Hi
I have an external wall that forms the boundary of the yard. It is in a ra= ther scruffy state and the pointing needs doing.
Ideally I=92d like to render and paint it, but if I render it, do I need to= do the pointing as well?
Also, presumably the render can=92t go below the damp proof course, so how = do you finish the area below there?
Many thanks
Se=E1n
You need bell beading to go along the bottom (dpc) which will form a dripper. Below this level, I normally paint with black bitumen paint. Don't render it while there's a chance of frost, or if there's frost still in the wall....you don't need to point it as the open joints will act as a key for the render, which will need doing in two coats
That's exactly what I needed to know thank you.
As frost pretty much rules out doing this for the foreseeable future, can you do the pointing when there is frost about?
do the pointing when there is frost about?
Looks up "you don't need to point it"
In fact the implication is you shouldn't, the render will hold on better if you don't.
Andy
do the pointing when there is frost about?
Pointing is not recommended while there is frost about for the same reasons you don't render when there's frost about. You don't do anything involving any cement based product when it's freezing unless it's an emergency, you know what you're doing and have the right additives sorted out, and even then it's accepted that it will be a temporary job, to be re-done when the temperature rises.
I suspected as much, arse :(
er... if the inside "core" of the wall is at -1 and the surface at say
+4 why would you have to wait until the core defrosts before rendering the surface?Jim K
Because the moisture frozen inside the wall has expanded, and when it thaws it shrinks....trying to render bricks that are still frozen on one side isn't a good idea
really? your "it" being moisture?
??? even though you would be rendering the unfrozen side?
Jim K
Yes, moisture, IE water - it expands, that is, it gets bigger when it freezes, then when it gets warmer, it thaws, that means it melts, which makes it smaller, kapeesh?
It's only 4 inches thick and the back part of it would still be frozen, which is why it's better to leave it untill the wall has completely defrosted
because...... IOW any theory in there?
Jim K
On the basis that freezing any cement products before they have fully cured is a bad idea, slapping render onto a wall which already has a core at -1 will, surely make it more likely than ever to freeze before achieving full cure? Especially as curing itself is slowed a lot by cold/freezing weather.
Maybe it would not be so important if you knew for sure that the curing period was going to coincide with a steady increase in temperature. But most of us don't.
That might not strictly be an answer to your question, but sure as hell, I wouldn't render anything in near-freezing conditions. With or without additives to prevent freezing.
well not if its warming up - no ;>)
comcrete slabs with hay/straw spread on them to retain heat also spring to mind - they can't retain "that" much heat but it appears to work enough to bother with?
weather forecast?
some variables in there need firming up - "curing period", "near freezing conditions"
Jim K
Because if the outside of the wal is +2 and the inside -1, it will only take a drop of a few degrees in air temperature to see the render fall off in lumps beause it's frozen bewfore it's set. Jezus, I can't believe you need this explaining
Don't render or point a wall if it's frosty or there's frost still in the wall - a 4 year old can comprehend this but not you, why is that?
Jim's being argumentative because in a different thread, he said he thinks that charging a customer for 2 bags of plaster @ £4 each is a rip off, wheras plasterers should charge them upwards of £200 for extra labour instead.
Really
A slab will be producing some heat due to the exothermic processes. The thinness of a render makes that ignorable.
I don't trust the weather forecast that much.
Several cement companies suggest not rendering when the environment is under 10 C.
Anyway, I said "I wouldn't ..." which would indeed be my choice. At least partly because I don't fancy freezing while doing it.
really??
ho ho ho tis the season!!
ISTR in said plastering thread you couldn't offer any rational reason for your "pro guide" of taking a flat smooth plasterboard wall, f**cking it up by slapping 1 coat of plaster on it "any old how" then slapping another coat on to "smooth it out again".....
where is the logic in that? apart from making more work for dodgy plasterers & halfwit billduhs?
Clearly you don;t know why- you just shout "its da way we always dun it guv" and appear unable to apply any logic to what you preach - same thing with the cold wall s*it - your "reasoning" is just regurgitated BS tripe as far as I can make out - were you appprentice "trained" perchance?
E.g. How TF would you know if the core of a wall is frozen?
Simples?
Jim K
??? I want you to explain it but you don;t seem able to - why is that?
If the wall surface is at +4 it's not frosty?
How would you tell if the middle of the wall is frozen ? ask your 4 year old - go on......
Jim K
Last time I had any significant plastering that was done by a friend at a very good price. He did two coats of board finish. He could easily have done one coat if he thought it better/the right approach.
Last night was a bit parky, better check the wall temperature with my IR thermometer.
He could do as many or as few coats as he wanted - could he explain why though?
remember to take your drill/big hammer to get to the "crucial" core temp tho......
Jim K
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