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"Hi-ho, hi-ho, it's off to work we go"

Nelliekins

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Ok, so maybe I got a bit ahead of myself again...

 

The second wagon that they filled with spoil didn't fare as well. Matter of fact, it managed to beach itself on every axle:

 

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The muck-away company had to send a 2nd wagon, fully loaded with 6F2 and a big-arsed chain. Then it dragged the beached wagon out across the street using the chain. The (now-freed) wagon drove off with our load of spoil. Since there was a load of crusher run on the rescue bus, we had it tipped on the front of the plot, to stabilise the ground and prevent a recurrence.

 

So, excavation continued apace for the next few days. Apart from a few more land drains excavated (including an abandoned rat nest), things went well. Here's a few more pics for your delectation:

 

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We decided on a stepped bank initially, to try and prevent bank collapse:

 

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But as this photo shows, we were still fighting the effects of the bad weather - some small cave-ins, and we started adding acrows to shore up parts of the banks:

 

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Now, when we started investigating the options for basement excavation, we had previously considered sheet piling the excavation. However the 2 quotes we received both sad that the steel sheets would need to be left in the ground ("sacrificial" was the word used) because the sheets wouldn't be able to be extracted. And with quotes coming in at over £60k for the sheet-piled excavation, it was well over our budget.

 

So when the groundworkers told me that the excavator was starting to fall into the excavation, and we needed to sheet-pile the front of the hole, I was more than a little concerned. Still, it appeared to work:

 

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So the hole was finished - only 74 wagons of spoil taken away... Concrete blinding was laid oversite to stabilise the clay underfoot, and the shuttering for the slab constructed. Then the mesh and starter bars were set into place, and we were ready for the slab to be poured:

 

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And lo, our first concrete pour arrived - the first of many!

 

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And before I knew what was happening, the slab was done (notice the increase in the number of props / acrows):

 

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Time for some ICF...

 

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Cripes, you wouldn't want somebody to take the ladder away if you were in that hole!

 

Is that all clay, or did you hit something more solid at the bottom?

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9 hours ago, Thedreamer said:

Cripes, you wouldn't want somebody to take the ladder away if you were in that hole!

 

Is that all clay, or did you hit something more solid at the bottom?

 

Clay all the way, baby! 😁

 

To be fair though, Building control looked at the borehole records we had prepared and said if it weren't for the 27m high poplar trees at the front of the plot, they'd have said the ground at 1m down was good enough to build our house off of. 

 

Mind you, we would have had to duck down a bit to get in the basement if that was the case! 🤣

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I think this blog has just served to ask the big question WHY? when it comes to basements.  Looking at that huge, deep, wet, fragile hole, that has cost you a lot of work and a lot of muck away, and will cost you more still to finish it and fill it in again, it does not take a genius to work out the cost per square metre of the basement room will be a lot more than the rest of the house.

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Actually, basements are normally cheaper per square metre than any other part of a build as they also incorporate the foundations. 

 

If you compare the cost of a basement to adding the same as floor area to a normal property, including windows, walls, floors, roof etc, then it’s surprisingly low. 

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Nicely written blog...like your humour and optimistic attitude

More power to you I'm guessing you're going to need it...

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3 hours ago, ProDave said:

I think this blog has just served to ask the big question WHY? when it comes to basements.  Looking at that huge, deep, wet, fragile hole, that has cost you a lot of work and a lot of muck away, and will cost you more still to finish it and fill it in again, it does not take a genius to work out the cost per square metre of the basement room will be a lot more than the rest of the house.

 

3 hours ago, PeterW said:

Actually, basements are normally cheaper per square metre than any other part of a build as they also incorporate the foundations. 

 

If you compare the cost of a basement to adding the same as floor area to a normal property, including windows, walls, floors, roof etc, then it’s surprisingly low. 

 

Truth be told, it's about equal to cost of above ground on this build. It would have been cheaper by about 20% going off our original costings, but for a massive cock up by me not checking what one of our so-called experts did when starting out one of the basement walls... 

 

<spoiler alert>

... As a consequence of which, we had a well-concealed but considerable leak in the basement that has led to internal tanking and a bunch of other remedial measures. 

</spoiler alert>

 

Anyway, more of that to come in the next couple of days (well, the next 9 months of blog time!) 😂

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We did a basement and used king piles - drill a hole every 1.8m with an auger (maybe 1.5m lower than the excavation bottom), lower in a steel h section, concrete the bottom 1.5m, as you excavate, infill between the steels with rail sleepers (which can be removed later).

 

The more critical bits, where there were adjacent buildings, we did augered holes and filled with concrete to create a sort of secant piled wall.

 

It meant we had a safe working space between the outside of the basement walls and the face of the excavation.

 

5 hours ago, PeterW said:

Actually, basements are normally cheaper per square metre than any other part of a build as they also incorporate the foundations. 

 

If you compare the cost of a basement to adding the same as floor area to a normal property, including windows, walls, floors, roof etc, then it’s surprisingly low. 

Basements are a substantial risk and cost.  I have experienced higher per metre build costs, while the space created is worth a fair bit less than above ground.

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14 minutes ago, Mr Punter said:

Basements are a substantial risk and cost.  I have experienced higher per metre build costs, while the space created is worth a fair bit less than above ground.

 

I agree on the risk front, although we had boreholes performed across site and a mining desk study performed to assess ground stability. 

 

Odd that you think the space created is worth less than above ground... We have had a number of valuations performed, both before and after construction, and it comes out as adding more value than a 3rd floor above ground every time? 

 

We wanted a decent sized cinema room, so a basement is perfect for our needs. Light control, and much better sound insulation than we would ever achieve above ground. We have got 9' ceilings though - rather higher than the average cellar! 

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1 hour ago, Nelliekins said:

Odd that you think the space created is worth less than above ground... We have had a number of valuations performed, both before and after construction, and it comes out as adding more value than a 3rd floor above ground every time? 

 

 

It is because they are more likely to be damp, flood prone, dark, poor mains drainage for WCs etc, difficult emergency escape and badly ventilated.  I don't understand why the valuers were keener on a basement than a 3rd floor unless the third floor was badly compromised with sloping ceilings and rooflights only.  My experience is a basement is valued at no more than 80% maximum of upper floors and only then if it has good natural lighting and access.

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15 hours ago, Mr Punter said:

 

It is because they are more likely to be damp, flood prone, dark, poor mains drainage for WCs etc, difficult emergency escape and badly ventilated.  I don't understand why the valuers were keener on a basement than a 3rd floor unless the third floor was badly compromised with sloping ceilings and rooflights only.  My experience is a basement is valued at no more than 80% maximum of upper floors and only then if it has good natural lighting and access.

 

All good points. 

 

Our basement was damp, and would have poor drainage if we had any plumbing in there, which is why we don't. The cause of the damp was identified and resolved. We have a fairly large stairwell (roughly 2.5m square) which goes through all 3 floors of the house with a nice big SE-facing window at the top of it (window is 2.2x2.1m) so lots of light in the front. We have a lightwell at the back, with a big window opening into it, which only leaves the cinema room without natural light (winner winner chicken dinner). 

 

Emergency escape is through the window at the back - our 7 year old has already used it during a game of hide and seek, so clearly easy enough to use! 🙂

 

Ventilation for the entire house comes from our MVHR unit - we have supply and extract in every basement space apart from the stairwell. 

 

I would guess our valuers agreed with me that the basement feels more like a normal house space than a third floor above ground would, because we don't have to have self closers on doors anywhere, which I find makes a house feel a bit like a public building... High ceilings help this sense of "normal" as well... I daresay if we had 7' ceilings like a lot of basements, it would feel claustrophobic... But we went with 9' ceilings, and it's great. 

 

There are problems with building basements, but good design and planning can overcome all of them. The self closing doors is regulated so you can't avoid it (although if you're being a bit naughty you can always remove them after Building Control sign off on the completion certificate). 

 

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1 hour ago, Nelliekins said:

because we don't have to have self closers on doors anywhere

 

Door closers are no longer required for 3 storeys.

 

Did you end up with internal drained cavity membrane, or was there a simpler solution?

 

That was a big hole you dug, especially as the site looks fairly flat.  A friend had a house with a deep basement, part of which was a swimming pool.  The neighbouring house made theirs into a squash court!

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I love the WTF Happened feel of picture 5.

 

I have seen that look on many students waking up in the bathroom of a different house!

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10 hours ago, Mr Punter said:

 

 

Door closers are no longer required for 3 storeys.

 

Hmm. Might have to speak to my architect about that... Oh wait, that's me! 🤣 Tbh I hadn't checked, although I know it used to be a requirement to provide a protected stairway for 3rd storey above ground, including self closers. 

 

10 hours ago, Mr Punter said:

Did you end up with internal drained cavity membrane, or was there a simpler solution?

 

That would be spoiling the surprise in an upcoming episode of the blog... Not long to wait, I promise!! 

 

10 hours ago, Mr Punter said:

That was a big hole you dug, especially as the site looks fairly flat.  A friend had a house with a deep basement, part of which was a swimming pool.  The neighbouring house made theirs into a squash court!

 

Yeah, 74 x 32T muck away wagons filled to the brim. About 900m3 of spoil shifted, all told. 

 

The original reason for the basement was actually because we have 3 poplar trees at the front of the plot - 2 of which are 27.5m tall, and only 12.5m from the house. Building Control were consulted before planning about this and the head honcho there said they'd insist on 3m deep trench foundations with clay heave precautions as a minimum. I said "balls to that, we'll put in a basement"... So we did! The second I said the b... word the missus started planning what would go in it, and thereafter it was just part of the plans. 

 

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4 hours ago, Ferdinand said:

I love the WTF Happened feel of picture 5.

 

I have seen that look on many students waking up in the bathroom of a different house!

 

That's not even me - it's the foreman of the groundworks firm. I think it was mild panic when he realised the size of the job! 😂

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1 hour ago, Nickfromwales said:

Basements rule. End of. 😎

 

I quite agree. Although mine has nearly been the end of me. The next instalments of the blog will reveal the reason why...

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I like the idea of having a basement, and would have built on if it wasn't for the practical issues surrounding our plot (as it was we had to remove over 900 tonnes of soil just to get it level).  Getting enough insulation around a basement seems key, though, especially as we wanted to achieve a passive house performance level, which would have meant at least 300mm of EPS around the outside of the walls and under the floor.  Our main problem was the EA, though, who declared that we couldn't have any habitable rooms with a finished floor level lower than about 1.5m above the level of the lane.

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I'm transported by your photos.....

In Uganda you wouldn't all be allowed to bugger off on a tea break together though.

ugandaVengland.jpg

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6 hours ago, JSHarris said:

I like the idea of having a basement, and would have built on if it wasn't for the practical issues surrounding our plot (as it was we had to remove over 900 tonnes of soil just to get it level).  Getting enough insulation around a basement seems key, though, especially as we wanted to achieve a passive house performance level, which would have meant at least 300mm of EPS around the outside of the walls and under the floor. 

 

The difference with us is that we never set out to achieve passive status. As it happens, we might beef up the insulation in our basement walls shortly, because we are in a position to do so with minimal cost (I will mention it in the blog when we get there - again though it is to do with the remedial action we have had to take...) 

 

Quote

Our main problem was the EA, though, who declared that we couldn't have any habitable rooms with a finished floor level lower than about 1.5m above the level of the lane.

 

Odd for the EA to get involved. In fact I am surprised that they even looked at the application at all... Most times they are consulted it gets rubber stamped (I know a fairly senior guy there, and he says they are so under resourced at the moment anything except nuclear and water related works tends to be passed as a matter of course... 

 

Edited by Nelliekins

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3 hours ago, mvincentd said:

I'm transported by your photos.....

In Uganda you wouldn't all be allowed to bugger off on a tea break together though.

ugandaVengland.jpg

 

I am sure if the boss said "go on a break" they went on a break! 

 

I think my hole was bigger though... 🤣

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4 minutes ago, Nelliekins said:

Odd for the EA to get involved. In fact I am surprised that they even looked at the application at all... Most times they are consulted it gets rubber stamped (I know a fairly senior guy there, and he says they are so under resourced at the moment anything except nuclear and water related works tends to be passed as a matter of course... 

 

 

We have a stream along one boundary, so the EA had a big say in the levels of both the finished floor in the house, the drive parking area and the garage floor level.  They mandated levels above Ordnance Datum that we couldn't go below, and that ruled out a basement.  The daft thing was that I was required to do a flood risk assessment, and that showed that even the 1:100 year flood risk level was only just covering part of the lane below our house - the EA made us have our FFL in the house 1.6m above this, which is daft, as the stream is small and fed from a spring about 3/4 mile up the valley.

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