Self build in Essex

[Herbie]

Hey all,we are doing a self build in Essex. Stress levels are already high haha.

 

We are all ready to go, just getting quotes and working out the best way to tackle it. We are going with timber frame in a dormer style. Unfortunately we need piling done which is expensive. Engineer has also put piling in for the double garage and store lodge which surprised me.

 

If anyone has any good trades for around this neck of the woods let me know. We haven't made any agreements with trades yet. We were meant to be going with a building contractor who were going to be doing everything but they aren't taking any work on at the moment as this would definitely have been our ideal route.

 

Will take a look around the forums. Cheers.

[Dreadnaught]

Welcome to BuildHub Herbie! 

 

What type of piles are you going for? I will be using screw piles for my build in Cambridge (once restrictions are lifted).

[Herbie]

2 hours ago, Dreadnaught said:

Welcome to BuildHub Herbie! 

 

What type of piles are you going for? I will be using screw piles for my build in Cambridge (once restrictions are lifted).

Hey mate.

 

Well the quote we had and will likely go for is for 30, 300mm open bore piles to go down up to 10m. Not sure if that's screw piles? It's because the ground is soft clay with high plasticity and we will need to level the land somewhat. Do you know what foundations you're putting down after the piles at all? I've not even looked at quotes for this. The piling alone is close to 40k. Certainly eye-watering but if it has to be done, then it has to be done. At least you know your house won't go anywhere.

 

Meeting the pilers on site next week, so ill see if he has a better idea to reduce the cost.

[Dreadnaught]

No, yours aren't screw piles from the sounds of it. With yours, they will drill a hole, remove the auger, and then fill the hole with a metal cage and concrete.

 

With screw piles, the steel pile itself has a screw ending. It is torqued in to the ground and left there; no concrete involved. See picture below.

 

 For mine, above the screw piles I will have insulated reinforced concrete raft, 100mm thick, with 200mm edge "beam" and cross-ribs, all tied in with the screw piles. The insulation under the raft, which is often EPS, will for mine be PIR. It is all being designed for me by a specialist in Ireland. 

 

Edited May 14, 2020 by Dreadnaught

[Herbie]

8 minutes ago, Dreadnaught said:

No, yours aren't screw piles from the sounds of it. With yours, they will drill a hole, remove the auger, and then fill the hole with a metal cage and concrete.

 

With screw piles, the steel pile itself has a screw ending. It is torqued in to the ground and left there; no concrete involved. See picture below.

 

 For mine, above the screw piles I will have insulated reinforced concrete raft, 100mm thick, with 200mm edge "beam" and cross-ribs, all tied in with the screw piles. The insulation under the raft, which is often EPS, will for mine be PIR. It is all being designed for me by a specialist in Ireland. 

 

Ah right, any reason you went with that type of design at all?

We are going to look at some windows tomorrow. I think we can do that on current lockdown leniencies...?

[Dreadnaught]

It seems so long ago that these decisions were taken, I can barely remember now (!) 

 

Thinking back, I bought the plot with planning permission already in place (I subsequently resubmitted and changed it) but that already specified the screw piles, which were chosen principally for their minimal impact on the tree roots of the protected trees that neighbour the plot.

 

I chose the insulated concrete raft after looking at the alternatives, such as beam-and-block or timber cassettes. I liked that a raft can be used as a form heat battery, with embedded underfloor heating within it; an approach used by some of the other members on this forum. And it of course gives a solid-feeling floor with no bounce or flex.

 

 

[Herbie]

12 hours ago, Dreadnaught said:

It seems so long ago that these decisions were taken, I can barely remember now (!) 

 

Thinking back, I bought the plot with planning permission already in place (I subsequently resubmitted and changed it) but that already specified the screw piles, which were chosen principally for their minimal impact on the tree roots of the protected trees that neighbour the plot.

 

I chose the insulated concrete raft after looking at the alternatives, such as beam-and-block or timber cassettes. I liked that a raft can be used as a form heat battery, with embedded underfloor heating within it; an approach used by some of the other members on this forum. And it of course gives a solid-feeling floor with no bounce or flex.

 

 

Hey I know how you feel, time flies right! 

 

The only thing that worries me about embedding the UFH is if something goes wrong and it needs to be fixed/changed. Seems like a lot of work if it is in the raft. Maybe me overthinking it though.

 

Are you mains gas or going eco?

[Dreadnaught]

14 minutes ago, Herbie said:

The only thing that worries me about embedding the UFH is if something goes wrong

 

Understandable concern but consider that the water pipes buried in the raft are continuous, no joins. I suspect and hope that the chance of a problem is remote. And attaching those pipes to the steel mesh when the raft is being constructed doesn't cost much.

 

12 minutes ago, Herbie said:

Are you mains gas or going eco?

 

I have mains gas in the road in front of the plot and for a long time assumed  that I would connect to it. But with the arrival of electricity tariffs with overnight electricity as low as 5p/kWh for a nighttime window, I have been persuaded that installing an ASHP is a better solution, especially for the long term. 

 

[Ferdinand]

25 minutes ago, Herbie said:

Hey I know how you feel, time flies right! 

 

The only thing that worries me about embedding the UFH is if something goes wrong and it needs to be fixed/changed. Seems like a lot of work if it is in the raft. Maybe me overthinking it though.

 

Are you mains gas or going eco?

 

Putting the ufh pipes themselves in the the slab is not *that* expensive in the scheme of things.

 

As to maitainability long term,  if I have ufh in the slab, I thinnk of the lifetime as one generation, and if it breaks it would be replaced by something else (eg a ufh 18mm mat system, or rads, and a ASHP).

 

As notes, the bits in the raft are like a long hose pipe - very little to go wrong, which would usually be joints and gubbins - which are not buried.

[Tom]

18 hours ago, Dreadnaught said:

 

 For mine, above the screw piles I will have insulated reinforced concrete raft, 100mm thick, with 200mm edge "beam" and cross-ribs, all tied in with the screw piles. The insulation under the raft, which is often EPS, will for mine be PIR. It is all being designed for me by a specialist in Ireland. 

 

 

Are the screw piles themselves isolated from the concrete in the raft? Thinking about thermal bridging...

[Dreadnaught]

3 minutes ago, Tom said:

Are the screw piles themselves isolated from the concrete in the raft? Thinking about thermal bridging...

 

Its an understandable question but, no, the tops of the screw piles, which are capped, are embedded in the concrete raft, so that the dwelling's weight is fully transmitted through the piles and does not bear upon the ground (and so the tree roots are happy).

 

The issue of thermal bridging from the piles is occasionally raised. It is a marginal thermal bridge that can be taken into consideration in the overall thermal modelling. The piles can be sheathed with insulation for some of their depth if needed (not in my case). 

[Steve247]

I agree with @Dreadnaught that the thermal bridging is minimal, but there again I'll be using metal screw piles for my build too, linked to a RC raft with thickening to load bearing walls. UFH will be in the raft also. I'm going for ICF concrete walls (150mm core) as my quotes for ICF, all things considered were cheaper when compared with timber frame quotes. Also big added benefit of ICF means very little procurement time from placing order to having somewhat standardised ICF forms delivered and it won't take long to get the ICF up by hand and then one concrete pour.

Only issue I am struggling with.... is how to mark or accurately locate the UFH pipes ( hidden in the raft slab) and making sure the bolt fixings into the slab for my ICF alignment frames DON'T hit the UFH pipes. Any suggestions on this would be welcome. 

 

@Herbie Don't know what you're building but £40k seems a lot of money. Have you or more importantly your SE properly considered and valued (£) alternative forms of piles? For example.... Metal screw,  Driven...  precast concrete or indeed steel - with these 3 options there isn't any costly muck away and all the mess that goes with it, plus they are quicker too for installation, no curing time ( so you can load on to them straight away so no standing times and delay) no cutting down the concrete pile tops etc. If it were me, I'd be looking at other options and or another SE and make sure the right informed decision is made.

[Herbie]

7 minutes ago, Steve247 said:

I agree with @Dreadnaught that the thermal bridging is minimal, but there again I'll be using metal screw piles for my build too, linked to a RC raft with thickening to load bearing walls. UFH will be in the raft also. I'm going for ICF concrete walls (150mm core) as my quotes for ICF, all things considered were cheaper when compared with timber frame quotes. Also big added benefit of ICF means very little procurement time from placing order to having somewhat standardised ICF forms delivered and it won't take long to get the ICF up by hand and then one concrete pour.

Only issue I am struggling with.... is how to mark or accurately locate the UFH pipes ( hidden in the raft slab) and making sure the bolt fixings into the slab for my ICF alignment frames DON'T hit the UFH pipes. Any suggestions on this would be welcome. 

 

@Herbie Don't know what you're building but £40k seems a lot of money. Have you or more importantly your SE properly considered and valued (£) alternative forms of piles? For example.... Metal screw,  Driven...  precast concrete or indeed steel - with these 3 options there isn't any costly muck away and all the mess that goes with it, plus they are quicker too for installation, no curing time ( so you can load on to them straight away so no standing times and delay) no cutting down the concrete pile tops etc. If it were me, I'd be looking at other options and or another SE and make sure the right informed decision is made.

 

We had 3 or 4 quotes and these guys were the cheapest and came recommended via a friend, plus their quote was more comprehensive. It's apparently because it is soft clay so needs to be piled. I'm meeting the MD on site next week so hopefully get more clarity out of them. 

 

Maybe I'll save the money somewhere else down the line... or not haha.

[Nick Laslett]

16 hours ago, Steve247 said:

...Only issue I am struggling with.... is how to mark or accurately locate the UFH pipes ( hidden in the raft slab) and making sure the bolt fixings into the slab for my ICF alignment frames DON'T hit the UFH pipes. Any suggestions on this would be welcome. ...

 

This was an issue I grappled with for awhile. There is a post here already on the topic. They suggested bolting the Wall Braces to Scaffold boards.

 

https://forum.buildhub.org.uk/topic/8040-passive-slab-is-this-sketch-correct/?tab=comments#comment-137076

Edited May 16, 2020 by Nick Laslett