Rendering retaining walls

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johniosaif

johniosaif

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We are doing a job in north London,large retaining walls built from cavity blocks filled with poured concrete and strengthened with re bar horizontally and vertically, as is Normal some of is under the water table and hydrostatic pressure is evident by damp areas and seeping water on on section, we got a basic spec ,use sika 1 and 18mm thickness of plaster, I asked for but got no more detail,

as the block work is smooth we scudded using Harling trowels giving an sbr splatter grip on the face,we have scratched with 4/1 and sika at 10/1 in the mix, I floated in the scratch and splatter coated it at 4/1 without sika for a grip for the second coat,
the area with seeping water is problematic, I am thinking of getting sika 4a applying a coat of neat cement as a barrier before rendering,

any thoughts guys?
 
Olican said:
Would vandex be an option John?
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Or k11 ,the usual builder and architects heads in the sand scenario,I might just go sik 4 neat cement,why can't the spec it, the young architect said he spoke to sika and the said sika 1 is perfect for the job,ps for the floating coat sika1 is hardto finish properly ..
 
If the water seepage is pushing through your render you need to drill a couple of drain hole to reduce the pressure until it cures.

After you have the render is done you need to plug the drain holes. Then patch the render up.

Hope that made sense.
 
carlos said:
If the water seepage is pushing through your render you need to drill a couple of drain hole to reduce the pressure until it cures.

After you have the render is done you need to plug the drain holes. Then patch the render up.

Hope that made sense.
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Yes it does, but the problem area is the section that meets the garden ,the next door garden is four foot higher so we must be under the water table, quite a decent dribble of water through some blocks and at the end of the wall.
 
why was the block work wall not tanked on the other side to prevent the water from seeping through?
 
malc said:
why was the block work wall not tanked on the other side to prevent the water from seeping through?
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Why indeed,? Because I expect ,no one thought to do it, no one was asked nor was it specced, the only spec is sika 1 in 18 mm of render
One wall is going to have planters and now they say weep holes,this is not the worst wall, I have rendered this ,floated and scudded to seal as best I could,

the other was has near running water..
 
johniosaif said:
Why indeed,? Because I expect ,no one thought to do it, no one was asked nor was it specced, the only spec is sika 1 in 18 mm of render
One wall is going to have planters and now they say weep holes,this is not the worst wall, I have rendered this ,floated and scudded to seal as best I could,

the other was has near running water..
Click to expand...

i think that you are being asked to perform an impossible task. the wall has not been built correctly therefore leave well alone!
 
I'd have thought if there's that much water coming through no matter what you put on the face of the wall the first hard frost will ruin it. Saturated blocks are always bad news, add concrete and steel and it'll all be knackered before long, but my money's on the render blowing first.

Sounds like one to make sure your misgivings are on the invoice or in your T&Cs.
 
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