Self-build in Perth & Kinross - hello

[markharro]

Thanks - no the concrete will be left as our final floor - insulation is already under the slab.....its a passive house

[saveasteading]

9 minutes ago, markharro said:

the concrete will be left as our final floor 

You seriously need crack control then to stop cracks coming through any tile or vinyl finishes. What is on your drawings?

It should indicate steel mesh or nylon fibre in the concrete  and show positions of crack inducing joints. 

[markharro]

Yes but we are having no tile or any other finish - the concrete is the final finish

[saveasteading]

2 hours ago, markharro said:

the concrete is the final finish

Now that is scary.

Cracks are simply not going to be acceptable.

You must have a very specialist contractor who should know all this stuff.

[Kelvin]

Yes we’ve got two isolation joints cut into both our house slabs

[saveasteading]

M.

Go to a retail outlet like b and a and look at the concrete floor. That is a high quality concrete floor. I expect there will be cracks everywhere. The millions of visible  tiny cracks can be avoided or concealed in a domestic situation by compressing minerals into the surface.

Anything bigger will be a problem, especially if spills emphasise the cracks.

I'm deliberately worrying you here because the exposed concrete is a big risk.   What a shame if you spend a lot and are later disappointed, or tile over it.

Talk to your designers and the contractor, none if whom will pay for or live with it.

[Jenki]

17 hours ago, markharro said:

Yes but we are having no tile or any other finish - the concrete is the final finish

Have you gone for any dry shake toppings?

[markharro]

I spoke to many people and spent hours on this...the contractors told me that if I wanted expansion gaps cut to organise this with a 3rd party - I think that they dont normally do this as most clients tile or screed etc. I spoke to our previous groundworkers but they were nervous about hitting an UFH pipe. When the contractor's experienced team were on site they basically said don't worry about it - they seemed to think that the lack of frost or wind or extreme heat would remove most concerns. I had bought and was going to use Sika Proseal W immediately after the powerfloat but that needs a min temp of 10C and we had more like 2/3C so I scrapped that idea but still intend to use the Proseal once the temps heat up.

 

Can't do anything about it now and got too much else to attend to anyway

[saveasteading]

The contractors are right that this should have been in your design. As you aren't answering about the spec, I am now assuming there isn't one.

An exposed concrete surface is brave. Keep us informed how it behaves please.

 

There is no such thing as an expansion joint in a floor slab. Concrete shrinks.

 

I suggest you budget for tiling over next year.

[markharro]

Sorry I dont know enough to confirm the spec - it was steel reinforced but I dont know the class of concrete used. Sorry I prob meant contraction gap then! Someone else told me just to brush cement dust into any cracks showing. There is no budget for tiling. We are not precious and will be living in the house long term - at this point I just want a roof over our heads

[saveasteading]

13 minutes ago, markharro said:

at this point I just want a roof over our heads

OK I have misunderstood, and thought this was going to be an exposed aggregate concrete floor.

 

So what is done is done. If there is plenty of mesh placed properly then the cracking should be in control. There should be shallow slices, at doors to control the cracking there is neat.

 

Keep the slab damp and covered as long as you can to minimise the cracks.

This will also keep some heat in the slab which is a good thing.

 

I'm still nervous for you. The contractors don't seem to know much so keep asking here.

 

The worst that can happen will be ugly jagged cracking. The slab will still be full strength.  But as long as you don't mind the looks of it, we will just have to hope  for minimal shrinkage. 

[Kelvin]

I decided to build the retaining wall two blocks higher after approving it with the SE. Also tidied the site up ready for the garage this week and the house in two weeks.
 

First proper balls up though. The brickies built a headwork chamber for the borehole. Completely incorrectly. No idea what design they thought they were following. I was away at the time so only spotted it when I was passing the site in the dark! Promptly pulled it apart while the mortar was setting. Consequently I’ve had to delay the treatment plant installation which is a PIA but it’s not as if we have an urgent need for water right now. I just want to get the borehole pumping water. 
 

 

[Kelvin]

This borehole chamber is a proper balls up. The pump company are recommending that I don’t do a below ground chamber after all and fit one of their above ground kiosks for a few reasons: 

 

1. They take responsibility for it I just need to install the foundation. Problem here is we have already installed the foundation but it’s not to their design to fit the kiosk so we can’t bring the ductwork in from underneath so it will need to go through the side of the kiosk making it visible. 
 

2. Below ground chambers are prone to flooding at some point down the line in their experience almost no matter how well made. While this might only cause localised water problems there is an outside risk it could contaminate the water environment generally and if SEPA traced it back to us we could be sued big time. The risk of this is tiny. 
 

The downside of the kiosk is it’s another £1200 unplanned cost, it’s big and it’s green and very visible as it would be plonked on too of the slope, the foundation has been poured such that it will sit below ground therefore will be liable to flooding anyway. I can grade the land away from it on the three high sides to lessen the likelihood but it would still be sitting in a big well. 
 

I do wish they had told me all of this a few months ago when we discussed how to do the headworks. 
 

This is the SEPA recommended below ground chamber only when an above ground install is impractical. Would mean it’s mostly hidden. 
 

Edited April 3, 2023 by Kelvin

[saveasteading]

Never assume that contractors will look at drawings.

You really have to treat them as professionals ( to not fall out,) but meanwhile assume they will behave as children...so diplomatic questions....how are you doing this...can you show me on the drawing....oh you haven't got one handy.

 

Re the foundation. Got any drawings as built and now intended?

 

[Kelvin]

What’s been built is 1.6m square with the borehole in the centre exposing 520mm of pipe from the foundation. The ground level is 340mm above the foundation at the highest point and 100mm above it at the lowest point. This is the design the kiosk needs. The pump company have confirmed they can work with what we’ve done. 

 

Edited April 3, 2023 by Kelvin

[saveasteading]

That's good then that they can use it.

As to possible flooding, can't it drain through the hole for the duct?

Stop press, just seen the CS in the earlier post with the drain hole. Sorted then?

Edited April 3, 2023 by saveasteading

[Kelvin]

Not sure which hole you’re referring to. If you mean the hole in the kiosk for the duct then no as that needs to be completely sealed. 
 

This drawing (to rough scale) shows the problem as I see it if I use their kiosk. 

 

 

 

Edited April 3, 2023 by Kelvin

[Kelvin]

Another possible solution I’ve just thought of is a concrete well ring and lid of suitable diameter (800mm say) and the right height say 500mm (borehole needs to be a minimum height above ground of 300mm) 

[saveasteading]

No I meant the drawing with the brown shaded brickwork. it shows a drain hole.  but from your excellent sketch you can easily include a drain.

 

I see a pattern in your posts. We start with a problem and it is a race for us to help out before you have already got a solution.

 

So you will have a kiosk above the house. Does the pump feed an intermediate tank or go straight to  feed pipes?

 

We have a piped trickle by gravity so need a holding tank. A pump and filter system then feeds the house.

Our water is barely above freezing in winter : a problem you won't have.

[Kelvin]

Posting on here helps me think the problem through as my other half isn’t interested 😂 

 

It will feed a tank in the garage after filtration and then is pumped to the house. 

Edited April 3, 2023 by Kelvin

[saveasteading]

3 hours ago, Kelvin said:

will feed a tank in the garage after filtration

Why does it need filtration?

[Kelvin]

Water analysis showed nitrites in the water so needed a reduction vessel. We’ve had a bit of back and forth about pumping the water for a couple of weeks and testing again. 

[Kelvin]

Exciting day today. Garage has been delivered. 
 

 

[Kelvin]

Other half went to see our kit being made today. I was waiting on the portaloo arriving 🙄 

 

The middle picture is the flat roof cassette which is a SIP panel rather than the 302mm space stud everywhere else. 

 

Edited April 6, 2023 by Kelvin

[Thorfun]

exciting!