Box screed sand and cement - internal

Cool, that makes sense thanks. Pictures to follow.... as soon as the blocks have dried a bit more.
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Just finished yesterday in fact, only just got round to pictures...

Blocking the wall was fairly straightforward, no problems there, you can see the wall up the lintel is plumb, then the builders wall from 1974 is definitely not plumb!
You can also see where i've tried to feather in the skim on the ceiling, not easy and I dont think it'll look great once painted, will multifinish sand down at all, gently?
The actual float coat was ok, far more difficult than it should have been - i need more practice for sure. I found that if i tried to fill out in one coat it just pulled off the wall, so i did it fairly thin, then went back to it an hour later or so and made it up to the thickness needed. Is that a good method? I didn't PVA the blocks, i just moistened them, but not too much. The render went on better when i mixed it fairly wet, for the second coat, still dried pretty quickly. When should i rule off with the feather edge too, i tried to do it pretty much as soon as i'd got it on the wall, whilst it was wet, this seemed to work out ok, but not sure if it's correct? Pretty flat though, except in the corners, it's a little wavy... bit probably still better than the original builders walls.
Have i scored/keyed it enough? I'm going to skim one side on Monday (float done on Saturday so a good week to cure) and the other side in a few months... Should i PVA either side at all first?

Criticisms welcomed, if constructive, I definitely have a lot to learn...
Yes you have keyed it enough you dont have to go to deep when you do the other side try and do it in a figure 8 pattern, you can either use water or pva but seeing you will have to pva the edges "overlap by about 6ins" you may as well use pva get a sponge or damp cloth and clean the muck off the edges first
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As one amateur to another, try to avoid feathering in (it's a difficult skill to master) - far better to butt up where you can and easi-fill/sand down if necessary. Hopefully you've finished your render 3-4mm back from the adjacent plaster? You need to consider the vertical join between the new blockwork and old brickwork which is prone to cracking (especially if not keyed in), as is that area round the lintel - I would have hacked back some of the existing plaster and set some mesh in there to bridge it or dabbed some plasterboard over it.

As to the application of the render, thin layers can be helpful for us beginners, but equally important is not overworking it - this is what makes it fall off - you need to push the render onto the wall, try to get it as flat as you can with a few strokes and then leave it - whatever state it's in. Hard to know when to start the next coat, but if the first coat moves when you try it's too soon. If you leave it overnight (often not a bad option) don't forget to PVA again and be wary that a very thin skim of render onto a set background can be hard work if you have the quite coarse building sand we seem to get these days.

I have absolutely no skill, but manage to achieve near millimeter perfect results on some doggy old walls just using screeds and bays:


This one was over 40mm out from top to bottom, did the screeds one day and filled in the next in two coats:


I have a go at most trades, but plastering is the only one that requires any real skill, so if you haven't got it you need to cheat - easi-fill, sanding down, speed skim and plazi-flex etc. There's a few other things I'm going to look into for my next project (skimming half my house) - extratime plaster retarder, possibly a sponge float and it all goes really wrong - "roll on" plaster!!

Remember, it's always the finish that counts, not how you achieved it. Sometimes, professional techniques are just too difficult to master, however if you can do that snazzy thing where you can spread it going backwards and forwards with your trowel (as opposed to someone who can only smear it one way) you're onto a winner - apparently it's all in the wrist action!
I must agree, i have found it difficult to feather it in, hence i need some practice. One wall will be papered so good to practice on, and the other will be a complete skim. Your walls do look smoother than mine, looks like nicer sand. I don't think i'm 'too' bad at the skimming, but i am a bit inconsistent, ie some days it goes well, others less so. I also cannot do the 'snazzy thing where you can spread it going backwards and forwards with your trowel (as opposed to someone who can only smear it one way) ' at all, i'm in the just go on in one direction group for sure. I'm just trying to get a bit more practice, and i think i'll be acceptable. Do you think the speedskim/plazi make a difference, it was discussed further up the page, but i've heard 50/50, ie best thing ever, and dont bother, so i cant make up my mind!

Thanks for the pictures too! How long did it take you to do the walls? And, how thick is your render, i was obviously restricted to the previous depth, and it was ridiculous how thick it was
Yeah, I'm a bit hit and miss with the skimming - don't know whether it's different backgrounds, inconsistent technique or just a bad day. Tried once with a steel trowel and it was a complete mess so I paid a pro to do it, it was only after after paying 3 different "professionals" lots of money to do 3 different jobs and being less than impressed with the results that I decided to try again and had much more success with the plazi and speedskim.

I'm thinking of doing a short course; I don't really get the "timings" and think I'd do a lot better with some guidance on that and my general "technique" - but I just want to learn about skimming (and with my choice if tools) and the courses seem to want to teach you all the general stuff - prep, bonding, d&d etc which I'm ok with.

The second wall in the photos ranged from nothing at the top to nearly 50mm at the bottom - with some sticky PVA and a fresh mix you can really throw it on. I won't tell you how long it took me as it's embarrassing but I just put it down to being part of the learning experience!
Sounds exactly the same as me tbh. I skimmed our front room ceiling, over artex... my first ever ceiling job - not the best job to try as a first attempt really. It came out acceptable, but I thought for the main room (same artex ceiling) I'd get a pro in.... It was when he said he was impressed and wanted to know who did it, that i thought i wouldn't trust the pros to do it for a huge sum of money when i could do it ok myself, so i did it... not a huge ceiling 12sqm over artex, it was ok, not great but still better than what the previous owners of the house had done for them in another room...

i want to go on a course, Covid has scuppered things around here for a while though... I've also decided to do the whole wall now, not feather it in... I need the practice really!

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