Tanking Bay Window

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herds

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Hi Guys,

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Around 2 months ago I removed the render all around the bay window because it was damp, in some areas the plaster would come off in my hands. I've heard that victorian places are notorious for this kind of damp and tanking is the way to fix.

I've done some reading about tanking and spoke to a friend of my dads thats an old school builder. He said this:

Clean the debris off the bricks
scratch bricks and add a thin layer of Sand and Cement
Apply tanking slurry with brush, he recommend one for about £25 a bag you get in local (KA Tanking Slurry ?)
Sand and cement again to bring up to level...
...ready to skim

Does this seem about right?
I've not used Sand and Cement before, just bonding. He didn't really know about bonding so ideally i'd rather use that if possible.



From KA's technical doc:
---
Q: Can KA Tanking Slurry be plastered over or can I only use a sand/cement render?

A: Remedial plaster systems may be used over KA Tanking Slurry, provided that an intermediate bonding compound is employed. Dilute SBR latex with an equal volume of water. Then apply to the cured Tanking Slurry and allow to become tacky but not dry. Plaster may then be applied as normal. Where cement rendering is required, use an intermediate bonding slurry mixed as two parts sand: one part cement gauged with a 1:1 SBR : water mix. Apply the slurry to the tanking and apply the first render coat before the slurry dries.

I don't really get what they're saying:

"intermediate bonding compound".. is that like undercoat plaster?

Would I require cement rendering?




Thanks in advance guys.
 
I will almost guarantee that it is a single-skin wall and the damp was nothing more than condensation. Line it with thermal plasterboards mate :RpS_thumbup:
 
Fatarm said:
Can you not put a damp membrane on it then replaster?
Click to expand...

Maybe, i'm a bit green to this. This is the first time i've had to tank something.

I've happy to pay for whatever materials are needed to do the best job so open to ideas.
 
Only need to tank if you have high ground levels , the cavity may be blocked ,take a brick out and have a look . If the outside is rendered ,make sure it has a bell bead ,and not bridging the DPC , hope that helps ,best of luck
 
keithuk said:
Only need to tank if you have high ground levels , the cavity may be blocked ,take a brick out and have a look . If the outside is rendered ,make sure it has a bell bead ,and not bridging the DPC , hope that helps ,best of luck
Click to expand...


No render on the outside

08092012042.jpg






Fatarm said:
DAMP PROOF MEMBRANE FOR DAMP PROOFING WALLS - BUY NOW | Newton
Hope that link works mate...
Its piss easy to install,you can dab boards to it or replaster

..
Hammer-white-plug_zps5f64a3aa.jpg

what's caused the damp??
Click to expand...


hmm interesting, i'll have to research this, what are the benefits to a membrane like this vs slurry?

The guttering on the house is shot to bits so water runs down hte side of the house, the pointing isn't great either and the house is generally neglected.


Artisan998 said:
out if interest are the floor joists rotting in the bay??
Click to expand...

The skirt was rotting in places. From memory the floor was bowing in the bay, i opened it up (as it is now) and found that the supports on the side holding the joists were not fixed right or just not fixed at all
 
I would be inclined to sort out the external problems first and like keith said, check the cavity isnt blocked and remove anything that might be bridging externally
 
doesnt need tanking use dri coat or washed sand cement water proofer as a backing plaster and tell them to get the windows changed looks like condensation to me
 
Fix the gutter, clean them cills and paint or ideally remove but sash windows are expensive, Spray some suitable acid to stop the salts, SBR then sand and cement with a waterproofer then skim.
 
After seeing your outside pics and the info bout gutter and pointin, it's not a tankin job, as said above sort the outside, make it watertight. Replaster with dri-coat or limelite,if your not keen on s&c?..... Oh and get the rubbish shifted:rolleyes) tut tut tut.
 
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hahah. When I bought the place that is what the previous occupiers left behind! as well as a whole house full of junk, luckily I found and then pawned a silver locket for a couple hundred so that soften the blow somewhat

Thanks for all the replies guys, really appreciated. I get the impression there is many ways to skin a cat. Everyone seems to agree that sorting the external issues first should be the priority. I'm going to phone the double glazing man today and get him in to replace this triple bay window he quoted the whole house for 3k (including 2 triple bays) so hoping I can get this window done for under 1k. I also have a mate that is a roofer that is going to give me some free scaf to use, been waiting about 3 months buy hey, free is free.

The main reason I was a bit apprehensive of S&C is that it might stain my lovely MT trowel :D actually I've never used S&C, only the premixed stuff from b and q (which I think is mortar).
 
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A quick little question as google hasn't helped me find a definitive answer:

Salt netraliser - Water that has penentraed the brick contains salt? and salt is bad because...?
SBR - this is like PVA however used externally or when sealing brick prior to applying render like S&C, dri-line or limelite



...thanks in advance
 
The salts just keep comin to the surface. Salt inhibitor stops the salts if your useing s&c., Dri coat or limlite have additives in them to prevent that comin thru to the surface. Sbr Is waterproof,pva ain't.
 
Great stuff, cheers again.

I've worked out material costs to be under £80. How is it damp companies charge the earth? because of all the making good and finished afterwards perhaps (?)
 
herds said:
Great stuff, cheers again.

I've worked out material costs to be under £80. How is it damp companies charge the earth? because of all the making good and finished afterwards perhaps (?)
Click to expand...

and they know what they are doing..........................:RpS_wink:
 
Tanking is three coat work ,first coat applied as a slurry usually mixed at one sand to one cement,sika added to water at ratio,10 to 1, second coat mixed at three to one sand /cement sika to water still ten to one, this coat is then scudded with a slurry at 3.5 to one with clean water, next day add a 4 to 1 coat with sika at 10 to 1 , float up smooth, keep dampening wall for seven days before skimming,sbr before you skim.. Damp proofing is two coat work which is what you need, Clean wall of dust and loose plaster, apply a render mix at 4 to one s/c with sika at 10 to 0ne then a second coat at 5 to 1 with sika at 10 to one water ratio. Float up leaving render lightly scratched, skim after 4/5 days,.. The slurry option that you first suggested is also good, there are many types, I use vandex.. Good photos, fix all the problems outside firstly, bad sign to see weeds growing in the wall. Have you considered a chemical injection for rising damp, ensure that your floor is ventilated,, good luck
 
Got eacatly the same situation in one of my rentals which tenant has raised. Salts showing through so going around tommorrow to hack of to bric under bay window. I need a quick fix to minimise tenant upheaval then look at the siatuation in a year or so when the property is void next. I was thinking hack off, membrane then foil lined boards then skim as quick fix? Do i need to let bricks dry out if im going to fit membrane???? What are the plugs called?
 
Hi Windy, google 'newton membranes' all info should be there. a quick fix would be to fit treated battens to the wall as is and fit foil back scrim to same..Membrane can go over the plaster and or the bricks..
 
windy said:
Got eacatly the same situation in one of my rentals which tenant has raised. Salts showing through so going around tommorrow to hack of to bric under bay window. I need a quick fix to minimise tenant upheaval then look at the siatuation in a year or so when the property is void next. I was thinking hack off, membrane then foil lined boards then skim as quick fix? Do i need to let bricks dry out if im going to fit membrane???? What are the plugs called?
Click to expand...

800 Mesh Plugs - Kingfisher Membrane Fixing Plug
 
windy said:
Got eacatly the same situation in one of my rentals which tenant has raised. Salts showing through so going around tommorrow to hack of to bric under bay window. I need a quick fix to minimise tenant upheaval then look at the siatuation in a year or so when the property is void next. I was thinking hack off, membrane then foil lined boards then skim as quick fix? Do i need to let bricks dry out if im going to fit membrane???? What are the plugs called?
Click to expand...

You can put membrane on without letting the wall dri out, make sure you extend the membrane 300 mm beyond damp area, membrane fixin plugs, mushroom plugs, cob plugs, depends who's system your using really, you can get plugs with holes in the middle that can take a screw, so you can fit membrane then screw battens into the plugs, then board and skim. You can dab onto the membrane or plaster onto it. Various options with using membrane:RpS_thumbup:.......
....
Feck sake listen to me!!! You would think I was sellin the stuff:RpS_laugh:
 
johniosaif said:
Tanking is three coat work ,first coat applied as a slurry usually mixed at one sand to one cement,sika added to water at ratio,10 to 1, second coat mixed at three to one sand /cement sika to water still ten to one, this coat is then scudded with a slurry at 3.5 to one with clean water, next day add a 4 to 1 coat with sika at 10 to 1 , float up smooth, keep dampening wall for seven days before skimming,sbr before you skim.. Damp proofing is two coat work which is what you need, Clean wall of dust and loose plaster, apply a render mix at 4 to one s/c with sika at 10 to 0ne then a second coat at 5 to 1 with sika at 10 to one water ratio. Float up leaving render lightly scratched, skim after 4/5 days,.. The slurry option that you first suggested is also good, there are many types, I use vandex.. Good photos, fix all the problems outside firstly, bad sign to see weeds growing in the wall. Have you considered a chemical injection for rising damp, ensure that your floor is ventilated,, good luck
Click to expand...

It was all goin good till you started the bullsit :)
 
Love learning about this stuff, haha.

Would I need a concrete mixer for S&C? or can I just mix it in a yellow bucket like i do for multi and bonding?

Looks like the window fitting is a month away... should I wait till the new window is in before cracking on or?
 
Fatarm said:
You can put membrane on without letting the wall dri out, make sure you extend the membrane 300 mm beyond damp area, membrane fixin plugs, mushroom plugs, cob plugs, depends who's system your using really, you can get plugs with holes in the middle that can take a screw, so you can fit membrane then screw battens into the plugs, then board and skim. You can dab onto the membrane or plaster onto it. Various options with using membrane:RpS_thumbup:.......
....
Feck sake listen to me!!! You would think I was sellin the stuff:RpS_laugh:
Click to expand...


If I was to go to the membrane route, I would need:

Membranes Products - Basement waterproofing, Damp proofing, Basement Tanking, plaster membranes, brick plugs & waterproofing Membranes

[h=3]803 Membrane (clear & mesh) * 1 @ Clear 1m x 10m - £72.46 +VAT[/h]800 Mesh Plugs * 1 @ 7mm x 50mm (250) - £42.00 +VA


Anything else? currently the above works out around £160 with postage.

After reevaluating that I I need a damp course and not tanking would the above be a tad excessive when compared to the S&C route?

Thanks
 
You still need to plaster on top of those products so your costs aren't finished yet. Why dont you just get someone local to come and give u some advice rather than guessing whats causing the damp and they can give u the correct and most cost effective solution
 
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