render a concrete ceiling

[dmacca3]

i have a concrete ceiling in my outhouse i wanted to know if it is possible to render it as it is in a poor state so that i can plaster it later. thanks

 

[JMLanders]

Would it not be easier to build a suspended ceiling?

 

[dmacca3]

i forgot to mention that it is letting water in, would bitumen work

 

[1john]

where is the water entering from, you need to stop it getting in, not keep it up there see. Trapped water will cause more damage and it always finds a way out too.

 

[dmacca3]

it has spread from next doors outhouse both are joined they have had a leak and it has started to come through to mine

 

[Micilin]

it has spread from next doors outhouse both are joined they have had a leak and it has started to come through to mine

As said , try to divert the water first . This is by far the best solution, and really the way to go if possible.

When you say poor state, will it take a render?


If not possible, you can render the ceiling and walls to keep the water out -'Tanking' with waterproof sand and cement. If the ceiling is very wet, it takes a bit of practice, tanking it while hoses keep the water diverted, then removing the hoses and plugging the hole with a rapid set waterproof additive - you can then give it the next tanking coats but better to rub up and not skim .

If it is not too wet ie you can coat it - scud (spritz etc ) , coat, scud, coat will do it, with all internals coved.

You could blackjack , blind it with sharp sand and then render

 

[dmacca3]

what do you mean when you say blind it with sharp sand

 

[roughcaster]

what do you mean when you say blind it with sharp sand

Brush on the Blackjack Bitumin paint, then blind/throw sharp sand onto it while the bitumin is still wet. The sharp sand will then stick to it. When the bitumin/sand has dried, that will give you a "key/rough surface" to scratch coat/render onto. Make sure you "blind it" evenly overall,,, plus,,the more sand that sticks to the bitumin, the rougher/stronger the key!!

 

[Richard C]

Is that the right way to go soundS a bit like trying to stop the Titanic sinking from below decks

 

[roughcaster]

Good point Rich',,, any cement render related work would be "after" the problem with the water ingress was fixed

 

[roy c]

Is that the right way to go soundS a bit like trying to stop the Titanic sinking from below decks

Believe or not Rich. We used to do that quite a lot in the early 80's when I was doing damp-proofing and preservation work. We used to use "syntapruf" which I think is now called "black-jack,(I think there is a post where we discussed this before).I think it was alistairreid who was into the preservation game aswell.

 

[Richard C]

We used to use "synthapruf"

Still got 1/2 tin of that in me garage

 

[roughcaster]

We used to use "synthapruf"

Still got 1/2 tin of that in me garage

It'll be "flat" by now,,, all the gas will be out of it!!!!

 

[Micilin]

Good point Rich',,, any cement render related work would be "after" the problem with the water ingress was fixed

Definitely , you've got to try and divert the water first -I maybe wasn't clear enough in my post above.

 

[dmacca3]

when i have blinded it evenly and has dried is it ready to render