etc. That puts it on the record that you are not being sneaky. They won't throw you out.

Agreed. One flush could spring the bend off the vertical pipe. If not the first then soon after guaranteed.

Agreed ' not as much'. But i think there will still be a big difference on most sites. There are much cheaper, yet efficient, ways to get the insulation at the perimeter than to insulate the footings. I'm not about to calculate the difference, but would be interested if someone has. I can see the attraction of the kit foundation idea though, for certainty and speed, for which there would be a premium. Hunch price? £15k extra on 200m2? As to muck away costs. Yes this is often ignored and can be significant on a small site in the SE. Often there is a design solution to this too, but it needs holistic design.

Let me know if any of this needs clarification. For a load-bearing slab we consider the slab, acting alone and supporting only the floor loading. The concrete sits on stone , on ground and the floor loads therefore act directly on the ground, (spread somewhat by the thickness, if the loads are uneven) The much heavier walls sit on footings in the ground, usually 1m or deeper, and not on the slabs. Reinforcement of the slab is generally only to control shrinkage cracking, and is a steel mesh, easily laid. Footings are usually mass concrete, a lo-tech process Rafts are structural slabs. The concrete is thicker and they have 2 layers of steel, top and bottom, to prevent bending and make the slab work like a big beam. Cost are higher because the concrete is thicker and the steel is heavier gauge as well as being in 2 layers. It may also require additional skill. The walls are supported on edge and cross beams made as deepenings of the slab, heavily reinforced and fully linked to the slab. These support the walls but also spread this heavy load over a wider area of ground, using the slab area. So a simple load-bearing slab sits on good ground. If a book-case wouldn't sink into the ground, then neither will it when there is concrete on top. Walls are very much heavier and so need strong ground. If the ground is not strong enough to support the walls then a raft may resolve the issue by spreading the load over a bigger area, and allow construction. Cost of slab and footings approximately double, perhaps more.

In simplistic terms, with cost and simplicity being the main drivers. Ground good and also level : load bearing slab and strip footings Ground good but sloping or liable to flood: beam and block Poor ground: raft. So why do major developers use B and B so much? Certainty, and repetition of designs. Also less liable to problems if using unknown ground-workers. Why are rafts specified so commonly? Not the designers' money, and perhaps don't realise the cost effect.

Did this in a daughter's terrace house about 5 years ago. Took maybe 2 hours, using stud and epoxy. Gallows bracket installed where a previous owner had just cut out bricks, only supporting the remaining chimney on some bits of wood on the joists. I say remove as little as you can, as the chimney is part of the structure, including next door. The party wall will be 1 brick thick (225) at most and the chimney is a major part of the strength,