Blogtastic!

[worldwidewebs]

I've decided to set up a blog. 

 

For now it's Wordpress only as I want to retain control but I may well duplicate it here if I get the time and people are interested. For those that are interested, it's here: https://selfbuildnoviceblog.wordpress.com

 

[Barney12]

Good work. Looking forward to following.

[Pete]

Great looking house. As Barney said, looking forward to following your build.

[worldwidewebs]

Cheers guys. I've no idea what direction I'll go with it but I think it'll end up more like a diary of sorts, hopefully with a few pics thrown in. I do have a very short attention span though so it may well go off-piste every now and again! lol

[gravelld]

A good choice to self host, but consider moving to your own domain if possible.

[TerryE]

BTW, just had a quick scan of your blog and you typically don't use MOT 1 for a passive slab,  but MOT 3 or crushed gravel over a fabric membrane.  This because you want the stone bed to be free draining.  However the crew do prefer to use MOT 1 for the last stone layer as this makes it easier for them to lay the blinding sand layer.   

 

The general area around the slab will get churned up from the stone delivery and laying, and once the crew have laid the blinding sand layer you've got a featureless "bowling green"  at least 1m wider on all sides than the former footprint.  They aren't going to want to wait around for half a day for some surveyor to turn up, so you need to be able to quickly and accurately mark out the slab corners.  So for this reason it is well worth you or your surveyor setting out some reference datum makers outside the dig area so you can triangulate or sight-line the former corners.

Edited September 5, 2016 by TerryE

[worldwidewebs]

@TerryE The type 1 was specified by MBC's engineer, although it will only be about 250mm thick. Below that is sand

 

We've had the dig area only marked up at the moment, but once the type 1 has been done and the groundworks guys go I'll get the surveyor to come back and mark the precise position of the slab - I'm guessing they'll use profile boards. It's all planned and in hand  (famous last words)

 

 

[worldwidewebs]

Just added today's little episode:

https://selfbuildnoviceblog.wordpress.com/2016/09/05/groundworks-begin/

[Pete]

Hopefully this will be us next year. I have already been doing a lot of the site preparation over the last year but seeing your build get under way has made me very envious. Keep up with the blog as I am sure it will help me and other's when we get to build our own houses. 

[worldwidewebs]

I think 'blog' is the wrong word. 'Blurt' is probably more appropriate! Not sure if it'll be much help as really it's just a story to myself for many years from now  

[TerryE]

OK, if your underlying base is sand then MOT 1 makes sense.

 

Unless MBC have changed their approach from every other slab that I know of, the same crew will do the ground works, EPS formwork, rebar and pour in one continuous operation over about 6-7 days.  There isn't a nice break to invite your surveyor back.

 

Have a chat with your MBC project manager.

Edited September 6, 2016 by TerryE

[jack]

Terry, I think he means groundworks in the sense of the stuff that happens before MBC arrives.

 

Is there an MBC start date?

[TerryE]

Even so my original comment applies: the MBC team will create a pad that is 1-1½m wider than the house footprint so any corner markers will get wiped out.  All www or his surveyer need to do is to bang in 4 rebar spikes well ouside this area to give two taught lines: one for the front and one for a side wall.  This will fix the slab precisely so the MBC crew will do the rest.

Edited September 6, 2016 by TerryE

[jack]

1 minute ago, TerryE said:

Even so my original comment applies: the MBC team will create a pad that is 1-1½m wider than the house footprint so any corner markers will get wiped out.  All www or his surveyer need to do is to bang in 4 rebar spikes well ouside this area to give a taught line for the front and a side wall and the MBC crew will do the rest.

 

In our case, MBC didn't go much beyond the position of the actual house with the blinding layer.  Certainly they didn't cover anything like the full surrounding metre of recycled railway ballast that we used as the base layer.

 

But agreed, external markers are desirable for sure.  We also had a height marker for FFL put in, which they appreciated.

[TerryE]

The FFL is a good point.  I just used my dumpy and a reference point at the pavement at our site entrance. The dumpy is optional so long as the reference is in line of sight / range of their site levelling laser.

Edited September 6, 2016 by TerryE

[Barney12]

We have an interesting challenge with this subject as our house design is split over two levels. with 600mm difference in the two.

Despite asking I still have no idea how the passive slab will be formed. I guess their structural engineers will decide! I'm just hoping we don't end up with the need for strip foundations and dwarf walls as well as the slab.

Add to this we also need to create a retaining wall as the plot is on a slope.

 

Here's a rough layout:

 

Blue (1m perimeter)

Green: level 1

Red: level 2 (600mm lower)

 

Edited September 6, 2016 by Barney12

[TerryE]

@Barney12, we had a ~450mm gradient over our slab footprint but have gone for a single FFL throughout.   The main driver here was keeping the ridgeline down.  The rear garden will be terraced, no lawn just paved areas and deep bed planters.  The lawn is on the level area out front.   I personally feel that having a split level GFL is a PITA and extremely wheelchair unfriendly. 

[worldwidewebs]

9 hours ago, jack said:

Terry, I think he means groundworks in the sense of the stuff that happens before MBC arrives.

 

Is there an MBC start date?

Correctamundo!

 

They start on the 26th.

[worldwidewebs]

10 hours ago, TerryE said:

OK, if your underlying base is sand then MOT 1 makes sense.

 

Unless MBC have changed their approach from every other slab that I know of, the same crew will do the ground works, EPS formwork, rebar and pour in one continuous operation over about 6-7 days.  There isn't a nice break to invite your surveyor back.

 

Have a chat with your MBC project manager.

 

The groundworks (site strip, level, dig, MOT1 etc) is all done in advance of MBC turning up - MBC will just lay the blinding layer and then the EPS (then rebar, UFH etc etc)

[worldwidewebs]

7 hours ago, TerryE said:

Even so my original comment applies: the MBC team will create a pad that is 1-1½m wider than the house footprint so any corner markers will get wiped out.  All www or his surveyer need to do is to bang in 4 rebar spikes well ouside this area to give two taught lines: one for the front and one for a side wall.  This will fix the slab precisely so the MBC crew will do the rest.

 

I'm doing a bit more than that actually. Once the groundworks guys have left, we will have MOT1 laid over an area 1m beyond the house footprint. The surveyor will then come back and mark up exactly where each of the corners of the slab will be. They have already marked levels on site, from which the dig and MOT1 are measured

[worldwidewebs]

Day 2 sneaky peek...

[Pete]

Who does the mains drainage? Been having a look at our MBC quote and it mentions passive foundation drainage pipes are laid to approx 1 metre from house for others to connect to. I think this to ensure the stone base is kept adequately drained and is not referring to mains drainage? Any advice would be great as I am in the very early stages of dealing with MBC. 

[TerryE]

What I did was to dig a sump hole and let the land drain vent into that.  OK, our plot was at the bottom of the garden or our current house, so it was convenient for us to do this manually. Even so,  our slab was lower than the gardens on 3 sides, so any heavy rain invariably created a moat around the house at its worst maybe 10-15cm below FFL.  Even so we used a pond-pump in the sump hole to dump the water onto the pavement and this could drop the water level maybe 20cm across the entire site in 3-4 hours.  The land drain and the MOT3 subbase did their job fantastically -- the moat around the entire house would drop and end up in the sump to be pumped away.

 

This was enough to keep the slab perimeter OK until our builder put in the land drains around 6 months later.

[Mikey_1980]

No it means mains drainage, they put 7 drain runs under our slab extending to 1 metre away from the base. They supplied all the pipes/bends etc. 

[TerryE]

@Mikey_1980, what MBC or any passive supplier does varies from client to client because soils conditions and water tables vary.  Mains drainage is only mains drainage when it is connected to the mains, which is very unlikely to happen these days.  Our slab design called for us to install a perimeter land drain at 0.5m outside the perimeter of our slab.  I cursed Hilliard (the MBC SE) for this at the time because installing it was a PITA for me, but I thanked him many times in retrospect over the next 6 months for him making us do this.  He knows his stuff