Amateur DIY Extension

Yes, all youve got to do is remove the brickwork from the inner skin where the door opening is.

It needs to be removed down to top of oversite.Then when you do the floor, the insulation will run across the door reveal and hit the back of the outer skin.

The screed and insulation needs dpm between it and the wall.

Either put in a few straps or some slates or similar to support the insulation across the gap.

Thanks Notch, I started another thread before I saw your reply - just to confirm, I can do this AFTER my oversite? So bring the concrete or insulation (I've not decided which way round yet) up to my second course of bricks, then take out the inner course where I want my door and screed it when I'm ready?
 
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Thanks Notch, I started another thread before I saw your reply - just to confirm, I can do this AFTER my oversite? So bring the concrete or insulation (I've not decided which way round yet) up to my second course of bricks, then take out the inner course where I want my door and screed it when I'm ready?

Yes -concrete first, knock out bricks run insulation across and screed.

If builders are wheelbarrowing they leave the brickwork near to oversite level.
 
Yes -concrete first, knock out bricks run insulation across and screed.

If builders are wheelbarrowing they leave the brickwork near to oversite level.

Riiight, that's all adding up a lot more now! Thank you!
 
I decided to buy an Evolution Disc Cutter for this project

One the best things i bought whilst doing mine! I've used it loads!

I did decide to pick up some Blakes profiles and I'm pretty glad I did

I didn't use Blakes but bought other profiles, absolute must in my opinion, plus when you've finished they'll still have a good second hand value.

I found that if you're just planning on doing a small bit of work (e.g., build up a corner) then hand mixing in the barrow was easier than dealing with getting the mixer and everything out. And on that note, I found evenings to be great for that - just a single small mix but spend some time getting a corner or two up. Then it just leaves you running in on a weekend, which also felt great.

I use my mixer for every mix, i find it too much like hard work to mix manually :LOL:. I'm not fast by any means but a small mix (my interpretation) lays me about 18 bricks and my double mix lays me 35-37 bricks (not surprisingly)! I agree, running in the brickwork is much nicer... kinda hate corners :mad:!

I used to do my mixes all day and then clean the mixer at the end, but now I just wheel the mixer out of the shed & load it up, then I hose the mixer after each mix so the mortar residue doesn't dry, plus you don't have to clean the mixer after finishing laying the last lot of bricks (knackered :sleep:). How many bricks did you lay on the hand mixed?

Keep up the good work.(y)
 
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One the best things i bought whilst doing mine! I've used it loads!

Yep, it's reallying paying for itself. Great piece of kit and much much nicer than using a grinder.


I didn't use Blakes but bought other profiles, absolute must in my opinion, plus when you've finished they'll still have a good second hand value.

Hope so, can't really justify keeping them around I don't think!


I use my mixer for every mix, i find it too much like hard work to mix manually :LOL:. I'm not fast by any means but a small mix (my interpretation) lays me about 18 bricks and my double mix lays me 35-37 bricks (not surprisingly)! I agree, running in the brickwork is much nicer... kinda hate corners :mad:!

I used to do my mixes all day and then clean the mixer at the end, but now I just wheel the mixer out of the shed & load it up, then I hose the mixer after each mix so the mortar residue doesn't dry, plus you don't have to clean the mixer after finishing laying the last lot of bricks (knackered :sleep:). How many bricks did you lay on the hand mixed?

Keep up the good work.(y)

I just find the mixer to be a real faff at times, but I should admit I've only done a few handmixes. For a small mix on the board that's only a couple of bricks, but good for just finishing something off. The barrow probably gets me about 10 - 20 at an absolute guess
 
Underground Drainage Inspection & Sign Off

Album here: https://imgur.com/a/nz5trJh

Not a particularly interesting or exciting update, but wanted to include it for those embarking on projects in future. I wanted to start backfilling my trenches as we've got an ever-expanding soil heap on the front garden that I'd like to get rid of and I also had some questions for BC so it seemed ideal.

So last weekend I got the rest of the underground drainage in, up to where an inspection chamber will go later on*. Had an initial panic when the pipe for the toilet (that's furthest from the house) was too high for the lintel, but after some checking I realised I'd gone a fair bit steeper than 1:40 (Relatively, I mean it wasn't like a waterfall!) so I had to pull it all back up and sort that. The final fit came out much more like how I'd planned, and the slope is pretty bob on.

One of the key questions I had for the inspector was regarding the pipes running through the gap as the regs state the need for a "rigid, inert board" and "compressible fill". I'd done lots of research but couldn't find many examples of it being done and no pictures etc, so left it. The BC Inspector confirmed that he was happy for me to fill the gap with pea shingle, put a bit of insulation or expanding foam above it and then my weak concrete mix above.

Other than that, points to note - I found the 4" grinder best for cutting and chamfering the pipe, and the spray silicone was great. I decided to use flexible joints either side of the lintels to create a pretend rocker pipe - not really required, but for the sake of £40 it was piece of mind.

*Finally, the reason for an inspection chamber at the top end is simply because I need an additional Tee for the extensions drainpipe gully, and adding a rodding point after that will start to take things into the grass. So I'm going to get the smallest IC I can find and pop it in there as the area will be paved anyway
 
Really enjoying this thread, will be bookmarking it for a possible similar endeavour myself.
 
Underground Drainage Inspection & Sign Off

Album here: https://imgur.com/a/nz5trJh

Not a particularly interesting or exciting update, but wanted to include it for those embarking on projects in future. I wanted to start backfilling my trenches as we've got an ever-expanding soil heap on the front garden that I'd like to get rid of and I also had some questions for BC so it seemed ideal.

So last weekend I got the rest of the underground drainage in, up to where an inspection chamber will go later on*. Had an initial panic when the pipe for the toilet (that's furthest from the house) was too high for the lintel, but after some checking I realised I'd gone a fair bit steeper than 1:40 (Relatively, I mean it wasn't like a waterfall!) so I had to pull it all back up and sort that. The final fit came out much more like how I'd planned, and the slope is pretty bob on.

One of the key questions I had for the inspector was regarding the pipes running through the gap as the regs state the need for a "rigid, inert board" and "compressible fill". I'd done lots of research but couldn't find many examples of it being done and no pictures etc, so left it. The BC Inspector confirmed that he was happy for me to fill the gap with pea shingle, put a bit of insulation or expanding foam above it and then my weak concrete mix above.

Other than that, points to note - I found the 4" grinder best for cutting and chamfering the pipe, and the spray silicone was great. I decided to use flexible joints either side of the lintels to create a pretend rocker pipe - not really required, but for the sake of £40 it was piece of mind.

*Finally, the reason for an inspection chamber at the top end is simply because I need an additional Tee for the extensions drainpipe gully, and adding a rodding point after that will start to take things into the grass. So I'm going to get the smallest IC I can find and pop it in there as the area will be paved anyway

This is all really helpful stuff, so thanks for sharing.

Loving the improvised access for the cat flap :D
 
Drain Test

Forgot to mention this in the other update, but the BCO didn't seem particularly fussed about formal drain testing. I explained that I'd attempted a water drop test by bunging the manhole but it leaked through the clay and that was that. But, being a bit paranoid I really wanted to properly test the portion that's under the slab.

So, this is what I did, I picked up an inflatable bung, some 8mm pipe (Because that's what came with the bung) and some connectors - stuffed the thing all the way down the long run of pipe (https://imgur.com/ngJDLLj) and inflated it. Then I added a temporary upstand at the end, because I couldn't bung it due to the inflatable pipe.

Anyway, it worked great and I filled the new waste connections up to the brim and watched as they didn't move a mm over an hour. So that gave me a lot of confidence to carry on forwards, and also a baseline to test against once the hardcore was down. At some point I'll do similar to test my new gully connection and everything before backfilling it all.

Oversite Preparation & Sign Off


Keep on going! Pics here: https://imgur.com/a/KV0gcrX
(For some reason, I didn't take many pics of this stage but it's not hugely technical!)

The first thing was to dig out the oversite (And how I wished I'd taken some off when I had the digger at the start). Because part of the "plot" had already been built on, I suspect the soil had previously been backfilled - to save any drama, I decided to just dig all the way back down to the sand layer. I also rediscovered the dreaded lead water pipe, so I simply reburied it with building sand. This was actually done before the drains above, and you can see on those pics where I've dug down.

After the drain sign off and agreement about the pea shingle approach for them, I moved back onto the oversite.

Next thing was to haunch in the rest bends. I couldn't decide if this was absolutely required or not, but it felt like the right thing to do. For ease and speed, I used quick setting cement and ballast in a dry-ish mix and mixed each haunch separately so as not to run out of time. Nothing special here, just put cement all around the bend and tamped it down slightly.

While that started to set we moved onto the 10mm gravel / pea shingle. I'd hired a little tracked dumper and enlisted some help (Because, frankly, I have enough back trouble as it is and this project was never about killing myself) and loading and moving the pea shingle was a doddle. We literally just poured it all around the pipes and through the lintel opening and then kept going until the two pipes were covered under a mound of it. To be clear, I didn't FILL the space with shingle, just mounded over the pipes.

Next in was the Type 1 MOT. This took me a bit by surprise because it's next to impossible to dig out of the bulk bags so we had to cut them open and spread it over the front drive. But once down, it wasn't too bad. To get the height, I'd sprayed a course of bricks on the wall, as I knew I was going to be above the minimum 150 anyway, I decide to err on the low side and make up the rest of the floor with extra concrete,insulation and screed rather than risk being too high.

We put it down in layers, wacker plating in between. Never having laid Type 1 before, I felt that there were too many big stones and some of them didn't really seem to compact - the small stuff was great, almost created a tarmac type surface. But, truth be told, I figured if the last concrete slab that was there could survive 50 years on top of loose soil so long as I'd gone over mine with a wacker it'd be fine. I didn't worry too much about levels - as I say, we'd marked the wall for the edges and the rest was mostly by eye

And finally the last bulk material was building sand, for binding. I opted for something around a 2" layer of sand - initially we just chucked a load in thinking we'd be able to level it fairly easily. It wasn't too bad, but at this stage I was still considering putting insulation down straight after and I wasn't happy so I decided to chuck in two lengths of CLS at the height I wanted (i.e., dug out a strip of sand and put the timber in there) and then used a long spirit level to "screed it". Didn't take long, but the end result was far better.

Struggled a bit with the wacker plate, probably because of the small area - it seemed to just keep pulling up the sand and making a mess of the place. In the end I just compacted it in straight lines, picking it up and putting it back to the start after each line. Probably a whole load of overkill, but I think it finished off the prep really nicely and the surface is rock solid.

After this, I retested my water pipes just to make sure I hadn't broken anything!

Aand then I covered the whole lot with DPM, just need to tape up around the pipes before the concrete goes down.

Finally, I'm happy to report that a BCO came out to inspect and has cleared the work.
 
After this, I retested my water pipes just to make sure I hadn't broken anything!
I assume there is a small risk with wackers that it could crack the drain pipe under your shingle/type 1, is this what you were worried about?
 
I assume there is a small risk with wackers that it could crack the drain pipe under your shingle/type 1, is this what you were worried about?

Pretty much - I'm sure it's just paranoia on my part as they're incredibly strong pipes, but I figured it was the last chance to fix anything before it gets expensive
 
Costs?

After this weekend I'm having to take a few weeks off the project, though I'm going to make a concerted effort to finish totting up all my costs so far. I've been recording as much as I can, from tool purchases, materials, hire, skips etc.

I thought it'd be fun to ask the following questions:

  • Bearing in mind the need to buy a whole set of tools for this, realistically what would you expect a DIYer to spend so far.
  • If you didn't want to lift a finger, how much you pay a designer and builder to get this far.
This far being, on a 3m x 2.7m extension:
  • Draw up basic plans for builder, building control and planning department (issuance of an LDC)
  • Demolish existing utility room, existing concrete floor and external concrete slab, including disposal
  • Dig foundations, concrete, build footings to DPC including soil disposal
  • Install new drains, including replacing existing house gully
  • Install new concrete ground floor (not including insulation)
I'm going to be as honest as I can with my costs, accepting that often I went and purchased the wrong thing, or too much or whatever while also acknowledging that it's not meant to be a shoestring budget build, but rather an enjoyable project!
 
Very helpful thread.
I am hoping to undertake a similar task, I want to build a conservatory with a tiled roof which is a continuation of the existing kitchen roof and fit large roof windows and mainly glass front and sides, sitting on dwarf walls. My question I hope you can help me with is what size foundation do I need for a double brick wall bearing in mind it has to support the weight of the roof.
It is a traditional 3 bed semi with the kitchen extending to the rear of the house.

Keep us up to date with your project.

Andy
 

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