Mike's ext'n & renovation (solar panels)

[Rod]

I'd go with Steve but why use cheap bricks I always thought the ones "underground" had to be durable, engineering types?

Rod

 

[Mike G]

Yep, Steve's got it spot on.

It is very difficult to get a foundation perfect, and it is easier to build up a mortar course under a brick, or to chop a brick down a bit thinner (buy one with a deep frog), to get to coursing. Trying to adjust a block by say 10mm would be very difficult indeed.

"B" because it is the critical one for the timber frame. A is essentially decoration. Besides, blocks are easier to get exactly right than bricks.

Bob..... the timber frame supports the roof, so I'll crack on with B, then the frame, then the roof, before doing the inner blockwork skin "C". Doing masonry in the complete dry is a luxury not many bricklayers ever experience!! "A" can happen at any time, but I don't like leaving jobs too far out of order, so i won't leave it long.

 

[9fingers]

Y
Bob..... the timber frame supports the roof ...

Ah! I did not realise that. My only experience has been with traditional brick and block building where the inner block skin carries the roof.

Learning all the time! - not that I anticipate any more building projects now. I plan to leave this property in a box, probably of my own making if that is not too macabre :lol:

Bob

 

[Mike G]

I only got half a day on site today. I quickly finished the setting out left from yesterday, and made a gauge rod:



Sorry the photo doesn't show up well.....it's only a piece of wood marked up at 65mm & 10mm intervals, denoting brick and mortar courses.

I didn't show this a few days ago when I did it, but it's important. It is the levels peg for the extension floor. By putting a spirit level through a window and measuring down I transferred finished floor level to the peg, then marked down 75mm for screed, 100mm for insulation, giving me the critical SSL (structural slab level). That peg will stay in place for months.



A whole lot of render fell off the old plinth today, and this is why:



They'd rendered onto soil. I'm pretty sure that's not the right thing to do......

Then it was time to knock up some mortar and lay some bricks.

Remember what I said about being able to adjust bricks easily if the foundation concrete isn't perfect?



Frogs up where the levels are fine:



Frogs down where I have chopped the bricks and need to get them low:



Here's one corner done:



And another:



It doesn't look much for 4 hours work, but I'm happy with that. The important thing (for me anyway), is that it is accurate.

 

[Mike G]

I've been very slow. The weather hasn't helped, and I've had to do one or two other things, but I thought I would update the thread with a progress report.

Here is where I have got to:



Here is the start of the fireplace:



An overview, from the top of a step ladder:



Right, I know how much you all like something to puzzle over. Can anyone explain what is going on here:

 

[9fingers]

Are you fitting an air intake for a woodburner to save burning pre-warmed air.

If you have not thought of this, it is well worth putting in at this stage.

Bob

 

[RogerS]

Are you fitting an air intake for a woodburner to save burning pre-warmed air.

If you have not thought of this, it is well worth putting in at this stage.

Bob

I think it's the Dutch who have twin concentric flues where they draw down air to feed the fire from the top of the flue and so it's already been warmed by the hot air going up the inner flue.

Mike..pardon me for asking but I'm surprised that you are having a fire. Surely that creates lots of draughts etc/ heat loss etc?

 

[Mike G]

Are you fitting an air intake for a woodburner to save burning pre-warmed air.

If you have not thought of this, it is well worth putting in at this stage.

Bob

Bugger. That was quick. That's exactly what this is: an opening in the blockwork for the vertical element of a duct bringing in fresh air to the underside of a woodburning stove.

 

[TrimTheKing]

Without going back through the thread, didn't he say earlier it was a fake fireplace…?

:eusa-think:

Cheers
Mark

 

[Mike G]

......Mike..pardon me for asking but I'm surprised that you are having a fire. Surely that creates lots of draughts etc/ heat loss etc?

Roger, there will only be a fake fireplace in the lounge, albeit properly built with an oak bressumer. It is actually structural, holding up a major beam which supports the 1st floor and the roof. The woodburner will have a flue, and is room-sealed. In other words, you would have to open its door to let cold air into the house. These super-insulated houses are so efficient that sometimes the underfloor heating is a sledgehammer to crack a nut. We will probably be able to be without central heating until after christmas typically with a tiny woodburning stove. It will have a direct connection to the air supply (ie, not draw any air from the room, as it has a spigot on the bottom which fits directly in the air supply pipe)

 

[AndyP]

Thats what I was going to say but it took me so long to write on the iPlod that there were at least 3 replies when I came to send it.

 

[9fingers]

Are you fitting an air intake for a woodburner to save burning pre-warmed air.

If you have not thought of this, it is well worth putting in at this stage.

Bob

I think it's the Dutch who have twin concentric flues where they draw down air to feed the fire from the top of the flue and so it's already been warmed by the hot air going up the inner flue.

Mike..pardon me for asking but I'm surprised that you are having a fire. Surely that creates lots of draughts etc/ heat loss etc?

Getting flue temperatures right is an artform. Too cool and the either fire wont draw or the liner gets tarry deposits leading to flue fires and too hot is inefficient.

Bob

 

[Mike G]

I was just cracking on with the masonry, but around Wednesday or Thursday last week got utterly fed up with wading around in mud.......so decided on a change of tack. I am going to get the concrete base down ASAP, so that I have somewhere solid and clean to work on. This meant putting a couple of pipes in (one foul drain, one air supply pipe for the woodburner), filling in the gaps in the hardcore, doing some shuttering, then blinding the site with sand, and finally putting some polythene down.

Batteries went flat on me, so I only have these two photos. Firstly, the utility room base, showing shuttering on the right, the foul waste surrounded by pea-shingle, and some hardcore:



Secondly, the blinding started on the two storey part of the building. Note the shuttering set 6 or 7" off the side of the existing house. This is to enable me to dig out foundations underneath the existing house when I come to renovating it. This is going to mean some interesting temporary junctions between new and old.



Since then, I have spread, tamped, and levelled the sand. The area of concrete I am going to pour is 55.4 sq metres. Six cubic metres (the contents of a concrete lorry), divided by 55.4 sq metres equals 108mm, so this is the depth of concrete I need to lay. To achieve this, I cut a notch out of the end of a long length of 6 x 1, attached my spirit level to it, and using the notched part on top of the brickwork and formwork, I worked the sand until it was exactly 108 mm down all over, and level.

Tomorrow I lay the plastic DPM, and start preparing a chute for the utility room base, which is hard to get concrete to. Then concrete on Tuesday, and resume brickwork on Thursday.

 

[StevieB]

Looking good Mike, especially given how wet (and Foggy) it has been here for the last week or so.

I will be interested to see how you manage the foundations you mention on the existing build - 6 inches is not a lot of space to work in!

Steve

 

[Frank]

Best of luck with your concrete pour Mike, from the looks of the up coming weather you will need some luck.
I'm just hoping for a good frost on my brussels before Christmas.


Kind regards,


Frank

 

[Mike G]

I will be interested to see how you manage the foundations you mention on the existing build - 6 inches is not a lot of space to work in!

Steve

Well, you've spotted the hardest thing about this whole job, Steve. I am hoping that I can remove the existing plinth in sections, knock the pegs out of the M&T joints, take the timber away to first floor level (in sections), and having previously removed the existing floor slab, then have plenty of room to get a mini digger in to dig a footing. 225 + 150 each side is 525.......and I will only need a 400 wide footing, so if everything falls into place, I should have loads of room. Then rebuild the plinth, and put the timber back where it came from.

One suspects that may all be wishful thinking. Until I bash all the render off the existing house, I won't know what I am dealing with, so until then this hangs over me like the sword of Damocles.

 

[Mike G]

Best of luck with your concrete pour Mike, from the looks of the up coming weather you will need some luck......
Frank

Thanks Frank. I've picked Tuesday because the forecast is good for here.

 

[Rod]

Good luck especially doing building work this time of year.

Rod

 

[Mike G]

Good luck especially doing building work this time of year.

Rod

Thanks Rod. Once that concrete is in the ground, I'll be out of the mud. A week or so of bricklaying, a week or two of timber framing, and then I'll be building the roof......and after that the weather can do what it likes.

 

[Mike G]

Here is the blinding all but finished. After this I just tamped it with a scaffold board to get it flat and firm.



I mentioned yesterday my little jig for getting the sand (and thus the concrete) to exactly the right depth. Well here it is:



The next job was the DPM (damp proof membrane: a plastic sheet under the concrete slab to prevent moisture penetrating the building from below). There is a little bit more to this than meets the eye, particularly if there are joins, as in this case. The plastic sheet is 4 metres wide. This meant 4 pieces across the width of the extension, thus 3 joins. Now, joins are supposed to lap a minimum of 150mm and be taped, but mine lapped about 600mm simply because of the size of the footing and the plastic. There was no point reducing the lap and putting the spare in the bin, so big laps.

When laying the sheet, ask yourself where the concrete is being poured, and lap the sheets in such a way that the flowing concrete isn't trying to push under the next sheet as it flows over a join. Think of it as wanting the concrete to flow downstairs, rather than upstairs. You also have to have lots of slackness in the polythene, because the concrete will stretch and pull it into every corner, and the last thing you want is a rip. Mine is quite an awkward shape, so lots of folding, and lots of slack. Weight everything down with some blocks when you have it in the right position, then tape up the joints with the specialist tape made for the purpose:





Note the large amount of plastic fixed up the wall of the existing house. This is to make a good lap with the new slab under the existing house in the future, but also to keep concrete out of the 6" void that I mentioned yesterday. I want that clear.

Annoyingly, the brand new plastic seems to have a few manufacturing flaws like this:



The repair involves taping a large patch, about a foot square.

 

[RogerS]

Mike, I understand your rationale re 'pouring concrete downhill' but, surely, if the joints are taped then it doesn't matter which direction the concrete is poured?

 

[Mike G]

If the tape were infallible, Roger, you'd be right. But with damp polythene, and sand around from the blinding, even with an array of towels it is difficult to get a couple of good clean surfaces and a guaranteed bond.

 

[Wizard9999]

Annoyingly, the brand new plastic seems to have a few manufacturing flaws like this:



The repair involves taping a large patch, about a foot square.

Mike

I put my DPM in over the weekend and found exactly the same thing, right in the middle of the roll so without doubt a manufacturing fault not damage from transit. I took a photo and plan to write to manufacturing to tell them I am unimpressed. My was from Visqueen.

Bit worried my patch was not big enough though from reading this , although as I joined mine first and then moved it in to place I did put a patch on both sides.

Two questions if I may...
1. Whilst there is not much rain forecast this week one of my concerns is what to do if I do get water laying on the DPM before the concrete pour. Can't really get the water out as I have two blinking great sections of steel reinforcing mesh on top of the DPM now.
2. Like you I have loads of slack DPM around the edges of my slab. If I didn't have this I would use the shuttering as something to rest a board across the base to initially level the concrete, but I worry that if I do this by putting the board on top of the DPM the board cold damage the DPM.
Any words of wisdom from the master on these two issues?

Again, your pace of work is stunning and it is all looking very good.

Terry.

 

[Mike G]

Hi Terry.

A patch on both sides is a great repair. Don't worry. Nor worry about water in the "pond". The concrete will push the water out. The worst that can happen is a film of water on top of your finished concrete, and you can soon push that off with a broom before the concrete sets. The concrete is so much heavier than water that the water always floats to the surface, immediately, and will get pushed away as you tamp. It doesn't mix with your concrete, unless you allow it to stay on the surface after you finish tamping.

As for tamping with the DPM in place..........well, it's standard practise, and I have never heard of damage to the plastic. I shall be doing just that myself, although obviously you do take care. A bigger deal with this situation is that the folds in the plastic around corners become very hard and prominent when the concrete has pushed everything tightly to the formwork, and that can make finding the top of the formwork a bit awkward when you are tamping.

Talking of tamping: prepare your tamper beforehand, put some handles on it, and make sure you have another person there to help at the appropriate time.

Have fun with the pour! Do a last check on your formwork.....make sure it is strong enough to resist bowing under the pressure of many tons of liquid.

 

[RogerS]

Mike, your nifty sand levelling jig. Is it a scraping motion or a tamping motion that you use? Presumably you need three people. One at each end and one person end on to watch the spirit level bubble? Those bubbles are very small...just wondered how easy it was ?

 

[Mike G]

Mike, your nifty sand levelling jig. Is it a scraping motion or a tamping motion that you use? Presumably you need three people. One at each end and one person end on to watch the spirit level bubble? Those bubbles are very small...just wondered how easy it was ?

Tamping the sand was a quick one man job, just scraping and occasionally tamping a strip 3 or 4 feet wide around the perimeter, then using a straight edge to infil the stuff in the middle. For doing concrete, there is no need for a spirit level, as you have formwork all round and your tamper is long enough to span across. It's like levelling off a tablespoon of sugar using a knife.

 

[RogerS]

Ah, my mistake. Seeing the spirit level there I'd thought you used it to keep the jig level. But it's just storage, yes?

 

[Mike G]

No, it's to get this jig level. But this jig isn't what I would use for concrete, this is only for the sand blinding.

 

[Wizard9999]

A patch on both sides is a great repair.

Good news, thanks.

Don't worry. Nor worry about water in the "pond". The concrete will push the water out. The worst that can happen is a film of water on top of your finished concrete, and you can soon push that off with a broom before the concrete sets. The concrete is so much heavier than water that the water always floats to the surface, immediately, and will get pushed away as you tamp. It doesn't mix with your concrete, unless you allow it to stay on the surface after you finish tamping.

Even better news, as despite the forecast for "light showers" I lay awake for a large part of last night fretting as the rain poured down!

As for tamping with the DPM in place..........well, it's standard practise, and I have never heard of damage to the plastic. I shall be doing just that myself, although obviously you do take care. A bigger deal with this situation is that the folds in the plastic around corners become very hard and prominent when the concrete has pushed everything tightly to the formwork, and that can make finding the top of the formwork a bit awkward when you are tamping.

Talking of tamping: prepare your tamper beforehand, put some handles on it, and make sure you have another person there to help at the appropriate time.

Have fun with the pour! Do a last check on your formwork.....make sure it is strong enough to resist bowing under the pressure of many tons of liquid.

As ever, your wise counsel is ery much appreciated.

Terry.

 

[Mike G]

After about 18 hours of rain yesterday and overnight, this sight greeted me this morning:



I spent an hour or so bailing, and discovered a big problem. You can't see it in the photo above: the air-supply pipe had popped out of the ground. Yep, they float. The building inspector turned up and could see the pickle I was in, but that I was doing all the right things. He was happy to let me pour concrete tomorrow, knowing that I'll have everything ready.

I turned back the plastic sheet, and the sand had turned to quicksand.



This is the bouyant pipe. You can see how it has picked up the form-work, which should be flush with the top of the bricks:



I went and hired a sump pump, and whilst it was running, I built a chute for the concrete at the utility end of the build. I forgot to take piccies with the sides on, or the polythene in position, but you'll see them tomorrow with concrete puring down it.





I'll have to get up early in the morning:



The pump still hasn't cleared everything. Once the water is away it will only take me half an hour to sort the pipe out, touch-up the sand, and relay the polythene.

 

[Wizard9999]

I spent an hour or so bailing, and discovered a big problem.

Mike

I hope you have time in the morning to get everything you need to do finished, fingers crossed. But I am confused. Given your post earlier today re water on the DPM not being a problem, why did you have to bail out? Was it only to get to the buoyant pipe, or is there a limit to how much water is acceptable?

Terry.

 

[Mike G]

It wasn't the water on top of the DPM which I bailed, particularly, it was the 9 inches of water in the trenches which was at the same level as the water under the DPM. In places the DPM was floating. Reducing the general level of water within the excavation was my aim, and, having had a look this morning, I am going to be OK for concrete in a couple of hours time.

 

[Wizard9999]

It wasn't the water on top of the DPM which I bailed, particularly, it was the 9 inches of water in the trenches which was at the same level as the water under the DPM. In places the DPM was floating. Reducing the general level of water within the excavation was my aim, and, having had a look this morning, I am going to be OK for concrete in a couple of hours time.

Mike

Sounds like you had even more rain on Sunday evening Han we did. Glad you're back on track and hope all goes well today.

Terry.

 

[Rod]

Brings back lots of memories - Oh the joys of working in wet weather - though I suppose a hard frost is worse when laying concrete?!!

If you hadn't suffered the other issues, I suppose filling the air duct with water would have kept it down - then suction pump it out afterwards?

Hope everything goes well?

Rod

 

[Mike G]

We're done. The concrete is in the ground, tamped & levelled:





The chute worked extremely well. I've turned the plastic up here and put a block in the way to stop the rain running down it and washing the "fines" away below.





It was hard work, as I only had one friend helping. In the middle of the job it poured with rain for half an hour, not only making the job pretty miserable, but leaving me with quite a bit of water puddling on the surface. this made tamping difficult. At the end of the tamping, I pushed most of the spare water off the end and into the trenches.

Most pleasing of all........I had 2 buckets full of concrete spare at the end. That is just about perfect in terms of judging concrete volumes, so I needn't have lain awake in the middle of last night worrying after all!!

 

[RogerS]

Well done, Mike. You must be dead chuffed. Time for several beers, I think.

:eusa-clap: :eusa-clap:

 

[Robert]

Amazing progress and fascinating to follow.

Thanks for taking the time to keep this updated so regularly.

Just thinking... I don't think I've ever seen a brand new scaffold board before

 

[Mike G]

Just thinking... I don't think I've ever seen a brand new scaffold board before

I haven't either, other than in a pile at a Builder's Merchant. Now I own four :eusa-dance:

 

[Mike G]

Well done, Mike. You must be dead chuffed. Time for several beers, I think.

:eusa-clap: :eusa-clap:

Thanks Roger. Yes, I'm very pleased indeed. Getting the oversite poured is one of those landmarks in a job: digging the footings, oversite, finishing the roof, weather-tight (usually when the windows go in), breaking through (where appropriate), plastering. All moments for a self-congratulatory pat on the back, and a celebratory cup of tea .

 

[9fingers]

Less of this supping tea Mike! You have a couple of hours daylight left, time to knock up some muck and get some blocks laid!! :lol:

I always think this is the best bit of a building project as the new work rises out of the ground. Thanks for the dedication to posting in the topic.

Bob