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Posted: Sun Jul 25, 2010 8:59 am
by michaelthegardener
Yesterday i went to one of my customers to cut her hedge last year i re layed a few slabs on her patio its terraced so there are renderd walls with the paveing on top i had to repair the render in places to where it had allready come off its now crumbled again ??? its stupidly thick though ??? 20mm ish could that be a problem ?
ive also got another customer with a very badly laid patio its on an angle infact and the retaining wall is going down hill :O its also made of london brick its "perrished" and she had some joker render it last year its now all come off i am right in telling her theres nothing you can do about it arnt i ?
unfortunately i forgot my camera on boath of these
Posted: Sun Jul 25, 2010 9:28 am
by seanandruby
michaelthegardener wrote:Yesterday i went to one of my customers to cut her hedge last year i re layed a few slabs on her patio its terraced so there are renderd walls with the paveing on top i had to repair the render in places to where it had allready come off its now crumbled again ??? its stupidly thick though ??? 20mm ish could that be a problem ?
ive also got another customer with a very badly laid patio its on an angle infact and the retaining wall is going down hill :O its also made of london brick its "perrished" and she had some joker render it last year its now all come off i am right in telling her theres nothing you can do about it arnt i ?
unfortunately i forgot my camera on boath of these
What material did you use and how many layers? Did you use a bonding agent in the mix?
Posted: Sun Jul 25, 2010 9:30 am
by seanandruby
Photos of the wall would help.
Posted: Sun Jul 25, 2010 2:11 pm
by michaelthegardener
yeah i know photos would help but i forgot my camera 
i also meant its 40mm ish thick i didnt use any bonding agent i just used the mortar i was laying the slabs with about 3 layres its not a massive bit thats fallen off just the corner as such but some of the other stuff i didnt do is also starting to crack up now
Posted: Mon Jul 26, 2010 1:30 pm
by GB_Groundworks
if your rendering that thick you render in layers and scratch coat it as you go till the final layer, you want plastering sand really and i'd add some additives to aid adhesion, make sure the wall being rendered is rubbed up to give a key and remove and flakey bits etc.
Posted: Mon Jul 26, 2010 6:08 pm
by local patios and driveway
micheal, you are in the trade now so although i hate to say it as i sound rude, you cant go round doing work incorrectly. it makes you a cowboy. you shouldnt attempt to do repairs as a profesional without knowing how things are done. google is your friend and you can look up pretty much anything, how things are done and why they are done the way they are, this will build your knowledge no end and make you a far better tradesman. although that said the internet can be full of people giving advice who dont have a clue. telling off over, at least you are here now trying to learn the correct way to do things
Posted: Mon Jul 26, 2010 8:20 pm
by GB_Groundworks
this site is an excellent reference for most things you'll come across, if not just ask here no question is to silly.
Posted: Mon Jul 26, 2010 8:35 pm
by michaelthegardener
Ok so what should i have done ? 
its not a massive bit anyway about the size of a fiver but going round the corner if you get what i mean everything else is ok though the slabs and the other little render repairs
Posted: Mon Jul 26, 2010 9:35 pm
by local patios and driveway
for me i would chip out any loose render, if you are aiming to do the job properly for your customer, and your reputation locally is based on these kinds of considerations, make sure you go as far as you need to go until the exsisting render is solid. knock up a 5-1 mix of rendering sand with a pva mixed in with the water (you dont need loads but it will help the bond and make the render smoother to work with, aim for maybe 5-10 capfuls of pva in a 3/4 full bucket of water), also paint the bare wall with the mix of water and pva before starting the scratch coat. the wetter the better as it stops the render drying out too fast and shrinking as it dries. add a thin coat and after 25-120 mins score it diagonally left and right, this is the key for your final coat. come back the next day and pva the scratch coat and finish the render, there are many ways to finish the final coat depending on the finish you have to match but for me i prefer a damp sponge, get the finish smooth and close to perfect as you can with the trowel, and im not here to tell anyone how to suck eggs but work from the bottom up as you apply the render, run it over the render about 20 mins after its been finished in circlular motions and it will get a build up of wet render you can then use this to fill any imperfections and blend in to whats already exsisting to get a flawless joint. (you can also use the sponge technique on plastering but thats a whole nother kettle of fish)
good luck
Dan
Posted: Mon Jul 26, 2010 10:15 pm
by michaelthegardener
Well i said to her about it and shes fine with it as it is :rock: but it anoys me its only a little bit thats come off mind the rest is solid enough i think ill offer to re do it next time she calls me
thanks for that info rendering isnt something i really want to be doing to be honest just it had to be done to finish the job off
Posted: Mon Jul 26, 2010 11:13 pm
by lutonlagerlout
for PVA read SBR
I used PVA for years with no problems but I am reliably informed SBR is the way forwards for outdoors
LLL
Posted: Tue Jul 27, 2010 3:02 pm
by local patios and driveway
my bad, i didnt know pva had issues with frost, we all got lots to learn right?
Posted: Tue Jul 27, 2010 5:09 pm
by lutonlagerlout
well being darn sarf same as your self local,we probably dont get the real hard winters they do oop north
where small children freeze into blocks of ice for months at a time,and you need a blow torch to thaw the head on your tetleys :;):
I never had any comebacks with PVA but SBR seems even stickier
and so it should be at more than double the cost!
LLL
PS and even better still for those with deep pockets is ronafix
Posted: Tue Jul 27, 2010 5:56 pm
by mickg
I personally have never had any come backs with PVA either and lets not forget PVA has been available for over 30 years that I can remember, why was it OK to use it then but now its the witches curse if you use it externally
but if the way forward is using SBR then so be it ???
Posted: Tue Jul 27, 2010 6:02 pm
by simeonronacrete
PVA and water don't go together; the PVA breaks down, and what was once stuck is now unstuck.
Use Ronafix SBR instead.
Ronafix and its uses