40m2 Extension Self-Build

[WoOt]

Time to give back a little to the community here. Have bit the bullet to extend the house myself (or as much as I can), so thought I'd share my progress here.

For context, I'm 38 and work in an office. So no real building experience, apart from watching hours of YouTube videos of other people building, and reading a lot of posts on DiyNot.

This is what I'm starting with:

 

[WoOt]

First things first. Removing the old back porch. The weather was great over the last two weeks, so this was quite fun. It helped that the roof wasn't actually fixed to anything and the bricks must've been built with a 57 to 1 mix. Honestly, the roof was just added on top and wasn't fixed to any walls! The majority of the bricks came off just by grabbing them and pulling up. Clearly a self-built addition of poor quality.

Bit of cleaning up to do, but almost done.

 

[WoOt]

After weeks of no progress, as I couldn't find a digger driver with time (just didn't feel confident enough digging close to neighbors house), I get a phone call at 16H30 last Thursday: "Are you home, can I drop by in 10 min for a chat.".

Long story short, guy finished a job earlier than expected 2 streets a way and can start on Monday - if he can leave the digger today. Considering I was starting to think I'd have to wait until next summer before someone became available I agree.

16H45, he's off back to finish something and I realize I have not figured out any of the details of the building yet, nor have I sorted Building Control.

A frantic 30 min. of rushing around trying to create locations plans and filling out some paperwork later and all is submitted and paid for. I was genuinely stressed about the 48H notice.

17H30, call the digger driver and ask whether he can sort out a dumper and some other bits. Luckily he agrees. Couple less things to worry about.

Oh, I have a digger behind the house now.

 

[WoOt]

Day 1 of digging today. Took out the old concrete patio (30m²) in about 2H in the morning, and started digging the footings. 80cm in we hit a lot of flint, so much so, the digger driver couldn't get through it. He advised calling the Building Inspector out for tomorrow morning and seeing if he'd be OK with that.

I tell him that the BCO previously advised I'd have to dig to 1m20, but digger driver insists this would be OK as it's solid ground.

We spend the rest of the day reducing the oversite to 40cm below DPM, and at 15H a grab lorry picks up all the old concrete.

Fingers crossed for tomorrow. Only having to go down to 800mm would save me a lot of money in spoil removal and concrete, especially as the digger driver said it would take another week to dig out that flint.

 

[BIGbadmarky]

Good luck with your build.
I wish I could have got a mini digger and dumper in for my build. I have to dig out my footings by hand...... through clay!

 

[HERTS P&D]

What are your plans?

Andy

 

[WoOt]

What are your plans?

The plan is somewhat fluid, but I'm hoping to end up with something along these lines. The bits in red are the extension.

 

[WoOt]

Day 1 of digging today. Took out the old concrete patio (30m²) in about 2H in the morning, and started digging the footings. 80cm in we hit a lot of flint, so much so, the digger driver couldn't get through it. He advised calling the Building Inspector out for tomorrow morning and seeing if he'd be OK with that.

BCO previously advised I'd have to dig to 1m20, but digger driver insists this would be OK as it's solid ground.

Tuesday morning the BCO came out and confirmed he was happy for us to only dig down to 800mm. He was also happy for us to use a 450mm wide bucket instead of the 600mm bucket. Talk about good news! Digger driver basically paid for himself now, as I'm sure I would've continued to the previously agreed 1.2m.

We continued to reduce the oversite and dig out the patio on Tuesday and also did a little more on the footings.

 

[WoOt]

Wednesday morning we dug out the soakaway and the rest of the footings. We finished about 5 min. before BCO arrived and signed off the soakaway and the footings.

He also offered quite a lot of useful advice (or homework, depending on how you look at it).

Wednesday afternoon concrete arrived, which I moved around the house in the dumper.

 

[WoOt]

Thursday morning I finished the soakaway, lifting the crates in place, wrapping them in geotextile and covering all sides in pea shingle. I ended up doing 150mm bottom and sides and about 250mm on top, covering it all with about 400mm of soil.

I was feeling it after shoveling 2 Ton of pea shingle in to a wheelbarrows, moving it about 50m around the house. Luckily the Type1 could be moved by the dumper (...).

22 Ton of Type 1 had arrived Thursday morning, and after 2 loads with the dumper, the thing broke! In an effort to keep going while the digger was there (and I didn't have to shovel and wheelbarrow it), I continued with a wheelbarrow. Using the digger to load it and wheelbarrows to move it. Managed to get it all done by the end of the day, but to say I was knackered is an understatement.

 

[kingandy2nd]

Good work! You’ve done more there that I did in about 2 years

Next time, hire a digger and drive yourself…it’s great fun!!

You’ve got a great space/garden there

 

[WoOt]

Good work! You’ve done more there that I did in about 2 years

Thanks @kingandy2nd I'm now on week 2 of recovery though

Next weekend I'm starting to build up to DPC, with the concrete for the floor hopefully following the week after.

Like you with your temporary first floor, I've got to think about it taking longer than normal. As I'm not doing a screed, my plan is to stay 10mm below DPC when I pour the concrete, so any water standing on the slab while I slowly build walls won't create (too many) damp issues. Plan is to bring it up to current internal floor level with self-leveling compound once the roof is on.

 

[kingandy2nd]

Thanks @kingandy2nd I'm now on week 2 of recovery though

Next weekend I'm starting to build up to DPC, with the concrete for the floor hopefully following the week after.

Like you with your temporary first floor, I've got to think about it taking longer than normal. As I'm not doing a screed, my plan is to stay 10mm below DPC when I pour the concrete, so any water standing on the slab while I slowly build walls won't create (too many) damp issues. Plan is to bring it up to current internal floor level with self-leveling compound once the roof is on.

I was left with a permanent pond in my new kitchen in about 2 inches of water…just invest in some good Wellington boots and ensure nothing is left anywhere near the ground inside.

Take your time with setting out. And I found a water level to be the simplest but best tool for getting all your corner heights right

 

[Notch7]

Plan is to bring it up to current internal floor level with self-leveling compound once the roof is on

In my experience concrete slabs on extensions are pretty difficult to get level.

One of the biggest problems is the DPM comes up the walls and there's nothing to mark around the perimeter.

I would be quite nervous about not doing conventional floating screed over insulation.

 

[WoOt]

Quick update, we're now up to DPC level. That was 1 foundation block on the concrete foundations + 3 engineering bricks on the outside, and 1 concrete block on the inside.