Good system for Rock face block

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theblones

Active Member
What system would be 100% bombproof for application over rock face blocks. The problem is the rock face blocks are part of a massive retaining wall and they are slowly crumbling away. I suspect the water and frost is making them crumble. The owner has tried to repair it with cement last year and paint it and it has gone again. The work he did last year has fallen back out.

Would a render only system with mesh be the answer what could happen if these bits of block continued to crumble. They may crumble away but would not be able to drop anywhere because they would be sandwiched in.

Or
Fix timber to the wall and Calcium board it and render
or
Even insulation with fixings

advice please
 

flynnyman

Well-Known Member
Unless you can dig a foot back in behind the wall and build another wall or build a wall in front of it it might always happen but if no choice, the good news is, eml overlapped by around half or over kill and double up, then a sand and cement maybe 3 coats and the bad news is you wont be able to use your machine :RpS_tongue:
 

theblones

Active Member
i could use CPI Flinn and that goes through a machine. Ha

Any other ideas EML is an option but i don't fancy putting it up.
 

henry

Private Member
feck me mate it sounds like one of those jobs you tend to back away from. There is a housing estate in doncaster with them .I was on refurb work we used sika 2 pack render on the walls internal walls , they were damp and crumbling. I have to say it was good gear. I would go down the tanking solution
k11 sbr slurry that will seal your wall there is also a sealing liquid which will form a water impervious bond . Also you can also use dramex lath 2500mm x700mm sheets. Its all down to cost as always.
 

Render Systems

Private Member
dunno how concrete blocks are crumbling or is it just the mortar? is so sika would sort it out with sand cement mortar as its impervious and sets even when water is seeping through or you could use a nhl 5 lime mortar.. that sets like s**t and is used in bridge repairs over rivers and on harbour walls...
 

henry

Private Member
What about limelite canal grout is that of any help. It sounds like your trying to cover this wall over but the blocks are f--- how can you make it bombproof.
 

CKJ

Member
Did a wall that was 200yrs old 50m2 and all the bricks were frost blown, soft and crumbling. All the mortar had fell out, we did a scratch coat with rendaid and mesh then went over with weber pral. This was an existing listed wall on a new estate and the architect was happy with the spec.
 

Chris W

Well-Known Member
by the sounds of it the problem is hydrostatic pressure...
1 foot head of water will lift a 4" slab of concrete right out the ground so whatever you stick on the front is gonna need to be completely impermeable and stuck like the proverbial...
or remove the pressure problem completely, membrane the front... (im assuming this wall is so massive that digging out the back and using a drainage membrane isnt paractical)..
never tried it but whats to say you cant use the internal membrane same way you'd waterproof a basement with a high water table? membrane, alco channel, soakaway, should be end of problem?
i saw henry mentio dramex... im guessing its something similar? stuff im on about is platon, some call it newton? theres 2 types that i know of, one goes externally, allows the water to drain down away from the building whilst holding the soil back...
the other works in reverse, allows you to plaster the front whilst draining the water behind...
freeze thaw process always gonna cause problems if your correct (which i suspect you are), basement tanking doesnt suffer from it so it doesnt blow the tanking off the face, but if you got water directly behind any form of cementious tanking and it freezes, its coming off...
hence the at membrane... remove the problem... then you can put what you want over the top...
 

Chris W

Well-Known Member
but all that said, in winter, the first thing thats gonna freeze is gonna be the outside face, so what youll end up with is a build up of ice behind the membrane which will eventually bulge out and f'ck up whatever you stick on it so you'll have to insulate the face first...
so membrane followed by eps followed by thincoat should do it..
 
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