Damp in victorian property

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Smar

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In a victorian terrace house, I've had a chemical dpc to treat rising damp and the plaster has been chipped off to 1.2m. Which is the best type of plaster to use- i've been advised that a breathable renderlite would be best (old brick with lime picking & sandstone construction). Is the renderlite much different to the original lime plaster?
 
I think but not 100% sure that the British Gypsum equivalent is the dry coat might even be produced by them. But follow spec if required, or you could use a thermal board
 
spreadeasy said:
I think but not 100% sure that the British Gypsum equivalent is the dry coat might even be produced by them. But follow spec if required, or you could use a thermal board
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Dry coat is a cheaper version and is not really good for real damp , it is useless for salts, I loved it but suffered watching it dry. Love it for patching etc..
 
Damp proof in company said sand & cement with water proofing & salt retardant. Not much confidence in them though, as it turns out that the there was a cracked water pipe under the floor and that was the cause of the damp; they didn't spot it- just wanted to drill holes.

I've heard a few people say that I should stick to breathable plasters instead of sand & cement.
 
Been an old fool, I still use sand and cement with sika 1 ,done properly its perfect but hese new products are handy although expensive at nearly £30 for 25kg
 
You should use Lime and maintain the breathability of the building. Injections DPMs are a waste of money. As you said yourself they should have spotted the cause of the damp and cured it. Not just charge you to drill holes and inject. All Damproofing is a waste of time unless you resolve the initial cause of damp. Renderlite could be used but isn't really any more breathable than S&C. If there is damp still in the wall you want leave it to dry out as long as you can. Maybe run a dehumidifier in the middle of the room to help draw some moisture out. Then I'd use an NHL ideally 2 but 3.5 is fine if not, mixed with a washed sharp sand. This will give you a set to the mix and you won't be waiting weeks for it to catch up. If not you can buy dry mixes. I think St Astier do one, pretty sure it's called R50 Eco mortar but if you check out there website they have plenty of info and also should be able to track down localish stockist to you.
 
Same as John ,always used s/c ,still sub for a company, that does it that way ,they have been in the game for over 30 years
 
How does the cost of lime compare to renderlite. Will the lime hold back any salts in the brickwork and mortar?
 
bodders13 said:
You should use Lime and maintain the breathability of the building. Injections DPMs are a waste of money. As you said yourself they should have spotted the cause of the damp and cured it. Not just charge you to drill holes and inject. All Damproofing is a waste of time unless you resolve the initial cause of damp. Renderlite could be used but isn't really any more breathable than S&C. If there is damp still in the wall you want leave it to dry out as long as you can. Maybe run a dehumidifier in the middle of the room to help draw some moisture out. Then I'd use an NHL ideally 2 but 3.5 is fine if not, mixed with a washed sharp sand. This will give you a set to the mix and you won't be waiting weeks for it to catch up. If not you can buy dry mixes. I think St Astier do one, pretty sure it's called R50 Eco mortar but if you check out there website they have plenty of info and also should be able to track down localish stockist to you.
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Hi boddders, for this process,
do you do it in two passes,waiting time, one week ? Finish with ?
 
Smar said:
How does the cost of lime compare to renderlite. Will the lime hold back any salts in the brickwork and mortar?
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In short no. The render lite should contain salt inhibitors and water proofers to hold back any remaining damp while the wall drys out and any salts left after the wall has dried out.

I am with john, sand and cement render with an additive. We use this one


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johniosaif said:
Hand , old school fool
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What's the background? Brick, stone?

If using NHL- Normally I like to do a Harling or stipple coat first just to even up the suction and give a good key to the wall.

Allow 2/3 days then apply scratch.

Leave until it's hard enough you can't leave a thumb indent but still soft enough you can mark with your finger nail. Then apply float coat.

Wait until the same with finger indent and finally skim with Lime skim. If making your own 1:2 NHL to Kiln Dried sand.

Keep damping the walls and render down throughout the whole process making sure it doesn't dry out too quickly.
 
carlos said:
In short no. The render lite should contain salt inhibitors and water proofers to hold back any remaining damp while the wall drys out and any salts left after the wall has dried out.

I am with john, sand and cement render with an additive. We use this one


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Seems a great price compared to sika...
 
I use the sovereign system, I always use washed sand and plain cement with either sbr or render mix then multi finish, if you've cured the cause you won't have any problems
 
Smar said:
In a victorian terrace house, I've had a chemical dpc to treat rising damp and the plaster has been chipped off to 1.2m. Which is the best type of plaster to use- i've been advised that a breathable renderlite would be best (old brick with lime picking & sandstone construction). Is the renderlite much different to the original lime plaster?
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Renderlite is a renovating plaster which will probably be an equivilant to 6/1/1 sand/cement/lime. as bodders has stated about replaceing the original lime plaster with lime plaster would be better...........However, regarding the injection i find its normally bridging of the DPC which causes "Rising Damp" like symptoms and its usually the cavity is full of shite. Why isnt whoever did the injection not doing the plastering ??
 
Smar said:
How does the cost of lime compare to renderlite. Will the lime hold back any salts in the brickwork and mortar?
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you find there's is very little salt if any in 1908 mortar
They would wash it before it's the crap sand today where the salt comes from
 
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