Plastering Questions

Just to be sure Inside of the garage ?

 

C'mon, Sos - he ain't that much of an amateur...

Sean, is your garage single skin or cavity wall?

 

If it was my garage I would render and set it.

 

So what are you deciding to attempt on?

Are you dot dabbing skimming? Or just dry wall compounding. Rendering?

All I have to say is thing are about to get messy lol.

Why not give it a go! That is really how I learnt but I got so frustrated I then tried a night course.

And after many attempts I attempted my living room small wall then I started to pick it up. But I would be lying if I said it was easy as taken years to pick up. Can be very frustrating.

A tip is to use a quality worn in trowel as it doesn't leave lines. Always two coats! Good luck

 

It would be more beneficial and easier if you were to dot and dab it first. At least you will (or should have a clean flat lump free surface). And won't break the bank at say £5-7 per sheet of plasterboard and £5 per bag of dry wall adhesive.

 

Dot and dab is an bottom to fix to though.

 

After 30 years or so, I've been converted to using Refina Plaziflex Plastic Finishing Trowel, no need to wear the trowel in.
I find laying on & polishing is easier using the plazifles compare to a metal towel, & I can work quicker with it.
Did two artex ceilings last year, much easier on the arms & the old back.

http://www.refina.co.uk/plaziflex-trowels.php

 

Not

We can deal with that in his next post.

 

I would try cement render first, the lifetime of the mix is a lot longer than plaster based mixes and will give you a harder finish for the garage. For the top coat rather than put finish plaster a rough floated finish is quite easy to master.

 

There is quite a bit of difference mainly when you are starting off and by yourself.

With plaster it is going to be mix a tub up, get it on the wall, smooth it out, mix up another tub, get it on the wall mean while the first batch will be starting to go off. Plus even with an electric mixer (don't try by hand) it is really hard work.

With cement render you can mix up your whole amount on a spot board, get it on the wall, then smooth it out. Plus the first (scratch) coat is fairly thin, so easier to get on. The cement render is much more forgiving in time and skills.

Unless the walls are dirty or painted I would just wet the walls and put the mix straight on without the PVA.

The technique is to get the gear on the wall with a trowel and then smooth off the lumps and bumps with a Darby or straight edge. The top coat of render is finished with a wood or plastic float and then a sponge float. Plaster is finished and then polished with a trowel.

The speedskim tool i have only seen used on plaster top coats and synthetic coatings but this only used when the surface is really, really flat which will be difficult to achieve when starting out.

I will do the base coats but always leave the plaster top coat to the guys who do this everyday.

 

With the render top coat, if you rub a sponge over the top you get a nice smooth finish although not soft to the touch like polished plaster. The finish is good enough for a garage and takes paint well

It is quite common down here to have a scratch coat of cement render, then a top of cement render and then to get a smooth finish a thin coat of finishing plaster.

With plaster and cement you will have to wait 24 hours between coats

Ordinary cement will do but its best to put some plasticiser to make the mix more pliable.

You will need to get a good quality "worn" trowel and a metal hawk and I would get a 1.8m Darby / Feather edge. Silverline do a reasonable quality one for the money - I wouldn't go for a plasterers version you won't get the use out of it

 

Aren't breeze blocks - Thermalite - very porous & absorbent? If you splash/brush water on it, does it soak it up very quickly?

In which case you may struggle to get it evenly wet using chust water - and there's now't worse than plastering/rendering a wall with uneven levels of suction; some parts will be pliable and others almost powdery when you try and work it.

It all depends on how absorbent the surface is. Try a splash and see. Then try a second splash on the same spot. repeat...

My first plastering attempt - a real baptism of fire - was doing every wall and ceiling in a 4-storey Victorian terrace in London. Most was chust a skim on new p'boards, but all the downstairs walls were brick and the existing plaster could be removed with a shovel.

The mortar was in poor condition as well, and the central supporting wall - just one brick thick - had a frightening bow in it...

So on these surfaces I decided to cement render first, and then skim over. What I did was to get 15mmx10mm timber strips (chust your regular PAR mouldings) and tack then vertically to the bricks around - ooh, trying to remember - 5 feet apart? On the bowed walls, they needed some serious packing out - in the middle on one side, and at the top and bottoms on t'other!

Then I tested the bricks with a hose. I couldn't believe how much it soaked up - I was playing the hose over them for minutes and the water just disappeared...

Mixed up my render, applied it with a normal trowel, and used a straight edge (probably a 3x2) to level it all offski. Then on to the next section. Once that second section was finished, I pulled off the bead that was between them; this took the edges of the render off with it, but this was not a prob - I trowelled a line of mortar in to the gap using each rendered side to level it off. This was done before any of the mortar had fully set so's it would all bond together, but was stable enough to be firm.

Once fully set and dry, I then simply plaster skimmed over the top (after making sure there were no sticky-out or loose bits of render).

You could do similar on here Sean, and the depth beadings should be nicely flat or your walls anyway. IF your blocks soak up water a lot and you aren't sure you can get it evenly wet, then a PVA priming might well make sense.

The 'sponging' mentioned above is good fun. The render has to be nicely firm - not set, but will only 'dent' if you press firmly into it. Then you use a damp firm sponge in a circular motion, lightly applied flat to the surface. It should leave a flat gritty finish which is often what's used on rendered building surfaces, walls etc.

To be honest, if you are going to skim this, then I wouldn't sponge it - just get it level using a straight edge and bob's yer whatsit.

When using a straight edge, you will hopefully find that simply dragging a crisp edge upwards on the render will skim off any high areas leaving behind a nice finish - IF the render has partially dried first. If the render is still 'sloppy', then it'll just drag and possibly slump. You can also try - if it ain't quite ready for levelling (if some bits are nicely 'dry' but patches are still a bit sloppy) - shuffling the straight edge sideways back and forth in a sawing motion as you slowly move it upwards. But see if you can finish with chust a straight 'dragging' motion.

 

Totally different beastie.

Breeze block is concrete,but some refer to a breeze block as a clinker block, because some were made furnace s lag.( It's a prohited word).
Thermalite block is pulverised fuel ash (PFA) about 80%, waste from coal power stations.

Some reading matter:

http://forterra.co.uk/plugins/downloads/files/thermalite_technical_manual_2015.pdf

 

Oops - a 'breeze' block is just a 'block'?

Ah...

Even easier, then...


Sean, if you think there is any chance you'll want to cosy up that garage - ie fit a heater - then you'd be best going insulated board adhered to the blocks.

That'll also give you a perfect surface to practice your skimming on.