Fredds rule no2.

[Fredd]

Set your DPC height to save you ££££

 

Plots are not equal. some are pigs, pigs have to be made into bacon.

 

Generally, you want DPC to be as high as the planners will let you. Not all planners will be interested, mainly they will put  condition on the planning where you have to tell them slab height. MEasure it up accurate and then add 2 bricks and send it in. We havent yet had them come back and question it (they have no clue how to measure it anyway) and it means you have 2.55 ceilings and a higher roof if need be. Dont tell them i told you.

 

1 or worse 2 bricks difference in DPC can be a 5 figure sum in groundworks and muck away depending on size of build.

 

Tricks we have done in past, raise DPC by 3 bricks and dropp pitch of roof to keep ridge height with next door. £40000 saved.

 

 

[MikeSharp01]

Good thinking / advice @Fredd sadly in our case we had a ridge height criteria to meet and then once you deduct the internal heights then we end up about OK but we will have to do some landscaping around the slab to ensure we have clearance to the DPC.

[Ferdinand]

Good advice. That is the kind of "circumnavigate the problem" idea that I like.

Edited February 7, 2018 by Ferdinand

[Jeremy Harris]

1 hour ago, Fredd said:

Set your DPC height to save you ££££

 

Plots are not equal. some are pigs, pigs have to be made into bacon.

 

Generally, you want DPC to be as high as the planners will let you. Not all planners will be interested, mainly they will put  condition on the planning where you have to tell them slab height. MEasure it up accurate and then add 2 bricks and send it in. We havent yet had them come back and question it (they have no clue how to measure it anyway) and it means you have 2.55 ceilings and a higher roof if need be. Dont tell them i told you.

 

1 or worse 2 bricks difference in DPC can be a 5 figure sum in groundworks and muck away depending on size of build.

 

Tricks we have done in past, raise DPC by 3 bricks and dropp pitch of roof to keep ridge height with next door. £40000 saved.

 

 

 

How can a 100 to 200mm difference in DPM level make a difference that is close to the cost of our whole house, inc insulation and airtightness?

 

I just don't get it, personally, and don't see where the planning officer, or planning policy, has any bearing at all on this for a typical solo plot, such as a self-builder might be interested in.

 

We had probably a worst case where levels were both critical and cost a lot of money.  This is a photo of our plot on the day we finally started doing the ground works (which excluded the foundations, as they were a part of a the passive package from our main contractor):

 

 

To the extreme right of that photo, under the overgrown hedge and to the right of the reflective marker, there is a mill stream, that runs through the whole village, rising from springs around 1/2 a mile away, and becoming a fairly large river about a mile or so downstream, where it joins the river Nadder.

 

The Environment Agency demanded a flood risk survey (understandable, given recent major floods around the country) but rather than pay the demanded £4,500 from the only flood risk surveyors the local EA office would accept, I chose to do my own, using flood risk data obtained, free of charge, from the EA, by a mix of using their publicly available data and making an FoI request for more data (taxpayers pay for this, so are entitled to see it).  What was clear was that there were going to be levels for certain areas that were mandated by current EA policy (nothing to do with planning, other than PPG25 placing an obligation on the EA to make a determination, in effect).  The vehicle parking area and garage finished floor had to be a minimum of 83.1m AOD.  There was no ability to negotiate on this at all, as this was the stipulated level above the 1 in 100 year flood event and everyone, from central government to insurance companies were taking heed of it.

 

Furthermore, the EA stipulated that the finished floor level inside the house must be no lower than 83.5m AOD, and this level was, of course, only aout 13 to 14mm above our DPM level (the DPM being level with the top of the slab, as mandated by the build system chosen).

 

The height of the DPM above the external ground level is determined by a few factors.  Firstly there is statute law that sets the height of the DPM relative to the outside ground level, in the form of the Building Act 1984, with amendments.  This law also stipulates elements that have made their way into Approved Documents (which are not law, but guidance) and these provide some clarification on how the law may be complied with.  There are some potential conflicts that need careful work-arounds, as the law is very badly worded, especially the most recent amendments.  For example, whilst stipulating the distance external levels have to be below DPM, the same law later stipulates a near level threshold for wheelchair access, which means being a bit canny and leaving a tiny vertical slot between the ramped entrance (in our case the rear door) and the house.

 

The only thing planning were interested in was the ridge height, a common restriction, I understand. 

 

So, tying all the legal requirements together, we had to have a drive that was no more than 400mm lower than the house finished floor level, we had to have an external level around the house that was greater than or equal to 150mm (the required separation from the DPM to external level).

 

Getting to the crux of the point being wildly exaggerated here, we had to level our site a lot, this is what it looked like just before the foundation team arrived, after all the ground works had been completed:

 

 

We removed around 900 tonnes of soil and mixed surface waste by this point, and still had to remove a further 200 tonnes to get the drive and garden levels right.  The total cost of all the earth removal, excluding the cost of the retaining wall, the putting in of service ducts and pipes, the installation of the sewage treatment plant etc is separately itemised on our ground works invoice.  We dug down around 2.5 metres to get the site level, and got stung for the highest rate of landfill tax for the top layer, as it was classified as mixed waste, because of all the trees, shrubs etc in it.  Even so, the total ex-VAT cost of lowering this site by 2.5m came to £11,170.80.  Had we needed to take the site down by another 200mm, I doubt it would have added more than £1000 at the very most to the cost.

 

So, how do you get a "saving" of £40,000 by not removing 200mm of soil from a typical self build site?  That's 3.5 times the cost of our entire cost to remove 2.5m depth of soil!  Frankly I just don't believe this figure, and think it is either made up, or refers to a multiple house development site, not a typical self-build plot.

[ToughButterCup]

I'm off out to my shed to carve a massive wooden spoon-shaped object from a spare railway sleeper.

[nod]

1 hour ago, JSHarris said:

 

How can a 100 to 200mm difference in DPM level make a difference that is close to the cost of our whole house, inc insulation and airtightness?

 

I just don't get it, personally, and don't see where the planning officer, or planning policy, has any bearing at all on this for a typical solo plot, such as a self-builder might be interested in.

 

We had probably a worst case where levels were both critical and cost a lot of money.  This is a photo of our plot on the day we finally started doing the ground works (which excluded the foundations, as they were a part of a the passive package from our main contractor):

 

 

To the extreme right of that photo, under the overgrown hedge and to the right of the reflective marker, there is a mill stream, that runs through the whole village, rising from springs around 1/2 a mile away, and becoming a fairly large river about a mile or so downstream, where it joins the river Nadder.

 

The Environment Agency demanded a flood risk survey (understandable, given recent major floods around the country) but rather than pay the demanded £4,500 from the only flood risk surveyors the local EA office would accept, I chose to do my own, using flood risk data obtained, free of charge, from the EA, by a mix of using their publicly available data and making an FoI request for more data (taxpayers pay for this, so are entitled to see it).  What was clear was that there were going to be levels for certain areas that were mandated by current EA policy (nothing to do with planning, other than PPG25 placing an obligation on the EA to make a determination, in effect).  The vehicle parking area and garage finished floor had to be a minimum of 83.1m AOD.  There was no ability to negotiate on this at all, as this was the stipulated level above the 1 in 100 year flood event and everyone, from central government to insurance companies were taking heed of it.

 

Furthermore, the EA stipulated that the finished floor level inside the house must be no lower than 83.5m AOD, and this level was, of course, only aout 13 to 14mm above our DPM level (the DPM being level with the top of the slab, as mandated by the build system chosen).

 

The height of the DPM above the external ground level is determined by a few factors.  Firstly there is statute law that sets the height of the DPM relative to the outside ground level, in the form of the Building Act 1984, with amendments.  This law also stipulates elements that have made their way into Approved Documents (which are not law, but guidance) and these provide some clarification on how the law may be complied with.  There are some potential conflicts that need careful work-arounds, as the law is very badly worded, especially the most recent amendments.  For example, whilst stipulating the distance external levels have to be below DPM, the same law later stipulates a near level threshold for wheelchair access, which means being a bit canny and leaving a tiny vertical slot between the ramped entrance (in our case the rear door) and the house.

 

The only thing planning were interested in was the ridge height, a common restriction, I understand. 

 

So, tying all the legal requirements together, we had to have a drive that was no more than 400mm lower than the house finished floor level, we had to have an external level around the house that was greater than or equal to 150mm (the required separation from the DPM to external level).

 

Getting to the crux of the point being wildly exaggerated here, we had to level our site a lot, this is what it looked like just before the foundation team arrived, after all the ground works had been completed:

 

 

We removed around 900 tonnes of soil and mixed surface waste by this point, and still had to remove a further 200 tonnes to get the drive and garden levels right.  The total cost of all the earth removal, excluding the cost of the retaining wall, the putting in of service ducts and pipes, the installation of the sewage treatment plant etc is separately itemised on our ground works invoice.  We dug down around 2.5 metres to get the site level, and got stung for the highest rate of landfill tax for the top layer, as it was classified as mixed waste, because of all the trees, shrubs etc in it.  Even so, the total ex-VAT cost of lowering this site by 2.5m came to £11,170.80.  Had we needed to take the site down by another 200mm, I doubt it would have added more than £1000 at the very most to the cost.

 

So, how do you get a "saving" of £40,000 by not removing 200mm of soil from a typical self build site?  That's 3.5 times the cost of our entire cost to remove 2.5m depth of soil!  Frankly I just don't believe this figure, and think it is either made up, or refers to a multiple house development site, not a typical self-build plot.

We also had a fare amount of spoil to remove 450 off the whole site 

1.8 footings 

750 tons of muck away

8K

I raised the slab by 2 course Due to the Architecht trying to match my Dpc Height to the neighbours

200 year old Cottage 

 

[Jeremy Harris]

39 minutes ago, nod said:

We also had a fare amount of spoil to remove 450 off the whole site 

1.8 footings 

750 tons of muck away

8K

I raised the slab by 2 course Due to the Architecht trying to match my Dpc Height to the neighbours

200 year old Cottage 

 

 

Thanks, that tallies with our costs for removing soil and muck, and makes the figure of £40,000 to remove 200mm from  a typical self-build plot look seriously in error.

 

IIRC, our muck away trucks could take around 18 tonnes per load and were loaded with one of the diggers on site, probably the 15 tonne JCB. 

 

Assuming that the broken up uploaded soil was around 1.2 tonnes per cubic metre (probably a bit reasonable guess) then 200mm off 5 m² will be around 1.2 tonnes, so one muck away truck should be able to take away around 75m² of a 200mm layer.  Our plot total area would need around 10 truck loads to remove 200mm.  IIRC, we paid around £180 per load, including taxes, so that's a total cost of around £1800.

 

£40,000 to remove 200mm all over implies a plot size of well over 4 acres, and I doubt that there are that many self-builders that would need to take 200mm off an area this massive in order to get their house levels right.

 

Something here just doesn't ring at all true, and seems a bit alarmist to me.

 

[jack]

Rather than speculating about what Fredd's talking about, why not leave him to come back and answer the questions?

[Nickfromwales]

13 minutes ago, jack said:

Rather than speculating about what Fredd's talking about, why not leave him to come back and answer the questions?

I'm assuming he means £40k over time, not for a single build ?

@Fredd, your turn.  

[Jeremy Harris]

12 minutes ago, jack said:

Rather than speculating about what Fredd's talking about, why not leave him to come back and answer the questions?

 

 

Doesn't seem to be any speculation.  The statement's clear:

 

Quote

 

1 or worse 2 bricks difference in DPC can be a 5 figure sum in groundworks and muck away depending on size of build.

 

Tricks we have done in past, raise DPC by 3 bricks and dropp pitch of roof to keep ridge height with next door. £40000 saved.

 

£40,000 quoted

 

200mm quoted (two bricks high)

 

That's a house of well over 4 acres..........................

[Yzzy]

1 hour ago, recoveringacademic said:

I'm off out to my shed to carve a massive wooden spoon-shaped object from a spare railway sleeper.

 

This is literally the only bloody thing I understood from this whole thread.....!!!!!!

 

Can I borrow that spoon to slap my eyeballs out?

Edited February 7, 2018 by Vision Of Heaven
added an 's' .... shhhhhhh

[jack]

23 minutes ago, JSHarris said:

Doesn't seem to be any speculation.  The statement's clear:

 

Sorry, I disagree. Everyone's jumped on two bricks and £40k muckaway, but he talked about groundworks, muckaway, altered ridge heights and changes to ceiling heights in the initial post, and a "5 figure" saving for 1-2 bricks.

 

My point is that I think that rather than submitting any more arguments trying to prove him wrong, it'd be interesting to have @Fredd explain the figures. 

 

I absolutely agree that the proposed savings seem very high, and certainly that Fredd's initial post could have included more actual information. 

[nod]

17 minutes ago, jack said:

 

Sorry, I disagree. Everyone's jumped on two bricks and £40k muckaway, but he talked about groundworks, muckaway, altered ridge heights and changes to ceiling heights in the initial post, and a "5 figure" saving for 1-2 bricks.

 

My point is that I think that rather than submitting any more arguments trying to prove him wrong, it'd be interesting to have @Fredd explain the figures. 

 

I absolutely agree that the proposed savings seem very high, and certainly that Fredd's initial post could have included more actual information. 

I think he simply typed to many naughts

[Nickfromwales]

44 minutes ago, Vision Of Heaven said:

 

Can I borrow that spoon to slap my eyeballs out?

You may want it for the roots  

[Hecateh]

1 hour ago, Vision Of Heaven said:

 

This is literally the only bloody thing I understood from this whole thread.....!!!!!!

 

Can I borrow that spoon to slap my eyeballs out?

Plus 1

 

[nod]

Me thinks his post was perhaps tongue in cheek

ive been trying to work out if Fredd is an anagram for something 

[ToughButterCup]

Help yourselves folks; slaps all round

 

[Fredd]

morning you air tight eco builders!

 

my point here is not to let your architect set your DPC height he wont be the one digging out the muck and paying for it to be hauled off. Let him set the ridge height (if needed) and you work it down from there. Too much ££££ at stake.

 

You do not want to dig a big hole and put your house in it. 

 

This is my normal process now:

 

1. scrape off all the green crap 100-200mm. 

2. laser to see what levels are like. 

3. Hammer a spike into a corner, measure ridge height to adjoining and where DPC needs to be on the build, mark it on the spike. I use a leica D8 for this. cheap and brilliant little tool can even work out pitch.

4. Now if that mark is above ground, all well and good. if its the mark is minus more than 100mm then roof pitch it changed to accommodate. 

 

worst I've had is 550mm which we jiggered down to 220. Still a lot of wasted cash though.

 

The 40k example wasnt just muck away cost (15k) we had to get an adopted sewer moved as the footings were so  deep and too close. If we were 200mm higher then the sewer move would not have been needed. YOu drawn a diagonal line from your footing out into the build depending on depth and if it intersects sewer. ching ching. Oh yes the sewer company subs out the job, it gets costed by the subbie and you cough up. No other quotes obtained. Legalised scammery.

 

 

 

 

Edited February 8, 2018 by Fredd

[ToughButterCup]

Mornin' Fredd.

 

I'll get the tea on. Mind if Rollo does a shift today?

Been up all night makin' that sodding spoon, so I'm off back to bed.

[Jeremy Harris]

2 hours ago, Fredd said:

morning you air tight eco builders!

 

my point here is not to let your architect set your DPC height he wont be the one digging out the muck and paying for it to be hauled off. Let him set the ridge height (if needed) and you work it down from there. Too much ££££ at stake.

 

You do not want to dig a big hole and put your house in it. 

 

This is my normal process now:

 

1. scrape off all the green crap 100-200mm. 

2. laser to see what levels are like. 

3. Hammer a spike into a corner, measure ridge height to adjoining and where DPC needs to be on the build, mark it on the spike. I use a leica D8 for this. cheap and brilliant little tool can even work out pitch.

4. Now if that mark is above ground, all well and good. if its the mark is minus more than 100mm then roof pitch it changed to accommodate. 

 

worst I've had is 550mm which we jiggered down to 220. Still a lot of wasted cash though.

 

The 40k example wasnt just muck away cost (15k) we had to get an adopted sewer moved as the footings were so  deep and too close. If we were 200mm higher then the sewer move would not have been needed. YOu drawn a diagonal line from your footing out into the build depending on depth and if it intersects sewer. ching ching. Oh yes the sewer company subs out the job, it gets costed by the subbie and you cough up. No other quotes obtained. Legalised scammery.

 

 

 

 

 

 

I, and others here, must have had a real bargain deal in getting maybe 3 or 4 times that much muck shifted for a lot less than £15k, then.  In the scale of things, even on our pretty hard-to-develop plot, muck away costs weren't that massive when compared to some of the other costs.  If we'd wanted mains water that was going to cost us over £23k for example, so the less than £12k we paid to shift around 900 tonnes off site and dispose of it doesn't seem that high, and anyway it was factored in to the plot price when we bought it.

 

Anyone who doesn't get separate quotes for the contestable element of any utility works, like moving a foul drain, is unlikely to get a good deal.  The collective experience here is that a lot of the time using your own ground works contractor to do the contestable works and then only paying the utility company for the non-contestable element often saves a lot of money.  Certainly we did this, and knocked at least £2k off the price that the DNO had originally quoted.  Their costs for the contestable element were barking mad, but as they have to itemise them on the quote if you request it, there's no excuse for being ripped off by allowing them to sub-contract that element.

[Bitpipe]

2 hours ago, Fredd said:

 

You do not want to dig a big hole and put your house in it. 

 

 

 

I don't know, I quite like my basement. 

[Nickfromwales]

3 hours ago, recoveringacademic said:

Help yourselves folks; slaps all round

 

Don't let @Onoff see that ! He'll be off making the knife and fork to go with it.

[Nickfromwales]

@Fredd

See the patio slabs in that pic? How much compo do you think it took to lay those ? They're huge !

[Bitpipe]

12 minutes ago, Nickfromwales said:

Don't let @Onoff see that ! He'll be off making the knife and fork to go with it.

 

I thought it was a trebuchet...

[ToughButterCup]

Well since you pointed it out. let me tell you the story,

 

I had to take out a foot or so of topsoil, then put in 64 piles, bring in 400 tonnes of MoT1 for the piling mat , then there was the cage to put in, the wiring team had to come from Ghana, were all drunkards, so I sacked them : the NHBC got involved, but they were useless, so I asked a self  builder.

 

He did it on his own for half the price quoted by Wimpeys. 

Lovely bloke